Global Change Observation Mission (GCOM) is a follow on mission of ADEOS, ADEOS2 and TRMM. It is under phase A study in NASDA (National Space Development Agency of Japan). GCOM is not a series of satellites but a mission and its concept is to continuously monitor geophysical parameters which are critical to understand global change phenomena, especially phenomena related to climate change. Those parameters include, but not limited to, optical thickness of aerosols and clouds, water and energy fluxes, carbon fluxes, sink and source of greenhouse gases, atmospheric constituents, etc. The measurements of geophysical parameters will continue more than 15 years after the launch of ADEOS2 is now composed of 3 satellites, i.e. GOSAT (joint program of NASDA and MOE), CCOM(tentative name), and CPM core satellite (joint program of NASDA and NASA). The main target of GOSAT is to clarify the sinks and sources of greenhouse gases, especially carbon dioxide, in the continental scales by monitoring atmospheric greenhouse gases distribution. The target of CCOM is to measure geophysical parameters which are uncertain in the today’s climate models. GPM core satellite is a follow on TRMM and the target of GPM core satellite is to measure precipitation. GOSAT will carry at least 2 instruments, i.e. an instrument which can measure tropospheric carbon dioxide, and SWIFT (Stratospheric Wind Interferometer : stratospheric wind sensor). CCOM will carry three core instruments, i.e. SGLI (GLI follow on, which covers from UV to IR), AMSR2 (AMSR follow on), alpha-Scat (SeaWinds follow on). Other instruments may be added based on an AO process. GPM core satellite will carry 2 instruments, i.e. DPR (Dual Precipitation Radar : PR follow on) and a microwave radiometer. The orbit of CCOM will be a sun synchronous orbit, which is almost the same as ADEOS2. The orbits of GOSAT and GPM core satellite will be around 70 degree inclination orbit and the altitudes will be 700km and 400km, respectively. These 3 satellites are planned to be launched in 2007 and 2008. While GCOM mission is focused to global change, NASDA has other satellite series, starting from MOS-1 to JERS-1. The next satellite to follow the JERS-1 is ALOS (Advanced Land Observing Satellite), which will be launched in 2004. The mission of ALOS is to provide sufficient data, which enable to generate 1 to 25,000 scale base maps all over the world.

The Global Imager (GLI) on Advanced Earth Observing Satellite-II (ADEOS-II) launched on 14 December 2002 is an optical sensor to observe reflected solar radiation and infrared radiation. GLI has 36 channels from ultraviolet region (380nm) to thermal infrared (12micron). GLI data is used for understanding the global circulation of carbon, monitoring cloud, snow, ice, and sea surface temperature. NASDA carried out initial checkout to confirm GLI basic function until April 2003. Currently GLI calibration team that consists of sensor development division, ground system integration division, and science application group analyses calibration and validation to release L1 data at the end of this year. This report describes calibration and instrument status of GLI.

The ADEOS-II satellite was successfully launched with an H-IIA rocket from Tanegashima Space Center in southern Japan on December 14, 2002. Amongst the six remote sensing instruments on-board, the payload includes the Global Imager (GLI) - a 36-channel multi-spectral scanner developed by the National Space Development Agency of Japan (NASDA) for ocean, terrestrial, atmosphere and cryosphere applications. 30 bands operate with a 1 km spatial resolution, while the remaining six bands, primarily dedicated for terrestrial use, acquire data with 250 metres ground resolution at nadir. The cancellation of one of the two planned Data Relay Test Satellites (DRTS) required for data down-link however resulted in reduced acquisition capacity at 250 metre resolution and thus prompted the establishment of a dedicated 250-metre data observation strategy, which aims to optimise 250 m observations over land, and to provide spatially and temporally consistent, multi-seasonal global land coverage, on a repetitive basis during the life-time of the ADEOS-II satellite. Plans for 250 m data product generation are furthermore outlined briefly in this paper.

The Advanced Microwave Scanning Radiometer (AMSR) is the multi-frequency, passive microwave radiometer on board the Advanced Earth Observing Satellite-II (ADEOS-II), currently called Midori-II. The instrument has eight-frequency channels with dual polarization (except 50-GHz band) covering frequencies between 6.925 and 89.0 GHz. Measurement of 50-GHz channels is the first attempt by this kind of conically scanning microwave radiometers. Basic concept of the instrument including hardware configuration and calibration method is almost the same as that of ASMR for EOS (AMSR-E), the modified version of AMSR. Its swath width of 1,600 km is wider than that of AMSR-E. In parallel with the calibration and data evaluation of AMSR-E instrument, almost identical calibration activities have been made for AMSR instrument. After finished the initial checkout phase, the instrument has been continuously obtaining the data in global basis. Time series of radiometer sensitivities and automatic gain control telemetry indicate the stable instrument performance. For the radiometric calibration, we are now trying to apply the same procedure that is being used for AMSR-E. This paper provides an overview of the instrument characteristics, instrument status, and preliminary results of calibration and data evaluation activities.

The Improved Limb Atmospheric Spectrometer-II (ILAS-II) onboard the Advanced Earth Observing Satellite-II (ADEOS-II) was successfully launched on 14 December, 2002 from National Space Development Agency of Japan (NASDA)’s Tanegashima Space Center. ILAS-II is a solar-occupation atmospheric sensor which will measure vertical profiles of O₃, HNO₃, NO₂, N₂O, CH₄, H₂O, ClONO₂, aerosol extinction coefficients, etc. with four grating spectrometers. After the checkout period of the ILAS-II which is scheduled in January-February, 2003, ILAS-II will make routine measurements from early April. An initial checkout (ICO) operation was done on 20-23 January, 2003. Data taken during the ICO period suggest that ILAS-II was functioning normally as designed. Signal-to-noise ratio (SNR) for each channel showed good quality of the ILAS-II data except for Ch.3. Preliminary comparison of ILAS-II O₃ profiles with ozonesondes showed good agreements. A validation campaign is scheduled to be taken place in Kiruna, Sweden in 2003, when several balloon-borne measurements are planned.

A microwave scatterometer of the National Aeronautics and Space Administration (NASA) of the United States, SeaWinds, was launched on the second Advanced Earth Observing System (ADEOS-II) of the Japanese Space Agency (NASDA) in December 2002. A preliminary data set was released to the Ocean Vector Wind Science Team (OVWST) for calibration/validation on July 15, 2003. A comparison of this data set with ocean buoy measurements was performed and the quality of the data was found to be very similar to that from an identical scatterometer deployed on NASA QuikSCAT mission. An overview of potential unique impact of SeaWinds on ADEOS-2 is also presented.

ADEOS-II was launched successfully on December 14, 2002 by NASDA with H-IIA rocket flight IV, and named as “Midori II”. It carries six Earth observing sensors including Global Imager (GLI) and Advanced Microwave Scanning Radiometer (AMSR) developed by NASDA. These Earth observation sensors obtain data 24 hours a day. The observed data are relayed by “Kodama” (Data Relay Test Satellite (DRTS)), or are directly downlink to NASDA/EOC and foreign ground stations in Kiruna, Alaska, and Wallops. Level-1 and higher level processing is performed by GLI and AMSR data processing systems at EOC to create the science products. The products are archived at Data Storage Systems (DSS) and released to the users according to the requests after the products quality is confirmed through hardware checkout, calibration and validation process. NASDA performed the initial checkout of ADEOS-II satellite and onboard sensor hardware for four months after launch. The following eight months are to be used for the evaluation of ground system and products validation. Summary of ground system evaluation is shown and data processing system is focused.

The mission objectives of ADEOS-II (Midori-II) are to improve satellite-based global earth observation system, and to obtain earth observation data for the contribution to better understanding and elucidation of global change mechanism relevant to earth environmental issues. To implement the objectives, five onboard earth observation sensors are selected based on the science requirement primarily focused on the quantitative estimation of geophysical parameters to describe important processes of the earth system such as water and energy cycle, carbon cycle, and changes in polar stratospheric ozone. This paper describes the present status of level-2 products derived from AMSR and GLI observation data after the launch, in the middle of operational observation / calibration and validation phase, as of the beginning of August, 2003 after four months from the beginning of calibration and validation phase on April 15, 2003.

