This PDF file contains the Front Matter associated with SPIE Proceedings Volume 7738, including Title page, Copyright information, Table of Contents, and Conference Committee listing.

The Advanced Technology Solar Telescope (ATST) is a four-meter class instrument being built to perform diffractionlimited observations of the sun. This paper describes how ATST has dealt with system safety and in particular hazard analysis during the design and development (D&D) phase. For ATST the development of a system safety plan and the oversight of the hazard analysis fell, appropriately, to systems engineering. We have adopted the methodology described in MIL-STD-882E, "Standard Practice for System Safety." While these methods were developed for use by the U.S. Department of Defense, they are readily applicable to the safety needs of telescope projects. We describe the details of our process, how it was implemented by the ATST design team, and some useful lessons learned. We conclude with a discussion of our safety related plans during the construction phase of ATST and beyond.

The Galileoscope student telescope kit was developed by a volunteer team of astronomers, science education experts, and optical engineers in conjunction with the International Year of Astronomy 2009. This refracting telescope is in production with over 180,000 units produced and distributed with 25,000 units in production. The telescope was designed to be able to resolve the rings of Saturn and to be used in urban areas. The telescope system requirements, performance metrics, and architecture were established after an analysis of current inexpensive telescopes and student telescope kits. The optical design approaches used in the various prototypes and the optical system engineering tradeoffs will be described. Risk analysis, risk management, and change management were critical as was cost management since the final product was to cost around $15 (but had to perform as well as $100 telescopes). In the system engineering of the Galileoscope a variety of analysis and testing approaches were used, including stray light design and analysis using the powerful optical analysis program FRED™.

MUSE (Multi Unit Spectroscopic Explorer) is a second generation instrument developed for ESO (European Southern Observatory) and will be assembled to the VLT (Very Large Telescope) in 2012. The MUSE instrument can simultaneously record 90.000 spectra in the visible wavelength range (465-930nm), across a 1*1arcmin² field of view, thanks to 24 identical Integral Field Units (IFU). A collaboration of 7 institutes has successfully passed the Final Design Review and is currently working on the first sub-assemblies. The sharing of performances has been based on 5 main functional sub-systems. The Fore Optics sub-system derotates and anamorphoses the VLT Nasmyth focal plane image, the Splitting and Relay Optics associated with the Main Structure are feeding each IFU with 1/24^th of the field of view. Each IFU is composed of a 3D function insured by an image slicer system and a spectrograph, and a detection function by a 4k*4k CCD cooled down to 163°K. The 5^th function is the calibration and data reduction of the instrument. This article depicts the breakdown of performances between these sub-systems (throughput, image quality...), and underlines the constraining parameters of the interfaces either internal or with the VLT. The validation of all these requirements is a critical task started a few months ago which requires a clear traceability and performances analysis.

The Discovery Channel Telescope (DCT) is a 4.3-meter telescope designed for dual optical configurations, featuring an f/6.1, 0.5° FoV, Ritchey-Chretien prescription, and a corrected f/2.3, 2° FoV, prime focus. The DCT is expected to typically deliver sub-arcsecond images, with a telescope and local seeing contribution of <0.28" FWHM at the R-C focus and <0.38" FWHM at the prime focus. The Delivered Image Quality (DIQ) budget considers errors from design residuals, manufacturing, environmental effects, and control system limitations. We present an overview of the analytical methods used, including sensitivity analysis for determining collimation effects, and a summary of contributors to the overall system performance.

In this paper the results of the thermo-elastic analysis performed on the Stereo Imaging Channel of the imaging system SIMBIO-SYS for the BepiColombo ESA mission to Mercury is presented. The aim of the work is to determine the expected stereo reconstruction accuracy of the surface of the planet Mercury, i.e. the target of BepiColombo mission, due to the effects of the optics misalignments and deformations induced by temperature changes during the mission lifetime. The camera optics and their mountings are modeled and processed by a thermo-mechanical Finite Element Model (FEM) program, which reproduces the expected optics and structure thermo-elastic variations in the instrument foreseen operative temperature range, i.e. between -20 °C and 30 °C. The FEM outputs are elaborated using a MATLAB optimization routine: a non-linear least square algorithm is adopted to determine the surface equation (plane, spherical, n^th polynomial) which best fits the deformed optical surfaces. The obtained surfaces are then directly imported into ZEMAX raytracing code for sequential raytrace analysis. Variations of the optical center position, boresight direction, focal length and distortion are then computed together with the corresponding image shift on the detector. The overall analysis shows the preferable use of kinematic constraints, instead of glue classical solution, for optical element mountings, this minimize the uncertainty on the Mercury Digital Terrain Model (DTM) reconstructed via a stereo-vision algorithm based on the triangulation from two optical channels.

Many astrophysicists consider the mystery of accelerated expansion of the universe by a field called dark energy as the greatest challenge to solve in cosmology. Gravitational weak lensing has been identfied as one of the best methods to provide constraints on dark energy model parameters. Weak lensing introduces image shear which can be measured statistically from a large sample of galaxies by determining the ellipticity parameters. Several papers have suggested that a goal in the ability to measure shape biases should be <0.1% - this goal will be reviewed in terms of the observatory "transfer function" with comments interspersed regarding allocation inconsistencies. Time-varying effects introduced by thermoelastic deformations and vibration add bias and noise to the galaxy shape measurements. This is compounded by the wide field-of-view required for the weak lensing science which leads to a spatially varying point spead function (PSF). To fully understand these effects, a detailed integrated model (IM) was constructed which includes a coupled scene/ structure/ optics/ disturbance model. This IM was applied to the Joint Dark Energy Mission (JDEM) Omega design concept. Results indicate that previous models of vibration disturbance effects have been too simplified and the allocation for vibration needs to be re-evaluated. Furthermore, because of the complicated processing required to accurately extract shape parameters, it is argued that an IM is needed for maximizing science return by iterating the telescope/ instrument design against mission cost constraints, and processing e¤ectiveness of shape extraction algorithms, instrument calibration techniques and measurement desensitization of observatory effects.

The Kepler mission is designed to detect the transit of Earth-like planets around Sun-like stars by observing 100,000 stellar targets. Developing and testing the Kepler ground-segment processing system, in particular the data analysis pipeline, requires high-fidelity simulated data. This simulated data is provided by the Kepler Endto- End Model (ETEM). ETEM simulates the astrophysics of planetary transits and other phenomena, properties of the Kepler spacecraft and the format of the downlinked data. Major challenges addressed by ETEM include the rapid production of large amounts of simulated data, extensibility and maintainability.

