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- Front Matter: Volume 7010
- Herschel-Planck
- AKARI
- SPICA-WISE
- JWST Overview
- JWST: OTE Verification
- JWST: Instruments
- Planetary Missions
- JDEM
- Hubble
- Coronography
- TPF Concepts
- New Worlds Observer
- Mission Concepts I
- Mission Concepts II
- Interferometry from Space II: Joint Session with Conference 7013
- Technologies: Active Optics
- Technologies: Structures and Materials
- Technologies: Instruments
- Poster Session: Herschel-Planck
- Poster Session: AKARI-SPITZER
- Poster Session: SPICA-WISE
- Poster Session: JWST
- Poster Session: JDEM
- Poster Session: Cornography
- Poster Session: TPF
- Poster Session: Mission Concepts
- Poster Session: Active Optics Technologies
- Poster Session: Instruments Technologies
- Poster Session: Hubble
- Additional Paper
Front Matter: Volume 7010
Front Matter: Volume 7010
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This PDF file contains the front matter associated with SPIE
Proceedings Volume 7010, including the Title Page, Copyright
information, Table of Contents, Introduction (if any), and the
Conference Committee listing.
Herschel-Planck
Herschel mission overview and key programmes
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Herschel is the next astronomy mission in the European Space Agency (ESA) science programme. It is currently in
the final stages of assembly and verification in ESA's ESTEC facility in Noordwijk, and is scheduled to be flown to
the launch site at Europe's Spaceport in Kourou later this year. Herschel will carry a 3.5 metre diameter passively
cooled Cassegrain telescope which is the largest of its kind and utilises novel silicon carbide technology. The
science payload comprises three instruments: two direct detection cameras/medium resolution spectrometers,
PACS and SPIRE, and a very high resolution heterodyne spectrometer, HIFI. The focal plane units are housed
inside a superfluid helium cryostat based on ISO legacy. Herschel will be launched by an Ariane 5 ECA together
with the Planck satellite into a transfer trajectory towards the operational orbit around L2. When operational
Herschel will provide unprecedented observational opportunities in the 55-672 μm spectral range, much of which
has never before been accessible from a space observatory. It is an observatory facility available to the worldwide
astronomical community, nominally almost 20,000 hours will be available for astronomy, 32% is guaranteed time
and the remainder is open to the general astronomical community through a standard competitive proposal
procedure. The initial Key Programme Announcement of Opportunity (AO) was issued in Feb 2007. Both
the guaranteed and open time Key Programmes have been selected and are introduced, and future observing
opportunities are outlined.
The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI): instrument and pre-launch testing
Show abstract
This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI), to be launched onboard of ESA's Herschel Space Observatory, by 2008. It includes the first results from the instrument level tests. The instrument is designed to be electronically tuneable over a wide and continuous frequency range in the Far Infrared, with velocity resolutions better than 0.1 km/s with a high sensitivity. This will enable detailed investigations of a wide variety of astronomical sources, ranging from solar system objects, star formation regions to nuclei of galaxies.
The instrument comprises 5 frequency bands covering 480-1150 GHz with SIS mixers and a sixth dual frequency band, for the 1410-1910 GHz range, with Hot Electron Bolometer Mixers (HEB). The Local Oscillator (LO) subsystem consists of a dedicated Ka-band synthesizer followed by 7 times 2 chains of frequency multipliers, 2 chains for each frequency band. A pair of Auto-Correlators and a pair of Acousto-Optic spectrometers process the two IF signals from the dual-polarization front-ends to provide instantaneous frequency coverage of 4 GHz, with a set of resolutions (140 kHz to 1 MHz), better than < 0.1 km/s. After a successful qualification program, the flight instrument was delivered and entered the testing phase at satellite level. We will also report on the pre-flight test and calibration results together with the expected in-flight performance.
The Photodetector Array Camera and Spectrometer (PACS) for the Herschel Space Observatory
Show abstract
The Photodetector Array Camera and Spectrometer (PACS) is one of the three science instruments for ESA's
far infrared and submillimeter observatory Herschel. It employs two Ge:Ga photoconductor arrays (stressed and
unstressed) with 16 × 25 pixels, each, and two filled silicon bolometer arrays with 16 × 32 and 32 × 64 pixels,
respectively, to perform imaging line spectroscopy and imaging photometry in the 60 - 210μm wavelength band.
In photometry mode, it will simultaneously image two bands, 60 - 85μm or 85 - 125μm and 125 - 210μm,
over a field of view of ~ 1.75' × 3.5', with close to Nyquist beam sampling in each band. In spectroscopy
mode, it will image a field of ~ 50" × 50", resolved into 5 × 5 pixels, with an instantaneous spectral coverage of
~ 1500 km/s and a spectral resolution of ~ 175 km/s. In both modes the performance is expected to be not far
from background-noise limited, with sensitivities (5σ in 1h) of ~ 4 mJy or 3 - 20 × 10-18W/m2, respectively.
We summarize the design of the instrument, describe the observing modes in combination with the telescope
pointing modes, report results from instrument level performance tests and calibration of the Flight Model, and
present our current prediction of the in-orbit performance of the instrument based on the ground tests.
Herschel-SPIRE: design, ground test results, and predicted performance
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SPIRE, the Spectral and Photometric Imaging Receiver, is a submillimetre camera and spectrometer for Herschel. It
comprises a three-band camera operating at 250, 350 and 500 µm, and an imaging Fourier Transform Spectrometer
covering 194-672 μm. The photometer field of view is 4x8 arcmin., viewed simultaneously in the three bands. The FTS
has an approximately circular field of view of 2.6 arcmin. diameter and spectral resolution adjustable between 0.04 and 2
cm-1 ( λ/▵λ=20-1000 at 250 μm). Following successful testing in a dedicated facility designed to simulate the in-flight
operational conditions, SPIRE has been integrated in the Herschel spacecraft and is now undergoing system-level testing
prior to launch. The main design features of SPIRE are reviewed, the key results of instrument testing are outlined, and
a summary of the predicted in-flight performance is given.
Herschel payload: straylight design and performance
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Herschel is an ESA spaceborne far infrared observatory, to be launched late 2008. It's key science objectives emphasize
specifically the formation of stars and Galaxies. The focal plane of the 3.5m diameter telescope is shared by three
instruments located in the cryostat: PACS (imaging photometer and integral field line spectrometer, operating from
35μm to 205μm wavelength); SPIRE (imaging photometer and Mach-Zender interferometer, operating from 194μm to
572μm wavelength); and HIFI (heterodyne detector, from 157 to 625μm wavelength). Infrared straylight rejection is one
of the key performances of the Herschel observatory. In this paper, we present the straylight requirements, some specific
design issues, the estimated performances and test results.
Performance evaluation of the Herschel/SPIRE instrument flight model imaging Fourier transform spectrometer
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The Spectral and Photometric Imaging Receiver (SPIRE) is one of three scientific instruments onboard the
European Space Agency (ESA)'s Herschel Space Observatory. The low to medium resolution spectroscopic
capability of SPIRE is provided by an imaging Fourier transformspectrometer of the Mach-Zehnder configuration.
Instrument performance of the SPIRE flight model was evaluated during a series of test campaigns. The SPIRE
instrument performance verification was completed with instrument delivery to ESA in early 2007. In this paper
we present the resulting performance characteristics of the SPIRE spectrometer flight model as determined from
these test campaigns. We verify the instrument's conformance with fundamental design specifications such as
spectral coverage and resolution. Variations across the imaging array of such properties as spectral resolution,
vignetting, and instrumental line shape are explored. Additionally, instrumental artefacts observed during final
verification testing are identified and quantified; with explanations provided for potential causes, and proposed
methods to minimize their impact on scientific observations described.
Preparing Herschel's commissioning phase: Ge:Ga detector tuning
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The Photodetector Array Camera and Spectrometer (Pacs) instrument aboard the Herschel space observatory
contains an integral field spectrometer with two camera channels which consist of 25 linear arrays of 16
stressed Gallium doped Germanium crystals (Ge:Ga) each. The space radiation environment induces changes in
the detector performance. Therefore, testing the Ge:Ga detectors under space radiation environment during the
commissioning phase (CP) is important for optimization of later detector operation in orbit. The test program
for Ge:Ga detector tuning during this phase has been designed according to findings obtained in laboratory
experiments: Protons as well as a 137Cs-γ-source have been used to simulate the space radiation environment
and to induce the radiation impacts on the photoconductor arrays. From comparison of the performance of
the detectors during CP versus laboratory tests the best strategy for operating the detectors during scientific
observations will be derived. This includes annealing, proposals for on-board data reduction algorithms and the
best estimated strategy for well-calibrated scientific measurements.
AKARI
The infrared astronomical satellite AKARI: overview, highlights of the mission
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The AKARI, Japanese infrared astronomical satellite, is a 68.5 cm cooled telescope with two focal-plane instruments
providing continuous sky scan at six wavelength bands in mid- and far-infrared. The instruments also have capabilities of
imaging and spectroscopy in the wavelength range 2-180 μm in the pointing observations occasionally inserted into the
continuous survey. AKARI was launched on 21st Feb. 2006, and has performed the all-sky survey as well as 5380
pointing observations until the liquid helium exhaustion on 26th Aug. 2007. The all sky survey covers more than 90
percent of the entire sky with higher spatial resolutions and sensitivities than the IRAS. First version of the infrared
source catalogue will be released in 2009. Here we report the overview of the mission, highlights on the scientific results
as well as the performance of the focal-plane instruments. We also present the observation plan with the near infrared
camera during the post-helium mission phase started in June 2008.
Mid-infrared all-sky survey with AKARI/IRC
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AKARI is the first Japanese astronomical infrared satellite mission orbiting around the Earth in a sun-synchronous
polar orbit at the altitude of 700 km. One of the major observation programs of the AKARI is an all-sky survey in the
mid- to far-infrared spectral regions with 6 photometric bands. The mid-infrared part of the AKARI All-Sky Survey was
carried out with the Infrared Camera (IRC) at the 9 and 18 µm bands with the sensitivity of about 50 and 120 mJy (5σ
per scan), respectively. The spatial resolution is about 9.4" at both bands. AKARI mid-infrared (MIR) all-sky survey
substantially improves the MIR dataset of the IRAS survey of two decades ago and provides a significant database for
studies of various fields of astronomy ranging from star-formation and debris disk systems to cosmology. This paper
describes the current status of the data reduction and the characteristics of the AKARI MIR all-sky survey data.
The Infrared Camera (IRC) for AKARI: in-flight imaging performance and the post cryogen mission
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The Infrared Camera (IRC) is one of two focal-plane instruments on the AKARI satellite. It is designed for
wide-field deep imaging and low-resolution spectroscopy in the near- to mid-infrared (1.8-26.5 micron) in the
pointed observation mode of AKARI. The IRC is also operated in the survey mode to make an All-Sky Survey
at 9 and 18 microns. The IRC is composed of three channels. The NIR channel (1.8-5.5 micron) employs
a 512x412 InSb photodiode array, whereas both the MIR-S (4.6-13.4 micron) and MIR-L (12.6-26.5 micron)
channels use 256x256 Si:As impurity band conduction (IBC) arrays. Each of the three channels has a field-ofview
of approximately 10x10 arcmin., and they are operated simultaneously. The NIR and MIR-S channels share
the same field-of-view by virtue of a beam splitter. The MIR-L observes the sky about 25 arcmin. away from the
NIR/MIR-S field-of-view. The in-flight performance of the IRC has been confirmed to be in agreement with the
pre-flight expectation. More than 4000 pointed observations dedicated for the IRC are successfully completed,
and more than 90% of the sky are covered by the all-sky survey before the exhaustion of the Akari's cryogen. The
focal-plane instruments are currently cooled by the mechanical cooler and only the NIR channel is still working
properly. Brief introduction, in-flight performance and scientific highlights from the IRC cool mission, together
with the result of performance test in the warm mission, are presented.
Slow-scan performance of the Far-Infrared Surveyor (FIS) onboard AKARI
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We present the in-orbit performance of slow-scan observation of the Far-Infrared Surveyor (FIS) onboard the
AKARI satellite. The FIS, one of the two focal-plane instruments of AKARI, has four photometric bands from
50-180 μm with two kinds of Ge:Ga array detectors. In addition to the All-Sky Survey, the FIS also took images
of specific targets by the slow-scan. Because of the longer exposure time on a targeted source, the sensitivity
in the slow-scan mode is 1-2 orders of magnitude better than that in the All-Sky Survey mode. In order to
evaluate the point spread functions (PSFs), several bright point-like objects such as asteroids, stars, and galaxies
were observed. Though significant enhancements are seen at the tails of the PSFs, the derived full width at
the half maximum (FWHM) are consistent with those expected from the optical simulation and the laboratory
measurements; ~40" for two shorter wavelength bands and ~60" for two longer wavelength bands, respectively.
The absolute photometric calibration has been performed by observing well established photometric calibration
standards (asteroids and stars) in a wide range of fluxes. After the establishment for the method of the aperture
photometry, the photometric accuracy for point sources is less than 10% in all bands.
Far-Infrared Surveyor on AKARI: in-orbit characterization of transient response and radiation effects of Ge:Ga array detectors
Show abstract
We report the in-orbit performance of the AKARI/Far-Infrared Surveyor Ge:Ga photoconductors, focusing on the
transient response and the radiation effects, to perform the characterization of these effects for data analyses. The
behavior for these effects is found to be significantly different between the Short-Wavelength and Long-Wavelength
array detectors of the FIS, most probably due to the difference in the array configuration. We discuss cosmic-ray
radiation effects, referring to the results of pre-flight proton-beam irradiation measurements. We also describe our efforts
to correct the slow transient response of the detectors by adopting a physical approach.
Imaging Fourier transform spectrometer with photoconductive detector arrays: an application to the AKARI far-infrared instrument
Show abstract
We have developed an imaging Fourier transform spectrometer (iFTS) for space-based far-infrared astronomical
observations. The iFTS employs newly developed photoconductive detector arrays with a capacitive transimpedance
amplifier, which makes the iFTS a completely unique instrument. The iFTS was installed as a
function of the far-infrared instrument (FIS: Far-Infrared Surveyor) on the Japanese astronomical satellite,
AKARI, which was launched on February 21, 2006 (UT) from the Uchinoura Space Center. The iFTS had
worked properly in the space environment as well as in laboratory for more than one year before liquid helium
ran out on August 26, 2007. The iFTS was operated nearly six hundreds of pointed observations. More than
one hundred hours of astronomical observations and almost the same amount of time for calibrations have been
carried out in the mission life. Meanwhile, it becomes clear that the detector transient effect is a considerable
factor for FTSs with photoconductive detectors. In this paper, the instrumentation of the iFTS and interesting
phenomena related to FTSs using photoconductive detectors are described, and the calibration strategy of the
iFTS is discussed briefly.
SPICA-WISE
Wide-field Infrared Survey Explorer science payload update
Show abstract
The Wide Field Infrared Survey Explorer is a NASA Medium Class Explorer mission to perform a high-sensitivity, high
resolution, all-sky survey in four infrared wavelength bands. The science payload is a 40 cm aperture cryogenically
cooled infrared telescope with four 10242 infrared focal plane arrays covering from 2.8 to 26 μm. Mercury cadmium
telluride (MCT) detectors are used for the 3.3 μm and 4.6 μm channels, and Si:As detectors are used for the 12 μm and
23 μm wavelength channels. A cryogenic scan mirror freezes the field of view on the sky over the 9.9-second frame
integration time. A two-stage solid hydrogen cryostat provides cooling to temperatures less than 17 K and 8.3 K at the
telescope and Si:As focal planes, respectively. The science payload collects continuous data on orbit for the seven-month
baseline mission with a goal to support a year-long mission, if possible. As of the writing of this paper, the payload
subassemblies are complete, and the payload has begun integration and test. This paper provides a payload overview
and discusses instrument status and performance.
SPICA mission for mid- and far-infrared astronomy
Show abstract
SPICA (Space Infrared Telescope for Cosmology and Astrophysics) is an astronomical mission optimized for mid- and
far-infrared astronomy with a cryogenically cooled 3.5 m telescope. Its high spatial resolution and unprecedented
sensitivity in the mid- and far-infrared will enable us to address a number of key problems in present-day astronomy,
ranging from the star-formation history of the universe to the formation of planets. To reduce the mass of the whole
mission, SPICA will be launched at ambient temperature and cooled down on orbit by mechanical coolers on board with
an efficient radiative cooling system, a combination of which allows us to have a 3.5-m class cooled (5 K) telescope in
space with moderate total weight (3t). SPICA is proposed as a Japanese-led mission together with extensive international
collaboration. The assessment study on the European contribution to the SPICA project has started under the framework
of the ESA Cosmic Vision 2015-2025. US and Korean participations are also being discussed extensively. The target
launch year of SPICA is 2017.
The European contribution to the SPICA mission
Show abstract
The Japanese led Space Infrared telescope for Cosmology and Astrophysics (SPICA) will observe the universe over the
5 to 210 micron band with unprecedented sensitivity owing to its cold (~5 K) 3.5m telescope. The scientific case for a
European involvement in the SPICA mission has been accepted by the ESA advisory structure and a European
contribution to SPICA is undergoing an assessment study as a Mission of Opportunity within the ESA Cosmic Vision
1015-2015 science mission programme. In this paper we describe the elements that are being studied for provision by
Europe for the SPICA mission. These entail ESA directly providing the cryogenic telescope and ground segment
support and a consortium of European insitutes providing a Far Infrared focal plane instrument. In this paper we
describe the status of the ESA study and the design status of the FIR focal plane instrument.
