Proceedings Volume 8533

Sensors, Systems, and Next-Generation Satellites XVI

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Proceedings Volume 8533

Sensors, Systems, and Next-Generation Satellites XVI

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Volume Details

Date Published: 20 November 2012
Contents: 12 Sessions, 50 Papers, 0 Presentations
Conference: SPIE Remote Sensing 2012
Volume Number: 8533

Table of Contents

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Table of Contents

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  • Front Matter: Volume 8533
  • Japanese Missions
  • Japanese Missions II
  • US Missions
  • Missions and Sensing I
  • Missions and Sensing II
  • Mission and Sensing III
  • Focal Plane Assemblies
  • Calibration I
  • Calibration II
  • Calibration III
  • Poster Session
Front Matter: Volume 8533
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Front Matter: Volume 8533
This PDF file contains the front matter associated with SPIE Proceedings Volume 8533, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.
Japanese Missions
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Overview of Japanese Earth observation programs
Five programs, i.e. TRMM, AMSR-E, ASTER, GOSAT and GCOM-W1 are going on in Japanese Earth Observation programs. ASTER has lost its short wave infrared channels. AMSR-E stopped its operation, but it started its operation from Sep. 2012. GCOM-W1 was launched on 18, May, 2012 and is operating well as well as TRMM and GOSAT. ALOS (Advanced Land Observing Satellite) was successfully launched on 24th Jan. 2006. ALOS carries three instruments, i.e., PRISM (Panchromatic Remote Sensing Instrument for Stereo Mapping), AVNIR-2 (Advanced Visible and Near Infrared Radiometer), and PALSAR (Phased Array L band Synthetic Aperture Radar). PRISM is a 3 line panchromatic push broom scanner with 2.5m IFOV. AVNIR-2 is a 4 channel multi spectral scanner with 10m IFOV. PALSAR is a full polarimetric active phased array L-band SAR. PALSAR has many observation modes including full polarimetric mode and scan SAR mode. Unfortunately, ALOS has stopped its operation on 22nd, April, 2011 by power loss. GOSAT (Greenhouse Gas Observation Satellite) was successfully launched on 29, January, 2009. GOSAT carries 2 instruments, i.e. a green house gas sensor (TANSO-FTS) and a cloud/aerosol imager (TANSO-CAI). The main sensor is a Fourier transform spectrometer (FTS) and covers 0.76 to 15 μm region with 0.2 to 0.5 cm-1 resolution. SMILES (Super-conducting Millimeter wave Emission Spectrometer) was launched on September 2009 to ISS and started the observation, but stopped its operation on April 2010. After the unfortunate accident of ADEOS2, JAXA still have plans of Earth observation programs. Next generation satellites will be launched in 2012-2015 timeframe. They are, GCOM-W and GCOM-C (ADEOS-2 follow on), and GPM (Global Precipitation Mission) core satellite. GPM is a joint project with NASA and will carry two instruments. JAXA will develop DPR (Dual frequency Precipitation Radar) which is a follow on of PR on TRMM. Another project is EarthCare. It is a joint project with ESA and JAXA is going to provide CPR (Cloud Profiling Radar). ALOS F/O satellites are divided into two satellites, i.e. SAR and optical satellites The first one of ALOS F/O is called ALOS 2 and will carry L-band SAR, while second one is called ALOS3 and will carry optical sensors.
Onboard calibration of the ASTER instrument over twelve years
The ASTER is a high-resolution optical sensor for observing the Earth on the Terra satellite launched in December1999. The ASTER consists of three radiometers. The VNIR has three bands in the visible and near-infrared region, the SWIR has six bands in the shortwave infrared region, and the TIR has five bands in the thermal infrared region. The onboard calibration devices of the VNIR and SWIR were halogen lamps and photodiode monitors. In orbit three bands of the VNIR showed a rapid decrease in the output signal. The band 1, the shortest wavelength, decreased most to 70% in twelve years. The temperature of the onboard blackbody of the TIR is varied from 270 K to 340 K in the long term calibration for the offset and gain calibration. The long term calibration of the TIR showed a decrease in response after launch. The decrease was most remarkable at band 12 decreasing to 60% in eleven years. The degradation spectra of the TIR shows that the possible causes of the degradation might be silicone and hydrazine. ASTER onboard calibration is normally carried out once in 49 days but additional onboard calibrations were added just before and after the inclination adjustment maneuver (IAM) to check the effect on the RCC. This experiment was carried out three times for each IAM in the fiscal year 2011. The result showed that the change in the RCC was small for both VNIR and TIR.
The current status of GOSAT and the concept of GOSAT-2
GOSAT which is dedicated to monitor the column concentration of carbon dioxide and methane was launched almost 3 and half years ago, and the data processing algorithm have been improved a few times based on the calibration and validation, and the precision of the concentration data have been increased. These data gave us a realization of the availability of the GHG observation from space. And it has been required to expand this mission to make it useful for mankind. So we have investigated the requirements for the next generation greenhouse gases observations from space and have defined the mission requirements for GOSAT-2. The measurement accuracy target of Carbon Dioxide concentration defined in this mission requirement is 0.5 ppm at 500km and 2,000km mesh spatial resolution over the land and ocean, respectively and 1 month average. To achieve this target, GOSAT-2 will adopt the Fourier Transform Spectrometer (FTS) and the imager along with GOSAT, but the functions and performances will be improved. For example, the CO observation band will be added and the grating spectrometer for UV band of CAI will be adopted to measure NO2 and to improve the aerosol retrievals. Following the presentation of the GOSAT observation results, the concept of GOSAT-2 will be shown.
Status of AMSR2 on GCOM-W1
Marehito Kasahara, Keiji Imaoka, Misako Kachi, et al.
The Global Change Observation Mission (GCOM) consists of two polar orbiting satellite observing systems, GCOM-W (Water) and GCOM-C (Climate), and three generations to achieve global and long-term monitoring of the Earth. GCOM-W1, which is the first satellite of the GCOM-W series, was launched from the Tanegashima Space Center on May 18, 2012 (Japan Standard Time), and moved to the regular observation operation on August 10, 2012 (JST) after the early orbit checkout had been completed. The early initiation of the Advanced Microwave Scanning Radiometer-2 (AMSR2) on GCOM-W1 observation was highly desired since the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) had halted its observation in October 2011 due to the increase of antenna rotation torque. The calibration activity of AMSR2 is going on toward the data release of Level-1 product scheduled in the beginning of 2013. The initial checkout of the ground segment, including systems for receiving, processing, archiving, and distributing the GCOM-W1 data, is also completed successfully. At-launch retrieval algorithms were used for the checkout. These algorithms will be validated and updated through calibration and validation activities. Public data release is scheduled one year after launch for geophysical parameters. Standard products will be available via online, free of charge, from the GCOM-W1 data providing service system. The AMSR-E products are already available from the same system.
Japanese Missions II
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Land validation for GCOM-C1/SGLI using UAV
Yhosiaki Honda, Koji Kajiwara, Ram Sharma, et al.
Japan Aerospace Exploration Agency (JAXA) is going to launch new Earth observation satellite GCOM-C1 in near future. The core sensor of GCOM-C1, Second Generation Global Imager (SGLI) has a set of along track slant viewing Visible and Near Infrared Radiometer (VNR). These multi-angular views aim to detect the structural information from vegetation canopy, especially forest canopy, for estimating productivity of the vegetation. SGLI Land science team has been developing the algorithm for above ground biomass, canopy roughness index, shadow index, etc. In this paper, we introduce the ground observation method developed by using Unmanned Aerial Vehicle (UAV) in order to contribute the algorithm development and its validation. Mainly, multi-angular spectral observation method and simple BRF model have been developed for estimating slant view response of forest canopy. The BRF model developed by using multi-angular measurement has been able to obtain structural information from vegetation canopy. In addition, we have conducted some observation campaigns on typical forest in Japan in collaboration with other science team experienced with vegetation phenology and carbon flux measurement. Primary results of these observations are also be demonstrated.