The Multi Unit Spectroscopic Explorer (MUSE) instrument is a second-generation integral-field spectrograph in development for the Very Large Telescope (VLT), operating in the visible and near IR wavelength range (465-930 nm). Given the complexity of MUSE we have developed a numerical model of the instrument, which includes the whole chain of acquisition from the atmosphere down to the telescope and including the detectors, and taking into account both optical aberrations and diffraction effects. Simulating atmospheric effects such as turbulence, refraction and sky background within an instrument numerical simulator is computation intensive, and the simulation of these effects is usually beyond the scope of an instrument simulator as it is done in dedicated simulations from which only the results are available. In this paper we describe how these effects are simulated in the VLT/MUSE numerical simulator, the simplifications that are used, as well as the assumptions leading to these simplifications.

In a previous study we had presented a summary of the TMT Aero-Thermal modeling effort to support thermal seeing and dynamic loading estimates. In this paper a summary of the current status of Computational Fluid Dynamics (CFD) simulations for TMT is presented, with the focus shifted in particular towards the synergy between CFD and the TMT Finite Element Analysis (FEA) structural and optical models, so that the thermal and consequent optical deformations of the telescope can be calculated. To minimize thermal deformations and mirror seeing the TMT enclosure will be air conditioned during day-time to the expected night-time ambient temperature. Transient simulations with closed shutter were performed to investigate the optimum cooling configuration and power requirements for the standard telescope parking position. A complete model of the observatory on Mauna Kea was used to calculate night-time air temperature inside the enclosure (along with velocity and pressure) for a matrix of given telescope orientations and enclosure configurations. Generated records of temperature variations inside the air volume of the optical paths are also fed into the TMT thermal seeing model. The temperature and heat transfer coefficient outputs from both models are used as input surface boundary conditions in the telescope structure and optics FEA models. The results are parameterized so that sequential records several days long can be generated and used by the FEA model to estimate the observing spatial and temporal temperature range of the structure and optics.

Thermal performances of the Thirty Meter Telescope (TMT) structure were evaluated by finite element thermal models. The thermal models consist of the telescope optical assembly systems, instruments, laser facility, control and electronic equipments, and structural members. Temporal and spatial temperature distributions of the optical assembly systems and the telescope structure were calculated under various thermal conditions including air convections, conductions, heat flux loadings, and radiations. In order to capture thermal responses faithfully, a three-consecutive-day thermal environment data was implemented. This thermal boundary condition was created by CFD based on the environment conditions of the corresponding TMT site. The thermo-elastic analysis was made to predict thermal deformations of the telescope structure at every hour for three days. The line of sight calculation was made using the thermally induced structural deformations. Merit function was utilized to calculate the OPD maps after repositioning the optics based on a best fit of M1 segment deformations. The goal of this thermal analysis is to establish creditable thermal models by finite element analysis to simulate the thermal effects with the TMT site environment data. These thermal models can be utilized for estimating the thermal responses of the TMT structure. Thermal performance prediction of the TMT structure will guide us to assess the thermal impacts, and enables us to establish a thermal control strategy and requirements in order to minimize the thermal effects on the telescope structure due to heat dissipation from the telescope mounted equipment and systems.

The LSST camera is located above the LSST primary/tertiary mirror and in front of the secondary mirror in the shadow of its central obscuration. Due to this position within the optical path, heat released from the camera has a potential impact on the seeing degradation that is larger than traditionally estimated for Cassegrain or Nasmyth telescope configurations. This paper presents the results of thermal seeing modeling combined with Computational Fluid Dynamics (CFD) analyzes to define the thermal requirements on the LSST camera. Camera power output fluxes are applied to the CFD model as boundary conditions to calculate the steady-state temperature distribution on the camera and the air inside the enclosure. Using a previously presented post-processing analysis to calculate the optical seeing based on the mechanical turbulence and temperature variations along the optical path, the optical performance resulting from the seeing is determined. The CFD simulations are repeated for different wind speeds and orientations to identify the worst case scenario and generate an estimate of seeing contribution as a function of camera-air temperature difference. Finally, after comparing with the corresponding error budget term, a maximum allowable temperature for the camera is selected.

The principal dynamic disturbances acting on a telescope segmented primary mirror are unsteady wind pressure (turbulence) and narrowband vibration from rotating equipment. Understanding these disturbances is essential for the design of the segment support assembly (SSA), segment actuators, and primary mirror control system (M1CS). The wind disturbance is relatively low frequency, and is partially compensated by M1CS; the response depends on the control bandwidth and the quasi-static stiffness of the actuator and SSA. Equipment vibration is at frequencies higher than the M1CS bandwidth; the response depends on segment damping, and the proximity of segment support resonances to dominant vibration tones. We present here both disturbance models and parametric response. Wind modeling is informed by CFD and based on propagation of a von Karman pressure screen. The vibration model is informed by analysis of accelerometer and adaptive optics data from Keck. This information is extrapolated to TMT and applied to the telescope structural model to understand the response dependence on actuator design parameters in particular. Whether the vibration response or the wind response is larger depends on these design choices; "soft" (e.g. voice-coil) actuators provide better vibration reduction but require high servo bandwidth for wind rejection, while "hard" (e.g. piezo-electric) actuators provide good wind rejection but require damping to avoid excessive vibration transmission to the primary mirror segments. The results for both nominal and worst-case disturbances and design parameters are incorporated into the TMT actuator performance assessment.

We study the capability of the European Extremely Large Telescope to image exoplanets. For this task we have developed a simulation which models the telescope, adaptive-optics systems, coronagraphs, science instrument, which is the integral field spectrograph in our case, and image post-processing.

The Normalized Point Source Sensitivity (PSSN) has previously been defined and analyzed as an On-Axis seeing-limited telescope performance metric. In this paper, we expand the scope of the PSSN definition to include Off-Axis field of view (FoV) points and apply this generalized metric for performance evaluation of the Thirty Meter Telescope (TMT). We first propose various possible choices for the PSSN definition and select one as our baseline. We show that our baseline metric has useful properties including the multiplicative feature even when considering Off-Axis FoV points, which has proven to be useful for optimizing the telescope error budget. Various TMT optical errors are considered for the performance evaluation including segment alignment and phasing, segment surface figures, temperature, and gravity, whose On-Axis PSSN values have previously been published by our group.

We evaluate how well the performance of the Thirty Meter Telescope (TMT) can be maintained against thermally induced errors during a night of observation. We first demonstrate that using look-up-table style correction for TMT thermal errors is unlikely to meet the required optical performance specifications. Therefore, we primarily investigate the use of a Shack-Hartmann Wavefront Sensor (SH WFS) to sense and correct the low spatial frequency errors induced by the dynamic thermal environment. Given a basic SH WFS design, we position single or multiple sensors within the telescope field of view and assess telescope performance using the JPL optical ray tracing tool MACOS for wavefront simulation. Performance for each error source, wavefront sensing configuration, and control scheme is evaluated using wavefront error, plate scale, pupil motion, pointing error, and the Point Source Sensitivity (PSSN) as metrics. This study provides insight into optimizing the active optics control methodology for TMT in conjunction with the Alignment and Phasing System (APS) and primary mirror control system (M1CS).