Focal plane instruments onboard SPICA
Show abstract
The SPICA, Japanese next generation infrared space telescope with a cooled 3.5 m primary mirror, will be a quite unique
observatory in the mid and far-infrared with unprecedented sensitivity and the spatial resolving power. Here we briefly
describe the key scientific objectives which can be performed only with SPICA, based on its unique design concepts. We
then describe the scientific requirements for the focal plane instruments, and summarize the constraints on the various
resources available for the focal plane instruments, derived from the spacecraft system design. We also outline the
concept of the planned focal plane instruments, and the future development plan.
Within the focal-plane instrument space (2.5m diameter, 0.5m height), two major instruments are so far planned to be
equipped: one is a mid-infrared instrument, consisting of a mid-infrared camera, mid-infrared spectrometers, and a midinfrared
coronagraph, while the another is a far-infrared camera and spectrometer. The mid-infrared camera will consist
of four channels covering 5-38 μm with approximately 25-40 square arcminutes, while the mid-infrared spectrometer
will have high-dispersion (R=30000) channels at 4-18 μm and moderate-dispersion (R=3000) channels at 16-38 μm.
The mid-infrared coronagraph will have both imaging and spectroscopic capability at 5-27 μm, with the contrast higher
than 10-6. As for the far-infrared camera and spectrometer, a Fourier-type imaging spectrometer covering 30-210 μm is
proposed and extensively studied by the European consortium (SAFARI consortium). A far-infrared and sub-millimeter
grating spectrometer instrument is also under consideration by the US SPICA team.
JWST Overview
The scientific capabilities of the James Webb Space Telescope
Show abstract
The scientific capabilities of the James Webb Space Telescope fall into four themes. The End of the Dark Ages: First
Light and Reionization theme seeks to identify the first luminous sources to form and to determine the ionization history
of the universe. The Assembly of Galaxies theme seeks to determine how galaxies and the dark matter, gas, stars, metals,
morphological structures, and active nuclei within them evolved from the epoch of reionization to the present. The Birth
of Stars and Protoplanetary Systems theme seeks to unravel the birth and early evolution of stars, from infall onto dustenshrouded
protostars, to the genesis of planetary systems. The Planetary Systems and the Origins of Life theme seeks to
determine the physical and chemical properties of planetary systems around nearby stars and of our own, and investigate
the potential for life in those systems.
Status of the James Webb Space Telescope (JWST)
Show abstract
The James Webb Space Telescope (JWST) is a 6.5-meter, space telescope designed for infrared imaging and
spectroscopy. Its planned launch in 2013, aboard an Ariane 5, will place it in n L2 orbit. The JWST program is a
cooperative program with the Goddard Space Flight Center (GSFC) managing the project for NASA. The prime
contractor for JWST is Northrop Grumman Space Technology (NGST). JWST's international partners are the European
Space Agency (ESA) and the Canadian Space Agency (CSA). JWST will address four major science themes: First light
and re-ionization; the assembly of galaxies, the birth of stars and protoplanetary systems; and the formation of planetary
systems and the origins of life. We discuss the design of the observatory as it is currently base-lined, and review recent
progress with the observatory.
Design status of the James Webb Space Telescope
Show abstract
The James Webb Space Telescope (JWST) is NASA's next great astronomical mission. At the time of this
paper, the mission has just passed its preliminary design review. This paper will visit three areas of
significant maturation since the design was initially introduced. The three areas discussed are; addition of
a heater to the fine steering mirror, spacecraft bus rearchiteture, and redesign of the sunshield core. Each of
these design evolutions enables the mission through improved performance, reduced risk or complexity.
These three design changes are examples of the efforts being exerted on the other aspects of the design that
are not covered in this paper.
Applying HST lessons learned to JWST
Show abstract
The James Webb Space Telescope (JWST) is a
6.5 meter cryogenic observatory planned to launch in
2013. The observatory includes a three mirror anastigmat
telescope with a deployed 18 segment primary mirror.
Unlike the Hubble Space Telescope (HST), JWST will be
difficult to service and therefore the development team
needs to be highly confident the telescope will work after
launch. Consequently, it is imperative that the team
building JWST apply the lessons learned from the HST
program so as to avoid repeating mistakes that led to a
major optical error in HST. The purpose of this paper is
to summarize what the JWST program is doing to apply
the lessons learned from HST. It includes a summary of
how the HST optical error was made, the lessons learned
there from, and how the JWST program is applying these
lessons to avoid the mistakes of the past and ensure
correct JWST optical performance.
Towards observing extrasolar giant-planet environments with JWST
Show abstract
With its high Strehl ratio near- and mid-infrared imaging capabilities, wide field of view, and multiple spectroscopic
options, the James Webb Space Telescope (JWST) will provide crucial information on the circumstellar
environments of stars thought to harbor debris disks, brown dwarfs or extrasolar giant planets. However, the
successful study of such faint targets around nearby, bright stars requires the effective removal of the target
star's contribution from the image. In this work, we use simple models of the temporal behavior JWST's wavefront
error of JWST over time to examine whether frequent measurements of that changing wavefront can be
used to provide an effective point spread function subtraction for high-contrast imaging studies without use of
coronagraphic techniques.
JWST: OTE Verification
Optical performance verification of the James Webb Space Telescope
Show abstract
The James Webb Space Telescope (JWST) is a large aperture (6.6 m primary mirror) cryogenic telescope with active
control of the segmented primary and secondary mirror optical elements. The architecture of the telescope makes full
end-to-end testing on the ground prohibitive due to both cost and technical considerations. Additionally, because the
telescope will be launched in a folded configuration to fit in the Ariane V launch fairing and aligned during flight using
image-based Wavefront Sensing and Control (WFS&C), the telescope cannot be tested in the classical "test-as-you-fly"
architecture. Due to these considerations, the primary optical performance requirements will be verified through analysis.
In order to have high confidence in this approach, a robust analysis validation program has been developed based on
testing from the component level through the integrated telescope level. This verification approach focuses on ground
testing at the telescope level to ensure there will be adequate range in the adjustable optics for alignment on orbit. In
addition to the incremental test program planned for optical verification, a double-pass sampled aperture test of the integrated
telescope and instruments is planned at flight-like temperatures as a crosscheck to the analytic verification for
flight. Error budgets have been developed to understand the uncertainty propagation through the test and analysis program.
Architecting a revised optical test approach for JWST
Show abstract
It is imperative that we have high confidence that the optical performance capability of JWST is well-understood
before launch. With the telescope operating at cryogenic temperatures and sporting a 6.6 meter primary mirror
diameter, the optical metrology equipment required to measure the optical performance can be quite complex. The
JWST Test team undertook an effort to greatly simplify the optical metrology approach, while retaining the key
measurements and verification methodology. The result is a cryogenic optical test configuration and
implementation using Chamber A at NASA's Johnson Space Center that uses the science instruments to help
understand JWST's optical performance.
Development of interferometry for testing the JWST Optical Telescope Element (OTE)
Show abstract
Instantaneous phase shifting interferometry is key to successful development and testing of the large, deployable,
cryogenic telescope for the James Webb Space Telescope (JWST) mission. Two new interferometers have been
developed to meet the needs of the JWST program. Spatially Phase-Shifted Digital Speckle Pattern Interferometer (SPSDSPI)
was developed to verify structural deformations to nanometer level accuracy in large, deployable, lightweight,
precision structures such as the JWST telescope primary mirror backplane. Multi- wavelength interferometer was
developed to verify the performance of the segmented primary mirror at cryogenic temperatures.
This paper discusses application of SPS-DSPI for measuring structural deformations in large composite structures at
cryogenic temperatures. Additionally development of a multi-wavelength interferometer for verifying JWST OTE
primary mirror performance at cryogenic temperatures will be discussed.
Verification of the James Webb Space Telescope (JWST) wavefront sensing and control system
Show abstract
From its orbit around the Earth-Sun second Lagrange point some million miles from Earth, the James Webb Space Telescope
(JWST) will be uniquely suited to study early galaxy and star formation with its suite of infrared instruments.[1]
To maintain exceptional image quality using its 6.6 meter segmented primary mirror, wavefront sensing and control
(WFS&C) is vital to ensure the optical alignment of the telescope throughout the mission. After deployment of the observatory
structure and mirrors from the "folded" launch configuration, WFS&C is used to align the telescope[2], as well
as maintain that alignment. WFS&C verification includes the verification of the software and its incorporated algorithms,
along with the supporting aspects of the integrated ground segment, instrumentation, and telescope through increasing
levels of assembly. The software and process are verified with the Integrated Telescope Model (ITM), which is
a Matlab/Simulink integrated observatory model which interfaces to CodeV/OSLO/IDL. In addition to lower level testing,
the Near-Infrared Camera[3] (NIRCam) with its wavefront sensing optical components is verified with the other instruments
with a cryogenic optical telescope simulator (OSIM) before moving on to the final WFS&C testing in Chamber
A at the Johnson Space Center (JSC) where additional observatory verification occurs.
JWST: Instruments
Design and development of MIRI, the mid-IR instrument for JWST
Show abstract
MIRI is the mid-IR instrument for the James Webb Space Telescope and provides imaging, coronography and integral
field spectroscopy over the 5-28μm wavelength range. MIRI is the only instrument which is cooled to 7K by a dedicated
cooler, much lower than the passively cooled 40K of the rest of JWST, which introduces unique challenges. The paper
will describe the key features of the overall instrument design. The flight model design of the MIRI Optical System is
completed, with hardware now in manufacture across Europe and the USA, while the MIRI Cooler System is at PDR
level development. A brief description of how the different development stages of the optical and cooling systems are
accommodated is provided, but the paper largely describes progress with the MIRI Optical System. We report the
current status of the development and provide an overview of the results from the qualification and test programme.
Development approach and first infrared test results of JWST/Mid Infra Red Imager Optical Bench
Show abstract
The present paper describes the different steps leading to the Flight Model integration of the Mid-Infra Red IMager
Optical Bench MIRIM-OB which is part of the scientific payload of the JWST. In order to demonstrate a space
instrument capability to survive the challenging space environment and deliver the expected scientific data, a specific
development approach is applied in order to reduce the high level of risks. The global approach for MIRIM-OB, and the
principal results associated to the two main models, the Structural Qualification Model for vibration and the Engineering
and Test Model for optical performance measured in the infra red at cryogenic temperature will be described in this
paper.
First tests of the coronagraphic device of MIRI/JWST
Show abstract
One of the main objectives of the instrument MIRI, the Mid-InfraRed Instrument, of the JWST is the direct
detection and characterization of extrasolar giant planets. For that purpose, a coronagraphic device including
three Four-Quadrant Phase Masks and a Lyot coronagraph working in mid-infrared, has been developed. We
present here the results of the first test campaign of the coronagraphic system in the mid-infrared in the facility
developed at the CEA. The performances are compared to the expected ones from the coronagraphic simulations.
The accuracy of the centering procedures is also evaluated to validate the choice of the on-board centering
algorithm.
The JWST tunable filter imager (TFI)
Show abstract
The Fine Guidance Sensor (FGS) of the James Webb Space Telescope (JWST) features a tunable filter imager (TFI)
module covering the wavelength range from 1.6 to 4.9 μm at a resolving power of ~100 over a field of view of
2.2'x2.2'. TFI also features a set of 4 occulting spots for coronagraphy. A review of the current design and development
status of TFI is presented along with two key TFI science programs: the detection of first light, high-redshift Lyα
emitters and the detection/characterization of exoplanets.
Opto-mechanical test results for the Near Infra-red Camera on the James Webb Space Telescope
Show abstract
The Near Infrared Camera (NIRCam) for the James Webb Space Telescope (JWST) has undergone Pathfinder
component testing and evaluation. This paper presents the opto-mechanical test results. An overview of the optomechanical
system requirements is provided, followed by a discussion of the opto-mechanical system design and
assembly process. Tolerances in the opto-mechanical system as they relate to system level alignment are also presented.
Mechanical analysis related to vibration and thermal behavior of the design is shown. Finally, the overall performance
of the opto-mechanical system is discussed as it relates to instrument optical performance.
Cryogenic test results of engineering test unit optical components of the Near Infrared Camera for the James Webb Space Telescope
Show abstract
The Near InfraRed Camera (NIRCam) for the James Webb Space Telescope (JWST) is a refracting instrument. Its
unique optical performance derives from the Lithium Fluoride, Barium Fluoride and Zinc Selenide lenses that provide
aberration and color correction over the large operating wavelengths, 0.6-5 microns. This paper describes cryogenic test
results of the mounted camera lenses in a flight-like configuration. These data, which evaluate the foundation for
NIRCam optical performance, reveals design strengths and challenges. This is a follow-up paper from SPIE paper
590409 (1) which presented the initial camera lens design.
The Integral Field Unit on the James Webb Space Telescope's Near-Infrared Spectrograph
Show abstract
The James Webb Space Telescope (JWST) mission is a collaborative project between the National Aeronautics and
Space Administration (NASA), the European Space Agency (ESA) and the Canadian Space Agency (CSA). On board
JWST, the NIRSpec instrument developed by EADS Astrium for ESA is a near-infrared spectrograph covering the 0.6-5.0 μm domain at spectral resolutions of 100, 1000 and 2700.
NIRSpec will be primarily operated as a multi-object spectrograph (MOS) but it also includes an integral field unit (IFU)
allowing to continuously sample a 3"x3" field of view with 0.1". This IFU, based on the "advanced" image slicer
concept, is a very compact athermal unit made of aluminium. The slicer, pupil and slit mirror arrays are each machined
from monolithic blocks using diamond-turning techniques.
This paper presents the integral-field spectroscopy (IFS) mode of NIRSpec. After a brief presentation of its main
scientific objectives and expected performance, we will focus on its implementation in NIRSpec and the design of the
IFU to the diamond machining techniques applied for manufacturing. We will finish with a presentation of the status of
the development and of recent results from mirror machining and metrology.
Planetary Missions
NEOSSat: a Canadian small space telescope for near Earth asteroid detection
Show abstract
Although there is some success in finding Near Earth asteroids from ground-based telescopes, there is a marked
advantage in performing the search from space. The ability to search at closer elongations from the sun and
being able to observe continuously, allowing quick revisits of new asteroids, are some of the unique benefits of
a space platform. The Canadian Space Agency (CSA) together with Defense Research and Development
Canada (DRDC) are planning a micro-satellite platform with a 15 cm telescope dedicated for near space
surveillance. The NEOSSat (Near Earth Object Surveillance) spacecraft is expected to be able to detect 20 v
magnitude objects with a 100 sec exposure, with a 0.85 deg FOV, on a 1024x1024 CCD, and sub arcsec
pointing stability. For detection of NEO small bodies, it will be able to search an area from 45 degrees solar
elongation and approximately 40 degrees north to south degrees in elevation. The observation strategy will be
optimized to find as many asteroids as possible, based on recent models of asteroid population. Ground based
telescopes will also be used to complement follow-ups for orbit determination when possible. The microsatellite
is based on the CSA very successful MOST micro-satellite, operating since 2003. Baselined for launch
in 2010, the NEOSSat is a shared project with DRDC to demonstrate the technology of an inexpensive space
platform to detect High Earth Orbit (HEOSS) earth-orbiting satellites and debris.
SPEX: an in-orbit spectropolarimeter for planetary exploration
Show abstract
SPEX (Spectropolarimeter for Planetary EXploration) is an innovative, compact remote-sensing instrument for
detecting and characterizing aerosols. With its 1-liter volume it is capable of full linear spectropolarimetry,
without moving parts. High precision polarimetry is performed through encoding the degree and angle of linear
polarization of the incoming light in a sinusoidal modulation of the intensity spectrum. This is achieved by
using an achromatic quarter-wave retarder, an athermal multiple-order retarder and a polarizing beamsplitter
behind each entrance pupil. Measuring a single intensity spectrum thus provides the spectral dependence of the
degree and angle of linear polarization. Polarimetry has proven to be an excellent tool to study microphysical
properties (size, shape, composition) of atmospheric particles. Such information is essential to better understand
the weather and climate of a planet. Although SPEX can be used to study any planetary atmosphere, including
the Earth's, the current design of SPEX is tailored to study Martian dust and ice clouds from an orbiting
platform: a compact module with 9 entrance pupils to simultaneously measure intensity spectra from 350 to
800 nm, in different directions along the flight direction (including two limb viewing directions). This way, both
the intensity and polarization scattering phase functions of dust and cloud particles within a ground pixel are
sampled while flying over it. In the absence of significant amounts of dust and clouds, the surface properties
can be studied. SPEX provides synergy with instruments on rovers and landers, as it provides a global view of
spatial and temporal variations of the planet.
Novel TMA telescope based on ultra precise metal mirrors
Show abstract
Modern telescopes for space applications use complex optical elements like aspheres or freeforms. For the multispectral
pushbroom scanner for spaceborne Earth remote sensing the Jena-Optonik GmbH has developed a Jena-Spaceborne-
Scanner JSS product line. The optic of JSS-56 imager is realised by a Three-Mirror-Anastigmat (TMA) telescope
designed in aluminium [1]. For brilliant pictures, mirrors with high shape accuracy and very smooth surfaces are
required. The combination of precise diamond turning and post polishing techniques enables the classical infrared
application for the visible and ultra-violet range. A wide variety of complex mirror shapes are feasible. A special new
solution for lightweight design was applied. Ultra precise metal mirrors with aspherical surface are developed at the
Fraunhofer IOF from design to system integration.