Status of proto-flight model of the dual-frequency precipitation radar for the global precipitation measurement
T. Miura, M. Kojima, K. Furukawa, et al.
The Dual-frequency Precipitation Radar (DPR) on the Global Precipitation Measurement (GPM) core spacecraft is being developed by Japan Aerospace Exploration Agency (JAXA) and National Institute of Information and Communications Technology (NICT). The GPM is a follow-on mission of the Tropical Rainfall Measuring Mission (TRMM). The objectives of the GPM mission are to observe global precipitation more frequently and accurately than TRMM. The frequent precipitation measurement about every three hours will be achieved by some constellation satellites with microwave radiometers (MWRs) or microwave sounders (MWSs), which will be developed by various countries. The accurate measurement of precipitation in mid-high latitudes will be achieved by the DPR. The GPM core satellite is a joint product of National Aeronautics and Space Administration (NASA), JAXA and NICT. NASA is developing the satellite bus and the GPM microwave radiometer (GMI), and JAXA and NICT are developing the DPR. JAXA and NICT are developing the DPR through procurement. The contractor for DPR is NEC TOSHIBA Space Systems, Ltd. The configuration of precipitation measurement using an active radar and a passive radiometer is similar to TRMM. The major difference is that DPR is used in GPM instead of the precipitation radar (PR) in TRMM. The inclination of the core spacecraft is 65 degrees, and the flight altitude is about 407 km. The non-sun-synchronous circular orbit is necessary for measuring the diurnal change of rainfall similarly to TRMM. The DPR consists of two radars, which are Ku-band (13.6 GHz) precipitation radar (KuPR) and Ka-band (35.55 GHz) precipitation radar (KaPR). According to the different detectable dynamic ranges, The KaPR will detect snow and light rain, and the KuPR will detect heavy rain. In an effective dynamic range in both KuPR and KaPR, drop size distribution information and more accurate rainfall estimates will be provided by a dual-frequency algorithm. The proto-flight test for DPR have finished in February 2012 and DPR integration on GPM core spacecraft was successfully completed in May 2012. The status of proto-flight model of DPR will be presented.
ALOS-2 development status and draft acquisition strategy
Shinichi Suzuki, Yukihiro Kankaku, Yuji Osawa
The Advanced Land Observing Satellite-2 (ALOS-2) will succeed to the radar mission of the ALOS “Daichi” which had contributed to cartography, regional observation, disaster monitoring, and earth resources surveys for more than 5 years until its termination of operation in May 2011. The state-of-the-art L-band Synthetic Aperture Radar (SAR) called PALSAR-2 onboard ALOS-2 will have enhanced performance in both high resolution (1m * 3m at finest in the Spotlight mode) and wide swath (up to 490km in the ScanSAR wide mode), compared to ALOS/PALSAR. Wider bandwidth and shorter revisit time will give better conference for INSAR data analysis such as crustal deformation and deforestation. The SAR antenna consists of 5 panels with total 1,080 radiation elements which are driven by 180 Transmit-Receive-Modules in order to steer and form a beam in both range and azimuth direction. In order to reduce range ambiguities,PALSAR-2 is capable to transmit up or down chirp signal alternatively and has phase modulation with zero or pi as well. The Proto Flight Model of ALOS-2 including PALSAR-2 is under integration and testing at JAXA’s Tsukuba Space Center. From experiences of the ALOS operation, a systematic observation strategy to achieve consistent data acquisitions in time and space was crucial. Since more observation modes of PALSAR-2 than those of PALSAR may trigger more conflicts among user requests, a basic observation scenario must be prepared to fulfill the mission requirements. This paper describes the current development status of ALOS-2 and a draft acquisition strategy for PALSAR-2.
A conceptual design of PRISM-2 for Advanced Land Observing Satellite-3(ALOS-3)
Hiroko Imai, Haruyoshi Katayama, Masakazu Sagisaka, et al.
The Japan Aerospace Exploration Agency (JAXA) is planning a satellite system including Advanced Land Observing Satellites 2 and 3 (ALOS-2 and ALOS-3) for the ALOS follow-on program. ALOS-3 will carry the optical sensor named “PRISM-2” and extend the capabilities of earlier ALOS missions. PRISM-2 will be able to collect high-resolution (0.8m) and wide-swath (50 km) imagery with high geo-location accuracy, as well as provide precise digital surface models (DSMs) using stereo pair images acquired by two telescopes. These capabilities are ideal for obtaining large-scale geographical information such as elevation and land cover-maps for use in many research areas and practical applications, including disaster management support.

JAXA has conducted a phase A study of the ALOS-3 spacecraft and PRISM-2, and is now working on prototype models of key components of PRISM-2’s telescope, focal plane, and data compressor.

This paper introduces a conceptual design for PRISM-2 and the ALOS-3 system.
Effect of temperature on onboard calibration reference material for spectral response function retrieval of the hyperspectral sensor of HISUI-SWIR spectral case
Kenji Tatsumi, Jun Tanii, Hisashi Harada, et al.
HISUI (Hyperspectral Imager SUIte) is the next Japanese earth observation sensor, which consists of hyperspectral and multispectral sensors. The hyperspectral sensor is an imaging spectrometer with the VNIR (400-970nm) and the SWIR (900-2500nm) spectral channels. Spatial resolution is 30 m with swath width of 30km. The spectral resolution will be better than 10nm in the VNIR and 12.5nm in the SWIR. The multispectral sensor has four VNIR spectral bands with spatial resolution of 5m and swath width of 90km. HISUI will be installed in ALOS-3 that is an earth observing satellite by JAXA. It will be launched in FY 2015. This paper is concerned with the effect of temperature on onboard calibration reference material (NIST SRM2065) for spectral response functions (SRFs) retrieval of the hyperspectral sensor. Since the location and intensity of absorption features are sensitive to material temperature, the estimated center wavelength and bandwidth of the SRFs may include the uncertainty. Therefore, it is necessary to estimate the deviation of the wavelength and the bandwidth broadening of the SRFs when the material temperature changes. In this paper we describe the evaluation of uncertainty of the SRF’s parameters retrieval and show some simulation’s results.
EarthCARE/CPR design and verification status
The Earth, Clouds, Aerosols and Radiation Explorer (EarthCARE) mission is joint mission between Europe and Japan for the launch year of 2015. Mission objective is to improve scientific understanding of cloud-aerosol-radiation interactions that is one of the biggest uncertain factors for numerical climate and weather predictions. The EarthCARE spacecraft equips four instruments such as an ultra violet lidar (ATLID), a cloud profiling radar (CPR), a broadband radiometer (BBR), and a multi-spectral imager (MSI) to observe aerosols, clouds and their interactions simultaneously from the orbit. Japan aerospace exploration agency (JAXA) is responsible for development of the CPR that will be the first space-borne W-band Doppler radar. The CPR is defined with minimum radar sensitivity of -35dBz, radiometric accuracy of 2.7 dB, and Doppler velocity measurement accuracy of 1m/s. These specifications require highly accurate pointing technique in orbit and high power source with large antenna dish. JAXA and National Institute of Information and Communications Technology (NICT) have been jointly developed this CPR to meet these requirements. In addition, new ground calibration technique is also being progressed for the launch of EarthCARE/CPR. This evaluation method will also be the first use for spacecraft as well as Doppler cloud radar. This paper shows the summary of the CPR design and verification status, and activity status of development of ground calibration method with a few results of experiment using current space-borne cloud radar (CloudSat, NASA).