One of the key aspects of the Wide-Field Upgrade (WFU) for the 10m Hobby-Eberly Telescope (HET) is the use of wavefront sensing (WFS) to close the loop of active alignment control of the new four-mirror Wide-Field Corrector (WFC), as it tracks sidereal motion, with respect to the fixed spherical segmented primary mirror. This makes the telescope pupil dynamically change in shape. This is a unique challenge to the WFS on the HET, in addition to various influences of seeing, primary mirror segment errors, and dynamic deflection of the internal optical components of the WFC. We conducted extensive simulations to understand the robustness of the WFS in the face of these errors and the results of these analyses are discussed in this paper.

The design of astronomical instrument is growing in dimension and complexity, following the new requirements imposed by ELT class telescopes. The availability of new structural material like composite ones is asking for more robust and reliable designing numerical tools. This paper wants to show a possible integrated design framework. The procedure starts from the developing of a raw structure consisting in an assembly of plates and beams directly from the optical design. The basic Finite Element Model is then prepared joining together plate and beam elements for the structure and mass and semi-rigid element for the the opto-mechanical subsystems. The technique developed is based onto Matlab® commands and run the FEA, extrapolate the optical displacements, implement them into the optical design and evaluates the image quality in terms of displacement and spot size. Thanks to a simplified procedure the routine is able to derive the full field of displacements from a reduced sequence of three different load sets. The automatic optimization routine modifies the properties of plates and beams considering also different materials and, in case of composites different lamination sequences. The algorithm is oriented to find the best compromise in terms of overall weights w.r.t. eigen-frequencies, image stability and quality.

The NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA) employs a 2.5-meter reflector telescope in a Boeing 747SP. The telescope is housed in an open cavity and will be subjected to aeroacoustic and inertial disturbances. The image stability goal for SOFIA is 0.2 arc-seconds (RMS). Throughout the development phase of the project, analytical models were employed to predict the image stability performance of the telescope, and to evaluate pointing performance improvement measures. These analyses clearly demonstrated that key aspects which determined performance were: 1) Disturbance environment and relevant load-paths 2) Telescope modal behavior 3) Sensor and actuator placement 4) Control algorithm design The SOFIA program is now entering an exciting phase in which the characteristics of the telescope and the cavity environment are being verified through ground and airborne testing. A modal survey test (MST) was conducted in early 2008 to quantify the telescope modal behavior. We will give a brief overview of analytical methods which have been employed to assess/improve the pointing stability performance of the SOFIA telescope. In this context, we will describe the motivation for the MST, and the pre-test analysis which determined the modes of interest and the required MST sensor/shaker placement. A summary will then be given of the FEM-test correlation effort, updated end-to-end simulation results, and actual data coming from telescope activation test flights.

Kepler is the National Aeronautics and Space Administration's (NASA's) first mission capable of detecting Earth-size planets orbiting in the habitable zones around stars other than the sun. Selected for implementation in 2001 and launched in 2009, Kepler seeks to determine whether Earth-like planets are common or rare in the galaxy. The investigation requires a large, space-based photometer capable of simultaneously measuring the brightnesses of 100,000 stars at partper- million level of precision. This paper traces the development of the mission from the perspective of project management and systems engineering and describes various methodologies and tools that were found to be effective. The experience of the Kepler development is used to illuminate lessons that can be applied to future missions.

The Wide-field Infrared Survey Explorer (WISE), a NASA Medium-Class Explorer (MIDEX) mission, is surveying the entire sky in four bands from 3.4 to 22 microns with a sensitivity hundreds to hundreds of thousands times better than previous all-sky surveys at these wavelengths. The single WISE instrument consists of a 40 cm three-mirror anastigmatic telescope, a two-stage solid hydrogen cryostat, a scan mirror mechanism, and reimaging optics giving 6" resolution (fullwidth- half-maximum). WISE was placed into a Sun-synchronous polar orbit on a Delta II 7320 launch vehicle on December 14, 2009. NASA selected WISE as a MIDEX in 2002 following a rigorous competitive selection process. To gain further confidence in WISE, NASA extended the development period one year with an option to cancel the mission if certain criteria were not met. MIDEX missions are led by the principal investigator who in this case delegated day-today management to the project manager. With a cost cap and relatively short development schedule, it was essential for all WISE partners to work seamlessly together. This was accomplished with an integrated management team representing all key partners and disciplines. The project was developed on budget and on schedule in spite of the need to surmount significant technical challenges. This paper describes our management approach, key challenges and critical decisions made. Results are described from a programmatic, technical and scientific point of view. Lessons learned are offered for projects of this type.

The Large Synoptic Survey Telescope (LSST) project has evolved from just a few staff members in 2003 to about 100 in 2010; the affiliation of four founding institutions has grown to 32 universities, government laboratories, and industry. The public private collaboration aims to complete the estimated $450 M observatory in the 2017 timeframe. During the design phase of the project from 2003 to the present the management structure has been remarkably stable. At the same time, the funding levels, staffing levels and scientific community participation have grown dramatically. The LSSTC has introduced project controls and tools required to manage the LSST's complex funding model, technical structure and distributed work force. Project controls have been configured to comply with the requirements of federal funding agencies. Some of these tools for risk management, configuration control and resource-loaded schedule have been effective and others have not. Technical tasks associated with building the LSST are distributed into three subsystems: Telescope & Site, Camera, and Data Management. Each sub-system has its own experienced Project Manager and System Scientist. Delegation of authority is enabling and effective; it encourages a strong sense of ownership within the project. At the project level, subsystem management follows the principle that there is one Board of Directors, Director, and Project Manager who have overall authority.

The Advanced Technology Solar Telescope (ATST) has recently received National Science Foundation (NSF) approval to begin the construction process. ATST will be the most powerful solar telescope and the world's leading resource for studying solar magnetism that controls the solar wind, flares, coronal mass ejections and variability in the Sun's output. This paper gives an overview of the project, and describes the project management principles and practices that have been developed to optimize both the project's success as well as meeting requirements of the project's funding agency.

This paper presents an accumulation of knowledge from both sides of the design review table. Using experience gained over many reviews and post-mortems, some painful, some less painful; examining stakeholder's viewpoints and expectations; challenging aspects of accepted wisdom and posing awkward questions, the author brings out what he considers to be key criteria for a constructive design review. While this is not a guarantee to a successful outcome, it may nudge the balance from the reviews being an obligatory milestone (millstone?) towards them being a beneficial mechanism for project development.