This paper summarizes technologies and results for design, fabrication and surface finish of ultra lightweight aspherical
metal mirrors for novel TMA telescopes.
Design of a Fabry-Perot interferometer for the SO/PHI instrument on Solar Orbiter
Show abstract
We present our work on the spectral analyser of the Polarimetric and Helioseismic Imager (PHI) instrument to
be flown aboard ESA's Solar Orbiter mission. We detail the choices that were made to determine the concept
of the spectral analyser, a Lithium Niobate Fabry-Perot interferometer, and its characteristics, as to fulfil both
scientific needs and technical requirements. We will present the first experimental results - including stability,
repeatability, parallelism, spectral homogeneity and imaging capability - on an air-spaced piezoelectric-tunable
etalon, which is the backup solution for PHI.
JDEM
Summary of the DUNE mission concept
Show abstract
The Dark UNiverse Explorer (DUNE) is a wide-field imaging mission concept whose primary goal is the study
of dark energy and dark matter with unprecedented precision. To this end, DUNE is optimised for weak gravitational
lensing, and also uses complementary cosmological probes, such as baryonic oscillations, the integrated
Sachs-Wolf effect, and cluster counts. Immediate additional goals concern the evolution of galaxies, to be studied
with groundbreaking statistics, the detailed structure of the Milky Way and nearby galaxies, and the demographics
of Earth-mass planets. DUNE is a medium class mission consisting of a 1.2m telescope designed to carry out
an all-sky survey in one visible and three NIR bands (1deg2 field-of-view) which will form a unique legacy for
astronomy. DUNE has been selected jointly with SPACE for an ESA Assessment phase which has led to the
Euclid merged mission concept.
An integral field spectrograph for SNAP
Show abstract
A well-adapted visible and infrared spectrograph has been developed for the SNAP (SuperNova/Acceleration Probe)
experiment proposed for JDEM. The primary goal of this instrument is to ensure the control of Type Ia supernovae. The
spectrograph is also a key element for calibration and is able to measure redshift of some thousands of galaxy spectra
both in visible and IR.
An instrument based on an integral field method with the powerful concept of imager slicing has been designed and is
presented. We present the current design and expected performances. We show that with the current optimization and
the proposed technology, we expect the most sensitive instrument proposed on this kind of mission. We recall the
readiness of the concept and of the slicer technology thanks to large prototyping efforts performed in France which
validate the proposition. This work is supported in France by CNRS/INSU, CNRS/IN2P3 and by the French spatial
agency (CNES).
Setup and performances of the SNAP spectrograph demonstrator
Show abstract
An integral field spectrograph concept has been developed for the SNAP/JDEM(SuperNova/Acceleration Probe)
experiment. This spectrograph will be optimized for faint supernovae and galaxies in a 3×6 arsec2 at low spectral
resolution (R~100) through the wavelength range (0.35-1.7 μm). The integral field method is based on glass
image slicer. A prototype of this instrument has been build to validate the concept and prove the optical and
functional requirements of the SNAP spectrograph.
In this paper, we present the first results of this demonstrator. We describe the demonstrator philosophy, set
up and functional performances. We present then the first experimental results obtained in the visible range.
We validate the slicer optical quality through a set of measurements: PSF, optical losses.
The Observatory for Multi-Epoch Gravitational Lens Astrophysics (OMEGA)
Show abstract
Dark matter in a universe dominated by a cosmological constant seeds the formation of structure and is the scaffolding
for galaxy formation. The nature of dark matter remains one of the fundamental unsolved problems in astrophysics and
physics even though it represents 85% of the mass in the universe, and nearly one quarter of its total mass-energy
budget. The mass function of dark matter "substructure" on sub-galactic scales may be enormously sensitive to the mass
and properties of the dark matter particle. On astrophysical scales, especially at cosmological distances, dark matter
substructure may only be detected through its gravitational influence on light from distant varying sources. Specifically,
these are largely active galactic nuclei (AGN), which are accreting super-massive black holes in the centers of galaxies,
some of the most extreme objects ever found. With enough measurements of the flux from AGN at different
wavelengths, and their variability over time, the detailed structure around AGN, and even the mass of the super-massive
black hole can be measured. The Observatory for Multi-Epoch Gravitational Lens Astrophysics (OMEGA) is a mission
concept for a 1.5-m near-UV through near-IR space observatory that will be dedicated to frequent imaging and
spectroscopic monitoring of ~100 multiply-imaged active galactic nuclei over the whole sky. Using wavelength-tailored
dichroics with extremely high transmittance, efficient imaging in six channels will be done simultaneously during each
visit to each target. The separate spectroscopic mode, engaged through a flip-in mirror, uses an image slicer
spectrograph. After a period of many visits to all targets, the resulting multidimensional movies can then be analyzed to
a) measure the mass function of dark matter substructure; b) measure precise masses of the accreting black holes as well
as the structure of their accretion disks and their environments over several decades of physical scale; and c) measure a
combination of Hubble's local expansion constant and cosmological distances to unprecedented precision. We present
the novel OMEGA instrumentation suite, and how its integrated design is ideal for opening the time domain of known
cosmologically-distant variable sources, to achieve the stated scientific goals.
The focal plane instrumentation for the DUNE mission
Show abstract
DUNE (Dark Universe Explorer) is a proposed mission to measure parameters of dark energy using weak gravitational
lensing The particular challenges of both optical and infrared focal planes and the DUNE baseline solution is discussed.
The DUNE visible Focal Plane Array (VFP) consists of 36 large format red-sensitive CCDs, arranged in a 9x4 array
together with the associated mechanical support structure and electronics processing chains. Four additional CCDs
dedicated to attitude control measurements are located at the edge of the array. All CCDs are 4096 pixel red-enhanced
e2v CCD203-82 devices with square 12 μm pixels, operating from 550-920nm. Combining four rows of CCDs provides
a total exposure time of 1500s. The VFP will be used in a closed-loop system by the spacecraft, which operates in a drift
scan mode, in order to synchronize the scan and readout rates. The Near Infrared (NIR) FPA consists of a 5 x 12 mosaic
of 60 Hawaii 2RG detector arrays from Teledyne, NIR bandpass filters for the wavelength bands Y, J, and H, the
mechanical support structure, and the detector readout and signal processing electronics. The FPA is operated at a
maximum temperature of 140 K for low dark current of 0.02-/s. Each sensor chip assembly has 2048 x 2048 square
pixels of 18 μm size (0.15 arcsec), sensitive in the 0.8 to 1.7 μm wavelength range. As the spacecraft is scanning the sky,
the image motion on the NIR FPA is stabilized by a de-scanning mirror during the integration time of 300 s per detector.
The total integration time of 1500 seconds is split among the three NIR wavelengths bands. DUNE has been proposed to
ESA's Cosmic Vision program and has been jointly selected with SPACE for an ESA Assessment Phase which has led
to the joint Euclid mission concept.
Hubble
Wide Field Camera 3: a powerful new imager for the Hubble Space Telescope
Show abstract
Wide Field Camera 3 (WFC3) is a powerful UV/visible/near-infrared camera that has just completed development for
installation into the Hubble Space Telescope during upcoming Servicing Mission 4. WFC3 provides two imaging
channels. The UVIS channel incorporates a 4102 × 4096 pixel CCD focal plane with sensitivity from 200 to 1000 nm
and a 162 × 162 arcsec field of view. The UVIS channel features unprecedented sensitivity and field of view in the near
ultraviolet for HST, as well as a rich filter set that complements the visible capabilities of the HST/Advanced Camera for
Surveys, whose repair will be attempted in the Servicing Mission. The IR channel features a 1024 × 1024 pixel HgCdTe
focal plane covering 850 to 1700 nm with a 136 × 123 arcsec field of view, providing a major advance in IR survey
efficiency for HST. We report here on the design of the instrument, on recent activities that have completed the
integration of the instrument for flight, and on results of the ground test and calibration program.
Wide Field Camera 3: science capabilities and plans for flight operation
Show abstract
Wide Field Camera 3 is the next generation of Hubble Space Telescope imaging instruments. Designed to complement
and extend the existing capabilities of the HST, WFC3 will provide large increases in scientific performance in the near
ultraviolet and near infrared wavelength regions. This paper describes the scientific capabilities of WFC3, provides a
projection of its anticipated scientific performance, and discusses the plans for on-orbit testing and calibration during the
Servicing Mission Orbital Verification period.
Coronography
New perspectives in solar coronagraphy offered by formation flying: from PROBA-3 to Cosmic Vision
Show abstract
Formation flying opens new perspectives in solar physics, and allow to conceive giant, externally-occulted coronagraphs
using a two-component space system with the external occulter on one spacecraft and the optical
instrument on the other spacecraft at a distance of hundred meters. Conditions close to those of a solar total
eclipse can then be achieved offering the capability of imaging the solar corona down to the limb at very high
spatial resolution. ASPIICS (Association de Satellites Pour l'Imagerie et l'Interférométrie de la Couronne Solaire)
is a mission proposed to ESA in the framework of its PROBA-3 demonstration program of formation flying
which is presently in phase A. ASPIICS is a single coronagraph which will perform both high spatial resolution
imaging of the solar corona as well as 2-dimensional spectroscopy of several emission lines from the coronal base
out to 3 R&beye; using a Fabry-Pérot étalon interferometer. The classical design of an externally-occulted coronagraph
is adapted to the formation flying configuration allowing the detection of the very inner corona as close as
0.01 R&beye; from the solar limb. Super-ASPIICS is an even more ambitious instrument part of the scientific payload
of HiRise, the High Resolution Imaging and Spectroscopy Explorer proposed to ESA in the framework of its
Cosmic Vision program. With an increased inter-satellite distance of 280 m, an aperture of 300 mm, a spectral
domain extending from the ultraviolet to the near-infrared, and spectroscopic capabilities, Super-ASPIICS will
offer unprecedented diagnostic capabilities, including the measurement of coronal magnetic fields.
In-orbit calibration of the polarization flat fields of the SOHO-LASCO coronagraphs
Show abstract
Since 11 years SOHO-LASCO coronagraphs are producing a unique set of the Sun corona images in the 2-32 solar
radius range. For the first time a complete set of coronal calibrated images in WL (polarized and unpolarized)
for the full solar cycle is available. The telescopes are equipped with 3 polarizers at -60,0 and 60 degrees, one
all pass channel and a set filters. Ground calibrations were completed with in orbit calibrations. To control the
evolution of sensivity for each bandpass and for each polarizer, the LASCO-C2 and LASCO-C3 coronographs
were provided with an internal system of calibration in orbit. The measures obtained in 1996 and 2003 have been
used to determine the CCD flat field for each filter bandpass, the gain constant (ADU to phe- conversion) and
the polarizers transmittance map. The solar corona itself was also used to control the local response. Spacecraft
rotations by 45 and 90 complete the test, and allowed for a ultimate but relevant global correction of the polarized
images.
Laboratory experiments on the 8-octant phase-mask coronagraph
Show abstract
A four-quadrant phase-mask (FQPM) coronagraph can suppress perfectly stellar light when a star can be regarded as
a point-like source. However, the FQPM coronagraph is highly sensitive to partially resolved stars, and shows
second-order sensitivity to tip-tilt error leakage. Higher-order sensitivity is required for extremely high-contrast imaging
of nearby stars.
We propose an eight-octant phase-mask (EOPM) for achieving fourth-order sensitivity to tip-tilt errors. We
manufactured the phase-mask utilizing a nematic liquid crystal (LC) device, which is composed of eight segments. A
phase retardation of the LC can be adjustable by an applied voltage to the device. The LC phase-mask can be switched
between FQPM-mode and EOPM-mode by applying appropriate voltages to the segments. We carry out experiments on
the phase-mask coronagraph with various tip-tilt errors. The experimental results show the higher-order behavior of the
EOPM compared to the FQPM.
We present a current status of the laboratory experiments on the EOPM coronagraph, and also show coronagraphic
performance of the EOPM derived from numerical simulations.
Terrestrial planet detection approaches: externally occulted hybrid coronagraphs
Show abstract
Externally occulted coronagraphs have garnered widespread attention as a potentially viable approach to starlight
suppression to enable direct detection and characterization of exo-solar terrestrial planets. Externally occulted
coronagraphs consist of a large mask (occulter) in front of the telescope as compared to an internal coronagraph which
performs all suppression within the telescope system using combinations of pupil and/or focal plane masks. The
advantages of external over internal are that the (i) inner working angle (IWA) is nearly independent of wavelength and
(ii) diffracted light is suppressed prior to the telescope; allowing science over a wide spectral band with a conventional
telescope with little or no wavefront control. For an internal coronagraph the IWA generally increases with wavelength
and scattered/diffracted light levy exquisite tolerances on wavefront, amplitude and polarization errors. An external
coronagraph comes with the added complexity and expense of requiring two spacecraft, flying in formation, at
separation distances of tens of thousands of kilometers. Re-targeting requires flying one or both spacecraft and aligning
them to the target star and hence added fuel and time as well as closed-loop control between them.
One approach may be to construct a smaller occulter possibly at closer distances and use it in series with a simple
internal coronagraph, i.e. a hybrid, approach. This may simplify requirements on the external occulter but requires more
precise tolerances on the telescope system. The question remains as to whether an acceptable balance between the two
approaches exists. Herein we look at one approach to designing a hybrid occulter system.
TPF Concepts
The Transit Characterization Explorer (TRACER)
Show abstract
The Transit Characterization Explorer (Tracer) is Small Explorer (SMEX) class mission that would characterize the
properties of exoplanets that transit their parent star. Tracer will measure the physical conditions, chemistry dynamics
and cloud properties of exoplanet atmospheres. Tracer will detect unseen terrestrial planets by observing them directly in
transit or by detecting them via perturbations of transit timings. Tracer will return transit light curves that provide robust
radii estimates, and can detect planetary rings and/or satellites. Tracer is an ideal SMEX mission presenting the
opportunity for timely exploitation of discoveries from the rapid growth of ground-based surveys for transiting systems
and providing the ideal complement to missions such as JWST.
Detecting biomarkers in exoplanetary atmospheres with a Terrestrial Planet Finder
Show abstract
There are good reasons for extending the spectral range of observation to shorter wavelengths than currently envisaged
for terrestrial planet-finding missions utilizing a 4-m, diffraction-limited, optical telescope. The angular resolution at
shorter wavelengths is higher, so that the image of an exoplanet is better separated from that of the much brighter star.
Due to the higher resolution, the exozodiacal background per resolution element is smaller, so exposure times are
reduced for the same incident flux. Most importantly, the sensitivity to the presence of life on habitable exoplanets is
increased over a hundred-fold by access to the ozone biomarker in the mid-ultraviolet. These benefits must be weighed
against challenges arising from the faintness of exoplanets in the mid-UV. Here, we describe the benefits, technical
challenges and some proposed solutions for detecting ozone in the atmospheres of Earth-like exoplanets.
Spectral characterization of Earth-like transiting exoplanets
Show abstract
We calculate the expected signal-to-noise ratio (SNR) for spectral features in the transit spectrum of an Earth-like
exoplanet, for the case of the nearest likely transit of a G and an M star, for a 6-m telescope in space. We find that the
SNR values for all important spectral features, in the visible and infrared, are in the range 0.2 to 1.1, making the
detection of such features difficult.
Polarization analysis as a means of detecting exoplanets and measuring their objective spectra
Show abstract
We present a method of the polarization degree analysis of exoplanets' objective-prism spectra. The polarization
analysis of the objective spectra can be used for discerning planet signal from noisy stellar light. The light reflected from
the planet is expected to be partially polarized, while the direct stellar light can be considered to be unpolarized. For
measuring objective spectra we use a four-quadrant polarization mask (FQPoM) coronagraph and a prism. The primary
suppression of starlight is achieved by destructive interference of the light passing through the central region of FQPoM.
For further suppression of starlight we use a polarization differential technique. By taking the difference between two
orthogonally polarized components of incoming light we can further suppress unpolarized starlight and reveal the
spectrum of the exoplanet. However, when the intensity contrast between the star and its planet is high, the starlight
noise impedes detection of the planetary spectrum. The analysis of the degree of polarization relieves the separation of
the planetary spectrum from the stellar noise. Moreover, any peculiar features in the objective spectra would be useful to
find out the location of the exoplanet. We obtained the experimental results under an intensity contrast of 3.5×10-5 and an
angular separation of 4.9 λ/D.
New Worlds Observer
The New Worlds Observer: scientific and technical advantages of external occulters
Show abstract
Perhaps the most compelling piece of science and exploration now under discussion for future space missions is the
direct study of planets circling other stars. Indirect means have established planets as common in the universe but have
given us a limited view of their actual characteristics. Direct observation holds the potential to map entire planetary
systems, view newly forming planets, find Earth-like planets and perform photometry to search for major surface
features. Direct observations will also enable spectroscopy of exoplanets and the search for evidence of simple life in
the universe. Recent advances in the design of external occulters - starshades that block the light from the star while
passing exoplanet light - have lowered their cost and improved their performance to the point where we can now
envision a New Worlds Observer that is both buildable and affordable with today's technology. In this paper we explore
the comparison of scientific capability of external occulters relative to indirect means and to internal coronagraph
missions. We conclude that external occulters logically provide the architecture for the next space mission for exoplanet
studies.