The monitoring of the carbon stock in terrestrial environments, as well as the improved understanding of the surface-atmosphere interactions controlling the exchange of matter, energy and momentum, is of immediate interest for an improved assessment of the various components of the global carbon cycle. Studies of the Earth System processes at the global scale rely on models that require an advanced understanding and proper characterization of processes at smaller scales. The prime objective of the Surface Processes and Ecosystem Changes Through Response Analysis (SPECTRA) Mission is to determine the amount, assess the conditions and understand the response of terrestrial vegetation to climate variability and its role in the coupled cycles of energy, water and carbon. The amount and state of vegetation will be determined by the combination of observed vegetation properties and data assimilation. Many vegetation properties are related to features of reflectance spectra in the region 400 nm - 2500 nm. Detailed observations of spectral reflectance reveal subtle features related to biochemical components of leaves such as chlorophyll and water. The architecture of vegetation canopies determines complex changes of observed reflectance spectra with view and illumination angle. Quantitative analysis of reflectance spectra requires, therefore, an accurate characterization of the anisotropy of reflected radiance. This can be achieved with nearly - simultaneous observations at different view angles. Exchange of energy between the biosphere and the atmosphere is an important mechanism determining the response of vegetation to climate variability. This requires measurements of the component temperature of foliage and soil. The latter are closely related to the angular variation in thermal infrared emittance. Scientific preparations for SPECTRA are pursued along two avenues: a) the nature of the expected data and candidate algorithms are evaluated by generating and using synthetic hyper - spectral multi - angular\radiometric data; algorithms are evaluated with actual hyper -spectral data collected with a variety of airborne systems and concurrent ground measurements;

At present there is an increasing interest in remote sensing of aerosols from space because of the large impact of aerosols on climate, earth observation and health. TNO has performed a study aimed at improving aerosol characterisation using a space based instrument and state-of-the-art aerosol retrieval algorithms, based on requirements for up-to-date regional and global aerosol transport models. The study has resulted in instrument specifications and a concept design for aerosol detection from space. Based on the study the main requirements for a dedicated aerosol spectrometer are: a spectral range from 330-1000 nm with a spectral resolution from 2 nm (UV) to > 30 nm (NIR), observation in at least 3 polarisation directions (Stokes parameters) over a field of view (FOV) in swath directions of > 114 degrees and observation in at least 3 viewing directions (backwards, nadir, forward). The spectrometer design is a prism imaging spectrometer using a single detector array to measure the complete spectra for 2 polarisation directions. In this way the requirements for each viewing direction can be met with only 2 detector arrays. The system has a modular set-up, which makes the implementation of, for example, a change in the number of observation directions very simple. The basic requirements to discriminate between aerosol types are currently only met POLDER, that combines multiple view angles with polarization. The DARE concept shows an attractive potential for the development of next generation aerosol sensors.

RAMOS, the Russian American Observational Satellite program, is a cooperative space-based research and development program between the Russian Federation and the United States. The planned system configuration is a constellation of two satellites orbiting in approximately the same plane at an altitude of about 500 km, separated from one another by a variable distance centering on about 500 km. These satellites are equipped with passive electro-optical sensors, both US- and Russian-built, that operate over a range from infrared (IR) to ultraviolet (UV) and are designed for near-simultaneous stereo imaging capability. The sensor suite will include visible, IR and UV imaging radiometers, an IR spectrometer, and a short-wave infrared (SWIR) polarimeter. The projected launch date is 2008 with a planned minimum on-orbit lifetime of two years, and a five-year lifetime possible. This paper summarizes the program objectives, anticipated measurements and expected data, and presents the basic system design, expected performance characteristics, and the capabilities of each of the sensors.

Understanding the Earth's climate and how it responds to climate perturbations relies on knowledge of how atmospheric moisture, clouds, latent heating, and the large-scale circulation vary with changing climate conditions. The physical process that links these key climate elements is precipitation. GPM will establish a benchmark for global rainfall, building upon the highly successful joint US/Japan Tropical Rainfall Measuring Mission (TRMM). GPM's global atmospheric monitoring of water and energy will be a key contributor to answering the science research strategy questions: (1) How are global precipitation, evaporation, and the cycling of water changing? (2) How are variations in local weather, precipitation, and water resources related to global climate variation? (3) How can weather forecast duration and reliability be improved by new space-based observations, data assimilation and modeling? In an era of climatic uncertainty we need to be able to detect, understand and react to early signs that rainfall patterns may be changing in concert with better-understood climate variables. The transient nature of rainfall makes the detection of subtle changes difficult. Rainfall information over ~3 hours time scale is needed to improve weather forecast models, data assimilation models, hydrological models and flash flood forecasts. GPM is will substantially improve upon the temporal and spatial coverage of TRMM and extend the measurement of rainfall globally. Global Precipitation Measurement is a global endeavor that has sparked global interest. It has received overwhelming endorsement from the World Climate Research Programme, the World Meteorological Organization, and the Committee on Earth Observation Satellites. Japan's National Space Development Agency (NASDA) plans to contribute the radar for and launch of a core satellite. The European Space Agency (ESA) is currently conducting a feasibility study for a European constellation satellite contribution to GPM. India and France have expressed their interest in participating through the Megha-Tropiques project. South Korea is proposing the contribution of a constellation satellite bus in addition to regional ground validation sites. Other nations are also expected to play major a role in GPM. GPM is now in formulation and is one of the highest priority new missions for which NASA's Earth Science Enterprise seeks final approval. GPM launches are targeted to begin in 2009.

In the 1970’s a government study was conducted to assess the technological feasibility of obtaining wind profiles from space using a Doppler lidar. In the 80’s, NASA considered developing a Doppler wind lidar but put plans on hold as the projected costs rose. In the 90’s, global wind observations remained a unmet need and a series of model experiments (Observing System Simulation Experiments) were conducted to perform instrument trades and general weather forecast impact assessments. This paper reports on some recent results of OSSEs at NOAA’s NCEP (National Center for Environmental Prediction) and NASA’s DAO (Data Assimilation Office).

The NPOESS (National Polar-orbiting Operational Environmental Satellite System) program represents the merger of the NOAA POES (Polar-orbiting Environmental Satellite) program and the DoD DMSP (Defense Meteorological Satellite Program) satellites. Established by presidential directive in 1994, a tri-agency Integrated Program Office (IPO) in Silver Spring, Maryland, has been managing NPOESS development, and is staffed by representatives of NOAA, DoD, and NASA. NPOESS is being designed to provide 55 atmospheric, oceanographic, terrestrial, and solar-geophysical data products, and will disseminate them to civilian and military users worldwide. The first NPOESS satellite is scheduled to be launched late in this decade, with the other two satellites of the three-satellite constellation due to be launched over the ensuing four years. NPOESS will remain operational for at least ten years. The 55 Environmental Data Records (EDRs) will be provided by a number of instruments, many of which will be briefly described in this paper. The instruments will be hosted in various combinations on three NPOESS platforms in three distinct polar sun-synchronous orbits. The instrument complement represents the combined requirements of the weather, climate, and environmental remote sensing communities. The three critical instruments are VIIRS (Visible/Infrared Imager-Radiometer Suite), CMIS (Conical Microwave Imager/Sounder), and CrIS (Cross-track Infrared Sounder). The other IPO-developed instruments are OMPS (Ozone Mapper/Profiler Suite), GPSOS (Global Positioning System Occultation Sensor), the APS (Aerosol Polarimeter Sensor), and the SESS (Space Environment Sensor Suite). NPOESS will also carry various "leveraged" instruments, i.e., ones that do not require development by the IPO. These include the ATMS (Advanced Technology Microwave Sounder), the TSIS (Total Solar Irradiance Sensor), the ERBS (Earth Radiation Budget Sensor), and the ALT (Radar Altimeter).

This paper summarizes post-critical design review (CDR) design refinements and performance estimate updates to the National Polar-orbiting Operational Environmental Satellite Systems (NPOESS) Visible Infrared Imager Radiometer Suite (VIIRS) sensor. The design changes reduced manufacturing and performance risk to meet VIIRS sensor performance specifications. Electro-Magnetic Compatibility (EMC) and Electro-Magnetic Interference (EMI) requirements drove increased shielding and cable modifications. A telescope design modification was also required to remove modulated instrument background (MIB) discovered in the CDR optical design. Performance predictions were then generated from models and demonstration hardware based on the design refinements, and these are also reported here. VIIRS risk-reduction will continue as the Engineering Development Unit (EDU) is assembled and tested over the next year facilitating performance verification and lowering flight unit development risk.