US Missions
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NASA Earth Science Flight Program
Earth is a complex, dynamic system we do not yet fully understand. The Earth system, like the human body, comprises diverse components that interact in complex ways. We need to understand the Earth's atmosphere, lithosphere, hydrosphere, cryosphere, and biosphere as a single connected system. Our planet is changing on all spatial and temporal scales. The purpose of NASA's Earth Science Division (ESD) is to develop a scientific understanding of Earth's system and its response to natural or human-induced changes, and to improve prediction of climate, weather, and natural hazards. A major component of NASA’s ESD and residing in its Flight Program is a coordinated series of satellite and airborne missions for long-term global observations of the land surface, biosphere, solid Earth, atmosphere, and oceans. This coordinated approach enables an improved understanding of the Earth as an integrated system. NASA is completing the development and launch of a set of Foundational missions, Decadal Survey missions, and Climate Continuity missions. As a result of the recent launches of the Aquarius/SAC-D and Soumi National Polar-orbiting Partnership (NPP) satellites, 16 missions are currently operating on-orbit and the Flight Program has three mission in development and a further eight Decadal Survey and Climate Continuity missions under study. Technology development is continuing for a remaining five third tier Decadal Survey mission. The first Earth Venture low to moderate cost, small to medium-sized full orbital mission, EV-2 was competitively selected and its early development activities have commenced. The EV-1 sub-orbital projects continue in implementation. Instruments for orbital missions of opportunity and the second set of EV sub-orbital projects are also being planned. An overview of plans and current status will be presented.
Global Precipitation Measurement (GPM) L-18
Steven P. Neeck, Ramesh K. Kakar, Ardeshir A. Azarbarzin, et al.
The Global Precipitation Measurement (GPM) mission is an international network of satellites that provide the next-generation global space-based observations of rain and snow. Building upon the success of the Tropical Rainfall Measuring Mission (TRMM), the GPM concept centers on the deployment of a Core Observatory carrying an advanced radar / radiometer system to measure precipitation from space and serve as a reference standard to unify precipitation measurements from a constellation of research and operational satellites. Through improved measurements of precipitation globally, the GPM mission will help to advance our understanding of Earth's water and energy cycle, improve forecasting of extreme events that cause natural hazards and disasters, and extend current capabilities in using accurate and timely information of precipitation to directly benefit society. GPM, initiated by NASA and the Japan Aerospace Exploration Agency (JAXA) as a global successor to TRMM, comprises a consortium of international space agencies, including the Centre National d'Études Spatiales (CNES), the Indian Space Research Organisation (ISRO), the National Oceanic and Atmospheric Administration (NOAA), the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and others. The GPM Core Observatory is currently in its system level environmental test program (Phase D) following delivery and integration of the two science instruments, the JAXA Dual-frequency Precipitation Radar (DPR) and the NASA GPM Microwave Imager (GMI). Launch is scheduled for February 2014 from JAXA's Tanegashima Space Center on a H-IIA launch vehicle.
Surface Water and Ocean Topography (SWOT) mission
Steven P. Neeck, Eric J. Lindstrom, Parag V. Vaze, et al.
The Surface Water Ocean Topography (SWOT) mission was recommended in 2007 by the National Research Council’s Decadal Survey, “Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond”, for implementation by NASA. The SWOT mission is a partnership between two communities, the physical oceanography and the hydrology, to share high vertical accuracy and high spatial resolution topography data produced by the science payload, principally a Ka-band radar Interferometer (KaRIn). The SWOT payload also includes a precision orbit determination system consisting of GPS and DORIS receivers, a Laser Retro-reflector Assembly (LRA), a Jason-class nadir radar altimeter, and a JASON-class radiometer for tropospheric path delay corrections. The SWOT mission will provide large-scale data sets of ocean sea-surface height resolving scales of 15km and larger, allowing the characterization of ocean mesoscale and submesoscale circulation. The SWOT mission will also provide measurements of water storage changes in terrestrial surface water bodies and estimates of discharge in large (wider than 100m) rivers globally. The SWOT measurements will provide a key complement to other NASA spaceborne global measurements of the water cycle measurements by directly measuring the surface water (lakes, reservoirs, rivers, and wetlands) component of the water cycle. The SWOT mission is an international partnership between NASA and the Centre National d’Etudes Spatiales (CNES). The Canadian Space Agency (CSA) is also expected to contribute to the mission. SWOT is currently nearing entry to Formulation (Phase A). Its launch is targeted for October 2020.
Joint Polar Satellite System (JPSS) instrument transition to NASA and development status
Christopher W. Brann
The Joint Polar Satellite System (JPSS) Program is a cooperative program between the National Aeronautics and Space Agency (NASA) and the National Oceanic and Atmospheric Administration (NOAA) to design, develop, and fly the next suite of US civilian polar orbiting environmental sensing instruments. The JPSS Program is a product of the restructuring of the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Program, which occurred in 2010. With the transition to NASA, the JPSS instruments have undergone significant review with numerous updates to the designs as well as made significant progress toward delivering a superior capability to the Nation. This paper will discuss the program transition as it relates to the instruments and the associated transition review efforts, key findings, important changes to the instruments for JPSS and their current development status. The VIIRS instrument will be presented separately.
Missions and Sensing I
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Accomplishments from 9.5 years of AMSR-E observations
Elena S. Lobl
The retrieved atmospheric parameters using the observations from AMSR-E on Aqua are used primarily in climate research as well as in atmospheric models used in weather forecasting. This JAXA instrument performed exceptionally well for more than three times its design lifetime. Images of all retrieved atmospheric parameters will be shown, and examples of the science performed with the data will be given. A final algorithm update and data reprocessing will ensure the best quality products are archived at NSIDC for future research.
Simulation of the performance and image quality characteristics of the Landsat OLI and TIRS sensors using DIRSIG
The Digital Imaging and Remote Sensing (DIRS) Image Generation (DIRSIG) model has been significantly upgraded to support the Landsat Data Continuity Mission (LDCM). The DIRSIG improvements simulate the LDCM Thermal Infrared Sensor (TIRS) and the Operational Land Imager (OLI) sensor’s characteristics in support of the NASA and USGS image quality assessment programs. These improvements allow for simulation of spacecraft orbits using standard NORAD two line element (TLE) orbital descriptors. Sensor improvements include individual detector element lines of site, relative spectral response (RSR), bias, gain, non-linear response, and noise. Using DIRSIG’s existing source-targetsensor radiative transfer, atmospheric propagation, scene simulation, and thermal models, simulated Landsat 8 imagery was generated. These tools were developed to enable assessment of design trades during instrument development and build, and evaluation of expected performance during instrument test, as test data is used to refine the modeled instrument performance. Current efforts are aimed at refining predicted performance models, simulating on-orbit calibration maneuvers and generation of data to test data processing and analysis algorithms. Initial studies are aimed at assessing the impact of RSR variation on banding and striping in both OLI and TIRS and the use of side slither (90° Yaw) as a possible method to characterize and potentially compensate for non-linearity effects. Ongoing work aimed at simulating targets to support image based registration of the OLI and TIRS instruments is also presented. In general, the use of advanced simulation and modeling tools to support instrument design trades, image quality prediction, on-orbit image quality assessment and operational trades is reviewed. The overall effort is designed to provide simulated imagery incorporating all aspects of the instrument acquisition physics and scene phenomenology in support of instrument developers, operators, and Earth observation scientists.
Missions and Sensing II
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Concept and technology development for the multispectral imager of the Canadian Polar Communications and Weather mission
Louis Moreau, Patrick Dubois, Frédéric Girard, et al.
The Polar Communications and Weather (PCW) mission is proposed by the Canadian Space Agency (CSA), in partnership with Environment Canada, the Department of National Defence, and several other Canadian government departments. The objectives of the PCW mission are to offer meteorological observations and telecommunication services for the Canadian North. These capabilities are particularly important because of increasing interest in the Arctic and the desire to maintain Canadian sovereignty in this region. The PCW mission has completed its Phase A in 2011. The PCW Meteorological Payload is a Multi-Spectral Imager (MSI) that will provide near-real time weather imagery for the entire circumpolar region with a refresh period of 15 to 30 minutes. Two satellites on a Highly Elliptical Orbit (HEO) will carry the instrument so as to observe the high latitudes 24 hours per day from a point of view that is almost geostationary. The data from the imagers are expected to greatly enhance accuracy of numerical weather prediction models for North America and globally. The mission will also produce useful information on environment and climate in the North. During Phase A, a certain number of critical technologies were identified. The CSA has initiated an effort to develop some of these so that their Technology Readiness Level (TRL) will be suitable for the follow-on phases of the program. An industrial team lead by ABB has been selected to perform technology development activities for the Meteorological Payload. The goal of the project is to enhance the TRL of the telescope, the spectral separation optics, and the infrared multispectral cameras of the PCW Meteorological Payload by fabricating and testing breadboards for these items. We will describe the Meteorological Payload concept and report on the status of the development activities.