New Worlds Observer system architecture
Show abstract
The New Worlds Observer (NWO) is a mission concept for the detection and characterization of extra-solar
planets. It employs an external starshade and a space telescope. The starshade suppressed the parent star's
light making detection of the extra-solar planet possible. This paper formulates system performance based
on fundamental systems parameters and explores their interaction.
Design reference mission construction for planet finders
Show abstract
In this paper, we present methods for constructing design reference missions (DRMs) for space-borne telescopes
for the direct detection and characterization of extra-solar planets. Unlike most existing DRMs, which present
results based on an assumed fixed rate for the occurrence of
extra-solar planets, we calculate the approximate
distribution of mission results conditional on the distribution of planets. We also improve on previous models
by incorporating optimal integration time modeling that allows for the setting of desired missed-detection and
false-alarm probabilities, and by optimizing re-visit timing for systems with and without initial visit detections.
Sample DRMs are constructed and evaluated for a telescope with an internal coronagraph, an external occulter,
and a hybrid design composed of both elements.
Sensitivity analysis of the New Worlds starshade's shadow
Show abstract
This paper presents analysis showing the sensitivity of the hypergaussian starshade to various types of
errors. These errors are defined and classified. Using a single exemplar of the starshade the sensitivity to
various kinds of errors, the kind now envisioned for the New Worlds Observer mission. After review of
the basics of starshade diffraction, the error classes are defined. The errors include, static errors in global
shape, correlated errors, being the same on all petals, and uncorrelated errors, the errors being unique to
each petal edge. The effects of the first two classes of errors are evaluated using computerized numerical
solutions to the diffraction problem. In the case of uncorrelated errors, a statistical approach is taken.
New Worlds Observer: Minotaur to Ares V
Show abstract
As currently envisioned, New Worlds Observer is a NASA flagship class mission, designed to fulfill the
Terrestrial Planet Finding mission objectives with a much more flexible architecture than the current TPF
design concepts. In this paper, we discuss the scalability of NWO for a variety of telescope sizes and briefly
discuss the associated science capability. In particular, the paper will address in detail three mission categories:
medium, large, and future mission concepts. Medium missions are missions with life cycle costs under $600
million dollars, including a version of NWO that may potentially fit within a MIDEX budget. Large missions
are flagship missions that involve significant science returns on a Observatory class level; this is our current
realization of NWO for the TPF mission. Future concepts use the NWO architecture, in conjunction with
enabling technologies such as in-space servicing, to solve long-term NASA missions such as Lifefinder and
Planet Imager. We present a multi-starshade NWO architecture designed for launch on an Ares V launch
vehicle as an example of a future concept.
Performance of hybrid occulters using apodized pupil Lyot coronagraphy
Show abstract
The internal coronagraph and the external occulter have both been proposed for imaging extrasolar planets;
each has its own strengths and weaknesses. Internal coronagraphs require very accurate wavefront control,
while occulters require accurate positioning and alignment, and a precisely manufactured shape. A hybrid
occulter, which combines the two technologies, ideally reduces the tolerances on each, making both sytems more
manufacturable. Our hybrid occulter concept combines the apodized pupil Lyot coronagraph with an external
occulter. We present a number of designs which cover a wide span of suppression levels, and give a framework
for creating further families of occulters with desired potential science bandwidths, occulter angular sizes, and
diameters of the telescope secondary. All of these designs are capable of reaching 1010 contrast over their entire
spectrum of design. We also characterize the edge tolerances required for both systems.
Mission Concepts I
Pupil mapping Exoplanet Coronagraphic Observer (PECO)
Show abstract
The Pupil mapping Exoplanet Coronagraphic Observer (PECO) mission concept is a 1.4-m telescope aimed at
imaging and characterizing extra-solar planetary systems at optical wavelengths. The coronagraphic method
employed, Phase-Induced Amplitude Apodization or PIAA (a.k.a. pupil mapping) can deliver 1e-10 contrast at
2 lambda/D and uses almost all the starlight that passes through the aperture to maintain higher throughput and
higher angular resolution than any other coronagraph or nuller, making PECO the theoretically most efficient
existing approach for imaging extra-solar planetary systems. PECO's instrument also incorporates deformable
mirrors for high accuracy wavefront control. Our studies show that a probe-scale PECO mission with 1.4 m
aperture is extremely powerful, with the capability of imaging at spectral resolution R≈∠15 the habitable zones
of already known F, G, K stars with sensitivity sufficient to detect planets down to Earth size, and to map
dust clouds down to a fraction of our zodiacal cloud dust brightness. PECO will acquire narrow field images
simultaneously in 10 to 20 spectral bands covering wavelengths from 0.4 to 1.0 μm and will utilize all available
photons for maximum wavefront sensing and imaging/spectroscopy sensitivity. This approach is well suited for
low-resolution spectral characterization of both planets and dust clouds with a moderately sized telescope.
We also report on recent results obtained with the laboratory prototype of a coronagraphic low order wavefront
sensor (CLOWFS) for PIAA coronagraph. The CLOWFS is a key part of PECO's design and will enable high
contrast at the very small PECO inner working angle.
CALISTO: the Cryogenic Aperture Large Infrared Space Telescope Observatory
Show abstract
CALISTO, the Cryogenic Aperture Large Infrared Space Telescope Observatory, will enable extraordinarily high
sensitivity far-infrared continuum and moderate (R ~ 1000) resolution spectroscopic observations at wavelengths from
~30µm to ~300 μm - the wavelengths between those accessible by JWST and future ground based facilities.
CALISTO's observations will provide vital information about a wide range of important astronomical questions
including (1) the first stars and initial heavy element production in the universe; (2) structures in the universe traced by
H2 emission; (3) the evolution of galaxies and the star formation within them (4) the formation of planetary systems
through observations of protostellar and debris disks; (5) the outermost portions of our solar system through observations
of Trans-Neptunian Objects (TNOs) and the Oort cloud. With optics cooled to below 5 K, the photon fluctuations from
the astronomical background (Zodiacal, Galactic, and extragalactic) exceed those from the telescope. Detectors with a
noise equivalent power below that set by the background will make possible astronomical-background-limited sensitivity
through the submillimeter/far-infrared region. CALISTO builds on studies for the SAFIR (Single Aperture Far Infrared)
telescope mission, employing a 4m x 6m off-axis Gregorian telescope which has a simple deployment using an Atlas V
launch vehicle. The unblocked telescope with a cold stop has minimal sidelobes and scattering. The clean beam will
allow astronomical background limited observations over a large fraction of the sky, which is what is required to achieve
CALISTO's exciting science goals. The maximum angular resolution varies from 1.2" at 30 µm to 12" at 300 μm. The
5σ 1 hr detectable fluxes are ▵S(dν/ν = 1.0) = 2.2x10-20 Wm-2, and ▵S(dν/ν = 0.001) = 6.2x10-22 Wm-2. The 8 beams per
source confusion limit at 70 μm is estimated to be 5 μJy. We discuss CALISTO optics, performance, instrument
complement, and mission design, and give an overview of key science goals and required technology development to
enable this promising far IR/submm mission.
Mission Concepts II
Science with an 8-meter to 16-meter optical/UV space telescope
Show abstract
A key component of our 2008 NASA Astrophysics Strategic Mission Concept Study entitled "An Advanced
Technology Large-Aperture Space Telescope: A Technology Roadmap for the Next Decade" is the
identification of the astrophysics that can be uniquely accomplished using a filled, large-aperture UV/optical
space telescope with an angular resolution 5 - 10 times better than JWST. We summarize here four research
areas that are amongst the prime drivers for such an advanced astronomical facility: 1) the detection of
habitability and bio-signatures on terrestrial mass exoplanets, 2) the reconstruction of the detailed history of
the assembly of stellar mass in the local universe, 3) establishing the mass function and characterizing the
accretion environments of supermassive black holes out to redshifts of z ~ 7, and 4) the precise determination
of growth of structure in the universe by kinematic mapping of the dark matter halos of galaxies as functions
of time and environment.
Design study of 8 meter monolithic mirror UV/optical space telescope
Show abstract
The planned Ares V launch vehicle with its 10 meter fairing shroud and 55,000 kg capacity to the Sun Earth L2 point
enables entirely new classes of space telescopes. NASA MSFC has conducted a preliminary study that demonstrates the
feasibility of launching a 6 to 8 meter class monolithic primary mirror telescope to Sun-Earth L2 using an Ares V.
Specific technical areas studied included optical design; structural design/analysis including primary mirror support
structure, sun shade and secondary mirror support structure; thermal analysis; launch vehicle performance and trajectory;
spacecraft including structure, propulsion, GN&C, avionics, power systems and reaction wheels; operations & servicing;
mass and power budgets; and system cost.
The challenges posed by future far-IR and sub-mm space missions: an overview
Show abstract
The response to the ESA Cosmic Vision 2015-2025 Call for Proposals has confirmed a strong interest in the scientific
community for far-IR and sub-mm space science missions. Such missions would build on the heritage of projects such as
ISO, Akari, Planck, Herschel and Spitzer, with even more demanding requirements and ambitious science goals. The
paper, based on the results obtained during two ESA Technology Reference Studies, analyses the requirements of
mission studies such as the Far IR Interferometer and the Cosmic Microwave Polarisation Mapper, identifying the main
technical challenges and critical technology developments required in order to achieve an adequate level of technology
readiness in the future.
VSOP-2 project
Show abstract
VSOP-2 project is a next generation Space-VLBI project approved in Institute of Space and Astronautical Science
(ISAS) of Japan Aerospace Exploration Agency (JAXA). The nominal launch of the VSOP-2 spacecraft, ASTRO-G, is
planed in FY2012 by a HIIA rocket as the 7th astronomy satellite in ISAS/JAXA. ASTRO-G satellite will employ a
9.23-m off-axis deployable reflector antenna (LDR) with a surface accuracy of 0.4 mm rms and cryogenically cooled
receivers at 22, and 43 GHz and passively cooled receivers at 8 GHz in dual-polarization. A major axis of the orbit is
35,000 km, which will yield an angular resolution of 38 micro-arcseconds achievable at 43 GHz. Then VSOP-2 can
observe innermost regions of AGN jets and astronomical masers at 10 times higher angular resolution compared to the
previous Space-VLBI, VSOP(-1). These are ideal laboratories to experience physical phenomena in extreme conditions,
which cannot be made in any laboratories on the earth. A phase-referencing capability of ASTRO-G satellite makes
dramatic improvement of sensitivity and astrometric measurements possible. Basic design for the mechanical and
thermal parts of ASTRO-G itself is on going. The radio telescope including the LDR is in EM phase. We would present
the overview of VSOP-2 project.
Durham optical design of EUCLID, the merged SPACE/DUNE ESA Dark Energy Mission
Show abstract
The SPACE and DUNE proposals for the ESA Cosmic Vision 2015-2025 have been pre-selected for a Dark Energy
Mission. An assessment study was performed in the past few months resulting in a merged mission called EUCLID. The
study led to a possible concept for the mission and the payload, paving the way for the industrial studies. I will describe a
fully integrated optical design proposed for EUCLID as well as the different steps and difficulties to meet the optical
specifications. ESA used the optical design of the telescope, the spectroscopic channel (ex-SPACE), and the space
envelope of the visible imaging and NIR photometric channels (ex-DUNE) to derive a tentative mechanical design and
related accommodation constraints for EUCLID. Starting with the preliminary design of the DUNE mission for the
telescope and instrument, a series of modifications were made to make space for the spectroscopic channel and minimize
the weight. The design of DUNE used a 3 mirror telescope of 1.2-m and a dichroic to obtain imaging in both visible and
infrared. The design of SPACE, mostly a Durham design, was made of 4 channels each re-imaging a sub-field from the
Cassegrain focus of a 2 mirror telescope onto a Digital Micromirror Device (DMD) containing ~2.2 millions
micromirrors. A prism spectrograph followed each array. This design was modified to reduce the number of optics and
spectrographs, and add an imaging capability. The total field of EUCLID is almost 1 square degree nearly equally split
between the spectroscopic and imaging channels.
A wide-field Imaging FTS for the Molecular Hydrogen Explorer space mission (H2EX)
Show abstract
The Molecular Hydrogen Explorer (H2EX) proposed for the 2015 - 2025 Cosmic Vision Call issued by ESA in
2007 was designed to make surveys of the molecular gas from its first rotational lines in various extragalactic and
galactic sites. The design study led to the proposition of a mid-infrared (8 to 29 μm) Imaging Fourier transform
Spectrometer (IFTS) making possible integral field spectroscopy on a 20' wide field and a maximum resolution
up to 3×104 at 10 μm. To reach this goal, an all-mirror payload was outlined, made of a 1.2m telescope matched
to a dual output interferometer, imaging the field on two 1024×1024 Si:As IBC detectors. The payload was
designed to re-use the platform developed for the Planck mission. Such a wide field and high spectral resolution
IFTS on a large spectral domain can have further applications, with the necessary adaptation to each case, for
future large aperture cryogenic telescopes in the mid-infrared, or in the near-infrared behind future ELTs, in a
site like Dome C in Antarctica, and out of astronomy, for remote sensing of Earth atmosphere.
GAME: Gamma Astrometric Measurement Experiment
Show abstract
The GAME mission concept aims at the very precise measurement of the gravitational deflection of light by the
Sun, by means of an optimised telescope operating in the visible and launched in orbit on a small class satellite.
The targeted precision on the γ parameter of the Parametrised Post-Newtonian formulation of General Relativity
is 10-6 or better, i.e. one to two orders of magnitude better than the best currently available results. Such
precision is suitable to detect possible deviations from the unity value, associated to generalised Einstein models
for gravitation, with potentially huge impacts on the cosmological distribution of dark matter and dark energy.
The measurement principle is based on the differential astrometric signature on the stellar positions, i.e., based
on the spatial component of the effect rather than the temporal component as in the most recent experiments
using radio link delay timing. The observation strategy also allows some additional scientific objectives related
to other tests of General Relativity and to the study of exo-planetary field, multiple aperture Fizeau interferometer, observing simultaneously two regions close to the Solar
limb. The diluted optics approach is selected for achieving an efficient rejection of the scattered solar radiation,
while retaining an acceptable angular resolution on the science targets. We describe the science motivation, the
proposed mission profile, the possible payload implementation and the expected performance.
Interferometry from Space II: Joint Session with Conference 7013
The Space Infrared Interferometric Telescope (SPIRIT): the mission design solution space and the art of the possible
Show abstract
Although the Space Infrared Interferometric Telescope (SPIRIT) was studied as a candidate NASA Origins Probe
mission, the real world presents a broader set of options, pressures, and constraints. Fundamentally, SPIRIT is a far-IR
observatory for high-resolution imaging and spectroscopy designed to address a variety of compelling scientific
questions. How do planetary systems form from protostellar disks, dousing some planets in water while leaving others
dry? Where do planets form, and why are some ice giants while others are rocky? How did high-redshift galaxies form
and merge to form the present-day population of galaxies? This paper takes a pragmatic look at the mission design
solution space for SPIRIT, presents Probe-class and facility-class mission scenarios, and describes optional design
changes. The costs and benefits of various mission design alternatives are roughly evaluated, giving a basis for further
study and to serve as guidance to policy makers.
Technologies: Active Optics
ACCESS: a NASA mission concept study of an Actively Corrected Coronagraph for Exoplanet System Studies
Show abstract
ACCESS (Actively-Corrected Coronagraph for Exoplanet System Studies) develops the science and engineering case for
an investigation of exosolar giant planets, super-earths, exo-earths, and dust/debris fields that would be accessible to a
medium-scale NASA mission. The study begins with the observation that coronagraph architectures of all types (other
than the external occulter) call for an exceptionally stable telescope and spacecraft, as well as active wavefront
correction with one or more deformable mirrors (DMs). During the study, the Lyot, shaped pupil, PIAA, and a number
of other coronagraph architectures will all be evaluated on a level playing field that considers science capability
(including contrast at the inner working angle (IWA), throughput efficiency, and spectral bandwidth), engineering
readiness (including maturity of technology, instrument complexity, and sensitivity to wavefront errors), and mission
cost so that a preferred coronagraph architecture can be selected and developed for a medium-class mission.
Virtual wavefront compensation and speckle reduction in coronagraph by unbalanced nulling interferometer (UNI) and phase and amplitude correction (PAC)
Show abstract
We proposed a novel method based on a pre-optics setup that behaves partly as a low-efficiency coronagraph, and partly
as a high-sensitivity wavefront aberration compensator (phase and amplitude). The combination of the two effects results
in a highly accurate corrected wavefront. First, an (intensity-) unbalanced nulling interferometer (UNI) performs a
rejection of part of the wavefront electric field. Then the recombined output wavefront has its input aberrations
magnified. Because of the unbalanced recombination scheme, aberrations can be free of phase singular points (zeros) and
can therefore be compensated by a downstream phase and amplitude correction (PAC) adaptive optics system, using two
deformable mirrors. In the image plane, the central star's peak intensity and the noise level of its speckled halo are
reduced by the UNI-PAC combination: the output-corrected wavefront aberrations can be interpreted as an improved
compensation of the initial (eventually already corrected) incident wavefront aberrations. The important conclusion is
that not all the elements in the optical setup using UNI-PAC need to reach the lambda/10000 rms surface error quality. In
the experiments, we observed the aberration magnification of more than 5 times and compensated to about lambda/70
rms which is the current limit of the AO system. This means that we reached to lambda/350 level virtually. We observed
the speckle reduction in the focal plane with a coronagraph.