The Crosstrack Infrared Sounder (CrIS) is one of the sensors now under development for the National Polar-orbiting Operational Environmental Satellite System (NPOESS) program. In order to reduce program risk and verify instrument performance rapid prototyping of the sensor and critical subsystems has been utilized. Key among these was a prototype instrument and a prototype interferometer. This prototype instrument is referred to as the EDU1 (Engineering Development Unit). A second effort was the build of a prototype interferometer as a part of an internal ITT effort. This was an uncompensated version of the CrIS interferometer. This was referred to as the Aluminum Prototype Interferometer. The idea was to move rapidly to hardware while exploring new technologies. This was built in 4 months. There were key success factors for both efforts. A set of clear cardinal requirements was established. The layout and the cardinal requirements therefore provided a conceptual overview and a basis for deriving lower level requirements. These requirements remained basically unchanged throughout the effort. Vendors were closely worked with but; key to this was the GD&T dimensions and datum’s that were established. These enabled sub systems to be independently produced and “snapped together” to produce a final assembly in a minimum time. Essentially many of the critical optical alignments were built in to the individual parts so the subsequent shiming was not required. Electronics to control the porchswing and Dynamic Alignment Mechanism were developed in existing servo control test beds and designed to be FPGA based. This allowed a high degree of flexibility. Success was also based on continuity of the key engineering leadership and effective communications between the team and a clear understanding of the technical issues by the engineering leadership team.

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), one of five sensors on Terra, has bands 4 to 9 in the short-wave infrared (SWIR) region. These bands, particularly bands 5 and 9, are affected by band-to-band crosstalk. A crosstalk correction algorithm already developed is practically used for reducing a leaked ghost image, but does not satisfactorily work for all scenes. We therefore analyze crosstalk effects in more detail for improving this algorithm. As the results, it is shown that crosstalk includes several band-to-band/intra-band components, and the cause of each component is estimated to be reflection, scattering, and/or refraction in a CCD chip and/or interference filters. Based on these facts, a new crosstalk correction algorithm is developed by improving the original algorithm. In the new algorithm, all known crosstalk components are included, kernel functions for convolution with a source image are updated, and sensitivity correction applied for keeping consistency with radiometric calibration is improved. Comparison results indicate that the new algorithm reduces ghost images more correctly than the original algorithm.

ASTER, launched in December, 1999, composed of three subsystems, each of which multispectrally observes the reflected or emitted radiation from the surface of the earth to space in VNIR (visible and near infrared), SWIR (shortwave infrared) and TIR (thermal infrared) wavelength regions, respectively. ASTER-VNIR has three spectral bands with a spatial resolution of 15m, and the one of which in near infrared has an along track stereo observation capability to produce high quality Digital Elevation Model (DEM). ASTER-SWIR has six spectral bands with a spatial resolution of 30m, which are mainly designed for discriminating altered minerals bearing hydroxyl group. ASTER-TIR has five spectral bands with a spatial resolution of 90m, which presents us a powerful tool for identifying quartz and carbonate minerals as well as discriminating types of silicate rocks. The author have successfully developed a robust method for detecting quartzite and carbonate rocks as well as classifying type of igneous rocks with ASTER TIR data without atmospheric corrections (Level-1B data). Here in this paper, reflectance spectra of minerals in SWIR region measured in the laboratory are analyzed to define calcite index, OH-bearing silicate index, kaolinite index and alunite index for discriminating each mineral by ASTER-SWIR. The defined indices are applied to SWIR data of ASTER Level-1B radiance at the sensor data observing Cuprite area in Nevada, USA, and the discussions are made on the results by comparing the well-known geology of the area. Also, the result of calcite index is compared with the result of applying well-characterized carbonate index defined for ASTER-TIR to clarify the strong point of each index.

Over the past few years, a joint Swiss/Belgium ESA initiative resulted in a project to build a precursor mission of future spaceborne imaging spectrometers, namely APEX (Airborne Prism Experiment). APEX is designed to be an airborne dispersive pushbroom imaging spectrometer operating in the solar reflected wavelength range between 4000 and 2500 nm. The system is optimized for land applications including limnology, snow, and soil, amongst others. The instrument is optimized with various steps taken to allow for absolute calibrated radiance measurements. This includes the use of a pre- and post-data acquisition internal calibration facility as well as a laboratory calibration and a performance model serving as a stable reference. The instrument is currently in its breadboarding phase, including some new results with respect to detector development and design optimization for imaging spectrometers. In the same APEX framework, a complete processing and archiving facility (PAF) is developed. The PAF not only includes imaging spectrometer data processing up to physical units, but also geometric and atmospheric correction for each scene, as well as calibration data input. The PAF software includes an Internet based web-server and provides interfaces to data users as well as instrument operators and programmers. The software design, the tools and its life cycle are discussed as well.

The underlying algorithmic architecture of the level 0 to 1 processing of the APEX spectrometer is presented. This processing step calculates the observed radiances in physical units from the recorded raw digital numbers. APEX will operate airborne and record radiance in the solar reflected wavelength range. The system is optimized for land applciations including limnology, snow, soil, amongst others. The instrument will be calibrated with a flexible setup in a laboratory as well as on-board. A concept for the dynamic update of the radiance calibration coefficients for the APEX spectrometer is presented. The time evolution of the coefficients is calculated from the heterogeneous calibration measurements with a data assimilation technique. We propose a Kalman filter for the initial version of the processor. Additionally, the structure of the instrument model suitable for the analysis of APEX data is developed. We show that this model can be used for the processing of observations as well as for the calculation of calibration coefficients. Both processes can be understood as inverse problems with the same forward model, i.e. the instrument model.

The high resolution airborne imaging spectrometer APEX (Airborne Prism Experiment) is currently being built. In parallel, its data processing calibration chain is being designed. The complex design of this high resolution pushbroom instrument bears the risk of optical aberrations in the registered spatio-spectral frames. Such aberrations consist of so-called frown and smile effects, as well as ghost image, smear, and stray light contributions. A concept is presented which shall operationally improve image calibration by inversion of the sensor model.

Current optical remote sensing instrument technology allows the acquisition and digitization of all of the reflected energy (light) across the full spectral range of interest. The current method for acquiring, transmitting, and processing this data is still based on the "multi-band" approach that has been used for the past thirty years. This approach was required due to limitations imposed by early instrument technology. This paper will present generalized concepts for acquiring, pre-processing, transmitting, and extracting information from full-spectral, remotely sensed data. The goal of the paper is to propose methods for changing from the current "bytes-per-band" approach to the "spectral curve" approach. The paper will describe how the Full Spectral Imaging (FSI) approach has the potential to greatly simplify instrument characterization and calibration and to significantly reduce data transmission and storage requirements. I will suggest how these improvements may be accomplished with no loss of remotely sensed information.

Spectral Sciences, Inc., in collaboration with NASA and AFRL, are developing a high fidelity model for hyperspectral image (HSI) simulation. The simulation is based on a Direct Simulation Monte Carlo (DSMC) approach for modeling topographic effects. Synthetic “ground-truth” is specified as surface and atmospheric property inputs, and it is practical to consider wide variations of these properties. The model includes treatment of land and ocean surfaces, 3D terrain and bathymetry, 3D surface objects, and effects of finite clouds with surface shadowing. The computed HSI data cubes can serve as both a surrogate for and a supplement to field validation data for algorithm development efforts or for sensor design trade-studies. The initial version of the software package developed in collaboration with NASA treated the reflective spectral domain from the visible to the SWIR. In this paper, we review the reflective spectral domain model and present our approach for extending the HSI scene simulation package into the thermal infrared. The model is demonstrated with a variety of Visible and LWIR scene simulations.