PCW/PHEOS-WCA: quasi-geostationary Arctic measurements for weather, climate, and air quality from highly eccentric orbits
Richard L. Lachance, John C. McConnell, C. Tom McElroy, et al.
The PCW (Polar Communications and Weather) mission is a dual satellite mission with each satellite in a highly eccentric orbit with apogee ~42,000 km and a period (to be decided) in the 12–24 hour range to deliver continuous communications and meteorological data over the Arctic and environs. Such as satellite duo can give 24×7 coverage over the Arctic. The operational meteorological instrument is a 21-channel spectral imager similar to the Advanced Baseline Imager (ABI). The PHEOS-WCA (weather, climate and air quality) mission is intended as an atmospheric science complement to the operational PCW mission. The target PHEOS-WCA instrument package considered optimal to meet the full suite of science team objectives consists of FTS and UVS imaging sounders with viewing range of ~4.5° or a Field of Regard (FoR) ~ 3400×3400 km2 from near apogee. The goal for the spatial resolution at apogee of each imaging sounder is 10×10 km2 or better and the goal for the image repeat time is targeted at ~2 hours or better. The FTS has 4 bands that span the MIR and NIR with a spectral resolution of 0.25 cm−1. They should provide vertical tropospheric profiles of temperature and water vapour in addition to partial columns of many other gases of interest for air quality. The two NIR bands target columns of CO2, CH4 and aerosol optical depth (OD). The UVS is an imaging spectrometer that covers the spectral range of 280–650 nm with 0.9 nm resolution and targets the tropospheric column densities of O3 and NO2 and several other Air Quality (AQ) gases as well the Aerosol Index (AI).
Novel pole-sitter mission concepts for continuous polar remote sensing
Matteo Ceriotti, Jeannette Heiligers, Colin R. McInnes
The pole-sitter concept is a solution to the poor temporal resolution of polar observations from highly inclined, low Earth orbits and the poor high latitude coverage from geostationary orbit. It considers a spacecraft that is continuously above either the North or South Pole and, as such, can provide real-time, continuous and hemispheric coverage of the polar regions. Despite the significant distance from the Earth, the utility of this platform for Earth observation and telecommunications is clear, and applications include polar weather forecasting and atmospheric science, glaciology and ice pack monitoring, ultraviolet imaging for aurora studies, continuous telecommunication links with polar regions, arctic ship routing and support for future high latitude oil and gas exploration. The paper presents a full mission design, including launch (Ariane 5 and Soyuz vehicles), for two propulsion options (a near-term solar electric propulsion (SEP) system and a more advanced combination of a solar sail with an SEP system). An optional transfer from the North Pole to South Pole and vice-versa allows viewing of both poles in summer. The paper furthermore focuses on payloads that could be used in such a mission concept. In particular, by using instruments designed for past deep space missions (DSCOVR), it is estimated that resolutions up to about 20 km/pixel in the visible wavelengths can be obtained. The mass of these instruments is well within the capabilities of the pole-sitter design, allowing an SEP-only mission lifetime of about 4 years, while the SEP/sail propulsion technology enables missions of up to 7 years.
A novel design concept for space-based polar remote sensing
Malcolm Macdonald, Pamela Anderson, Carl Warren
Space-based remote sensing of the Earth is conducted from a fleet of spacecraft in two basic orbital positions, near-polar low-Earth orbits and geosynchronous orbits, with each offering its own advantages and disadvantages. Low-Earth orbits provide high-resolution observations at the expense of large-scale contextual information, while geosynchronous orbits provide near-global, continuous coverage at reduced resolutions. However, due to the rapidly decreasing horizontal resolution data-products derived from geosynchronous orbits are of degraded value beyond approximately 55 degrees of latitude. A novel mission design is introduced to enable continuous observation of all longitudes at latitudes between 55 and 90 degrees with an observation zenith angle of less than 60 degrees, without the use of composite images. A single Soyuz launch is used to deliver three spacecraft to 12-hr, highly eccentric true-polar orbits with apogee at 40170 km and electric propulsion is used to maintain the orbit apse-line coincident with the Earth’s poles. It is shown that the science payload mass can be traded against the mission duration, with a payload mass varying between 120 – 90 kg for mission durations between 3 – 5 years, respectively. It is further shown that the payload would have approximately of 2kW of power available during operations as the electric propulsion system is not operated at these times. Whilst the payload mass is less than a typical remote sensing platform in geosynchronous orbit it is considered that the concept would offer an excellent technology demonstrator mission for operational missions, whilst also enabling unique and valuable science.
Invitation to a forum: architecting operational ‘next generation’ earth monitoring satellites based on best modeling, existing sensor capabilities, with constellation efficiencies to secure trusted datasets for the next 20 years
Douglas B. Helmuth, Raymond M. Bell, David A. Grant, et al.
Architecting the operational Next Generation of earth monitoring satellites based on matured climate modeling, reuse of existing sensor & satellite capabilities, attention to affordability and evolutionary improvements integrated with constellation efficiencies - becomes our collective goal for an open architectural design forum. Understanding the earth's climate and collecting requisite signatures over the next 30 years is a shared mandate by many of the world's governments. But there remains a daunting challenge to bridge scientific missions to 'operational' systems that truly support the demands of decision makers, scientific investigators and global users' requirements for trusted data. In this paper we will suggest an architectural structure that takes advantage of current earth modeling examples including cross-model verification and a first order set of critical climate parameters and metrics; that in turn, are matched up with existing space borne collection capabilities and sensors. The tools used and the frameworks offered are designed to allow collaborative overlays by other stakeholders nominating different critical parameters and their own treaded connections to existing international collection experience. These aggregate design suggestions will be held up to group review and prioritized as potential constellation solutions including incremental and spiral developments - including cost benefits and organizational opportunities. This Part IV effort is focused on being an inclusive 'Next Gen Constellation' design discussion and is the natural extension to earlier papers.
Mission and Sensing III
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PERSIST: prototype Earth observing system using image slicer mirrors
David Lee, J. Barlow, A. Vick, et al.
The measurement of the atmospheric concentration of greenhouse gases such as carbon dioxide (CO2) requires the simultaneous observation of a number of wavelength channels. Current and planned CO2 missions typically measure three wavebands using a hyperspectral sensor containing three spectrometers fed by an optical relay system to separate the wavelength channels. The use of one spectrometer per wavelength channel is inefficient in terms of number of detectors required and the mass and volume. This paper describes the development of an alternative solution which uses two key technologies to enable a more compact design; an image slicer mirror placed at the focal plane, and a multiple slit spectrometer operating in multiple diffraction orders. Both of these technologies are in common use in advanced astronomical spectrometers on large telescopes. The imager slicer mirror technology, as used on the James Webb Space Telescope instrument MIRI, enables the spectrometer to be illuminated with three input slits, each at a different wavelength. The spectrometer then disperses the light into multiple diffraction orders, via an echelle grating, to simultaneously capture spectra for three wavelength channels.
DubaiSat-2 mission overview
DubaiSat-­2 is a low earth orbit (LEO) remote sensing satellite. The spacecraft generates high-resolution optical images with 1 m resolution in panchromatic (PAN) and 4 m resolution in Multi-­Spectral bands (MS: red, green, blue and near-infrared). It will provide different end users with valuable images for a wide range of applications. DubaiSat-2 is a follow on project aimed at building the skills gained from the first satellite project DubiaiSat-1, which was launched on 29th of July 2009. DubaiSat-2 is scheduled for launch in the last quarter of 2012. The purpose of this paper is to present an overview about DubaiSat-2 and the potential applications for its high-­resolution images.