MUSE (Multi Unit Spectroscopic Explorer) is a second generation instrument developed for ESO (European Southern Observatory) to be installed on the VLT (Very Large Telescope) in year 2012. The MUSE project is supported by a European consortium of 7 institutes. After a successful Final Design Review the project is now facing a turning point which consist in shifting from design to manufacturing, from calculation to test, ... from dream to reality. At the start, many technical and management challenges were there as well as unknowns. They could all be derived of the same simple question: How to deal with complexity? The complexity of the instrument, of the work to de done, of the organization, of the interfaces, of financial and procurement rules, etc. This particular moment in the project life cycle is the opportunity to look back and evaluate the management methods implemented during the design phase regarding this original question. What are the lessons learn? What has been successful? What could have been done differently? Finally, we will look forward and review the main challenges of the MAIT (Manufacturing Assembly Integration and Test) phase which has just started as well as the associated new processes and evolutions needed.

The development of the Herschel and Planck Programme, the largest scientific space programme of the European Space Agency (ESA), has culminated in May 2009 with the successful launch of the Herschel and Planck satellites onboard an Ariane 5 from the European Spaceport in Kourou. Both satellites are operating flawlessly since then and the scientific payload instruments provide world-class science. The Herschel/Planck Programme is a multi national cooperation with the managerial lead being taken by the European Space Agency with the major contributions from European industry for the spacecraft development and from scientific institutes, organized in five international consortia, for the payload instruments. The overall programme complexity called for various, adapted, management approaches to resolve technical and programmatic difficulties. Some of the management experiences of over a decade needed to realize such a satellite programme will be presented giving the lessons learnt for future programmes with the similar complexities.

The Javalambre Astrophysical Observatory is a new ground based facility under construction at the Sierra de Javalambre (Teruel, Spain). The observatory is defined for carrying out large all-sky surveys in robotic mode. It will consist of two telescopes: T250, a large etendue telescope of 2.5m aperture and 3 deg diameter field of view, and T80, a 0.8m auxiliary telescope with a field of view diameter of 2 deg. The immediate objective of the T250 is a photometric survey of 8000 square degrees projected on the sky, using narrow-band filters (~ 100Å width) in the whole optical range, following the specifications defined in this paper1 for the measurement of Baryon Acoustic Oscillations along the line of sight with photometric redshifts. To do this, T250 will hold a panoramic camera of ~ 14 large format (~ 10.5k×10.5k) CCDs covering the entire focal plane. The present paper describes the overall project conceived to comply with the scientific and technical requirements and the managerial approach considered. Other aspects such as the expected instrumentation at the telescopes, the operation of the observatory, the software/hardware specifications, and the data handling will be also outlined.

Total Cost of Ownership (TCO) is a metric from management accounting that helps expose both the direct and indirect costs of a business decision. However, TCO can sometimes be too simplistic for "make vs. buy" decisions (or even choosing between competing design alternatives) when value and extensibility are more critical than total cost. A three-dimensional value-based TCO, which was developed to clarify product decisions for an observatory prior to Final Design Review (FDR), will be presented in this session. This value-based approach incorporates priority of requirements, satisfiability of requirements, and cost, and can be easily applied in any environment.

The James Web Space Telescope (JWST) is a large, infrared-optimized space telescope scheduled for launch in 2014. System-level verification of critical performance requirements will rely on integrated observatory models that predict the wavefront error accurately enough to verify that allocated top-level wavefront error of 150 nm root-mean-squared (rms) through to the wave-front sensor focal plane is met. This paper describes the systems engineering approach used on the JWST through the detailed design phase.

This paper emphasizes how the Chandra telescope hardware was designed, tested, verified, and accepted for flight to benefit all future missions that must find efficient ways to drive out cost and schedule while still maintaining an acceptable level of risk. Examples of how the verification methodology mitigated risk will be provided, along with actual flight telemetry which confirms the robustness of the Chandra Telescope design and its verification methodology.

The Nuclear Spectroscopic Telescope Array (NuSTAR) is a NASA Small Explorer mission that will make the first sensitive images of the sky in the high energy X-ray band (6 - 80 keV). The NuSTAR observatory consists of two co-aligned grazing incidence hard X-ray telescopes with a ~10 meter focal length, achieved by the on-orbit extension of a deployable mast. A principal science objective of the mission is to locate previously unknown high-energy X-ray sources to an accuracy of 10 arcseconds (3-sigma), sufficient to uniquely identify counterparts at other wavelengths. In order to achieve this, a star tracker and laser metrology system are an integral part of the instrument; in conjunction, they will determine the orientation of the optics bench in celestial coordinates and also measure the flexures in the deployable mast as it responds to the varying on-orbit thermal environment, as well as aerodynamic and control torques. The architecture of the NuSTAR system for solving the attitude and aspect problems differs from that of previous X-ray telescopes, which did not require ex post facto reconstruction of the instantaneous observatory alignment on-orbit. In this paper we describe the NuSTAR instrument metrology system architecture and implementation, focusing on the systems engineering challenges associated with validating the instantaneous transformations between focal plane and celestial coordinates to within the required accuracy. We present a mathematical solution to photon source reconstruction, along with a detailed error budget that relates component errors to science performance. We also describe the architecture of the instrument simulation software being used to validate the end-to-end performance model.

Gaia is Europe's future astrometry satellite which is currently under development. The data collected by Gaia will be treated and analyzed by the "Data Processing and Analysis Consortium" (DPAC). DPAC consists of over 400 scientists in more than 22 countries, which are currently developing the required data reduction, analysis and handling algorithms and routines. DPAC is organized in Coordination Units (CU's) and Data Processing Centres (DPCs). Each of these entities is individually responsible for the development of software for the processing of the different data. In 2008, the DPAC Project Office (PO) has been set-up with the task to manage the day-to-day activities of the consortium including implementation, development and operations. This paper describes the tasks DPAC faces and the role of the DPAC PO in the Gaia framework and how it supports the DPAC entities in their effort to fulfill the Gaia promise.

Stray light modeling and analysis play a key role in new technology assessment, system engineering, and the overall performance assessment of telescope/instrument systems under real use conditions. It also is a key tool in risk reduction as stray light problems that appear late in the program are usually severe, expensive to fix, and often compromise final system performance. This paper will review the current stray light software and testing tools of value to the astronomical community and their capabilities/ limitations for general and specialized telescope systems. We will describe the role of stray light analysis in end-to-end modeling and integrated modeling for a number of systems we have analyzed and discuss in detail the stray light modeling and analysis cycle for different types of programs. A key issue is how managers might deal with the issues revealed by an analysis as well as the risks of an incomplete or improperly-timed analysis. The importance of stray light analysis for end-to-end performance assessment and whether such an analysis can reduce life-cycle costs will also be discussed. The paper will use examples from ground and space-based astronomical telescope/instrument systems.