Photon detectors and focal plane arrays (FPAs) are fabricated from HgCdTe and silicon in many varieties. With appropriate choices for bandgap in HgCdTe, detector architecture, dopants, and operating temperature, HgCdTe and silicon can cover the spectral range from ultraviolet to the very-long-wavelength infrared (VLWIR), exhibit high internal gain to allow photon counting over this broad spectral range, and can be made in large array formats for imaging. DRS makes HgCdTe and silicon detectors and FPAs with unique architectures for a variety of applications. Detector characteristics of High Density Vertically Integrated Photodiode (HDVIP) HdCdTe detectors as well as Focal Plane Arrays (FPAs) are presented in this paper. MWIR[λ_c(78 K) = 5 μm] HDVIP detectors RoA performance was measured to within a factor or two or three of theoretical. In addition, 256 x 256 detector arrays were fabricated. Initial measurements had seven out of ten FPAs having operabilities greater than 99.45% with the best 256 x 256 array having only two inoperable pixels. LWIR [λ_c(78K)~10 μm] 640 X 480 arrays and a variety of single color linear arrays have also been fabricated. In addition, two-color arrays have been fabricated. DRS has explored HgCdTe avalanche photo diodes (APDs) in the λ_c = 2.2 μm to 5 μm range. The λ_c = 5 μm APDs have greater than 200 DC gain values at 8 Volts bias. Large-format to 1024² Arsenic-doped (Si:As, λ_c ~ 28 μm), Blocked-Impurity-Band (BIB) detectors have been developed for a variety of pixel formats and have been optimized for low, moderate, and high infrared backgrounds. Antimony-doped silicon (Si:Sb) BIB arrays having response to wavelengths > 40 μm have also been demonstrated. Avalanche processes in Si:As at low temperatures (~ 8 K) have led to two unique solid-state photon-counting detectors adapted to infrared and visible wavelengths. The infrared device is the solid-state photomultiplier (SSPM). A related device optimized for the visible spectral region is the visible-light photon counter (VLPC). The VLPC is a nearly ideal device for detection of small bunches of photons with excellent time resolution. Finally, DRS makes imaging arrays of pin-diodes utilizing the intrinsic silicon photoresponse to provide high performance over the 0.4-1.0 μm spectral range operating near room temperature. pin-diode arrays are particularly attractive as an alternative to charge-coupled devices (CCDs) for space applications where radiation hardening is needed. In addition, wire grid micropolarizers have been demonstrated and two color doped silicon detectors using diffractive microlenses are being developed. Precision alignment of sensor chips with respect to a base mounting plate has been demonstrated to be within 2 μm. A similar technique is also utilized to align single large detectors for sounder applications in focal plane arrays (FPAs). FPAs for space applications with the associated cold and warm electronics and packaging/cables have been fabricated.

A 640x512 pixel, long-wavelength cutoff, narrow-band (Δλ/λ~10%) quantum well infrared photodetector (QWIP) focal plane array (FPA), a four-band QWIP FPA in 4-16 μm spectral region, and a broad-band (Δλ/λ~42%) QWIP FPA having 15.4 μm cutoff have been demonstrated. In this paper we discuss the detector designs, dark currents, quantum efficiencies, responsivities, detectivities, noise equivalent differential temperatures (NEDTs), the effect of FPA nonuniformity on performance, and the operabilities of these QWIP FPAs. In addition, we discuss the development of a very sensitive (NEDT~10.6 mK) 640x512 pixel thermal imaging camera having 9 μm cutoff.

Transferring the image information in analog form between the FPA and the external electronics causes the disturbance of the outside noise. On-chip A/D converter into the readout circuit (ROIC) can eliminate the possibilities of the cross-talk of noise. Also, the information can be transported more efficiently in power in the digital domain compared to the analog domain. In designing on-chip A/D converter for cooled type high density infrared detector array, the most stringent requirements are power dissipation, number of bits, die area and throughput. In this study, pipelined type A/D converter was adopted because it has high operation speed characteristics with medium power consumption. Capacitor averaging technique and digital error correction for high resolution was used to eliminate the error which is brought out from the device mismatch. The readout circuit was fabricated using 0.6μm CMOS process for 128 x 128 mid-wavelength infrared (MWIR) HgCdTe detector array. Fabricated circuit used direct injection type for input stage, and then S/N ratio could be maximized with increasing the integration capacitor. The measured performance of the 14 b A/D converter exhibited 0.2 LSB differential non-linearity (DNL) and 4LSB integral non-linearity (INL). A/D converter had a 1 MHz operation speed with 100mW power dissipation at 5V. It took the die area of 5.6 mm². It showed the good performance that can apply for cooled type high density infrared detector array.

In this paper, a readout technique involving current mode background suppression is studied for 2-dimensional infrared focal plane arrays (IR FPA’s). This technique has a current memory per pixel, and the suppression current can be optimized per pixel element. Capacitive transimpedende amplifier (CTIA) and feedback amplifier structure are adopted for input circuit and background suppression circuit, respectively. Feedback amplifier structure can minimize skimming error due to channel length modulation. The area size of the pixel circuit is generally limited in the case of 2-D application. So, the amplifier used in the CTIA input circuit adopts timesharing for background suppression. To further improve the area limitation, a half circuit of the CTIA is shared in row circuit out of the pixel array. Because of the leakage of the current memory, the skimming data of the current memory in the pixel array is stored in SRAM array through ADC, and is refreshed periodically with SRAM data through DAC. The readout circuit was fabricated using 0.6um 2-poly 3-metal CMOS process for 64 x 64 LWIR HgCdTe IR array with the pixel size of 50um x 50um. The measurement performance of the skimming circuit exhibits about only 3% error for 100nA background current. The simulation results exhibit that skimming error can be reduced further to 0.3% when the ratioed current mirror scheme and/or multi step refresh scheme is adopted.

The Millimetre-wave Acquisitions for Stratosphere-Troposphere Exchange Research (MASTER) instrument is intended to sound the gaseous composition of the upper troposphere and lower stratosphere (UTLS) in a future ESA space mission. A significant and inherent advantage of operation at millimetre and sub-millimetre wavelengths in comparison to limb-sounders operating at infra-red and shorter wavelengths is low sensitivity to cirrus clouds. MASTER will employ relatively small vertical and horizontal spacings between limb views, in order to over-sample the atmosphere in the orbit plane. By viewing each air mass from different directions, and including this information in the retrieval, horizontal as well as vertical structure of atmospheric fields may be captured. In order to examine this tomographic limb-sounding approach for MASTER, a state-of-the-art 2-D radiative transfer model and retrieval model have been developed and used in simulation experiments. A linear analysis has been performed to establish achievable horizontal and vertical retrieval resolution for target species and to identify additional parameters to include in the state vector in order to reduce error sensitivities. A realistic mid-latitude scenario and appropriate instrument and model errors have been considered. By accurately modelling radiative transfer in two dimensions within the orbit plane, and using multiple limb-sequences simultaneously in a 2-D retrieval, a horizontal resolution better than 200 km can be achieved, together with ~2 km vertical resolution for retrievals of water vapour, ozone and other trace gases in the UTLS.

The Stratospheric Wind Interferometer for Transport studies (SWIFT) instrument is designed to measure stratospheric winds in the altitude region of 20-45 km with a target accuracy of 3-5 m s^-1. It is one of two scientific instruments on the Greenhouse Gases Observations Satellite (GOSAT) proposed for launch in 2008. The winds are to be determined by measuring the Doppler shift of thermal emission lines in a narrow spectral range using a limb viewing field widened Michelson interferometer. The instrument spectral range for this study is centered about a reference ozone line at 1133.4335 cm^-1 with a full-width at half-maximum of ~0.1 cm^-1 for the instrument transmittance function. Measurement simulation and data retrieval are applied in the present investigation to evaluate and elaborate on measurement and processing conditions required to satisfy the desired wind accuracy. The related principles, processes, and tools are summarized. Radiative transfer and instrumental measurement simulations are conducted to produce raw image measurements. These raw images are processed up to and including inversions performed using the maximum a posteriori solution equation with differential regularization. In addition to retrieving the Doppler wind and ozone number density profiles, allowance is made to investigate the additional recovery of parameters such a pressure scaling factor and profiles of temperature and nitrous oxide. Retrieval characterization and an error analysis have been undertaken. Introductory results are presented. Retrieval Doppler wind noise levels of under 3 m s^-1 are obtained.