Research of the multispectral camera of ZY-3 satellite
Bin Fan, Xiaohong Zhang, Weijun Cai, et al.
The multispectral camera mounted on ZY-3 satellite has been developed according to the requirements of a mapping camera. Many advanced techniques have been adopted to improve image quality of the camera. An off-axis three mirrors anastigmatic (TMA) telescope with high MTF, low distortion and wide field of view has been developed. High mechanical stability has been achieved by using flexible mounting technique. The radiometric quality of the camera system has been improved by using high integrated and low noise technology of the circuit. Testing in orbit proved that the functions and performances of the camera completely meet to the requirements, and some beyond. The camera intrinsic parameters remain stable. After geometrical testing and correcting, the location accuracy achieves high level. The paper describes the technology of design, fabricating, alignment and tests of the camera. The result will be useful for the other similar cameras.
An effective unloading opto-structure design of the multispectral camera on ZY-3
Weijun Cai, Bin Fan, Fengqin Zhang, et al.
The Multi-Spectral Camera is one of main payloads of ZY-3 satellite, which was launched in 2012 in China, and was used to land surveying, resources exploring, and 3D mapping. The Multi-Spectral Camera provides color image for the map. Due to the applying to mapping, the stability of elements of interior orientation becomes more important. The Multi-Spectral camera applies a three mirror off-axis optical system, so reflectors of the camera are key factors for imaging quality. Under the condition of space, the change of thermal environment will lead to distortion of opt-structure, so the location of the reflectors will change, which affects the imaging quality and the stability of elements of interior orientation. So the first problem for the mechanical design is to insure the stability of reflectors' position throughout alignment, experiments, and launch. In one word, the structure of tree mirror off-axis optical system must have excellent stability; include mechanics and thermal stability. Based on the imaging quality of the Multi-Spectral Camera, the paper analyzes the requirement of the opt-structure's stability, and presents an effective thermal-structure stabilizing design of the camera. The camera uses a design of unloading structure on the principle of flexible hinge. There are four mounting feet on the Camera. One mounting foot constraints all the six freedoms, flexible hinges on the other three of mounting feet can release the freedom at the thermal-distortion direction, so the camera is quasi statically determinate system on the satellite. The structure can release the thermal-distortion of the satellite effectively, when the temperature of the satellite frame is ranged from 25℃ to 15℃ on-orbit, besides the structure can provide enough stiffness. Combining the FME method with the experiments, it is validated that the flexible hinge structure can satisfied the stability requirement of the opt-structure.
Focal Plane Assemblies
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Infrared focal plane detector modules for space applications at AIM
Dominique Hübner, Stefan Hanna, Richard Thöt, et al.
In the framework of this paper, AIM presents the actual status of some of its currently ongoing focal plane detector module developments for space applications covering the spectral range from the short-wavelength infrared (SWIR) to the long-wavelength infrared (LWIR) and very-long-wavelength infrared (VLWIR), where both imaging and spectroscopy applications will be addressed. In particular, the integrated detector cooler assemblies for a mid-wavelength infrared (MWIR) push-broom imaging satellite mission, for the German hyperspectral satellite mission EnMAP will be elaborated. Additionally dedicated detector modules for LWIR/VLWIR sounding, providing the possibility to have two different PVs driven by one ROIC will be addressed.
New Sofradir VISIR-SWIR large format detector for next generation space missions
Bruno Fieque, Nicolas Jamin, Philippe Chorier, et al.
For now more than 10 years, Sofradir is involved in SWIR detector manufacturing, developing and improving its SWIR detectors technology, leading to a mature technology that enables to address most of missions needs in term of performances, but also with respect to hard environmental constraints. SWIR detection range at Sofradir has been qualified for space applications thanks to various programs already run (APEX or Bepi-Colombo programs) or currently running (Sentinel 2, PRISMA mission). Recently, for PRISMA mission, Sofradir is extending its Visible-Near infra-red technology, called VISIR, to 1000x256 hyperspectral arrays. This technology has the huge advantage to enable detection in both visible range and SWIR detection range (0.4μm up to 2.5μm). As part of the development of large format infrared detectors, Sofradir has developed Jupiter 1280x1024, 15μm pixel pitch detector in mid 2000s and this detector is available at production level since the end of year 2000s. Based on the experiences acquired in SWIR and VISIR technologies as well as in the development of large format infrared detectors, since 2011, in the frame of an ESA program (named Next Generation Panchromatic detector), Sofradir is developing a new VISIR 1kx1k detector. This new detector has a format of 1024x1024 pixels with a 15 μm pixel pitch and it is adapted to spectral range from UV to SWIR domain. This development contains mainly two challenges: - the extension of the detector sensitivity down to UV spectral range - the development of a large format Readout Integrated Circuit (ROIC) with 15μm pixel pitch adapted to VISIR and SWIR spectral range involving in particular low input fluxes. In this paper, we will describe the architecture and functionalities of this new detector. The expected performances will be presented as well. Finally, main applications of this kind of detectors and expected spatial missions will be presented.
Overview of p-on-n planar IRFPAs at DEFIR
In this paper, we report on results obtained both at CEA/LETI and SOFRADIR on p-on-n Infra-Red Focal Plane Arrays (IR FPAs) from the Short-Wave (SW) to the Very-Long-Wave (VLW) spectral range. For many years, p-on-n arsenicion implanted planar technology has been developed and improved within the framework of the joint laboratory DEFIR, a collaborative effort bringing together the expertise of both teams. Compared to n-on-p architecture, p-on-n technology allows to lower dark current density and series resistance by means of respectively long-lifetime minority carriers (hole) and high-mobility majority carriers (electrons). As a consequence, p-on-n photodiodes are well-adapted for very large FPAs operating either at high temperature or very low flux. The Mid-Wave (MW) and Long-Wave (LW) spectral ranges have been firstly addressed with TV/4 FPAs, 30 μm pitch, principally for defence and security applications. Our results showed state-of-the-art detector performances, consistent with “Rule 07” model, a relevant indicator of the p-on-n technology maturity. The subsequent developments of p-on-n imagers have produced more compact, less energy consuming systems, with a substantial resolution enhancement. In this way, MW and LW FPAs, TV format, with 15 μm pixel pitch have been designed. First results obtained in MW (λc=5.3 μm @80 K) for High Operating Temperature (HOT) applications have showed highly promising Electro-Optical (EO) performances. Space applications are another exciting but challenging domains where p-on-n is a good candidate. In this way, imagers dedicated to low-flux detection have first been realized as TV/4 FPAs, with 15μm pitch in the SW spectral range (2 μm). The dark currents obtained are coherent with those published in the literature. Finally, TV/4 arrays, 30 μm pixel pitch, have been manufactured for the very long wave spectral range. For this detection range, the quality of material and reliability of technology are the most critical. The measured dark current fits “Rule 07” well, with homogeneous imagers. In conclusion, DEFIR team have developed, improved and characterized p-on-n IR FPAs from SW to VLW spectral range. In all spectral ranges, we have demonstrated state-of-the-art results, which highlight the quality of material and viability of our p-on-n technology. This technology, currently industrialized by SOFRADIR, opens new ways for next generation of imagers.
Evaluation of very long wave p-on-n MCT FPAs for space applications
Developments made last years at CEA-LETI on p-on-n planar HgCdTe (MCT) photodiodes technology on long-, midand short-wavelength led to the manufacture of focal plane arrays (FPA) demonstrators with high performances. Improvements have been done on both technology and process to index very long-wavelength spectral band. Such detectors is currently being evaluated for space applications such as IASI-NG [1] or EChO [2] as they give the opportunity to address low flux detection conditions or higher operating temperature (lowering the electrical power consumption). Various process settings were tested to find optimized conditions in order to obtain the best detector performances. Cutoff wavelength of the manufactured detectors ranges from 9.5 to 15.5 μm at 78K. MCT base layer has been grown by liquid phase epitaxy (LPE) on lattice matched CdZnTe. The n-type doping is achieved during epitaxy by Indium incorporation. Planar p-on-n photodiodes were manufactured by Arsenic incorporation using ion-implantation and activation is done by post-implantation annealing under Hg overpressure. Electro-optical characterizations were performed both on test arrays and FPAs. Results show excellent operabilities (over 99.9% with ±0.5×mean value criterion) in responsivity and NETD. Measured RMS noise of the photodiodes is comparable to calculated current shot noise. The dark current is following the well-known Rule07 for every component and on a large temperature range.