NIRCam Long Wavelength Channel grisms as the Dispersed Fringe Sensor for JWST segment mirror coarse phasing
Show abstract
The baseline wavefront sensing and control for James Webb Space Telescope (JWST) includes the Dispersed Hartmann
Sensors (DHS) for segment mirror coarse phasing. The two DHS devices, residing on the pupil wheel of the JWST's
Near Infrared Camera (NIRCam) Short Wavelength Channel (SWC), can sense the JWST segment mirror pistons by
measuring the heights of 20 inter-segment edges from the dispersed fringes. JWST also incorporates two identical
grisms in the NIRCam's Long Wavelength Channel (LWC). The two grisms, designed as the Dispersed Fringe Sensor
(DFS), are used as the backup sensor for JWST segment mirror coarse phasing. The versatility of DFS enables a very
flexible JWST segment coarse phasing process and the DFS is designed to have larger piston capture range than that of
DHS, making the coarse phasing more robust. The DFS can also be a useful tool during JWST ground integration and
test (I&T). In this paper we describe the DFS design details and use the JWST optical model to demonstrate the DFS
coarse phasing process during flight and ground I&T.
Technologies: Structures and Materials
Large aperture space telescope mirror fabrication trades
Show abstract
A number of upcoming astrophysical investigation concepts are based on large aperture spaceborne telescopes. The basic
science goals drive the required aperture to gather sufficient resolution and signal for reasonable integrations to complete
their planned design reference missions. In addition, certain fundamental requirements may dictate whether or not
a monolithic aperture is required or a segmented mirror array is acceptable. The operating temperature and required performance
(absolute and stability over time) are other important drivers. Based on such performance requirements a
number of mirror manufacturing trades can be performed to balance the technical performance, cost, and schedule.
We will discuss some of the overarching architectural and material trades along with particular manufacturing processes
(and their related step functions) that are integral to selecting primary mirror approaches. We will include examples
ranging from a few meters up to 16 meters which can be packaged into existing launch shrouds or in significantly expanded
future resources such as the Ares V.
Assembly of a Large Modular Optical Telescope (ALMOST)
Show abstract
Future space telescope programs need to assess in-space robotic assembly of large apertures at GEO and ESL2 to support
ever increasing aperture sizes. Since such large apertures will not fit within a fairing, they must rely on robotic
assembly/deployment. Proper assessment requires hardware-in-the-loop testing in a representative environment.
Developing, testing, and flight qualifying the myriad of technologies needed to perform such a test is complex and
expensive using conventional means. Therefore, the objective of the ALMOST program is to develop a methodology for
hardware-in-the-loop assessment of in-space robotic assembly of a telescope under micro-gravity conditions in a more
cost-effective and risk-tolerant manner. The approach uses SPHERES, currently operating inside ISS, to demonstrate inspace
robotic assembly of a telescope that will phase its primary mirror to optical tolerances to compensate for assembly
misalignment. Such a demonstration, exploiting the low cost and risk of SPHERES, will dramatically improve the
maturity of the guidance, navigation and control algorithms, as well as the mechanisms and concept of operations,
needed to properly assess such a capability.
Integrated modeling for determining launch survival and limitations for actuated lightweight mirrors
Show abstract
The future of space telescopes lies in large, lightweight, segmented aperture systems. Segmented apertures eliminate
manufacturability and launch vehicle fairing diameter as apertures size constraints. Low areal density,
actuated segments allow the systems to meet both launch mass restrictions and on-orbit wavefront error requirements.
These systems, with silicon carbide as a leading material, have great potential for increasing the
productivity, affordability, and manufacturability of future space-based optical systems.
Thus far, progress has been made on the manufacturing, sensing, actuation, and on-orbit control of such
systems. However, relatively little attention has been paid to the harsh environment of launch. The launch
environment may dominate aspects of the design of the mirror segments, with survivability requirements eliminating
many potentially good designs. Integrated modeling of a mirror segment can help identify trends in
mirror geometries that maximize launch performance, ensuring survivability without drastically over designing
the mirror. A finite element model of a single, ribbed, actuated, silicon carbide mirror segment is created, and is
used to develop a dynamic, state-space model, with launch load spectra as disturbance inputs, and mirror stresses
as performance outputs. The parametric nature of this model allows analysis of many geometrically different
mirror segments, helping to identify key parameters for launch survival. The modeling method described herein
will enable identification of the design decisions that are dominated by launch, and will allow for development
of launch-load alleviation techniques to further push the areal density boundaries in support of the creation of
larger and lighter mirrors than previously possible.
Large ultra-lightweight photonic muscle membrane mirror telescope
Show abstract
Photons weigh nothing. Why must even small space telescopes weigh tons? Primary mirrors require sub-wavelength
figure (shape) error in order to achieve acceptable Strehl ratios. Traditional telescopy methods require rigid and
therefore heavy mirrors and reaction structures as well as proportionally heavy and expensive spacecraft busses and
launch vehicles. Our team's vision is to demonstrate the technology for making giant space telescopes with 1/2000 the
areal density of the Hubble. Progress on a novel actuation approach is presented. The goal is to lay groundwork to
achieve a 10 to 100 fold improvement in spatial resolution and a factor of 10 reduction in production and deployment
cost of active optics. This entailed the synthesis and incorporation of photoactive isomers into crystals and polyimides to
develop nanomachine laser controlled molecular actuators.
A large photomechanical effect is obtained in polymers 10-50 μm thick. Laser-induced figure variations include the
following: 1) reversible bi-directional bending; 2) large deformation range; 3) high speed deformation; and 4) control
with a single laser (~0.1 W/cm2). Photolyzation data presented showing reversible semi-permanence of the
photoisomerization indicates that a scanned 1 watt laser rather than a megawatt will suffice for large gossamer structure
actuation.
Areal density can be reduced by increasing actuation. Making every molecule of a substrate an actuator approaches the
limit of the design trade space. Presented is a photomechanical system where nearly every molecule of a mirror
substrate is itself an optically powered actuator. Why must even small space telescopes weigh tons? Data suggests they
need not.
Technologies: Instruments
The Kepler photometer focal plane array
Show abstract
The Kepler instrument is designed to detect Earth size planets in the "habitable zone" orbiting 9
Lessons learned from SCUBA-2 for future cryogenic instrumentation in space
Show abstract
Various planned space astronomy missions such as SPICA, SAFIR, Constellation-X and XEUS will require detectors
operating at ultra-low temperatures. Our current relevant experience in space is limited, and future instruments are in any
case likely to have more demanding requirements. We must therefore take advantage of experience on the ground. The
SCUBA-2 ground-based instrument is probably the largest and (thermally) most complex astronomical instrument ever
built to operate at such low temperatures. The thermal design has been very successful, and I discuss techniques we have
developed and lessons we have learned that will be applicable to future space missions.
Pico meter metrology for the GAIA mission
Show abstract
To measure the relative motions of GAIA's telescopes, the angle between the telescopes is monitored by an all Silicon
Carbide Basic Angle Monitoring subsystem (BAM OMA). TNO is developing this metrology system. The stability
requirements for this metrology system go into the pico meter and pico radian range. Such accuracies require extreme
measures and extreme stability.
Specific topics addressed are mountings of opto-mechanical components, gravity deformation, materials and tests that
were necessary to prove that the requirements are feasible. Especially mounting glass components on Silicon Carbide
and mastering the Silicon Carbide material proved to be a challenge.
SPIDER: a balloon-borne large-scale CMB polarimeter
Show abstract
Spider is a balloon-borne experiment that will measure the polarization of the Cosmic Microwave Background
over a large fraction of a sky at ~ 1° resolution. Six monochromatic refracting millimeter-wave telescopes with
large arrays of antenna-coupled transition-edge superconducting bolometers will provide system sensitivities of
4.2 and 3.1 μKcmb√s at 100 and 150 GHz, respectively. A rotating half-wave plate will modulate the polarization
sensitivity of each telescope, controlling systematics. Bolometer arrays operating at 225 GHz and 275 GHz will
allow removal of polarized galactic foregrounds. In a 2-6 day first flight from Alice Springs, Australia in 2010,
Spider will map 50% of the sky to a depth necessary to improve our knowledge of the reionization optical depth
by a large factor.
Poster Session: Herschel-Planck
The Herschel-SPIRE photometer data processing pipeline
Show abstract
We describe the on-board electronics chain and the on-ground data processing pipeline that will operate on data from the
Herschel-SPIRE photometer to produce calibrated astronomical products. Data from the three photometer arrays will be
conditioned and digitised by on-board electronics and sent to the ground with no further on-board data processing. On
the ground, the data pipeline will process the data from point source, jiggle-map, and scan-map observations in a fully
automatic manner, producing measured flux densities (for point source observations) or maps. It includes calculation of
the bolometer voltages from the raw telemetry, glitch removal, and corrections for various effects including time
constants associated with the detectors and electronics, electrical and optical crosstalk, detector temperature drifts, flatfielding,
and non-linear response of the bolometers to strong sources. Flux density calibration will be with respect to
standard astronomical sources with the planets Uranus and Neptune being adopted as the baseline primary standards.
The pipeline will compute estimated values of in-beam flux density for a standard flat νS(ν) source spectrum.
The ESA Herschel Telescope Tiger Team metrology review: test results
Show abstract
ESA commissioned a Tiger Team to review the discrepancy between the prediction and measurement of the telescope
back focal length. A team of 16 engineers and scientists collocated at ESA's Estec facility to review the test results in
the context of the mission requirements and predictions for behavior of the telescope. Extensive analysis was performed
on the random and systematic errors in the test results. Both room temperature and cryogenic test data was scrutinized.
Error budgets, test results, and conclusions from the Tiger Team will be discussed.
The ESA Herschel Telescope Tiger Team metrology review: modeling
Show abstract
ESA commissioned a Tiger Team to review the discrepancy between the prediction and measurement of the telescope
back focal length. A team of 16 engineers and scientists collocated at ESA's Estec facility to review the finite element
models, optical models, and supporting data to validate the methodology of prediction and verify the results. The team
used several modeling techniques including: paraxial models, first order thermal expansion models, full system and
metrology raytracing, deterministic and stochastic finite element models. The techniques, assumptions, and results will
be discussed.
The data processing pipeline for the Herschel/SPIRE imaging Fourier Transform Spectrometer
Show abstract
We present the data processing pipeline to generate calibrated data products from the Spectral and Photometric Imaging
Receiver (SPIRE) imaging Fourier Transform Spectrometer. The pipeline processes telemetry from SPIRE point source,
jiggle- and raster-map observations, producing calibrated spectra in low-, medium-, high-, and mixed low- and highresolution
modes. The spectrometer pipeline shares some elements with the SPIRE photometer pipeline, including the
conversion of telemetry packets into data timelines and the calculation of bolometer voltages from the raw telemetry. We
present the following fundamental processing steps unique to the spectrometer: temporal and spatial interpolation of the
stage mechanism and detector data to create interferograms; apodization; Fourier transform, and creation of a
hyperspectral data cube. We also describe the corrections for various instrumental effects including first- and secondlevel
glitch identification and removal, correction of the effects due to the Herschel primary mirror and the spectrometer
calibrator, interferogram baseline correction, channel fringe correction, temporal and spatial phase correction, non-linear
response of the bolometers, variation of instrument performance across the focal plane arrays, and variation of spectral
efficiency. Astronomical calibration is based on combinations of observations of standard astronomical sources and
regions of space known to contain minimal emission.
Characterisation of Herschel-SPIRE flight model optical performances
Show abstract
The Spectral and Photometric Imaging Receiver (SPIRE) is one of three scientific instruments on ESA's Herschel Space
Observatory. This long wavelength instrument covers 200 to 670μm with a three band photometric camera and a two
band imaging Fourier Transform Spectrometer (IFTS). Following first results reported in a previous paper, we discuss
the in-band optical performances of the flight model as measured extensively during several dedicated test campaigns.
Complementary to the experimentally probed spectral characteristics of the instrument detailed in an accompanying
paper (see L.D. Spencer et al., in these proceedings), attention is focused here on a set of standard but key tests aimed at
measuring the spatial response of the Photometer and Spectrometer end-to-end optical chain, including detector. Effects
of defocus as well as source size extent, in-band wavelength, and polarization are also investigated over respective
Photometer and Spectrometer field-of-views. Comparison with optical modelling, based on instrument design knowledge
and some of the internal component measured characteristics, is performed. Beyond the specific characterisation of each
effect, this allows estimating in each band where optical behaviour and detector behaviour respectively dominates and
also reconstructing some of the contributors to the instrument throughput. Based on this analysis, retrieved optical
performances are finally assessed against the related science-driven instrument requirements.
Poster Session: AKARI-SPITZER
Stability of the Infrared Array Camera for the Spitzer Space Telescope
Show abstract
We present an analysis of the stability of the Infrared Array Camera (IRAC) on board the Spitzer Space Telescope over
the first 4.5 years of in-flight operations. IRAC consists of two InSb and two Si:As 256x256 imaging arrays with
passbands centered on 3.6, 4.5. 5.8 and 8.0 microns. Variations in photometric stability, read noise, dark offsets, pixel
responsivity and number of hot and noisy pixels for each detector array are trended with time. To within our
measurement uncertainty, the performance of the IRAC arrays has not changed with time. The most significant variation
is that number of hot pixels in the 8 micron array has increased linearly with time at a rate of 60 pixels per year. We
expect that the 3.6 and 4.5 micron arrays should remain stable during the post-cryogenic phase of the Spitzer mission.
We will briefly discuss some science that is enabled by the excellent stability of IRAC.
Improving the photometric precision of IRAC Channel 1
Show abstract
Planning is underway for a possible post-cryogenic mission with the Spitzer Space Telescope. Only Channels 1
and 2 (3.6 and 4.5 μm) of the Infrared Array Camera (IRAC) will be operational; they will have unmatched
sensitivity from 3 to 5 microns until the James Webb Space Telescope is launched. At SPIE Orlando, Mighell
described his NASA-funded MATPHOT algorithm for precision stellar photometry and astrometry and presented
MATPHOT-based simulations that suggested Channel 1 stellar photometry may be significantly improved by
modeling the nonuniform RQE within each pixel, which, when not taken into account in aperture photometry,
causes the derived flux to vary according to where the centroid falls within a single pixel (the pixel-phase
effect). We analyze archival observations of calibration stars and compare the precision of stellar aperture
photometry, with the recommended 1-dimensional and a new 2-dimensional pixel-phase aperture-flux correction,
and MATPHOT-based PSF-fitting photometry which accounts for the observed loss of stellar flux due to the
nonuniform intrapixel quantum efficiency. We show how the precision of aperture photometry of bright isolated
stars corrected with the new 2-dimensional aperture-flux correction function can yield photometry that is almost
as precise as that produced by PSF-fitting procedures. This timely research effort is intended to enhance the
science return not only of observations already in Spitzer data archive but also those that would be made during
the Spitzer Warm Mission.
In-orbit focal adjustment of the AKARI telescope with and without liquid helium cryogen
Show abstract
The AKARI satellite carries a cryogenically cooled telescope of an F/6 Richey-Chetien system with a sandwich-type
silicon carbide (SiC) primary mirror of 685mm in effective diameter. The AKARI satellite ran out of the liquid helium
(LHe) cryogen on 26 August 2006. With LHe the telescope system was kept around 6K, whereas it is kept around 40K
by the on-board cryocoolers after the LHe exhaustion. The telescope system has a focus adjustment mechanism in the
secondary mirror assembly. The telescope focus on orbit was adjusted referring to images taken with the Infrared
Camera (IRC) on board. The focus adjustment was made both at 6 and 40K. The in-orbit imaging performance at 6K
was estimated to be diffraction limited at 7.3μm, a little worse than the laboratory measurements prior to the launch. It
was slightly degraded to be approximately diffraction limited at 8μm at 40K as expected from the laboratory test, but the
movement of the focus position was in the opposite sense to the ground test. The AKARI mission provided us data of the
focus shift with temperature on orbit for the first time. We report an overview of the AKARI telescope system and the
focus adjustment operations at 6 and 40K.
Data reduction techniques for slit and slit-less spectroscopy of diffuse emission with the Infrared Camera onboard AKARI
Show abstract
Infrared Camera (IRC) onboard AKARI satellite has carried out more than 4000 pointed observations during the phases
1 and 2, a significant amount of which were performed in the spectroscopic mode. In this paper, we investigate the
properties of the spectroscopic data taken with MIR-S channel and propose a new data reduction procedure for slit-less
spectroscopy of sources embedded in complicated diffuse background structures. The relative strengths of the 0th to 1st
order light as well as the efficiency profiles of the 2nd order light are examined for various objects taken with MIR-S
dispersers. The boundary shapes of the aperture mask are determined by using the spectroscopic data of uniform zodiacal
emission. Based on these results, if the appropriate template spectra of zodiacal light emission and the diffuse
background emission are prepared and the geometries of the diffuse structures are obtained by the imaging data, we can
reproduce the slit-less spectroscopic patterns made by a uniform zodiacal emission and the diffuse background emission
by a convolution of those template profiles. This technique enables us to obtain the spectra of infrared sources in highly
complicated diffuse background and/or foreground structures, such as in the Galactic plane and in nearby galaxies.