Design study and algorithm development efforts are overviewed with cloud profiling radar (CPR) for EarthCARE mission. EarthCARE is a candidate for the ESA Earth Explore Core Missions and presently Phase A study is ongoing. EarthCARE is jointly proposed by European and Japanese scientists, and CPR is being studied by CRL and NASDA, Japan. The EarthCARE CPR is characterized by very high sensitivity 94 GHz radar with nadir pointing and Doppler measurement capability. CPR is designed to maximize synergy performance in combination with other onboard active and passive sensors. In this report, after summarizing CPR objectives and expected performance in responding to requirements, study topics concerning Doppler capability and variable PRF techniques are discussed. The EarthCARE synergy algorithm development efforts through airborne campaign experiment are also introduced.

The Atmospheric Dynamics Mission (ADM-Aeolus) has been selected as the second of a series of Earth Explorer Core Missions. The payload aims at providing measurements of atmospheric wind profiles with global coverage. The key element of ADM-Aeolus is the Atmospheric Laser Doppler Lidar Instrument (ALADIN), a Direct Detection Doppler Lidar. The ALADIN instrument belongs to a completely new class of earth-observation lidar payloads with limited power requirements and high reliability over a three-year lifetime. Technological challenges are addressed in an early stage by the development of a Pre-Development Model (PDM), which is a functional representative model of the receiver of ALADIN. The PDM is being established to validate the technologies used in the ALADIN design, evaluate the flight-worthiness of its major subsystems and verify the instrument overall performances. The purpose of this paper is to present the latest results on the status of the ALADIN Pre-Development Model.

ALCATEL-SPACE has been involved for years in the development of highest performance space optical payload for Earth observation, notably in the domain of multi/super/hyperspectral observation, through the successful development of VEGETATION (for CNES) and MERIS (for ESA). The paper will analyse how the lessons of the development of MERIS are key benefits for the definition of the next generation hyperspectral payload of the ESA SPECTRA mission. It will highlight the areas where a direct heritage is applicable, such as the calibration strategy, and domains where technology progresses allow major evolutions, such as for instance in the definition of the payload's data processing architecture. SPECTRA (Surface Processes and Ecosystem Changes Through Response Analysis) is one of the three candidate missions in the ESA Earth Core Explorer program of research oriented missions that is currently under phase A study. Its scientific objective is to describe, understand and model the role of terrestrial vegetation in the global carbon cycle and its response to climate variability under the increasing pressure of human activity.

Following a survey of commercial-off-the-shelf (COTS) un-cooled infrared technology, a micro-bolometer array has been selected to form the basis of a low-cost, compact thermal infrared imager intended for use on an Earth observation micro-satellite. The preliminary instrument concept has been designed to yield a 500 metre ground sample distance over a 150 kilometre swath width, from 710 km altitude. The radiometric performance is expected to yield a NETD less than 1 K for a 300 K ground scene. The imager is designed to be compatible with Surrey’s existing microsatellite imagers, which operate in the visible and near-IR bands. The proposed imaging suite will be suitable for many thermal imaging and hot spot detection mission scenarios. Fabrication and characterization of a 1-3 kg space-ready instrument is planned for late 2004.

In order to optically vary the magnification of an imaging system, mechanical zoom lenses, such as those found on 35mm cameras, require multiple optical elements and use cams or gears to adjust the spacing between individual or groups of lenses. By incorporating active elements in the optical design, we can eliminate the need to change lens separations and create an imaging system with variable optical magnification that has no macroscopic moving parts.

Envisat is ESA's environmental research satellite launched on 1 March 2002. It carries a suit of sensors offering opportunities for a broad range of scientific research and applications. The calibration results from the first year of operation of the MEdium Resolution Imaging Spectrometer (MERIS) will be presented, including in-flight verification and radiometric, spectral and geometric characterization of the instrument. Radiometric calibration using the on-board diffuser will be discussed and comparison with vicarious calibration results over desert sites or well-characterized marine sites will be presented. The image quality will be assessed, and improvements resulting from the in-flight characterization will be presented.

The MODerate Resolution Imaging Spectroradiometer (MODIS) Flight Model 1 (FM1) was launched on May 4, 2002 onboard the NASA Earth Observing System (EOS) Aqua spacecraft. It has provided more than a year of global data for studies of the Earth’s land, oceans, and atmosphere in support of the science community and public users. To assure the quality of the data and science products, extensive efforts have been made to collect and analyze data on the instrument’s on-orbit performance using its on-board calibrators (OBCs). MODIS has 36 spectral bands: 20 reflective solar bands (RSBs) with wavelengths from 0.41 micrometer to 2.2 micrometers and 16 thermal emissive bands (TEBs) from 3.7 to 14.2 micrometers. For radiometry, the RSBs are calibrated by a solar diffuser (SD) and a solar diffuser stability monitor (SDSM) system and the TEBs by a blackbody (BB). An on-board Spectroradiometric Calibration Assembly (SRCA) is used for the instrument’s spectral (RSBs only) and spatial (all 36 bands) characterization. Using the first year’s calibration data sets, this paper presents Aqua MODIS on-orbit performance in three areas: radiometric, spatial, and spectral. Comparisons with the sensor’s specifications and with the performance of its predecessor, Terra MODIS (launched in December 1999), are discussed. Excluding a few problems identified pre-launch, such as non-functional detectors in the 1.6 micrometers band and the out of specification performance for the band to band registration (BBR), the on-orbit observations and analyses show that Aqua MODIS has been performing according to its design characteristics.

The Ozone Monitoring Instrument is an UV-Visible imaging spectrograph using two-dimensional CCD detectors to register both the spectrum and the swath perpendicular to the flight direction. This allows having a wide swath (114 degrees) combined with a small ground pixel (nominally 13 x 24 km²). The instrument is planned for launch on NASA’s EOS-AURA satellite in January 2004. The on-ground calibration measurement campaign of the instrument was performed May-October 2002, data is still being analyzed to produce the calibration key data set. The paper highlights selected topics from the calibration campaign, the radiometric calibration, spectral calibration including a new method to accurately calibrate the spectral slitfunction and results from the zenith sky measurements and gas cell measurements that were performed with the instrument.

The technological innovations embodied in the instrument described in this paper can significantly improve the performance of black bodies and their associated thermometry and electronics as used for on-board calibration in many space-borne infrared radiometer instruments, whilst simultaneously reducing mass and power requirements. The same innovations can provide similar advantages for terrestrial based calibrations for both pre-flight and validation activities.

The Geostationary Earth Radiation Budget (GERB) instrument aboard the Meteosat Second Generation Satellite has 256 channels which measure total radiance and 256 channels which measure solar radiation reflected from the Earth. In order to validate the calibration of these channels, the Clouds and Earth Radiant Energy System (CERES) instrument aboard the Terra spacecraft is operated in such a way as to view Earth scenes from the same direction as the GERB, so as to measure the same total and reflected solar radiances. The method uses the capability to program the azimuth of the CERES scan plane, such that the scan plane includes the GERB.

From October 1984 until September 30, 1999, on-orbit, the Earth Radiation Budget Satellite (ERBS)/Earth Radiation Budget Experiment (ERBE) nonscanning, active cavity radiometers (ACR) were calibrated using observations of the incoming total solar irradiance, and of reference irradiances from an on-board tungsten lamp and blackbodies in order to determine drifts and shifts in the ACR responses. On October 7, 1999, the ERBE elevation drive system failed near the earth nadir viewing configuration. Thereafter, the elevation failure prevented observations of the on-board, built-in calibration systems. On July 23, August 8, and December 10, 2002, the ERBS was pitched 180 degrees to observe cold space, representative of a 3 Kelvin blackbody, in order to determine the ACR's zero-irradiance offsets. On December 4, 2002, the ERBS was pitched 180 degrees away from the earth in order to observe the sun, and to determine the ACR's gains. In this paper, the 2002, 180-degree pitch calibrations are compared with the earlier 1984-1999, calibrations which were obtained using the on-orbit, built-in calibration systems. In addition, the 2002 calibrations are compared with earlier scheduled November 21, 1984, and October 20, 1985, 180-degree pitch calibrations, as well as with deep space calibrations from unscheduled July 2, 1987, January 16, 1999, and November 16, 2000, ERBS spacecraft tumbles. The 2002 ACR offsets were found to be consistent with 1984-2000 offsets at the 1.0 Wm^-2. 1984-1999, ERBE top-of-the-atmosphere (TOA), and satellite altitude (SA) earth irradiances are presented. Analyses of the TOA ERBE earth irradiances indicate that the TOA irradiance time series exhibited a 1.7 Wm^-2 increase as a result of 1988-1992, and 1998-2002 satellite altitudinal decreases during periods of maximum solar magnetic activity.