NIRSpec is the near-infrared multi-object spectrograph for the future James Webb Space Telescope (JWST). It is developed by EADS Astrium for the European Space Agency. The Centre de Recherche Astrophysique de Lyon (CRAL) has developed the Instrument Performance Simulator (IPS) software that is being used for the modeling of NIRSpec's performances and to simulate raw NIRSpec exposures. In this paper, we present the IPS software itself (main simulation modules and user's interface) and discuss its intrinsic accuracy. We also show the results of simulations of calibration exposures as they will be obtained during the NIRSpec on-ground calibration campaign.

The James Webb Space Telescope (JWST) is the successor mission to the Hubble Space Telescope and will operate in the near- and mid-infrared wavelength ranges. One of the four science instruments on board the spacecraft is the multi-object spectrograph NIRSpec, currently developed by the European Space Agency (ESA) with EADS Astrium Germany GmbH as the prime contractor. NIRSpec will be able to measure the spectra of more than 100 objects simultaneously and will cover the near infrared wavelength range from 0.6 to 5.0 μm at various spectral resolutions. To verify the performance of NIRSpec and simulate future on-ground and in-orbit observations with this instrument, the Instrument Performance Simulator (IPS) software is developed at Centre de Recherche Astrophysique de Lyon (CRAL) as subcontractor to Astrium. In early and mid-2009, the NIRSpec Demonstration Model (DM), fully representative up to the slit plane, underwent cryogenic tests and calibration runs. The detector was placed at the slit plane in case of the DM to measure specific optical performance aspects. A simplified version of the IPS was prepared, matching the DM configuration and also serving as a testbed for the final software for the flight model. In this paper, we first present the simulation approach used in the IPS, followed by results of the DM calibration campaign. Then, for the first time, simulation outputs are confronted with measured data to verify their validity.

The James Web Space Telescope (JWST) is a large, infrared-optimized space telescope scheduled for launch in 2014. The imaging performance of the telescope will be diffraction limited at 2μm, defined as having a Strehl ratio >0.8. System-level verification of critical performance requirements will rely on integrated observatory models that predict the wavefront error accurately enough to verify that allocated top-level wavefront error of 150 nm root-mean-squared (rms) through to the wave-front sensor focal plane is met. Furthermore, responses in several key disciplines are strongly crosscoupled. The size of the lightweight observatory structure, coupled with the need to test at cryogenic temperatures, effectively precludes validation of the models and verification of optical performance with a single test in 1-g. Rather, a complex series of incremental tests and measurements are used to anchor components of the end-to-end models at various levels of subassembly, with the ultimate verification of optical performance is by analysis using the assembled models. The assembled models themselves are complex and require the insight of technical experts to assess their ability to meet their objectives. This paper describes the modeling approach used on the JWST through the detailed design phase.

The JWST optical performance verification poses challenges not yet encountered in space-based telescopes. In particular the large, lightweight deployable optics pose challenges to verification via direct measurement of the observatory on earth. For example, the lightweight optics have surface distortion due to gravity producing wavefront error greater than the wavefront error specification for the entire observatory. Because of difficulties such as this, the deployable, segmented Primary Mirror and deployable Secondary Mirror will be realigned after launch. The architecture of JWST was designed to accommodate these difficulties as these by including active positioning of the primary mirror segments and secondary. In fact, the requirements are written such that the active control system shall be used to meet the requirements. Therefore many of the optical requirements are necessarily based on modeling and simulations. This requires that the models used to predict the optical performance be verified and validated. This paper describes the validation approach taken and a companion paper describes the optical performance analyses¹.

In 2007, the Canada-France-Hawaii Telescope (CFHT) undertook a project to enable the remote control of the observatory at the summit of Mauna Kea from a control room in the Headquarters building in Waimea. Instead of having two people operating the telescope and performing the observations from the summit, this project will allow one operator to remotely control the observatory and perform observations for the night. It is not possible to have one person operate from the summit, as our Two Person Rule requires at least two people for work at the summit for safety reasons. This paper will describe how systems engineering concepts have shaped the design of the project structure and execution.

Core components of systems engineering are the proper understanding of the top level system requirements, their allocation to the subsystems, and then the verification of the system built against these requirements. System performance, ultimately relevant to all three of these components, is inherently a statistical variable, depending on random processes influencing even the otherwise deterministic components of performance, through their input conditions. The paper outlines the Stochastic Framework facilitating both the definition and estimate of system performance in a consistent way. The environmental constraints at the site of the observatory are significant design drivers and can be derived from the Stochastic Framework, as well. The paper explains the control architecture capable of achieving the overall system performance as well as its allocation to subsystems. An accounting for the error and disturbance sources, as well as their dependence on environmental and operational parameters is included. The most current simulations results validating the architecture and providing early verification of the preliminary TMT design are also summarized.

The merit function routine (MFR) is implemented in the National Research Council Canada Integrated Modeling (NRCIM) toolset and based in the MATLAB numerical computing environment. It links ANSYS finite element structural models with ZEMAX optical models to provide a powerful integrated opto-mechanical engineering tool. The MFR is utilized by the Thirty Meter Telescope Project to assess the telescope active optics system requirements and performance. This paper describes the MFR tool, including the interfaces to ANSYS, ZEMAX, the method of calculation of the results, and the internal data structures used. A summary of the required performance of the Thirty Meter Telescope, and the MFR results for the telescope system design are presented.

The Thirty Meter Telescope is comprised of thirty five individual sub-systems which include optical systems, instruments, adaptive optics systems, controls, mechanical systems, supporting software and hardware and the infrastructure required to support their operation. These thirty five sub-systems must operate together as a system to enable the telescope to meet the science cases for which it is being developed. These science cases are formalized and expressed as science requirements by the project's Science Advisory Committee. From these, a top down requirements engineering approach is used within the project to derive consistent operational, architectural and ultimately detailed design requirements for the sub-systems. The various layers of requirements are stored within a DOORS requirements database that also records the links between requirements, requirement rationale and requirement history. This paper describes the development of the design requirements from science cases, the reasons for recording the links between requirements and the benefits that documenting this traceability will yield during the design and verification of the telescope. Examples are given of particular science cases, the resulting operational and engineering requirements on the telescope system and how individual sub-systems will contribute to these being met.