Poster Session: SPICA-WISE
Mid-infrared coronagraph for SPICA
Show abstract
The SPace Infrared telescope for Cosmology and Astrophysics (SPICA) is a infrared space-borne telescope mission of
the next generation following AKARI. SPICA will carry a telescope with a 3.5 m diameter monolithic primary mirror
and the whole telescope will be cooled to 5 K. SPICA is planned to be launched in 2017, into the sun-earth L2 libration
halo orbit by an H II-A rocket and execute infrared observations at wavelengths mainly between 5 and 200 micron. The
large telescope aperture, the simple pupil shape, the capability of infrared observations from space, and the early launch
gives us with the SPICA mission a unique opportunity for coronagraphic observation. We have started development of a
coronagraphic instrument for SPICA. The primary target of the SPICA coronagraph is direct observation of extra-solar
Jovian planets. The main wavelengths of observation, the required contrast and the inner working angle (IWA) of the
SPICA coronagraph are set to be 5-27 micron (3.5-5 micron is optional), 10-6, and a few λ/D (and as small as possible),
respectively, in which λ is the observation wavelength and D is the diameter of the telescope aperture (3.5m). For our
laboratory demonstration, we focused first on a coronagraph with a binary shaped pupil mask as the primary candidate
for SPICA because of its feasibility. In an experiment with a binary shaped pupil coronagraph with a He-Ne laser
(λ=632.8nm), the achieved raw contrast was 6.7×10-8, derived from the average measured in the dark region without
active wavefront control. On the other hand, a study of Phase Induced Amplitude Apodization (PIAA) was initiated in an
attempt to achieve better performance, i.e., smaller IWA and higher throughput. A laboratory experiment was performed
using a He-Ne laser with active wavefront control, and a raw contrast of 6.5×10-7 was achieved. We also present recent
progress made in the cryogenic active optics for SPICA. Prototypes of cryogenic deformable by Micro Electro
Mechanical Systems (MEMS) techniques were developed and a first demonstration of the deformation of their surfaces
was performed with liquid nitrogen cooling. Experiments with piezo-actuators for a cryogenic tip-tilt mirror are also
ongoing.
Cryogenic system for the infrared space telescope SPICA
Show abstract
The SPICA mission has been proposed to JAXA as the second Japanese IR space telescope to be launched in 2017. The
SPICA spacecraft, launched with an H-IIA launch vehicle, is to be transferred into a halo orbit around the Sun-Earth L2,
where effective radiant cooling is feasible owing to solar rays and radiant heat fluxes from the Earth constantly coming
from the same direction. That optimal thermal environment enables this IR space telescope to use a large 3.5-mdiameter-
single-aperture primary mirror cooled to 4.5 K with advanced mechanical cryocoolers and effective radiant
cooling instead of a massive and short-lived cryogen. As a result of thermal and structural analyses, the thermal design of
cryogenic system was obtained. Then, mechanical cryocoolers have been developed to meet cooling requirement at 1.7
K, 4.5 K and 20 K. The latest results of upgrading of the 20 K-class two-stage Stirling cooler, the 4K-class JT cooler,
and the 1K-class JT cooler indicate that all cryocoolers gain a sufficient margin of cooling capacity with unprecedentedly
low power consumption for the cooling requirement. It is concluded that the feasibility of the SPICA mission was
confirmed for the critical cryogenic system design, while some attempts to achieve higher reliability, higher cooling
capacity and less vibration have been continued for stable operations throughout the entire mission period.
Mid-infrared high-resolution spectrograph for SPICA
Show abstract
We present a preliminary optical design and layout for the mid-infrared (4-18 μm) high-resolution spectrograph for
SPICA, Japanese next-generation space IR observatory with 3.5 m telescope. MIR high-resolution spectroscopy
is a powerful probe to study gas-phase molecules/atoms in a variety of astronomical objects. Space observation
provides a great opportunity to study many molecular lines especially in between the atmospheric windows.
SPICA gives us a chance to realize MIR high-resolution spectroscopy from space with the large telescope aperture.
The major technical challenge is the size of the spectrograph, which tends to be too large for space. We hope to
overcome this problem with a novel MIR immersion grating, which can make the instrument smaller by a factor
of the refractive index of the grating material. We plan to fabricate a large pitch ZnSe (n = 2.4) immersion
grating with the fly-cutting technique at LLNL (see Poster paper 7018-183 by Ikeda et al.1 and 7018-181 by
Kuzmenko et al.2 in the proceedings of this conference). We show our preliminary spectrograph designs with
a spectral resolution of ~30,000 in 4-8 μm (short mode) and 12-18 μm (long mode). The instrument size can
be as small as 200 × 400 mm thanks to the MIR immersion gratings. With unprecedented spectral resolution
in space, which is 10-times higher than ISO-SWS, the high-resolution spectrograph for SPICA (SPICA-HIRES)
could be a unique instrument that can provide most sensitive and clear spectra of this kind.
Poster Session: JWST
The on-ground calibration of the Near Infrared Spectrograph (NIRSpec instrument on-board the James Webb Space Telescope (JWST)
Show abstract
The James Webb Space Telescope (JWST) mission is a collaborative project between the National Aeronautics and
Space Administration (NASA), the European Space Agency (ESA) and the Canadian Space Agency (CSA).
JWST is considered the successor to the Hubble Space Telescope (HST) and although its design and science objectives
are quite different, JWST is expected to yield equivalently astonishing breakthroughs in infrared space science.
Due to be launched in 2013 from the French Guiana, the JWST observatory will be placed in an orbit around the anti-
Sun Earth-Sun Lagrangian point, L2, by an Ariane 5 launcher provided by ESA.
The payload on board the JWST observatory consists of four main scientific instruments: a near-infrared camera
(NIRCam), a mid-infrared camera/spectrograph (MIRI), a near-infrared tunable filter (TFI) and a near-infrared
spectrograph (NIRSpec). The instrument suite is completed by a Fine Guidance Sensor (FGS).
NIRSpec is a multi-object spectrograph capable of measuring the spectra of about 100 objects simultaneously at low
(R~100), medium (R~1000) and high (R~2700) resolutions over the wavelength range between 0.6 micron and 5.0
micron. It features also a classical fix-slits spectroscopy mode as well as a 3D-spectrography mode with spectral
resolutions up to 2700.
The availability of extensive and accurate calibration data of the NIRSpec instrument is a key element to ensure that the
nominal performance of the instrument will be achieved and that high-quality processed data will be made available to
the users. In this context, an on-ground calibration is planned at instrument level that will supplement the later in-flight
calibration campaign.
In this article we describe the overall on-ground instrument calibration campaigns and we provide an overview of the
main features and performances of the individual elements of the sophisticated cryogenic optical ground support
equipment (OGSE) used to calibrate NIRSpec.
JWST fine guidance sensor: guiding performance analysis
Show abstract
The Engineering Test Unit (ETU) of the Fine Guidance Sensor (FGS) for the James Webb Space Telescope (JWST) is
currently in fabrication. Extensive modeling of the key FGS-Guider performance parameters has been used throughout
the design process and continues to be used to evaluate the expected performance of the as-built instrument. A key
parameter of interest is the expected Noise Equivalent Angle (NEA) provided by the FGS. The NEA will, in part,
determine the ultimate image quality of the JWST Observatory. In this paper we use updated estimates of the End-oflife
impact of contamination to present the current expected NEA performance of the FGS flight model. As component
test data becomes available this data will be used as input to the FGS NEA performance model to assess the expected
performance of the instrument.
JWST tunable filter imager: etalon prototype test results
Show abstract
We present the prototyping results and laboratory characterization of a narrow band Fabry-Perot etalon flight model
which is one of the wavelength selecting elements of the Tunable Filter Imager. The latter is a part of the Fine Guidance
Sensor which represents the Canadian contribution to NASA's James Webb Space Telescope. The unique design of this
etalon provides the JWST observatory with the ability to image at 30 Kelvin, a 2.2'x2.2' portion of its field of view in a
narrow spectral bandwidth of R~100 at any wavelength ranging between 1.6 and 4.9 μm (with a gap in coverage
between 2.5 and 3.2 μm). Extensive testing has resulted in better understanding of the thermal properties of the
piezoelectric transducers used as an actuation system for the etalon gap tuning. Good throughput, spectral resolution and
contrast have been demonstrated for the full wavelength range.
MIRI Telescope Simulator
T. Belenguer,
M. A. Alcacera,
A. Aricha,
et al.
Show abstract
The MTS, MIRI Telescope Simulator, is developed by INTA as the Spanish contribution of
MIRI (Mid InfraRed Instrument) on board JWST (James Web Space Telescope).
The MTS is considered as optical equipment which is part of Optical Ground Support
Equipment for the AIV/Calibration phase of the instrument at Rutherford Appleton
Laboratory, UK.
It is an optical simulator of the JWST Telescope, which will provide a diffractionlimited test
beam, including the obscuration and mask pattern, in all the MIRI FOV and in all defocusing
range. The MTS will have to stand an environment similar to the flight conditions (35K) but
using a smaller set-up, typically at lab scales.
The MTS will be used to verify MIRI instrument-level tests, based on checking the
implementation/realisation of the interfaces and performances, as well as the instrument
properties not subject to interface control such as overall transmission of various modes of
operation.
This paper includes a functional description and a summary of the development status.
First results from MIRI verification model testing
Show abstract
The Mid-Infrared Instrument (MIRI) is one of the three scientific instruments to fly on the James Webb Space
Telescope (JWST), which is due for launch in 2013. MIRI contains two sub-instruments, an imager, which has low
resolution spectroscopy and coronagraphic capabilities in addition to imaging, and a medium resolution IFU
spectrometer. A verification model of MIRI was assembled in 2007 and a cold test campaign was conducted between
November 2007 and February 2008. This model was the first scientifically representative model, allowing a first
assessment to be made of the performance. This paper describes the test facility and testing done. It also reports on the
first results from this test campaign.
Optical ground support equipment for the alignment of JWST-NIRSpec
Show abstract
The alignment of the JWST NIRSpec spectrograph will use a customised set of optical light sources, imagers and wavefront sensors, which form part of the Optical Ground Support Equipment (OGSE). This has been developed by the Mullard Space Science Laboratory (MSSL) and the Centre for Advanced Instrumentation (CfAI) to be used at the Astrium GmbH, Ottobrunn (Germany) during NIRSpec integration. This paper describes the five precision illumination sources which form a key part of NIRSpec OGSE, and the optomechanical design of the three Shack-Hartmann wavefront sensors used.
Cryogenic pupil alignment test architecture for the James Webb Space Telescope integrated science instrument module
Show abstract
The James Webb Space Telescope (JWST) is a space-based, infrared observatory designed to study the early stages of
galaxy formation in the Universe. It is currently scheduled to be launched in 2013 and will go into orbit about the
second Lagrange point of the Sun-Earth system and passively cooled to 30-50 K to enable astronomical observations
from 0.6 to 28 μm. The JWST observatory consists of three primary elements: the spacecraft, the optical telescope
element (OTE) and the integrated science instrument module (ISIM). The ISIM Element primarily consists of a
mechanical metering structure, three science instruments and a fine guidance sensor with significant scientific capability.
One of the critical opto-mechanical alignments for mission success is the co-registration of the OTE exit pupil with the
entrance pupils of the ISIM instruments. To verify that the ISIM Element will be properly aligned with the nominal
OTE exit pupil when the two elements come together, we have developed a cryogenic pupil measurement test
architecture to measure three of the most critical pupil degrees-of-freedom during optical testing of the ISIM Element.
The pupil measurement scheme makes use of: specularly reflective pupil alignment references located inside of the
JWST instruments; ground support equipment that contains a pupil imaging module; an OTE simulator; and pupil
viewing channels in two of the JWST flight instruments. Current modeling and analysis activities indicate this
measurement approach will be able to verify pupil shear to an accuracy of 0.5-1%.
Microshutter arrays: high contrast programmable field masks for JWST NIRSpec
Show abstract
Microshutter arrays are one of the novel technologies developed for the James Webb Space Telescope (JWST).
It will allow Near Infrared Spectrometer (NIRSpec) to acquire spectra of hundreds of objects simultaneously
therefore increasing its efficiency tremendously. We have developed these programmable arrays that are based
on Micro-Electro Mechanical Structures (MEMS) technology. The arrays are 2D addressable masks that can
operate in cryogenic environment of JWST. Since the primary JWST science requires acquisition of spectra
of extremely faint objects, it is important to provide very high contrast of the open to closed shutters. This
high contrast is necessary to eliminate any possible contamination and confusion in the acquired spectra by
unwanted objects. We have developed and built a test system for the microshutter array functional and optical
characterization. This system is capable of measuring the contrast of the mciroshutter array both in visible and
infrared light of the NIRSpec wavelength range while the arrays are in their working cryogenic environment. We
have measured contrast ratio of several microshutter arrays and demonstrated that they satisfy and in many
cases far exceed the NIRSpec contrast requirement value of 2000.
The Optical Telescope Element Simulator for the James Webb Space Telescope
Show abstract
The James Webb Space Telescope Observatory will consist of three flight elements: (1) the Optical Telescope Element
(OTE), (2) the Integrated Science Instrument Module Element (ISIM), and (3) the Spacecraft Element. The ISIM
element consists of a composite bench structure that uses kinematic mounts to interface to each of the optical benches of
the three science instruments and the guider. The ISIM is also kinematically mounted to the telescope primary mirror
structure. An enclosure surrounds the ISIM structure, isolates the ISIM region thermally from the other thermal regions
of the Observatory, and serves as a radiator for the science instruments and guider. Cryogenic optical testing of the ISIM
Structure and the Science Instruments will be conducted at Goddard Space Flight Center using an optical telescope
simulator that is being developed by a team from Ball Aerospace and Goddard Space Flight Center, and other local
contractors. This simulator will be used to verify the performance of the ISIM element before delivery to the Northup
Grumman team for integration with the OTE. In this paper, we describe the O
OTE Sim TE Simulator (OSIM) and provide a brief
overview of the optical test program.
ulator
Optical coating performance for heat reflectors of JWST-ISIM electronic component
Show abstract
The James Webb Space Telescope (JWST) consists of an infrared-optimized Optical Telescope Element (OTE)
that is cooled down to 40 degrees Kelvin. A second adjacent component to the OTE is the Integrated Science
Instrument Module, or ISIM. This module includes the electronic compartment, which provides the mounting
surfaces and ambient thermally controlled environment for the instrument control electronics. Dissipating the 200
watts generated from the ISIM structure away from the OTE is of paramount importance so that the spacecraft's
own heat does not interfere with the infrared light detected from distant cosmic sources. This technical challenge
is overcome by a thermal subsystem unit that provides passive cooling to the ISIM control electronics. The
proposed design of this thermal radiator consists of a lightweight structure made out of composite materials
and low-emittance metal coatings. In this paper, we will present characterizations of the coating emittance,
bidirectional reflectance, and mechanical structure design that will affect the performance of this passive cooling
reflector.
IQLAC: a data analysis system for the NIRSpec on-ground test campaign
Show abstract
The future James Webb Space Telescope (JWST), developed jointly by the American, European and Canadian
space agencies (NASA, ESA and CSA), is scheduled for launch in 2013. The near-infrared spectrograph NIRSpec
will be a major element of its instrument suite and is built by EADS Astrium for ESA. NIRSpec is a multiobject
spectrograph allowing astronomers to obtain the spectra of more than one hundred objects in a single
exposure. NIRSpec is currently under construction and, when finished, will be subjected to a stringent onground
test campaign to verify its performance. These tests are conducted in collaboration with ESA. A rapid
and reliable system to handle and analyse the data is crucial in this phase as the time available to run the
cryogenic tests is limited. To facilitate this process we are developing a toolbox of dedicated algorithms and
interactive visualisation modules. These standalone modules form the basis of the Instrument Quick Look
Analysis and Calibration (IQLAC) software. Individual workflows, optimized for specific tests, can then be
generated efficiently using this toolbox. Furthermore, this set of dedicated algorithms will provide a reference
frame for the development of the operational data processing software by ESA.
Performance results of the TFI coronagraphic occulting mask prototypes
Show abstract
The JWST Fine Guidance Sensor (FGS) Tunable Filter Imager (TFI) will feature a coronagraph for high contrast
imaging applications. TFI will provide unique narrow-band imaging and coronagraphic capabilities impacting the
detection of "First Light", i.e. stellar systems formed just after the Big Bang, and the detection and characterization of
exoplanets. The TFI coronagraph is made of a set of four occulting spots and four Lyot stops. The TFI focal-plane masks
under consideration are apodized (Gaussian profile) or hard masks. The masks are operating in reflection and
implemented as small cones directly engraved on the pick-off mirror located at the telescope focus. This paper presents
laboratory performance of two prototype masks. The hard mask results are in good agreement with the expected
performance of a standard Lyot coronagraph. On the other hand, the halftone mask shows significant departure from
theoretical expectation; these results could be due to diffraction effects within the halftone mask.