The SeaWiFS sensor is required to provide spectral water leaving radiances with 5% absolute accuracies in the open ocean. This is extremely demanding because first the signal coming from the water body represents only 10% of the measured signal and second, calibration procedure of bands 7 and 8 is not direct like the vicarious calibration applied to bands 1 through 6. As a change of 5% in the sensitivity of these bands can imply errors of 10 to 50% on the water leaving radiance, it is suggested to revisit more accurately the SeaWiFS calibration in the near infrared. In this paper, we propose to apply a calibration method based on the use of CIMEL ground-based measurements. The radiance-based method, fully described in Santer and Martiny (2003), aims at the inversion of the atmospheric phase function from diffusion measurements in the principal plane with an accuracy of less than 1% using an iterative mode. Phase function, optical thickness and wind speed are the inputs of a radiative-transfer-code for computations of SeaWiFS top-of-atmosphere radiances. The method is quite sensitive to the CIMEL radiance calibration and to assumptions regarding the sea surface roughness. Nevertheless, its accuracy is of 2-3% depending on SeaWiFS geometry. Applications were conducted on Venice (Italy) and Lanai (Hawaii) datasets. The results depict an overestimate of the SeaWiFS calibration of 6.3% at 865 nm and 3% at 765 nm.

In this paper, we propose two approaches to achieve calibration of the SPOT5 satellite, both based on the use of ground-based measurements achieved with a CIMEL sun-photometer. These approaches present the originality not to require any hypothesis on the aerosol model, on the contrary of the standard SPOT5 calibration. The principle of one of them relies indeed on the inversion of the aerosol phase function - thus atmospheric - from the sky diffusion measurements in the principal plane. The radiance-based method, fully described in Santer and Martiny (2003), allows the retrieval of the phase function with an accuracy of less than 1% using an iterative mode. We use such phase function, optical thickness and surface reflectance as inputs of a radiative-transfer-code for computations of SPOT5 top-of-atmosphere radiances. A second approach, inspired by Biggar et al. (1990), relies more directly on the sky and surface radiances measured by the CIMEL instrument. In this paper, we remind the principles of the two methods and the radiance-based method is applied as an example on 20 July, 2002. Discrepancies up to 11% are found out with the standard calibration coefficients. To conclude on the efficiency of the SPOT5 calibration methods, we recommend applying them to a huge and adapted dataset, spread on a longer period. Moreover, if the methods are accurate at 2-3%, we know that they are weakly sensitive to the radiance calibration of the sun-photometers. Standard calibration methods using integrating spheres do not give satisfactory results especially at short wavelengths (accuracy up to 10%). We present thus in the first part of the paper in-situ radiance calibration methods, based on the Rayleigh scattering knowledge and we show up that these methods lead to an improvement of the accuracy of 5%. The study is conducted over the inland site of La Crau, South of France.

One method to assess in-flight Modulation Transfer Function (MTF) relies on couples of images of the same landscape acquired with two spatial resolutions. The higher resolution image stands for the landscape and the ratio of the spectra gives the lower resolution instrument MTF. The main drawback of this method is the sensitivity to aliasing. This papers begins with a brief recall of the method putting the stress on the theoretical basis of the aliasing. The next step presents a way of aliasing correction when an MTF model is available. If it is not the case, the correction will be limited to the surrounding of the Nyquist frequency. This correction is applied to a test couple made with an airborne image of Toulouse and a simple simulation. The lower resolution image is obtained by the convolution of the airborne image with a large triangular function so that the ratio of the pixel sizes is equal to 10. The choice of 10 comes from the available couples of real images planned to be processed. For this test couple the MTF model is a simple sinc². The first results are quite noisy. The analysis of the magnitude and phase of the high resolution image spectrum shows that the landscape spectrum behaves like an 1/f function in the interesting low resolution frequency domain and the phase behaves like a Gaussian random variable. This is used to improve the correction and obtain good results. Correction is then applied on the available couples of images leading to SPOT4 HRVIR and VEGETATION MTF measurements.

The moon is a very stable reference source that has been used for the space-borne sensors’ radiometric calibration and/or radiometric stability monitoring. In this paper, we present an approach that uses the sensors’ on-orbit lunar observations for their spatial characterization and apply the method to the MODIS instruments that are currently operating on board NASA EOS Terra and Aqua satellites. Both MODIS instruments perform monthly lunar observations. The spatial characterization results derived from the lunar observations using this algorithm are compared with those obtained from the MODIS Spectro-Radiometric Calibration Assembly (SRCA), which is an on-board calibrator capable of performing spatial characterizations for all MODIS spectral bands. The new approach can be applied to other remote sensing instruments.

ADEOS-2 is the Earth observing satellite which was successfully launched on December, 14, 2003. It is a follow-on mission to the ADEOS and the first mission of GCOM series which are planed to be operated for 20 years. The missions are (1) quantitative estimation of water and energy cycle relevant to the climatic change, (2) quantitative estimation of carbon cycle (biomass and net primary productivity) relevant to the global warming, and (3) detection of long term climatic change signal from data sets of ADEOS and ADEOS-II. Based on these missions scientific objectives are defined to be (1) quantitative estimation of water and energy cycle relevant to the climatic change,(2) quantitative estimation of carbon cycle (biomass and net primary productivity) relevant to the global warming, and (3) detection of long term climatic change signal from data sets of ADEOS and ADEOS-II. In order to achieve these goals, the ADEOS-2 Science program was established in NASDA. Standard and research products are defined there. Various validation projects are planned and will be implemented. The characteristics of the ADEOS-2 Science program can be summarized to be integrations in the following three fields, that is, (1) integration between different channels, (2) integration between different sensors and (3) integration between satellite remote sensing data and numerical models.

Passive microwave radiometers in the past have demerits of low spatial resolution, and of no lower frequencies. Advanced Microwave Scanning Radiometer (AMSR) and AMSR-E have the largest antenna, and it enables adopting 6 and 10GHz. From those lower frequencies, sea surface temperature (SST) and soil moisture can be retrieved. SST retrieved from AMSR-E has a fine spatial resolution and good accuracy. It shows a potential application, such as tracing oceanic eddies in the Kuroshio Extension region.

An application of satellite information to numerical weather predictions (NWPs) is one of the most expected achievements in satellite remote sensing. In some meteorological agencies, the data of the Special Sensor Microwave Imager (SSM/I) on the US Defense Meteorological Satellite Program (DSMP) satellites and the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) have been or will be used in their operational forecasts. Recently, National Space Development Agency of Japan (NASDA) launched the two microwave radiometers. One is the Advanced Microwave Scanning Radiometer (AMSR) on board the Advanced Earth Observing Satellite II "Midori II" (ADEOS-II), launched in December 2002, and the other is the AMSR-E (modified version of the AMSR) on board the NASA's EOS Aqua satellite, launched in May 2002. The AMSR makes measurements of Earth at approximately 10:30 am/pm in local time, while the AMSR-E at 1:30 pm/am. The utilization of the AMSR and AMSR-E data in addition to the previous microwave radiometers is highly expected to fill a critical gap of global observations. The Japan Meteorological Agency (JMA) introduced the three-dimensional variational data assimilation (3D-VAR) system for the operational Global Spectral Model in September 2001, and the four-dimensional variational data assimilation (4D-VAR) system for the operational Meso-Scale Model in March 2002. Currently, the real-time SSM/I and TMI data are available and tested for assimilation at JMA, while the AMSR and AMSR-E data will be available after initial check-out. We performed impact studies of the retrieved total-column-precipitable water and rainfall by SSM/I and TMI with the JMA NWP systems, and obtained considerable improvements in the predictions. These experiments will be extended to the AMSR and AMSR-E data.