Calibration I
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Overview of Aqua MODIS 10-year on-orbit calibration and performance
Since launch in May 2002, Aqua MODIS has successfully operated for over 10 years, continuously collecting global datasets for scientific studies of key parameters of the earth’s land, ocean, and atmospheric properties and their changes over time. The quality of these geophysical parameters relies on the input quality of sensor calibrated radiances. MODIS observations are made in 36 spectral bands with wavelengths ranging from visible (VIS) to long-wave infrared (LWIR). Its reflective solar bands (RSB) are calibrated using data collected from its on-board solar diffuser and regularly scheduled lunar views. The thermal emissive bands (TEB) are calibrated using an on-board blackbody (BB). The changes in the sensor’s spectral and spatial characteristics are monitored by an on-board spectroradiometric calibration assembly (SRCA). This paper presents an overview of Aqua MODIS 10-year on-orbit operation and calibration activities, from launch to present, and summarizes its on-orbit radiometric, spectral, and spatial calibration and characterization performance. In addition, on-orbit changes in sensor characteristics and corrections applied to continuously maintain level 1B (L1B) data quality are discussed, as well as lessons learned that could benefit future calibration efforts.
Evaluation of Terra and Aqua MODIS thermal emissive band calibration consistency
Terra and Aqua MODIS have operated continuously for more than 12 and 10 years respectively and are key instruments for NASA’s Earth Observing System missions. The 16 thermal emissive bands (TEB), covering wavelengths from 3.5 to 14.4 μm with a nadir spatial resolution of 1 km are used to regularly generate a variety of atmosphere, ocean and land science products. As the sensors age well past their prime design life of 6 years, understanding the instrument on-orbit performance is necessary to maintain consistency between sensors in the long-term data records. Recurrent observations of Dome C, Antarctica by both Terra and Aqua MODIS over mission lifetime are used to track the calibration consistency and stability of the two sensors. A ground temperature sensor provides a proxy reference measurement useful for determining the relative bias between the two instruments. This technique is most useful for the land surface sensing bands, such as bands 29, 31 and 32, but can be applied to all other TEB to provide a metric to assess long-term trends. A change in the TEB calibration approach for the MODIS Collection 6 reprocessing mitigate a cold scene bias previously observed for retrievals of brightness temperatures well below the on-board blackbody calibrator temperature range (270-315 K). The impact of the Collection 6 calibration changes are illustrated using the Dome C observations.
Comparison of MODIS and VIIRS On-board blackbody Performance
MODIS has 16 thermal emissive bands (TEB) with wavelengths ranging from 3.7 to 14.4 μm. MODIS TEB are calibrated on-orbit by a v-grooved blackbody (BB) on a scan-by-scan basis. The BB temperatures are measured by a set of 12 thermistors. As expected, the BB temperature uncertainty and stability have direct impact on TEB calibration quality and, therefore, the quality of the science products derived from TEB observations. Since launch, Terra and Aqua ODIS have successfully operated for more than 12 and 10 years, respectively. Overall performance of each on-board BB has been satisfactory, meeting the TEB on-orbit calibration requirements. The first VIIRS instrument was launched on-board the Suomi NPP spacecraft on October 28, 2011. It has successfully completed its initial Intensive Calibration and Validation (ICV) phase. As a followed-up instrument to MODIS, VIIRS has 7 TEB, covering wavelengths from 3.7 to 12.0 μm. Designed with strong MODIS heritage, VIIRS uses a similar BB for its TEB calibration. Like MODIS, VIIRS BB is nominally controlled at a constant temperature. Periodically, a BB Warm-Up and Cool-Down (WUCD) operation is performed, during which the BB temperatures vary from instrument ambient (temperature) to 315 K. Following a brief review of MODIS and VIIRS BB operation strategy, this paper examines and compares their on-orbit performance in terms of BB temperature scan-to-scan variations during sensor nominal operations as well as during periodic BB WUCD operations. In addition, this paper shows the noise characterization results for the closely matched MODIS and VIIRS spectral bands.
Modeling the detector radiometric response gains of the Suomi NPP VIIRS reflective solar bands
Ning Lei, Zhipeng Wang, Bruce Guenther, et al.
Right after the opening of the NADIR door of the Visible/Infrared Imager/Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership (NPP) satellite, the detector gains of the Near InfraRed (NIR) bands have decreased much faster than expected, indicating large degradation of the VIIRS sensor optical system. To determine the root cause and to access the potential outcome of the degradation, we developed a mathematical model based on physical hypotheses on the optical system, especially the Rotating Telescope Assembly mirror surfaces. Current detector gains are consistent with a model of a four-mirror system, with each mirror having a thin contaminant layer of material that reduces the mirror transmission and the reduction is activated by solar radiation. The ratios of the reduced transmission coefficients are in good agreement with those from the reflectance measurement of the Traveling Witness Mirror (after exposure of ultraviolet light from a test lamp) independently carried out as part of the degradation anomaly investigation. In this Proceeding, we describe the mathematical model and discuss the results.
Calibration of NPP VIIRS fire detection band using lunar observations
The National Polar-orbiting Partnership (NPP) Visible Infrared Imager Radiometer Suite (VIIRS) includes a fire detection band at roughly 4 μm. This spectral band has two gain states; fire detection occurs in the low gain state above approximately 343 K. VIIRS thermal bands utilize an on-board blackbody to provide on-orbit calibration. However, as the maximum temperature of this blackbody is 315 K, the low gain state of the 4 μm band cannot be calibrated in the same manner. Regular observations of the Moon provide an alternative calibration source, as the maximum surface temperature is around 390 K. The periodic on-board high gain calibration along with a surface temperature map based on LRO DIVINER observations was used to determine the emissivity and reflected radiance of the lunar surface at 4 μm; these factors and the lunar data are then used to calibrate the low gain state of the fire band. Our analysis suggests that the responsivity of the low gain state is lower than the pre-launch value currently in use.
Calibration II
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Method of comparing CERES and ScaRaB 3 measurements
The SCAnner for RAdiation Budget (ScaRaB) 3 instrument is aboard the Megha-Tropique spacecraft. The CERES Flight Model 5 was recently placed in orbit aboard the NPP spacecraft to replace the CERES FM-1 through -4 aboard the Terra and Aqua spacecraft which have provided Earth radiation budget measurement for twelve and ten years. The CERES instruments have been rotated in azimuth so the CERES can observe the same scene in the same direction as ScaRaB, thus both instruments measure the same radiance for shortwave (reflected solar) radiance and for longwave (Earth-emitted) radiance. The data collected in this manner serves to validate all of these instruments. The geometry of the operation of CERES as constrained by the orbits is described.
Development of dedicated target tracking capability for the CERES instruments through flight software: enhancing radiometric validation and on-orbit calibration
Kelly K. Teague, G. Louis Smith, Kory Priestley, et al.