EAGLE (Extremely large Adaptive telescope for GaLaxy Evolution) is one of the eight E-ELT instrument concepts that was developed as part of the Phase A E-ELT instrument studies. EAGLE is a near-infrared wide field multi object spectrograph1. It includes its own multi-object adaptive optics system (MOAO) and its subsystems are cooled down so as to ensure that the instrument can both achieve the desired spatial resolution and to be sure that the instrument is background limited, as required in the primary science case, to deliver the performance in the K-band. In this paper we discuss the performance matrix developed to allow us to partition and allocate the important characteristics to the various subsystems as well as to describe the process to verify that the current concept design will deliver the required performance. Due to the integrated nature of the instrument, a large number of AO parameters have to be controlled. The performance matrix also has to deal with the added complexity of active optical elements such as the science channel deformable mirrors (DMs). This paper also defines a method of how to convert the ensquared energy (EE) and signal-to-noise ratio (SNR) required by the science cases into the "as designed" wavefront error and the overall residue wavefront error. To ensure successful integration and verification of the next generation instruments for ELT it is of the utmost importance to have method to control and manage the instrument's critical performance characteristics at very early design steps.

Large Observatories require enormous efforts in preparing the Maintenance Manuals. The possibility to adopt a standardised system, associated to centralized data base and software tools is investigated. This strategy implies a revolution of Maintenance Manuals: from information collection (paper-based), to a modular approach where data modules are used. The initial efforts associated to data modules preparation is compensated by several benefits (time savings for end-users, reduced training requirements, reduced equipment down-time). Moreover, cost savings in the preparation process, even for different equipment, is also possible. Finally, this standardised strategy will assure compatibility between different programs or partners.

The Large Synoptic Survey Telescope is a complex hardware - software system of systems, making up a highly automated observatory in the form of an 8.4m wide-field telescope, a 3.2 billion pixel camera, and a peta-scale data processing and archiving system. As a project, the LSST is using model based systems engineering (MBSE) methodology for developing the overall system architecture coded with the Systems Modeling Language (SysML). With SysML we use a recursive process to establish three-fold relationships between requirements, logical & physical structural component definitions, and overall behavior (activities and sequences) at successively deeper levels of abstraction and detail. Using this process we have analyzed and refined the LSST system design, ensuring the consistency and completeness of the full set of requirements and their match to associated system structure and behavior. As the recursion process proceeds to deeper levels we derive more detailed requirements and specifications, and ensure their traceability. We also expose, define, and specify critical system interfaces, physical and information flows, and clarify the logic and control flows governing system behavior. The resulting integrated model database is used to generate documentation and specifications and will evolve to support activities from construction through final integration, test, and commissioning, serving as a living representation of the LSST as designed and built. We discuss the methodology and present several examples of its application to specific systems engineering challenges in the LSST design.

The Large Synoptic Survey Telescope (LSST) is a project envisioned as a system of systems with demanding science, technical, and operational requirements, that must perform as a fully integrated unit. The design and implementation of such a system poses big engineering challenges when performing requirements analysis, detailed interface definitions, operational modes and control strategy studies. The OMG System Modeling Language (SysML) has been selected as the framework for the systems engineering analysis and documentation for the LSST. Models for the overall system architecture and different observatory subsystems have been built describing requirements, structure, interfaces and behavior. In this paper we show the models for the Observatory Control System (OCS) and the Telescope Control System (TCS), and how this methodology has helped in the clarification of the design and requirements. In one common language, the relationships of the OCS, TCS, Camera and Data management subsystems are captured with models of the structure, behavior, requirements and the traceability between them.

This paper illustrates how the design of an instrument such as the Extremely Large Adaptive Telescope for GaLaxy Evolution (EAGLE) instrument can be simplified. EAGLE is a Wide Field Multi Object Integral Field Unit Spectrometer aimed as a cornerstone instrument for the European Extremely Large Telescope (E-ELT). The instrument is rich in capabilities and will require Adaptive Optics to ensure that the expected spatial resolution (typically 15 times finer than that of a seeing limited instrument) can be met. The complexities introduced by the need to include a Multi- Object Adaptive Optics system (MOAO) can be simplified by using well defined systems engineering processes. These processes include the capturing, analysis and flow down of requirements, functional and performance analysis and an integrated system design approach. In this paper we will also show by example why the discipline imposed by the UK ATC formal systems engineering process is necessary, especially given that projects such as EAGLE also have to deal with the complexities of international collaborations. It also illustrates how the process promotes innovation and creativity.

During the last two and half years ten phase-A instrument studies for the E-ELT have been launched by ESO and carried out by consortia of institutes in the ESO member states and Chile. These studies have been undertaken in parallel with the phase B of the E-ELT telescope. This effort has pursued two main goals: to prove the feasibility and performance of a set of instruments to meet the project science goals and to identify and incorporate in the telescope design those features that satisfy best the needs of the future hosts, i.e., the science instruments. To succeed on this goal it is crucial to identify such needs as early as possible in the design process. This concurrent approach definitively benefits both the instruments concept design and the telescope development, but implies as well a number of difficult tasks. This paper compiles, from a system-engineering point of view, the benefits and difficulties as well as the lesson learned during this concurrent process. In addition, the main outcomes of the process, in terms of telescope-instruments interfaces definition and requirements from the instruments to the telescope and vice-versa, are reported.

The European Solar Telescope (EST) is a European collaborative project to build a 4m class solar telescope in the Canary Islands, which is now in its design study phase. The telescope will provide diffraction limited performance for several instruments observing simultaneously at the Coudé focus at different wavelengths. In order to guarantee the achievement of the demanding scientific requirements, error budgets of main performance have been defined from the early design study phase in top-down fashion. During the design study, analyses are being performed in order to update the defined error budgets in bottom-up fashion. Error budget management is proposed from the design study phase to be used during the complete project life cycle.

The Chinese ever-ambitious project LAMOST (Large sky Area Multi-Object fibre Spectroscopic Telescope) has now come to its final completion of R&D stage. Major functions of the telescope have successfully passed a serial of pilot observation recently, and various kinds of applications integrated into the automation of the telescope chamber are being under vigorous site tests too. The TCS (Telescope Control System) is built on multi-layer distributed network platform with many sub-systems at different levels. How to efficiently process the enormous amount of message with particular implications running in and out the TCS is one of the major issues of the TCS software package. The paper focuses on the modelling of control system for LAMOST based on Petri net workflow. The model is also analyzed and verified with the matrix equation.

The project of much-anticipated LAMOST (Large sky Area Multi-Object fibre Spectroscopic Telescope) has successfully been inspected and accepted at national-level evaluation. It will become the world's most powerful meter-class level ground astronomical optical survey telescope. The ever-ambitious project throughout the development history of Chinese astronomical optics telescopes has brought an extraordinary challenge to its control system from all-round aspects. Painstaking effort has been made to the R&D of the control system from its design strategy, functionality analyses to most subtle technical solutions, and of course efficient engineering management is also included. A number of papers highlighting the anticipated LAMOST control system have previously been published during the course of the project evolving. However, much lesson and experience have been learned since 10 years ago. Now the telescope with all its facilities and observation chamber has been put into trial observation. This is the time to review the past and ponder over the future of the control system as a whole against the functional telescope in current reality. Lesson and experience are discussed. Some considerations for improving the system efficiency and the accessibility are presented too in this paper.