The JWST MIRI double-prism: design and science drivers
Show abstract
We present how it is achieved to mount a double prism in the filter wheel of MIRIM - the imager of JWST's Mid
Infrared Instrument. In order to cope with the extreme conditions of the prisms' surroundings, the low resolution
double prism assembly (LRSDPA) design makes high demands on manufacturing accuracy. The design and the
manufacturing of the mechanical parts are presented here, while 'Manufacturing and verification of ZnS and Ge
prisms for the JWST MIRI imager' are described in a second paper [1]. We also give insights on the astronomical
possibilities of a sensitive MIR spectrometer. Low resolution prism spectroscopy in the wavelength range from
5-10 microns will allow to spectroscopically determine redshifts of objects close to/at the re-ionization phase of
the universe.
Fabrication and test of silicon grisms for JWST-NIRCam
Show abstract
We report on the design, fabrication, and evaluation of a set of silicon grisms for the NIRCam instrument on
NASA's James Webb Space Telescope. The primary purpose of these devices is to aid in the alignment of JWST's
deployable primary mirror. The grisms will also offer opportunities for slitless astronomical spectroscopy. The
design of the grisms was driven by a need to fit into a constrained space, by a need for high resolving power
across a broad spectral band, and by the need to survive the cosmic ray dosage to which the instrument will
be subjected. The University of Texas Silicon Grating Laboratory is fabricating four identical grisms to cover
2.5-5 μm with a resolving power of 1770 at the blaze wavelength. There will be two grisms, with dispersion axes
oriented at 90°, in each arm of the NIRCam long-wavelength camera. We pattern the gratings lithographically
onto high resistivity float-zone silicon prisms following the recipe developed for the recently completed grism
suite for the FORCAST camera on SOFIA. We discuss the design and production of the NIRCam devices and
present the results of the optical testing of the grating surfaces showing that the devices will likely exceed their
performance requirements.
Poster Session: JDEM
Three mirror anastigmat survey telescope optimization
Show abstract
We investigate practical implementations of the Korsch1 (1977) annular field three mirror anastigmat
(AFTMA) telescope. This TMA offers a wide, diffraction-limited field of view (FOV) suitable for
space-based survey missions. The advantages of this configuration include superior stray light
baffling (distinct exit pupil) and the wide range of available focal lengths available from
geometrically similar configurations. Key in the design of an AFTMA is the location of the
Cassegrain focus (CF) and the exit pupil (EP). We investigate the effects of telescope geometry and
optimization constraints on the location of the CF and EP, and suggest a family of geometries
suitable for practical and vignetting-free AFTMA designs. The space of practical designs is
generalized in terms of mirror diameter, telescope focal ratio and field of view for an annular,
detector-tiled focal plane. Focal ratios between roughly f/10 and f/25 produce a geometric blur of
less than 0.1arcsec. For this range of f/numbers, the focal plane should be less than ½ the primary
mirror (PM) diameter, and the cross-axis should be located roughly 0.6 PM diameters behind the PM
vertex.
First results for the spectro-photometry calibration of the SNAP spectrograph demonstrator in the visible range
Show abstract
A visible and infrared spectrograph based on integral field method (IFU) using the slicer technology is proposed
for the SNAP(SuperNovae/Acceleration Probe) mission. The spectrograph is a key element to control supernovae
Type Ia measurements and to calibrate standards stars at the per cent level. The current concept has a low
spectral resolution (about 100) and is under-sampled in the infrared arm. A demonstrator has been manufactured
and is used to validate the performances. The calibration procedure has been developed using a full simulation
of the instrument at the pixel level and tested with the demonstrator. We present the first experimental results
performed in the visible range and we compare them with the results predicted by the simulation.
Poster Session: Cornography
Design and demonstration of hybrid Lyot coronagraph masks for improved spectral bandwidth and throughput
Show abstract
Coronagraph focal-plane occulting masks have generally been described in terms of attenuation profiles free of any
phase shift. However, phase shifts are expected and observed in physical occulting masks, with significant effect at
billion-to-one coronagraph contrast levels in spectrally broad light, as required for the direct imaging and spectroscopy
of nearby exoplanet systems.
We report progress in the design and fabrication of hybrid focal-plane masks for Lyot coronagraphy. These masks,
composed of thickness-profiled metallic and dielectric thin films superimposed on a glass substrate, are in principle
band-limited in both the real and imaginary parts of the occulter characteristics. Together with a deformable mirror for
control of wavefront phase, these masks offer Lyot coronagraph contrast performance better than 10-9 over spectral
bandwidths of 30% or more with throughput efficiencies up to 67%. We report recent laboratory coronagraph
demonstrations with vacuum-deposited nickel masks on fused silica, and preparations for the fabrication of masks with
superimposed metal and dielectric layers.
Diffraction effects in a giant saw-toothed edge externally occulted solar coronagraph
Show abstract
Typical diffraction and vignetting effects associated to the use of both externally and internally occulted coronagraphs
make the innermost solar corona quite unobserved. However, by increasing the distance between the coronagraph
telescope and the external occulter to hundred of meters, it is possible to observe the solar corona down to 1.01 solar
radii without vignetting. This is the case of ASPIICS (Association de Satellites Pour l'Imagerie et l'Interférométrie
Coronographique Solaire), a mission proposed to ESA for the PROBA3 program for formation flying. ASPIICS foresees
two satellites: the external occulter is located on one spacecraft, and the telescope on the other.
In this work we present the results obtained by a theoretical analysis of the apodization of the external occulter. This
technique allows the reduction of the diffracted light contribution. We have developed a code that can simulates the
effects of the giant external occulter (1 m diameter) on the photospheric light, and calculates the intensity of the
diffracted light on the coronagraph entrance aperture. It is possible, in this way, to analyze various shapes of the occulter
edge. In particular, we have focused our attention in the case of the serrated disc with variable number of teeth of
different length. We considered the simple occurrence of a point-like monochromatic source at infinity. The results show
that, employing a toothed disc, improvement of the S/N ratio of many order of magnitude (whit respect to a simple
circular flat disc) can be obtained.
In-flight validation of the formation flying technologies using the ASPIICS/PROBA-3 giant coronagraph
Show abstract
Classical externally-occulted coronagraphs are presently limited in their performances by the distance between
the external occulter and the front objective. Formation flyers open new perspectives and allow conceiving giant,
externally-occulted coronagraphs using two-spacecraft system. The PROBA-3 formation flying demonstration
mission, currently in its preparatory study phase, is intended to incorporate the ASPIICS (Association de
Satellites Pour l'Imagerie et l'Interfromtrie de la Couronne Solaire) scientific payload. ASPIICS is a solar
coronagraph designed to observe from the coronal base out to 3 solar radii with high spatial resolution in the
visible range. Formation flying technique imposes new constraints and major challenges in particular in terms
of metrology. ASPIICS will both use and demonstrate the formation flying features and performances. In order
to fully validate the formation flying technique and to improve the scientific return, original developments linked
to the formation flying constraints have been made these last years and are presented in this article.
Planetscope: an exoplanet coronagraph on a balloon platform
Show abstract
Direct detection of mature exoplanets is possible using a visible-wavelength telescope and coronagraph in the
stratosphere. We analyze two sources of dynamic wavefront perturbations: turbulence in the free atmosphere and locally
generated turbulence. We find that they are expected to have relatively small effects on the wavefront. We find that
neither source should limit observations at 10-9 contrast levels for planet-star separations of 0.5 arcsec. On this basis, we
expect that it is feasible to image and characterize several known radial-velocity exoplanets.
Poster Session: TPF
Verification, validation, and testing the New Worlds Observer: first thoughts
Show abstract
The New Worlds Observer is mission concept for detection of extra-solar planets made up of two spacecraft, one hosting the starshade and the other the telescope and detectors. These two spacecraft are located ten of thousands of kilometers apart, making full scale terrestrial based testing impossible. Key elements include (a) the starshade, a large scale precision structure; (b) alignment sensors accurate to a meter laterally at 20-80 megameter distances; and (c) high specific impulse thrusters for slew and fine alignment. Clearly, the "test as you fly" approach is simply inapplicable for this mission. However, the telescope requirements are those of a generic space astronomy observatory, alignment sensing has been simplified to solvable problems [Noecker 2007] and navigation is a straightforward application of known principles with flight heritage. From this patchwork, some cohesive testing plan is needed ensure proper performance of the system when deployed on orbit. We will describe our first thoughts on how to verify, validate and test this very large system. We will discuss the roles of subsystem and subscale testing, computer based modeling, model validation and full scale inspection.
THESIS: terrestrial and habitable zone infrared spectroscopy spacecraft
Show abstract
THESIS is a concept for a medium class mission designed for spectroscopic characterization of extrasolar planets
between 2-14 microns. The concept leverages off the recent first-steps made by Spitzer and Hubble in characterizing
the atmospheres of alien gas giants. Under favourable circumstances, THESIS is capable of identifying
biogenic molecules in habitable-zone planets, thereby determining conditions on worlds where life might exist.
By systematically characterizing many worlds, from rocky planets to gas-giants, THESIS would deliver
transformational science of profound interest to astronomers and the general public.
New Worlds Observer telescope and instrument optical design concepts
Show abstract
Optical design concepts for the telescope and instrumentation for NASA's New Worlds Observer program are presented. A four-meter multiple channel telescope is discussed, as well as a suite of science instrument concepts. Wide field instrumentation (imager and spectrograph) would be accommodated by a three-mirror-anastigmat
telescope design. Planet finding and characterization, and a UV instrument would use a separate channel that is picked off after the first two mirrors (primary and secondary). Guiding concepts are also discussed.
Analysis of exoplanet light curves with the New Worlds Observer
Show abstract
The orbital light curve of a terrestrial exoplanet will likely contain valuable information about the surface and
atmospheric features of the planet, both in its overall shape and hourly variations. We have constructed an empirically
based code capable of simulating observations with a New Worlds Observatory of Earth from any orientation, at any
time of year with continuously updated cloud and terrain coverage. By simulating these observations over a full orbital
revolution we determine that the detection of liquid surface water is possible during crescent phases of planetary systems
at high inclinations, while the detection of an obliquity / seasonal terrain change is possible at low inclinations. A New
Worlds Observer can accurately determine the rotation rate of the planet more than 50% of the time given only 5 days of
observations with a S/N of ~10.
Poster Session: Mission Concepts
The Star Formation Observatory (SFO) mission to study cosmic origins near and far
Show abstract
The Star Formation Observatory (SFO) is a 1.65m space telescope that addresses pivotal components in the 2007 NASA
Science Plan, with a primary focus on Cosmic Origins. The design under consideration provides 100 times greater
imaging efficiency and >10 times greater spectroscopic efficiency below 115 nm than existed on previous missions. The
mission has a well-defined Origins scientific program at its heart: a statistically significant survey of local, intermediate,
and high-redshift sites and indicators of star formation, to investigate and understand the range of environments,
feedback mechanisms, and other factors that most affect the outcome of the star and planet formation process. This
program relies on focused capabilities unique to space and that no other planned NASA mission will provide: near-
UV/visible (20-1100 nm) wide-field, diffraction-limited imaging; and high-efficiency, low- and high- resolution (R~40,000) UV (100-175 nm) spectroscopy using far-UV optimized coatings and recent advances in Micro-Channel Plate
(MCP) detector technology. The Observatory imager has a field of view in excess of 17' × 17' (>250 arcmin2) and uses a
dichroic to create optimized UV/blue and red/near-IR channels for simultaneous observations, employing detectors that
offer substantial quantum efficiency gains and that suffer lower losses due to cosmic rays.
Poster Session: Active Optics Technologies
Telescope multi-field wavefront control with a Kalman filter
Show abstract
An effective multi-field wavefront control (WFC) approach is demonstrated for an actuated, segmented space
telescope using wavefront measurements at the exit pupil, and the optical and computational implications of this
approach are discussed. The integration of a Kalman Filter as an optical state estimator into the wavefront control
process to further improve the robustness of the optical alignment of the telescope will also be discussed. Through a
comparison of WFC performances between on-orbit and ground-test optical system configurations, the connection (and a
possible disconnection) between WFC and optical system alignment under these circumstances are analyzed. Our
MACOS-based [2] computer simulation results will be presented and discussed.
Extraction of extrasolar planet spectra from realistically simulated wavefront-corrected coronagraphic fields
Show abstract
The observation of an extrasolar planet in reflected light using a coronagraphic telescope requires a several-orders-ofmagnitude
reduction of scattered light around a star by controlling instrumental wavefront errors with deformable
mirrors (DMs). This creates a "dark hole" in the background in which diminished speckles of scattered light are at a
level similar to or less than that of a planet. There are a number of methods for detecting the planet in this dark field,
including image subtraction from another telescope orientation. However, extracting the spectrum of the planet from
such a field may be more difficult because the chromatic variation of the speckles can hide spectral features, and the
need to disperse the light on a detector increases noise. To investigate the conditions in which spectral extractions are
feasible, a physical optics propagation simulation was created of a band-limited Lyot coronagraphic telescope with
realistic phase and amplitude errors on each optic and dual sequential DMs to correct the resulting wavefront errors. The
Electric Field Conjugation method was used to set the DMs to create a broadband (25%) dark hole from λ = 625 - 878
nm. Simulated planet spectra were then extracted from within this hole using a variety of methods including roll
subtraction and spectral filtering. The results of these experiments are presented.
Extrasolar Planetary Imaging Coronagraph (EPIC): visible nulling cornagraph testbed results
Show abstract
The Extrasolar Planetary Imaging Coronagraph (EPIC) is a NASA Astrophysics Strategic Mission Concept
under study for the upcoming Exoplanet Probe. EPIC's mission would be to image and characterize
extrasolar giant planets, and potential super-Earths, in orbits with semi-major axes between 2 and 10 AU.
EPIC will provide insights into the physical nature of a variety of planets in other solar systems
complimenting radial velocity (RV) and astrometric planet searches. It will detect and characterize the
atmospheres of planets identified by radial velocity surveys and potentially some transits, determine orbital
inclinations and masses, characterize the atmospheres of gas giants around A and F stars, observed the
inner spatial structure and colors of inner Spitzer selected debris disks. EPIC would be launched into a
heliocentric Earth trailing drift-away orbit, with a 3-year mission lifetime (5 year goal) and will revisit
planets at least three times.
The starlight suppression approach consists of a visible nulling coronagraph (VNC) that enables high order
starlight suppression in broadband light. To demonstrate the VNC approach and advance it's technology
readiness the NASA/Goddard Space Flight Center and Lockheed-Martin have developed a laboratory VNC
and have demonstrated white light nulling. We will discuss our ongoing VNC work and show the latest
results from the VNC testbed.
A SWIFTS operating in visible and near-infrared
Show abstract
SWIFTS (Stationary Wave Integrated Fourier Transform Spectrometer) is based on a very promising
technology. It permits a drastic reduction of the size of spectrometers while conserving, even improving,
their performances. We present the first attempt to realise a SWIFTS based on wave guides in glass
operating in visible and near infra-red.
Here, we present an original optical near-field detection in which nanowires of gold are used to directly
sample the evanescent standing wave in the waveguide. With this first prototype we have been able to
rebuild a spectrum with a resolution R=95.
Frequency stabilization of semiconductor lasers for onboard interferometers using both Rb-saturated absorption profiles and double-optical feedback systems
Show abstract
The precise interferometric systems employed in today's artificial satellites require semiconductor lasers of the
highest caliber. To this end, efforts to stabilize their oscillation frequencies and narrow spectrum line-widths
continue relentlessly. While a number of different approaches have been tested, none have provided overall,
long-term stability. Most recently, we employed a Doppler-free absorption line of Rb atoms, with a precision
temperature controller and an improved laser mount. In this instance, relative optical frequency stability rated
9.07×10-13≤σ(2,τ)≤7.54×10-10, in averaging time for 0.01s≤τ23s. By introducing an optical feedback, which
narrows the laser's linewidth, we obtained improved frequency stability.
Poster Session: Instruments Technologies
Programmable spectrometer using MOEMS devices for space applications
Show abstract
A new class of spectrometer can be designed using programmable components such as MOEMS which enable to tune
the beam in spectral width and central wavelength. It becomes possible to propose for space applications a spectrometer
with programmable resolution and adjustable spectral bandwidth.
The proposed way to tune the output beam is to use the diffraction effect with the so-called PMDG (Programmable
Micro Diffraction Gratings) diffractive MEMS. In that case, small moving structures can form programmable gratings,
diffracting or not the incoming light.
In the proposed concept, the MOEMS is placed in the focal plane of a first diffracting stage (using a grating for
instance). With such implementation, the MOEMS component can be used to select some wavelengths (for instance by
reflecting them) and to switch-off the others (for instance by diffracting them). A second diffracting stage is used to
recombine the beam composed by all the selected wavelengths. It becomes then possible to change and adjust the filter
in λ and Δλ.
This type of implementation is very interesting for space applications (astronomy, Earth observation, planetary
observation). Firstly because it becomes possible to tune the filtering function quasi instantaneously. And secondly
because the focal plane dimension can be reduced to a single detector (for application without field of view) or to a
linear detector instead of a 2D matrix detector (for application with field of view) thanks to a sequential acquisition of
the signal.