The first light images from the ADEOS-II (Midori-II) / GLI were obtained on January 25, 2003 successfully. The GLI is a cross tracking imager with 36 channels covering a wide spectral region from 380 nm to 12 μm. Six 250m channels and tilting ocean view mechanism are also unique features of the GLI. Obtained radiance images are now being analyzed at NASDA EORC to produce the level 2 geophysical products. This paper overviews some standard and new products and their implications for local and global researches. It is important to compare the satellite-derived results with model simulation results. We compared the MODIS result with cloud microphysical simulation with the NHM+HUCM model and found a similar distribution of cloud effective radii.

Global Imager (GLI) is the visible to infrared imager aboard ADEOS-II satellite with 30 and 6 channels for 1 km and 250m resolutions, respectively. The sensor was successfully captured the first image on January 25, 2003. Sea surface temperature (SST) will be retrieved in combination with simultaneous SST observation by low-resolution microwave sensor, AMSR-E. Distribution of chlorophyll and other constituents will be obtained from ocean color channels. Frequent observations with 250 m visible channels will be also available, and combination with 1 km ocean color and SST will be useful for coastal applications. Early scientific results of GLI ocean group will be presented in this presentation.

The objective of this paper is to demonstrate a suitable hierarchical networking solution to improve capabilities and performances of space systems, with significant recurrent costs saving and more efficient design & manufacturing flows. Classically, a satellite can be split in two functional sub-systems: the platform and the payload complement. The platform is in charge of providing power, attitude & orbit control and up/down-link services, whereas the payload represents the scientific and/or operational instruments/transponders and embodies the objectives of the mission. One major possibility to improve the performance of payloads, by limiting the data return to pertinent information, is to process data on board thanks to a proper implementation of the payload data system. In this way, it is possible to share non-recurring development costs by exploiting a system that can be adopted by the majority of space missions. It is believed that the Modular and Scalable Payload Data System, under development by ESA, provides a suitable solution to fulfil a large range of future mission requirements. The backbone of the system is the standardised high data rate SpaceWire network http://www.ecss.nl/. As complement, a lower speed command and control bus connecting peripherals is required. For instance, at instrument level, there is a need for a “local” low complexity bus, which gives the possibility to command and control sensors and actuators. Moreover, most of the connections at sub-system level are related to discrete signals management or simple telemetry acquisitions, which can easily and efficiently be handled by a local bus. An on-board hierarchical network can therefore be defined by interconnecting high-speed links and local buses. Additionally, it is worth stressing another important aspect of the design process: Agencies and ESA in particular are frequently confronted with a big consortium of geographically spread companies located in different countries, each one developing a part of the system. Only when all the units are delivered to the system integrator, it is possible to test the complete system. Consequently, this normally happens at the final development stage and it is then often costly to face serious compatibility problems. Pre-integration would be a possible way of anticipating problems during the integration phase. In this case, a scheme allowing the interconnection of unit models (simulators, breadboards and flight-representative hardware) must be defined. For this purpose intranets and Internet can be of significant help. As a consequence of these well-identified needs a new concept has been formulated by the Agency and will extensively be described in this paper. On-board hierarchical networks have to be seen as an integrated infrastructure able to support not only software level functions but also hardware oriented diagnostic tools. As a complement to presently developed SpaceWire networks, a lower level bus must be selected. It must be reliable, flexible, easy-to-implement and it should have a strong error control and management scheme in order to ensure an appropriate availability figure. Of course, the adoption of an industrial standard bus is advisable because of the existence of development tools, devices and experience. Therefore, the use of a standard bus provides the possibility of evaluating and potentially using commercial systems, with a significant reduction of non-recurrent costs. As a consequence, ESA has recently set-up a working group with the objective of evaluating and, if needed, customising the Controller Area Network (CAN) bus (http://groups.yahoo.com/group/CAN_Space/). On this basis, it has been decided to consider the use of the CAN bus for payload systems and steps are being issued for its on-board implementation in space. As far as the lowest hierarchical level is concerned, a JTAG-like interface appears to be adequate but this selection is still subject to investigations. In the scenario presented so far, it is necessary to have a “bridge” between the SpaceWire backbone and the local CAN bus in order to provide a fully integrated system. Moreover, some additional features are needed to give autonomy to remote terminals and to release the central processing chain from repetitive standard acquisitions and management duties. For these reasons, a new device, called Remote Terminal Interface (RTI), is under development and will fulfil the above described needs; it has been specified to be used both in intelligent and non-intelligent nodes. In particular, it will be remotely programmable by means of its embedded SpaceWire links, it will include a CAN bus controller, an embedded micro-controller allowing the customisation of local functions, ADC/DAC interfaces for analogue acquisitions/driving, standard interfaces (UARTs, JTAG for debugging) and other standard devices (timers, counters, general purpose I/Os).

Smart pushbroom imaging system (SMARTSCAN) solves the problem of image correction for satellite pushbroom cameras which are disturbed by satellite attitude instability effects. Satellite cameras with linear sensors are particularly sensitive to attitude errors, which cause considerable image distortions. A novel solution of distortions correction is presented, which is based on the real-time recording of the image motion in the focal plane of the satellite camera. This allows using such smart pushbroom cameras (multi-/hyperspectral) even on moderately stabilised satellites, e.g. small sat's, LEO comsat's. The SMARTSCAN concept uses in-situ measurements of the image motion with additional CCD-sensors in the focal plane and real-time image processing of these measurements by an onboard Joint Transform Optical Correlator. SMARTSCAN has been successfully demonstrated with breadboard models for the Optical Correlator and a Smart Pushbroom Camera at laboratory level (satellite motion simulator on base of a 5 DOF industrial robot) and by an airborne flight demonstration in July 2002. The paper describes briefly the principle of operation of the system and gives a description of the hardware model are provided. Detailed results of the airborne tests and performance analysis are given as well as detailed tests description.

This paper describes the methodology used to develop the spacecraft pointing stability constraints and instrument disturbance limits for the Geostationary Operational Environmental Satellite (GOES) R series of spacecraft launching on or after 2012. Instrument line of sight stability and control requirements drive the spacecraft pointing stability constraints. In turn, the spacecraft constraints are used to define the instrument disturbance limits. The resulting limits on the spacecraft and instruments are defined in terms of spacecraft pointing error displacement, velocity and acceleration.

The general trend in remote sensing is on one hand to increase the number of spectral bands and the geometric resolution of the imaging sensors which leads to higher data rates and data volumes. On the other hand the user is often only interested in special information of the received sensor data and not in the whole data mass. Concerning these two tendencies a main part of the signal pre-processing can already be done for special users and tasks on-board a satellite. For the BIRD (Bispectral InfraRed Detection) mission a new approach of an on-board data processing is made. The main goal of the BIRD mission is the fire recognition and the detection of hot spots. This paper describes the technical solution and the first results, of an on-board image data processing system based on the sensor system on two new IR-Sensors and the stereo line scanner WAOSS (Wide-Angle-Optoelectronic-Scanner). The aim of this data processing system is to reduce the data stream from the satellite due to generations of thematic maps. This reduction will be made by a multispectral classification. For this classification a special hardware based on the neural network processor NI1000 was designed. This hardware is integrated in the payload data handling system of the satellite.

With the Dutch-Finnish Ozone Monitoring Instrument (OMI) hardware mounted on NASA's EOS-AURA spacecraft and the AURA planned for launch in 2004, we are working to prepare for flight. An important step in this preparation is the science validation of the software converting the instrument bit stream into (ir-) radiances, the 0-1b processor. The paper contains a description of the main elements of the 0-1b processor and it discusses the methods we have chosen for the validation process. Next it we discuss the outcomes of the various tests and thereby reveal the criticality of each of the algorithms. The algorithms we are dealing with are CCD detector corrections, algorithms to implement radiometric sensitivity of the instrument, stray light correction and the Fraunhofer lines based wavelength calibration algorithm. Because of the CCD, the stray light correction algorithm is two dimensional and the wavelength calibration algorithm is complex due to the fact that we aim at an extreme accuracy of 1/100 pixel or 2.10-3 nm. The validation partly makes use of the OMI Instrument Response Simulator and partly of on-ground performance and calibration measurement data.