Primary mirror segment figure error is potentially deleterious to the wavefront sensing in the new Hobby-Eberly Telescope (HET) Wide-Field Upgrade (WFU). Previous measurements indicated the presence of figure errors including prominent surface astigmatism on the segments, but need a systematic analysis to quantify the amounts. We developed a Phase Retrieval procedure that estimates the surface figure map by applying the iterative transform method to a set of focus-diversed images of a point source formed by the 91 segments of the 11m HET primary mirror. In this paper, we discuss this analysis and the implication of the analysis results for wavefront sensing on the upgraded HET.

Wavefront sensing (WFS) is one of the key elements for active alignment of the new Wide-Field Corrector (WFC), as it tracks sidereal motion, with respect to the fixed Hobby-Eberly Telescope (HET) primary mirror. During a track, part of the 10m-pupil of the WFC can lie outside the primary periphery and be clipped off. An additional field-dependent central obscuration by the holes and baffles of the WFC leads to complex pupil geometries. The combination of these is a complicated dynamically varying non-circular telescope pupil. This unique problem to the WFS on the HET needs to be dealt with by choosing an appropriate set of orthonormal aberration polynomials during wavefront reconstruction. In this paper, three ways of computing orthonormal aberration polynomials and their coefficients are discussed. These are based on the Gram-Schmidt (GS) process, but differ in the way of computing key integrals during the GS process. The first method analytically computes the integrals, where a computer algebra program is used. The second uses the Gaussian quadrature over triangulated pupil geometries that approximate the true pupil shape. The last uses indirect numerical estimates of the integrals, which turned out to be natural by-products of the usual least-square Zernike polynomials fit. It is shown that the first method is limited to cases of simple pupil shapes, while the second can be applied to more general pupil shapes. However, when dealing with complicated dynamically varying non-circular pupils, the last method can be vastly more efficient than the second and enables the possibility of estimating orthonormal aberration coefficient on the fly. Also noticed is that the last method naturally takes into account the pixelation effect of pupil geometries due to pixel-based imaging sensors (e.g. CCDs). With these benefits, the last method can be used as a viable tool in real-time wavefront analysis over dynamically changing pupils as in the Hobby- Eberly Telescope, which is otherwise vastly inefficient with analytic methods used in past studies.

Over the past three decades, the staff of the MMT observatory used a variety of techniques to predict the summit wind characteristics including wind tunnel modeling and the release of smoke bombs. With the planned addition of a new instrument repair facility to be constructed on the summit of Mt. Hopkins, new computational fluid dynamic (CFD) models were made to determine the building's influence on the thermal environment around the telescope. The models compared the wind profiles and density contours above the telescope enclosure with and without the new building. The results show the steeply-sided Mount Hopkins dominates the summit wind profiles. In typical winds, the height of the telescope remains above the ground layer and is sufficiently separated from the new facility to insure the heat from the new building does not interfere with the telescope. The results also confirmed the observatories waste heat exhaust duct location needs to be relocated to prevent heat from being trapped in the wind shadow of the new building and lofting above the telescope. These useful models provide many insights into understanding the thermal environment of the summit.

Extracting science from the LSST data stream requires a detailed knowledge of the properties of the LSST catalogs and images (from their detection limits to the accuracy of the calibration to how well galaxy shapes can be characterized). These properties will depend on many of the LSST components including the design of the telescope, the conditions under which the data are taken and the overall survey strategy. To understand how these components impact the nature of the LSST data the simulations group is developing a framework for high fidelity simulations that scale to the volume of data expected from the LSST. This framework comprises galaxy, stellar and solar system catalogs designed to match the depths and properties of the LSST (to r=28), transient and moving sources, and image simulations that ray-trace the photons from above the atmosphere through the optics and to the camera. We describe here the state of the current simulation framework and its computational challenges.

The Gemini Observatory operates two telescopes, both in geographical areas that pose a significant risk of damage due to earthquakes. To assess the potential of damage to telescope systems due to earthquake induced ground motion, a system of accelerometers, data acquisition hardware and data analysis software is being installed at each telescope. Information from these sensors will be used to evaluate the response at various locations on the telescope including the primary and secondary mirror support structures, instruments, telescope mount, pier and adjacent ground. A detailed discussion of the design of this sensor system is presented. Real time applications and potential future upgrades are also discussed, including provisions for automatic subsystem parking and shutdown, laser shuttering, alarms and future structural modifications designed to reduce the dynamic response of the telescope and its subsystems to earthquake induced ground motion.

Current concepts for some future for space based astronomical observatories require extraordinary stability with respect to pointing and jitter disturbances. Exoplanet finding missions with internal coronagraphs require pointing stability of <10nrad 3σ (<2mas, 3σ). Closed-loop active dynamic isolation at the interface between a telescope and the spacecraft (where reaction wheels are the primary jitter source) can attain these requirements when incorporated with a robust overall pointing control system architecture which utilizes information from IRUs, star-trackers, and steering mirrors. ITT has developed a high TRL Active Isolation Mount System (AIMS) and through analyses and hardware test-bed work demonstrated that these stringent pointing and dynamic stability can be met for the Actively-Corrected Coronagraph for Exoplanet System Studies (ACCESS) [1] observatory.

The LSST Telescope has critical requirements on tracking error to meet image quality specifications, and will require closing a guiding loop, with the telescope servo control, to meet its mission. The guider subsystem consists of eight guiding sensors located inside the science focal plane at the edge of the 3.5deg field of view. All eight sensors will be read simultaneously at a high rate, and a centroid average will be fed to the telescope and rotator servo controls, for tracking error correction. A detailed model was developed to estimate the sensors centroid noise and the resulting telescope tracking error for a given frame rate and telescope servo control system. The centroid noise depends on the photo-electron flux, seeing conditions, and guide sensor specifications. The model for the photo-electron flux takes into consideration the guide star availability at different galactic latitudes, the atmospheric extinction, the optical losses at different filter bands, the detector quantum efficiency, the integration time and the number of stars sampled. A 7-layer atmospheric model was also developed to estimate the atmospheric decorrelation between the different guide sensors due to the 3.5deg field of view, to predict both correlated and decorrelated atmospheric tip/tilt components, and to determine the trade-offs of the guider servo loop.

Risk management is a dynamic activity that takes place throughout the development process from the concept phase to the retirement phase of the project. The successful management of risk is a critical part of the instrumentation development process at the AAO. The AAO has a risk management process based on the AS/ISO standard for risk management. Brainstorming sessions are conducted with the project team. Potential project risks are identified by the team and grouped into the categories of technical, political, operational, logistical, environmental, and safety. A risk matrix is populated with details of each risk. The risk is then ranked based on the consequence and likelihood according to the scale of Low, Moderate, Significant, and High. The level of risk is evaluated; mitigation control mechanisms are identified, and assigned to a specific team member for resolution. Risk management is used as a management tool for the HERMES project. The top 5 risks are identified, and management efforts are then concentrating on reducing these risks. Risk management is also used during the development process as a trade study tool to evaluate different design options and assist senior management to make informed decisions.