Precision attitude determination for an infrared space telescope
Show abstract
We have developed performance simulations for a precision attitude determination system using a focal plane star
tracker on an infrared space telescope. The telescope is being designed for the Destiny mission to measure
cosmologically distant supernovae as one of the candidate implementations for the Joint Dark Energy Mission. Repeat
observations of the supernovae require attitude control at the level of 0.010 arcseconds (0.05 microradians) during
integrations and at repeat intervals up to and over a year. While absolute accuracy is not required, the repoint precision is
challenging. We have simulated the performance of a focal plane star tracker in a multidimensional parameter space,
including pixel size, read noise, and readout rate. Systematic errors such as proper motion, velocity aberration, and
parallax can be measured and compensated out. Our prediction is that a relative attitude determination accuracy of 0.001
to 0.002 arcseconds (0.005 to 0.010 microradians) will be achievable. Attitude control will have a jitter of around 0.003
arcseconds and stability/repeatability to around 0.002 arcseconds.
MicrOmega: a VIS/NIR hyperspectral microscope for in situ analysis in space
Show abstract
MicrOmega is an ultra miniaturized spectral microscope for in situ analysis of samples. It is composed of 2 microscopes:
one with a spatial sampling of 5 μm, working in 4 color in the visible range and one NIR hyperspectral microscope in the
spectral range 0.9-4 μm with a spatial sampling of 20 μm per pixel (described in this paper). MicrOmega/NIR
illuminates and images samples a few mm in size and acquires the NIR spectrum of each resolved pixel in up to 600
contiguous spectral channels. The goal of this instrument is to analyse in situ the composition of collected samples at
almost their grain size scale, in a non destructive way. It should be among the first set of instruments who will analyse
the sample and enable other complementary analyses to be performed on it. With the spectral range and resolution
chosen, a wide variety of constituents can be identified: minerals, such as pyroxene and olivine, ferric oxides, hydrated
phyllosilicates, sulfates and carbonates; ices and organics. The composition of the various phases within a given sample
is a critical record of its formation and evolution. Coupled to the mapping information, it provides unique clues to
describe the history of the parent body. In particular, the capability to identify hydrated grains and to characterize their
adjacent phases has a huge potential in the search for potential bio-relics. We will present the major instrumental
principles and specifications of MicrOmega/NIR, and its expected performances in particular for the ESA/ExoMars
Mission.
Optical design and in situ fabrication of large telescopes on the Moon
Show abstract
We present a novel concept for the optical design and construction of large aperture astronomical telescopes on the
Moon.
1. A beam combiner that optically shuffles the 2D non-redundant aperture locations into a 1D non-redundant array and
brings them to focus on a spectrometer slit thereby encoding all the spatial frequencies of an image at a given wavelength
into a 1D image, but in such a manner that they are separable and hence allowing for construction of a 2D image at each
wavelength.
2. A process to fabricate optical and mechanical components of large telescopes in-situ using regolith material. The
optical elements can be of any size. The shapes can be flat or curved. The fabrication process employs simple apparatus
that can be robotic in nature. No special high temperature or high pressure equipment is required.
Durable silver coating for Kepler Space Telescope primary mirror
Show abstract
A durable silver coating was developed and applied to the Kepler Space Telescope primary mirror. The coating
was manufactured by an ion-assisted evaporation process and coating uniformity was better than 30-nm PTV over the
1.4-m mirror aperture. The protection scheme for silver was devised and patented twelve years ago by Lawrence
Livermore National Laboratory (LLNL) in the United States. An interference coating was added to the basic protected
silver design, to enhance the reflectance from 400-nm to the near infrared.
Phase errors in gossamer membrane primary objective gratings
Show abstract
A ribbon-shaped primary objective grating (POG) telescope lends itself to deployment in space, because it can be stowed
for transport on a roll. Unlike mirrors which need to be segmented for sizes beyond the diameter of the fairing or
payload bay, the ribbon is a continuous integral surface transported on a drum and unfurled during deployment. A flat
POG membrane abandons a standard three dimensional figure requirement of mirrors and solves the problem of making
primary objectives from tensile structures. Moreover, POG telescopes enjoy relaxed surface dimensional tolerances
compared with mirrors. We have demonstrated mathematically and empirically that the tolerance for flatness relaxes as
the receiving angle increases toward grazing exodus where the magnification of the POG is greatest. At the same time,
the tolerance for phase error is worsened as the angle of reconstruction moves toward grazing exodus. The problem will
be aggravated by the rigors of the space deployment environment. We give a mathematical treatment for the flatness and
phase error. We mention engineering methods that could ameliorate the error.
Optimal analysis for segmented mirror capture and alignment in space optics system
Show abstract
A great deal segmented mirror errors consisting of piston and tip-tilt exist when space large aperture segmented optics
system deploys. These errors will result in the departure of segmented mirrors images from the view. For that, proper
scanning function should be adopted to control actuators rotating the segmented mirror, so that the images of segmented
mirror can be put into the view and placed in the ideal position. In my paper, the scanning functions such as screw-type,
rose-type, and helianthus-type and so on are analyzed and discussed. And the optimal scanning function principle based
on capturing images by the fastest velocity is put forward. After capturing, each outer segmented mirror should be
brought back into alignment with the central segment. In my paper, the central and outer segments with surface errors
have the different figure, a new way to control the alignment accuracy is present, which can decrease the bad effects
from mirror surface and position errors effectively. As a sample, a simulation experiment is carried to study the
characteristics of different scanning functions and the effects of mirror surface and position errors on alignment
accuracy. In simulation experiment, the piston and tip-tilt errors scale and the ideal position of segmented mirror are
given, the capture and alignment process is realized by utilizing the improved optics design software ZEMAX, the
optimal scanning function and the alignment accuracy is determined.
The ST5000: a high-precision star tracker and attitude determination system
Show abstract
The University of Wisconsin's Space Astronomy Laboratory has designed and built a Star Tracker suitable for use on
sounding rockets and class D satellites. This device brings together autonomous attitude determination ("Lost in Space"
mode), multi-star tracking, and a novel form of Progressive Image Transmission (US patent #5,991,816), which allows
the device to be used as an ultra-low bandwidth imager. The Star Tracker 5000 (ST5000) reached operational status in a
suborbital sounding rocket flight in August 2007. The ST5000 determined the rocket's inertial (FK5) attitude with arcsecond
precision using its autonomous attitude determination capability, and then provided continuous sub-arc-second
tracking for the full 360-second on-target portion of the flight. The ST5000 RMS tracking error was 0.54 arc-seconds in
yaw and pitch, and 17 arc-seconds in roll. The vehicle RMS jitter was 0.5 arc-seconds in yaw and pitch, and 10 arc-seconds
in roll. The ST5000 was funded by NASA grants NAG5-7026 and NAG5-8588.
Performance study of photon imaging system for space application
Show abstract
Photon imaging system (PIS) is widely applied to astronomy observing, deep space exploration. To investigate the
system performance for space application, the process that target radiance converting to photons is presented. In this
processes, radiometry theory and astronomy units are used. Then a mathematical physical model for the imaging system
is used to calculate the system SNR. In the model, the system dark noise and the signal enhancement process are derived
as mathematical equations. The performance of the detection algorithm is also introduced to predict the PIS range
performance of the probability of detection and correct localization and the probability of false alarm based on SNR. At
last, the actual PIS range performance for space application is discussed and valuable data for space telescopes design and
deep space exploration also are provided.
Laboratory experiment of a coronagraph based on step-transmission filters
Show abstract
This paper presents the first results of a step-transmission-filter based coronagraph in the visible wavelengths. The
primary goal of this work is to demonstrate the feasibility of the coronagraph that employs step-transmission filters, with
a required contrast in the order of better than 10-5 at an angular distance larger than 4λ/D. Two 13-step-transmission
filters were manufactured with 5% transmission accuracy. The precision of the transmitted wave distortion and the
coating surface quality were not strictly controlled at this time. Although in perfect case the coronagraph can achieve
theoretical contrast of 10-10, it only delivers 10-5 contrast because of the transmission error, poor surface quality and
wave-front aberration stated above, which is in our estimation. Based on current techniques, step-transmission filters
with better coating surface quality and high-precision transmission can be made. As a follow-up effort, high-quality
step-transmission filters are being manufactured, which should deliver better performance. The step-transmission-filter
based coronagraph has the potential applications for future high-contrast direct imaging of earth-like planets.
IMaX opto-mechanical integration: the AIV process for a magnetograph
Show abstract
IMaX current status is reported on. IMaX, the Imaging Magnetograph eXperiment developed for a
Spanish consortium for the SUNRISE Mission, is a payload that will work simultaneously as a high
sensitivity polarimeter, a high resolving spectral power, and a near diffraction limited imager. Once every
mechanical element has been purchased, the assembly, integration, alignment and verification processes
(AIV process) has been carried out successfully. After a brief description of the IMaX opto-mechanical
elements that have been received, the integration sequence as well as the main results obtained during the
AIV process are presented.
Basically, AIV process consists on the opto-mechanical components assembly on the Optical Bench
(OB), the optical elements assembly on the previously integrated optomechanics, the alignment and
orientation of the opto-mechanical components, and the two-channels quality evaluation that allows to
leave the opto-mechanical components ready for the cameras integration and IMaX performance tests
characterization. Actually, the most relevant results related to the AIV process as well as the IMaX
performance firsts tests are presented.
Development of laser interferometric high-precision geometry monitor for JASMINE
Show abstract
The telescope geometry of JASMINE should be stabilized and monitored with the accuracy of about 10 to 100
picometer or 10 to 100 picoradian in root-mean-square over about 10 hours. For this purpose, a high-precision
interferometric laser metrology system is employed. One of useful techniques for measuring displacements in
extremely minute scales is the heterodyne interferometrical method. Experiment for verification of multi degree
of freedom measurement was performed and mirror motions were successfully monitored with three degree of
freedom.
The proximity electronics of the optical system for the Medusa experiment
Show abstract
MEDUSA (Martian Environmental DUst Systematic Analyzer) is one of the experiments selected for the ExoMars
mission, planned by the European Space Agency (ESA), with the scientific objective to study water and dust on Mars, in
relation to the search of signs of life forms. To achieve this goal, the MEDUSA experiment is based on an optical system
and two micro-balances, integrated together with a dust deposition and electrification sensor. This paper focuses on the
Proximity Electronics (PE) envisaged for the Optical System and reports the results obtained during the development
activities carried out in the breadboard implementation of the instrument. A photodiode amplifier with very high gain
(107) and large output dynamics was developed. The compensation of the offset due to stray light and electronic bias has
been implemented via an adaptive control. The environmental constraints imposed by the space mission to Mars have
been taken into account during the design, not only for the qualified components selection, but also for the minimization
of the overall mass and power consumption.
Six movements measurement system employed for GAIA secondary mirror positioning system vacuum tests at cryogenic temperatures
Show abstract
In this work, the optical measurement system employed to evaluate the performance of a 6 degrees of
freedom (dof) positioning mechanism under cryogenic conditions is explored. The mechanism, the flight
model of three translations and three rotations positioning mechanism, was developed by the Spanish
company SENER (for ASTRIUM) to fulfil the high performance requirements from ESA technology
preparatory program for the positioning of a secondary mirror within the GAIA Astrometric Mission. Its
performance has been evaluated under vacuum and temperature controlled conditions (up to a 10-6mbar
and 100K) at the facilities of the Space Instrumentation Laboratory (LINES) of the Aerospace Technical
Nacional Institute of Spain (INTA).
After the description of the 'alignment tool' developed to compare a fixed reference with the optical
signal corresponding to the movement under evaluation, the optical system that allows measuring the
displacements and the rotations in the three space directions is reported on. Two similar bread-boards
were defined and mounted for the measurements purpose, one containing two distancemeters, in order to
measure the displacements through the corresponding axis, and an autocollimator in order to obtain the
rotations on the plane whose normal vector is the axis mentioned before, and other one containing one
distancemeter and one autocollimator. Both distancemeter and autocollimator measurements have been
combined in order to extract the information about the accuracy of the mechanism movements as well as
their repeatability under adverse environmental conditions.
The design and experiment research on Hα and White Light Telescope
Show abstract
The H-alpha and White Light Telescope (HWT), one of the five payloads on board the Space Solar Telescope (SST), is
mainly for the observation of the chromosphere, solar flares and white light of the full solar disc, also as a location
reference for the detailed Main Optical Telescope (MOT). The HWT prototype experiment, structure analysis and modal
testing are discussed. The HWT alignment is addressed. The result of interferometric tests is presented. In order to
realize the mechanical characteristics of Hα and white light telescope (HWT), the analytical model of HWT is set up by
using the finite element analysis software MSC.PATRAN/NASTRAN, and the first several orders of natural frequencies
and modal shapes are calculated with eigenvectors method. Based on modal experiment with free hanging, single input /
multi-output methods, the modal parameters of HWT are identified. The maximum relative error between the experiment
results and the calculated results is 6.4%, and the vibration shapes of experiment are similar to ones of calculation. The
vibration environmental simulation test is accomplished to check the HWT structural strength.
Poster Session: Hubble
Wide field camera 3 ground testing and calibration
Show abstract
Wide Field Camera 3 (WFC3), a panchromatic imager developed for the Hubble Space Telescope (HST), is fully
integrated with its flight detectors and has undergone several rounds of ground testing and calibration at Goddard Space
Flight Center (GSFC). The testing processes are highly automated, with WFC3 and the optical stimulus, which is used to
provide external targets and illumination, being commanded by coordinated computer scripts. All test data are captured
and stored in the long-term Hubble Data Archive. A full suite of instrument characterization and calibration tests has
been performed, including the measurement of key detector properties such as dark current, read noise, flat field
response, gain, linearity, and persistence, as well as instrument-level properties like total system throughput, imaging
quality and encircled energy, grism dispersions, IR thermal background, and image stability. Nearly all instrument
characteristics have been shown to meet or exceed expectations and requirements.
Technical aspects of the Advanced Camera for Surveys repair
Show abstract
In January 2007, the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) lost its Wide-Field
Channel (WFC) and the High Resolution Channel (HRC) due to a failure in its Low Voltage Power Supply (LVPS). A
team was rapidly assembled to determine if the ACS could be repaired as part of HST Servicing Mission 4 (SM4). This
team includes contributors from NASA's Goddard Space Flight Center, Ball Aerospace, and Teledyne Imaging Sensors.
It determined that all of the capabilities of the ACS could be restored and created a concept for the ACS-Repair (ACS-R)
component of SM4. ACS-R will restore the WFC of ACS by replacing the existing CCD Electronics Box (CEB) with
the CEB-Replacement (CEB-R) and providing power from a new Low Voltage Power Supply Replacement (LVPS-R).
The new LVPS-R will also attempt to restore the HRC function by providing power through the original power bus. In
this presentation, we focus on the concept and technical aspects of the ACS-R.
Technical aspects of the Space Telescope Imaging Spectrograph Repair (STIS-R)
Show abstract
In August 2004, the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) ceased operation
due to a failure of the 5V mechanism power converter in the Side 2 Low Voltage Power Supply (LVPS2). The failure
precluded movement of any STIS mechanism and, because of the earlier (2001) loss of the Side 1 electronics chain, left
the instrument shuttered and in safe mode after 7.5 years of science operations. A team was assembled to analyze the
fault and to determine if STIS repair (STIS-R) was feasible. The team conclusively pinpointed the Side 2 failure to the
5V mechanism converter, and began studying EVA techniques for opening STIS during Servicing Mission 4 (SM4) to
replace the failed LVPS2 board. The restoration of STIS functionality via surgical repair by astronauts has by now
reached a mature and final design state, and will, along with a similar repair procedure for the Advanced Camera for
Surveys (ACS), represent a first for Hubble servicing. STIS-R will restore full scientific functionality of the
spectrograph on Side 2, while Side 1 will remain inoperative. Because of the high degree of complementarity between
STIS and the new Cosmic Origins Spectrograph (COS, to be installed during SM4)), successful repair of the older
spectrograph is an important scientific objective. In this presentation, we focus on the technical aspects associated with
STIS-R.
Additional Paper
Offspring of SPACE: the spectrograph channel of the ESA Dark Energy Mission EUCLID
Show abstract
The SPACE and DUNE proposals for the ESA Cosmic Vision 2015-2025 have been pre-selected for a Dark Energy
Mission. An assessment study was performed in the past few months resulting in a merged mission called EUCLID. The
study led to a possible concept for the mission and the payload, paving the way for the industrial studies. SPACE has
now become the EUCLID spectrograph channel (EUCLID-spectro). We will discuss its science and give a description of
the different studied optical designs. EUCLID-spectro aims to produce the largest three-dimensional map of the Universe
by taking near-IR spectra at R=400 and 0.9μm<λ<1.7μm for ~200 million galaxies at z<2 and H<22 over 20,000 deg2. It
will measure the expansion history of the Universe and the growth rate of structure using Baryonic Acoustic Oscillations,
redshift-space distortions and clusters of galaxies. It will distinguish true dark energy from a modification of Einstein's
gravity. The original design had 4 channels each re-imaging with mirrors a sub-field from the Casgrain focus onto a
Digital Micromirror Device (DMD). A prism spectrograph followed each array. This design was modified to adapt
EUCLID-spectro to a DUNE-type telescope, to reduce the number of optics and spectrographs, and add an imaging
capability. We studied grism spectrographs, especially for a slitless backup solution that have less optics but a smaller
field; we also studied compact prism and lens spectrographs, telescope corrector combined with micromirror arrays at
the Casgrain focus then eliminating the re-imaging, and TIR prisms over the arrays to help with packaging.