Five CERES scanning radiometers have been flown to date. The Proto-Flight Model flew aboard the Tropical Rainfall Measurement Mission spacecraft in November 1997. Two CERES instruments, Flight Models (FM) 1 and 2, are aboard the Terra spacecraft, which was launched in December 1999. Two more CERES instruments, FM-3 and FM-4, are on the Aqua spacecraft, which was placed in orbit in May 2002. These instruments continue to operate after providing over a decade of Earth Radiation Budget data. The CERES FM-5 instrument, onboard the Suomi-NPP spacecraft, launched in October 2011. The CERES FM- 6 instrument is manifested on the JPPS-1 spacecraft to be launched in December 2016. A successor to these instruments is presently in the definition stage. This paper describes the evolving role of flight software in the operation of these instruments to meet the Science objectives of the mission and also the ability to execute supplemental tasks as they evolve. In order to obtain and maintain high accuracy in the data products from these instruments, a number of operational activities have been developed and implemented since the instruments were originally designed and placed in orbit. These new activities are possible because of the ability to exploit and modify the flight software, which operates the instruments. The CERES Flight Software interface was designed to allow for on-orbit modification, and as such, constantly evolves to meet changing needs. The purpose of this paper is to provide a brief overview of modifications which have been developed to allow dedicated targeting of specific geographic locations as the CERES sensor flies overhead on its host spacecraft. This new observing strategy greatly increases the temporal and angular sampling for specific targets of high scientific interest.
Calibration III
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In-orbit calibration strategy for Sentinel-1
Paul Snoeij, Ignacio Navas-Traver, Dirk Geudtner, et al.
The ESA Sentinels constitute the first series of operational satellites responding to the Earth Observation needs of the EU-ESA Global Monitoring for Environment and Security (GMES) programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. In contrast to SAR systems already existing in C-band like ASAR/ENVISAT or RADARSAT-2, high demands on the radiometric stability and accuracy are made for Sentinel-1. The mission depends on the method of calibrating the entire Sentinel-1 system in an efficient way. This paper describes the strategy and provides a plan of all activities required for in-flight calibration of Sentinel-1.
Characterisation methods for the hyperspectral sensor HySpex at DLR's calibration home base
Andreas Baumgartner, Peter Gege, Claas Köhler, et al.
The German Aerospace Center’s (DLR) Remote Sensing Technology Institute (IMF) operates a laboratory for the characterisation of imaging spectrometers. Originally designed as Calibration Home Base (CHB) for the imaging spectrometer APEX, the laboratory can be used to characterise nearly every airborne hyperspectral system. Characterisation methods will be demonstrated exemplarily with HySpex, an airborne imaging spectrometer system from Norsk Elektro Optikks A/S (NEO). Consisting of two separate devices (VNIR-1600 and SWIR-320me) the setup covers the spectral range from 400 nm to 2500 nm. Both airborne sensors have been characterised at NEO. This includes measurement of spectral and spatial resolution and misregistration, polarisation sensitivity, signal to noise ratios and the radiometric response. The same parameters have been examined at the CHB and were used to validate the NEO measurements. Additionally, the line spread functions (LSF) in across and along track direction and the spectral response functions (SRF) for certain detector pixels were measured. The high degree of lab automation allows the determination of the SRFs and LSFs for a large amount of sampling points. Despite this, the measurement of these functions for every detector element would be too time-consuming as typical detectors have 105 elements. But with enough sampling points it is possible to interpolate the attributes of the remaining pixels. The knowledge of these properties for every detector element allows the quantification of spectral and spatial misregistration (smile and keystone) and a better calibration of airborne data. Further laboratory measurements are used to validate the models for the spectral and spatial properties of the imaging spectrometers. Compared to the future German spaceborne hyperspectral Imager EnMAP, the HySpex sensors have the same or higher spectral and spatial resolution. Therefore, airborne data will be used to prepare for and validate the spaceborne system’s data.
Laboratory test simulation for non-flat response calibration of global Earth albedo monitor
In this report, we present laboratory test simulation for directional responsivity of a global Earth albedo monitoring instrument. The sensor is to observe the Sun and the Earth, alternately, and measure their shortwave (<4μm) radiations around the L1 halo orbit to obtain global Earth albedo. The instrument consists of a broadband scanning radiometer (energy channel instrument) and an imager (visible channel instrument) with ±2° field-of-view. In the case of the energy channel instrument, radiations arriving at the viewing ports from the Sun and the Earth are directed toward the pyroelectric detector via two spherical folding mirrors and a 3D compound parabolic concentrator (CPC). The instrument responsivity is defined by the ratio of the incident radiation input to the instrument output signal. The radiometer’s relative directional responsivity needs to be characterized across the field-of-view to assist output signal calibration. For the laboratory test, the distant small source configuration consists of an off-axis collimator and the instrument with adjustable mounts. Using reconstructed 3D CPC surface, the laboratory test simulation for predicting the instrument directional responsivity was conducted by a radiative transfer computation with ray tracing technique. The technical details of the laboratory test simulation are presented together with future plan.
Poster Session
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Supercontinuum source-based system for pre-launch calibration of the hyperspectral sensor
Yu Yamaguchi, Yoshiro Yamada, Juntoro Ishii
In order to guarantee the observed data with high spatial and wavelength resolution of hyperspectral/multispectral imagers, it is necessary to evaluate the difference of the spectral sensitivity among the detector devices arrayed twodimensionally and correct spectral and spatial misregistrations and the effect of stray light. However, there are tens of thousands of detectors in hyperspectral imagers, so they have to be evaluated in parallel by the special technique. Therefore, a light-source system which has high radiance with the spatial uniformity and widely tunable wavelengthrange is required instead of the conventional lamp system. In this presentation, we report the new setup of the supercontinuum(SC)-source-monochromator system and its fundamental performance. The SC source covers a wavelength range of 450-2400 nm, and its total output power is up to 6 W. We effectively coupled a high-power SC laser to a single monochromator and obtained spatial uniformity through an integrating sphere or a relay-optics system. The radiance three or more magnitudes higher than a tungsten halogen lamp was measured with the supercontinuum-source based system. The stability of output power and the spatial uniformity of radiance at the integrating-sphere port were also evaluated. Using the system, spectral misregistrations and responsivities of a hyperspectral imager, which is consist of a polychromator and two-dimensional array of CCD, were measured.
MODIS TEB calibration approach in collection 6
The MODerate Resolution Imaging Spectroradiometer (MODIS) is a heritage sensor operating on both the Terra and Aqua platforms, and has collected remotely sensed data for a combined mission time of twenty plus years. The instrument robustness and performance over their lifetimes has been very satisfactory and is well calibrated using the onboard calibrators (OBC). The radiometric fidelity of the MODIS instruments has ensured the high quality of science products derived from the Level 1B (L1B) imagery. MODIS Thermal Emissive Bands (TEB) are calibrated on-orbit using an on-board blackbody (BB) and through the space-view (SV) port. The MODIS BB is nominally controlled at 290K for Terra and at 285K for Aqua. Periodically, a BB warm-up and cool-down (WUCD) process is implemented, during which the BB temperatures vary from instrument ambient (approximately 272K) to 315K. The calibration coefficients for the 16 TEB bands are characterized using the above mentioned on-board BB operations (i.e. using nominal and WUCD operations). This paper will focus on the calibration algorithms of the TEB developed for collection 6 (C6) processing, its impact on the Level 1B (L1B) product in comparison to collection 5 (C5), and the methodology for issuing a Look Up Table (LUT) update for L1B processing.
Stray light analysis of nearby slot source using integrated ray tracing technique
In the remote sensing researches, the reflected bright source from out of FOV has effects on the image quality of wanted signal. Even though those signal from bright source are adjusted in corresponding pixel level with atmospheric correction algorithm or radiometric correction, those can be problem to the nearby signal as one of the stray light source. Especially, in the step and stare observational method which makes one mosaic image with several snap shots, one of target area can affect next to the other snap shot each other. Presented in this paper focused on the stray light analysis from unwanted reflected source for geostationary ocean color sensor. The stray light effect for total 16 slot images to each other were analyzed from the unwanted surrounding slot sources. For the realistic simulation, we constructed system modeling with integrated ray tracing (IRT) technique which realizes the same space time in the remote sensing observation among the Sun, the Earth, and the satellite. Computed stray light effect in the results of paper demonstrates the distinguishable radiance value at the specific time and space.