This article presents a toolkit for defining simple but powerful systems. PORIS toolkit is an open and extensible source collaborative project that allows describing system graph-based systems and their behavior in a snapshot. It provides a web editor for a domain visual specific language (DSL) and transformation tools to generate software prototypes, system configurations, specific user interfaces and documentation. Different kind of instruments, like the astronomical ones, can be described and represented using PORIS specifications and models. A significant advantage of using PORIS toolkit is that it makes easy and lighter providing instant feedback to domain experts in the dynamic process of defining new instruments.

This paper considers the development and progression of the VISTA telescope, from conception to the point where it is now being operated by the scientific community (end user). It analyses and evaluates the value of effective project management and systems engineering practices with practical examples. The practical application of systems engineering is addressed throughout the requirement capture and management, design, manufacture, assembly, and installation, integration, verification and acceptance phases, highlighting the value gained by appropriate application of step-by-step procedures and tools. The special emphasis given to the importance of effective systems engineering during on-site installation, verification and validation will be illustrated. Project management aspects are covered from tendering and procurement through contractor management processes to final integration and commissioning, with great emphasis placed on the importance of a "win-win" approach and the benefits of effective, constructive customer/contractor liaison. Consideration is given to the details and practicalities of day-to-day site management, safety, housekeeping, and the management and support of site personnel and services. Recommendations are made to improve the effectiveness of UK ATC system engineering and project management so that future projects can benefit from the lessons learned on VISTA.

The JWST optical performance verification poses challenges not yet encountered in space based telescopes. The deployable, segmented Primary Mirror and Secondary Mirror require re-alignment after launch rendering ground alignment states moot. The architecture of JWST was designed to accommodate these difficulties by including active positioning of the Secondary Mirror and the Primary Mirror Segments. In fact, the requirements are written such that the active control system shall be used to meet the requirements. Therefore many of the optical requirements are necessarily based on modeling and simulations of the post-launch, re-alignment of the telescope. This paper provide an overview of a process of computer simulation using an end-to-end integrated model that is used to statistically evaluate the on-orbit, re-alignment performance based on the uncertainties in the integration and test program and deployments.

The VST telescope is a wide field survey telescope being installed at Cerro Paranal (Chile). Due to the geological nature of the area, telescopes in Chile are always submitted to unpredictable and sometimes severe earthquake conditions. In order to clarify some aspects of VST telescope seismic behavior not well represented by linear procedures like Response Spectrum Analysis, a transient nonlinear analysis of the whole telescope has been foreseen. A mixed approach Finite Element - Matlab-Simulink has been introduced and a linear FE model of the telescope has been developed, with all nonlinear devices sources modelled as linear elements. The FE model has been exported to Simulink, using a space state representation. In Simulink all nonlinearities are appropriately modeled and a base excitement corresponding to accelerograms compliant with Paranal MLE response spectrum is applied. Resulting force-time histories are then applied to a detailed finite element model of mirror, to compute stress field. The paper describes both Simulink and mirror FE analysis, giving also an overview of the actual safety system mechanical implementation, based on analysis results.

Over the years astronomical instrumentation projects are becoming increasingly complex making necessary to find efficient ways for project communication management. While all projects share the need to communicate project information, the required information and the methods of distribution vary widely between projects and project staff. A particular problem experienced on many projects regardless of their size, is related to the amount of design, planning information and how that is distributed among the project stakeholders. One way to improve project communications management is to use a workflow that offers a predefined way to share information in a project. Virtual Reality (VR) offers the possibility to get a visual feedback of designed components without the expenses of prototype building, giving an experience that mimics real life situations using a computer. In this contribution we explore VR as a communication technology that helps to manage instrumentation projects by means of a workflow implemented on a software package called Discut designed at Universidad Nacional Autónoma de Mexico (UNAM). The workflow can integrate VR environments generated as CAD models.

The engineering and design of systems as complex as the Hobby-Eberly Telescope's* new tracker require that multiple tasks be executed in parallel and overlapping efforts. When the design of individual subsystems is distributed among multiple organizations, teams, and individuals, challenges can arise with respect to managing design productivity and coordinating successful collaborative exchanges. This paper focuses on design management issues and current practices for the tracker design portion of the Hobby-Eberly Telescope Wide Field Upgrade project. The scope of the tracker upgrade requires engineering contributions and input from numerous fields including optics, instrumentation, electromechanics, software controls engineering, and site-operations. Successful system-level integration of tracker subsystems and interfaces is critical to the telescope's ultimate performance in astronomical observation. Software and process controls for design information and workflow management have been implemented to assist the collaborative transfer of tracker design data. The tracker system architecture and selection of subsystem interfaces has also proven to be a determining factor in design task formulation and team communication needs. Interface controls and requirements change controls will be discussed, and critical team interactions are recounted (a group-participation Failure Modes and Effects Analysis [FMEA] is one of special interest). This paper will be of interest to engineers, designers, and managers engaging in multi-disciplinary and parallel engineering projects that require coordination among multiple individuals, teams, and organizations.

Modern astronomy currently is dealing with an exciting but challenging dichotomy. On one hand, there has been and will continue to be countless advances in scientific discovery, but on the other the astronomical community is faced with what unfortunately is considered by many to be an insurmountable budgetary impasse for the foreseeable future. The National Academy of Sciences' Astro2010: Decadal Survey has been faced with the difficult challenge of prioritizing sciences and missions for the upcoming decade while still allowing room for new, yet to be discovered opportunities to receive funding. To this end, we propose the consideration of a paradigm shift to the astronomical community that may enable more cost efficient space-based telescope missions to be funded and still provide a high science return per dollar invested. The proposed paradigm shift has several aspects that make it worthy of consideration: 1) Telescopes would leverage existing Commercial Remote Sensing Satellite (CRSS) Architectures such as the 1.1m NextView systems developed by ITT, GeoEye-1, and WorldView-2, or the 0.7m IKONOS system (or perhaps other proprietary systems); 2) By using large EELV class fairings, multiple telescopes with different science missions could be flown on a single spacecraft bus sharing common features such as communications and telemetry (current Earth Science missions in early development phases are considering this approach); 3) Multiple smaller observatories (with multiple spacecraft) could be flown in a single launch vehicle for instances where the different science payloads had incompatible requirements; and 4) by leveraging CRSS architectures, vendors could supply telescopes at a fixed price. Here we discuss the implications and risks that the proposed paradigm shift would carry.