COMS normal operation for Earth Observation mission
Communication Ocean Meteorological Satellite (COMS) for the hybrid mission of meteorological observation, ocean monitoring, and telecommunication service was launched onto Geostationary Earth Orbit on June 27, 2010 and it is currently under normal operation service since April 2011. The COMS is located on 128.2° East of the geostationary orbit. In order to perform the three missions, the COMS has 3 separate payloads, the meteorological imager (MI), the Geostationary Ocean Color Imager (GOCI), and the Ka-band antenna. Each payload is dedicated to one of the three missions, respectively. The MI and GOCI perform the Earth observation mission of meteorological observation and ocean monitoring, respectively. For this Earth observation mission the COMS requires daily mission commands from the satellite control ground station and daily mission is affected by the satellite control activities. For this reason daily mission planning is required. The Earth observation mission operation of COMS is described in aspects of mission operation characteristics and mission planning for the normal operation services of meteorological observation and ocean monitoring. And the first year normal operation results after the In-Orbit-Test (IOT) are investigated through statistical approach to provide the achieved COMS normal operation status for the Earth observation mission.
Novel high sensitivity sensor design based on cascaded long-period fiber gratings
Zhengtian Gu, Xiuli Jiang, Haiyun Chen
A cascaded long-period fiber grating (CLPFG) sensor with film coating is presented in this paper. Two LPFGs are cascaded to form a Mach-Zehnder interferometer. The optical transmission spectrum and the sensing characteristics for ambient refractive index measurement of the cascaded LPFG sensor are analyzed in a form of transfer matrix based on rigorous coupled mode theory. The results indicate that it is highly sensitive to the film refractive index and surrounding refractive index, so it can be used as gas sensor or solution sensor. In addition, the influence of the film optical parameters on the sensitivity is analyzed. By using optimization method, the optimal film optical parameters and the grating structure parameters are obtained. Data simulation shows that the resolution of the refractive index of the films is predicted to be 10-7. Further, the cascaded chirped LPFG is introduced to study its sensing performance. The influence of the chirp coefficient and the grating structural parameters on the transmission spectrum of cascaded chirped LPFG is analyzed. Data simulation shows that the resolution of the refractive index of the films is predicted to be 10-9. In contrast to conventional measurement method based on interrogating the wavelength change, the intensity detection of this cascaded chirped LPFG sensor means that no optical spectrum analyzer is required in the measuring system, which is favorable for practical applications, especially for in situ environmental motoring.
The Radiance Standard RASTA of DLR's calibration facility for airborne imaging spectrometers
T. Schwarzmaier, A. Baumgartner, P. Gege, et al.
The German Aerospace Center (DLR) operates the Calibation Home Base (CHB) as a facility for the calibration of airborne imaging spectrometers and for field spectrometers. Until recently, absolute radiometric calibration was based on an integrating sphere that is traceable to SI units through calibration at the German Metrology Institute PTB. However, the stability of the radiance output was not monitored regularly and reliably. This was the motivation to develop a new radiance standard (RASTA) which allows monitoring in the wavelength range from 380 to 2500 nm. Radiance source is a diffuse reflector illuminated by a tungsten halogen lamp. Five radiometers mounted in a special geometry are used for monitoring. This setup improves twofold the uncertainty assessment compared to the previously used integrating sphere. Firstly, lamp irradiance and panel reflectance have been calibrated at PTB additionally to the radiance of the complete system. This calibration redundancy allows to detect systematic errors and to reduce calibration uncertainty. Secondly, the five radiometers form a redundant control system to measure changes of the spectral radiance. This enables long-time monitoring of the radiance source including assessment of the uncertainty caused by aging processes. Further advantages concern the reduction of periods of non-availability, applicability to sensors with larger field of view, and the possibility to alter intensity and spectral shape in a well-known way by exchanging the reflector. RASTA has been calibrated at PTB in November 2011 in the wavelength range from 350 to 2500 nm.
Rigorous geometrical modeling of ALSAT-2A Algerian satellite
Issam Boukerch, Mohammed Hadied, Redouane Mahmoudi, et al.
The use of the national very high resolution space system Alsat-2A is a primordial task having a significant technological and economical interest assuring the strengthening autonomy in terms of availability and coverage in the satellite data. Also it allows us to improve and update the base and thematic mapping throughout the national territory. Firstly, the characteristics of ALSAT-2A are presented, namely the images and the imaging system with a brief history of ALSAT program. Secondly, as a prerequisite, knowing the internal parameters is essentials to modelize the geometry of such imaging system. From metadata given by the images distributor and ground control points, several test are described and the results are presented. The test data are supplied by ASAL (Algerian Space Agency), the first dataset comprise a panchromatic image over the region of El Bayadh in the North West of Algeria equipped with nine GPS surveyed points. The second dataset is an along track stereoscopic panchromatic 1A level images over the town of sevilla in the south of Spain with 24 GCPs. Finally, a discussion on obtained results is dressed showing the geometric capability of ALSAT-2A.
Development of a large-size gold-coated integrating sphere
Masatomo Harada, Fumihiro Sakuma, Yasuji Yamamoto, et al.
We have developed a large-size gold-coated integrating sphere with an inner diameter of 1 m for use as a spectral radiance calibration standard in the short-wave infrared (SWIR) range. We anticipate that this integrating sphere will be used for the radiometric calibration of space-borne sensors such as SGLI (second-generation global imager) and HISUI (hyperspectal imager suite) prior to their launch. In this paper, we show the initial results of performance evaluation testing of the gold-coated integrating sphere system.
ALSAT-2A power subsystem behavior during launch, early operation, and in-orbit test
N. Larbi, M. Attaba, E. Beaufume
In 2006, Algerian Space Agency (ASAL) decided to design and built two optical Earth observation satellites. The first one, ALSAT-2A, was integrated and tested as a training and cooperation program with EADS Astrium. The second satellite ALSAT-2B will be integrated by ASAL engineers in the Satellite Development Center (CDS) at Oran in Algeria. On 12th July 2010, Algeria has launched ALSAT-2A onboard an Indian rocket PSLV-C15 from the Sriharikota launch base, Chennaï. ALSAT-2A is the first Earth observation satellite of the AstroSat-100 family; the design is based on the Myriade platform and comprising the first flight model of the New Astrosat Observation Modular Instrument (NAOMI). This Instrument offers a 2.5m ground resolution for the PAN channel and a 10m ground resolution for four multi-spectral channels which provides high imaging quality. The operations are performed from ALSAT-2 ground segment located in Ouargla (Algeria) and after the test phase ALSAT-2A provides successful images. ALSAT-2A electrical power subsystem (EPS) is composed of a Solar Array Generator (SAG ), a Li-ion battery dedicated to power storage and energy source during eclipse or high consumption phases and a Power Conditioning and Distribution Unit (PCDU). This paper focuses primarily on ALSAT-2A electrical power subsystem behavior during Launch and Early OPeration (LEOP) as well as In Orbit Test (IOT). The telemetry data related to the SAG voltage, current and temperature will be analyzed in addition to battery temperature, voltage, charge and discharge current. These parameters will be studied in function of satellite power consumption.
A laser ranging system operating at 1036 nm with Geiger-mode silicon avalanche photodiode
Guang Wu, Min Ren, Yan Liang, et al.
We demonstrated a laser ranging experiment obtained with a Geiger-mode silicon avalanche photodiode (Si GAPD). The Surface-to-surface resolution of 15 cm was achieved with the technique of time-correlated single-photon counting. In the experiment, a mode-locked Yb-doped fiber laser at 1036 nm was applied, as the detection efficiency at 1036 nm of Si GAPDs is much higher than that at 1064nm which was widely applied in remote sensing. Due to the single-photon detector, the laser ranging system was able to measure the reflected photon pulses at single-photon level. We realized 32- m laser ranging experiment with a 135-mm diameter Newtonian telescope in daylight. And the system could measure the non-cooperated object longer than 11.3 km far away, which was tested through inserting the optical loss. It presented a potential for hundreds-of-kilometer laser ranging at low-light level.