In this study, we analyzed for the first time the potential of Getis statistics compared to the coefficient of variation for the study of the radiometric spatial uniformity and temporal stability of the Railroad Valley Playa, Nevada (RVPN) test site. We evaluated multi-sensor and multi-scale image data acquired for the RVPN, including four SPOT HRV images acquired in 1997 and 1998, five NOAA AVHRR images acquired in 1999, and one Landsat TM image acquired in 1998. The results show the potential and the importance of the synergy generated by these two methods for analyzing the radiometric spatial uniformity and temporal stability of the RVPN site. Getis statistics provide an excellent spatial analysis of the site while the coefficient of variation provides complementary information on the temporal evolution of the site.

In the accurate radiometric calibration of earth observation instruments, diffusers are used as “white-references”. In the frame of on-ground calibration campaigns of instruments such as SCIAMACHY, GOME2 and OMI (all using on-board diffusers), which took place at TNO TPD, a modulation of the reflectance signal in the spectral domain was discovered. This modulation appears when two spectra, recorded under slightly different conditions, are compared. This modulation, referred to here as Spectral features, reduces the accuracy of spectrometers as used in earth observation satellites. The spectral features are caused by speckle phenomena in the entrance slit of the spectrometer. The work reported here describes the origin of the spectral features, the measurements performed in order to reproduce and characterize this effect and the result of simulations performed on speckle patterns thanks to a dedicated analysis tool. A new set-up dedicated to spectral features measurements is also described.

The MODerate Resolution Imaging Spectroradiometer (MODIS) has 36 spectral bands with wavelengths from 0.41 to 14.5 micrometers. The 36 spectral bands, with a total of 490 detectors, are distributed on four focal plane assemblies (FPAs): visible (VIS), near infrared (NIR), short- mid-wave infrared (SMIR), and long wave infrared (LWIR). Nearly identical copies of the MODIS are currently operating onboard the NASA EOS Terra (launched on December 18,1999) and Aqua spacecraft (launched on May 4, 2002). Prelaunch and on-orbit characterizations of both Terra and Aqua MODIS have shown small but non-negligible out-of-band (OOB) response in the sensor's short-wave infrared bands (SWIR): bands 5-7, and band 26. To minimize the impact due to OOB response on the MODIS SWIR bands calibration and the Earth scene product retrieval, an algorithm has been developed and implemented in the Level 1B (L1B) software for both Terra and Aqua MODIS. In this paper, we describe the algorithm and its applications to the MODIS L1B calibration algorithms. We illustrate how the correction coefficients are derived from on-orbit observations and discuss the test procedures involved before the final implementation in the L1B code. Performance is evaluated for both Terra and Aqua MODIS and the two results are compared.

The launch of ESA’s ENVISAT in March 2002 was followed by a commissioning phase for all ENVISAT instruments to verify the performance of ENVISAT instruments and recommend possible adjustments of the calibration or the product algorithms before the data was widely distributed. The focus of this paper is on the vicarious calibration of the Medium Resolution Imaging Spectrometer (MERIS) radiance product (Level 1b) over land. From August to October 2002, several vicarious calibration (VC) experiments for MERIS were performed by the Optical Sciences Center, University of Arizona, and the Remote Sensing Laboratories, University of Zurich. The purpose of these activities was the acquisition of in-situ measurements of surface and atmospheric conditions over a bright, uniform land target, preferably during the time of MERIS data acquisition. The experiment was performed on a dedicated desert site (Railroad Valley Playa, Nevada, USA), which has previously been used to calibrate most relevant satellite instruments (e.g., MODIS, ETM+, etc.). In-situ data were then used to compute top-of-atmosphere (TOA) radiances which were compared to the MERIS TOA radiances (Level 1b full resolution product) to determine the in-flight radiometric response of the on-orbit sensor. The absolute uncertainties of the vicarious calibration experiment are found between 3.36-7.15%, depending on the accuracies of the available ground truth data. Based on the uncertainties of the vicarious calibration method and the calibration accuracies of MERIS, no recommendation to update the MERIS calibration is given.

The prototype of He-Ne / He-Xe laser system for methane detection using differential absorption of radiation backscattered from topographic targets is described. Using radiation of the wavelengths 3.39 μm and 3.51 μm, the measurement of CH₄ at the distance of 50 m was carried out. To increase the range and accuracy of measurement, the Cassegrain optics and lasers of higher power can be used. The lasers have four-channel construction structure and they are excited with RF current.

The National Aerospace Laboratory (NAL) has developed a new type of imaging spectropolarimeter that uses a liquid crystal tunable filter (LCTF) which makes it possible to measure the optical properties of solar rays reflected from land and sea surfaces. The aim of this development is to pave the way for the establishment of polarimetric analysis of solar rays reflected from the Earth’s surface as a method of Earth environment observation. Two imaging LCTF spectropolarimeters that cover different wavelength bands have been developed: a visible light sensor for the 400-720 nm wavelength band, and a near-infrared sensor that covers the 650-1100 nm band. Efforts are now under way to apply these optical sensors to practical applications, for airborne and ultimately spaceborn Earth environment remote sensing. This paper first outlines the imaging optical sensors, including their operational principles and construction. Next, various spectral images acquired using the visible light optical sensor in outdoor field and flight evaluation experiments to measure spectral characteristics of solar rays reflected from land and water surfaces are shown. Then, the results of outdoor experiments conducted using the near-infrared optical sensor are shown, including the analyzed relative radiance of solar rays reflected from observed spots, and spectral images acquired at various wavelengths and polarization angles. These experimental results demonstrate clearly that solar rays reflected from targets with differing characteristics have different spectropolarimetric properties. Finally it is concluded that the way has been paved for determining surface conditions from the properties of the spectral images acquired by LCTF spectropolarimeters at wavelengths of 400-1100 nm.

Hyperspectral analysis of solar rays reflected from the Earth’s surface is expected to play an important role in future Earth observation. Two imaging liquid crystal tunable filter (LCTF) spectropolarimeters for the visible and near-infrared wavelength bands have been developed by NAL over the past several years for such analysis. In order to realize the practical application of these optical sensors, efforts are currently under way to develop them into sensor packages for airborne observation systems. This paper first presents the concept and architecture of an optical observation system using an LCTF spectropolarimeter which is sensitive to radiation in the 650-1100 nm near-infrared wavelength band, along with its construction. The results of a farm observation conducted using a visible wavelength LCTF imaging spectropolarimeter are then presented by the spectral images of the observed areas as an example of a preliminary application to agro-environmental sciences. The results of a second farm observation conducted using a near-infrared LCTF imaging spectropolarimeter are presented by spectral images of an observed crop specimen, and radiances of solar rays reflected from the specimen are also shown. Finally, the applicability of the LCTF spectropolarimeter to agriculture observation is summarized based on the results of these agricultural observations.

During the solar flares the absolute radiation flux increases essentially and the most significant increase (up to the factor of 10⁴) takes place the soft X-ray spectral range. In 2001-2002 the solar X-ray-spectrometer was built in the S.I. Vavilov Space Optical Institute in the framework of the project 1523 of the International Science and Technology Center with the support of European Community and Republic of Korea. The instrumentation is dedicated for permanent registration of absolute solar fluxes during the all periods of solar activity - from quiet Sun to the most powerful solar flares. The paper describes the results of our work in progress on development of optical-electronic apparatus for Space Patrol of solar soft X-ray and extreme ultraviolet radiations and presents the last device of this apparatus - solar X-ray-spectrometer and the first results of its laboratory testing. There are no plans to install this apparatus for the Space Solar Patrol at the Russian Module of the International Space Station and at the satellite with solar-synchronous orbit at the altitude of 550 km to be launched by the M.V. Khrunichev State Space Center.

The rational polynomial coefficients (RPC) model is a generalized sensor model that is used as an alternative for the physical sensor model for IKONOS of the Space Imaging. As the number of sensors increases along with greater complexity, and as the need for standard sensor model has become important, the applicability of the RPC model is also increasing. The RPC model can be substituted for all sensor models, such as the projective, the linear pushbroom and the SAR. This paper is aimed at generating a RPC model from the physical sensor model of the KOMPSAT-1 (Korean Multi-Purpose Satellite) and aerial photography. The KOMPSAT-1 collects 510 ~ 710 nm panchromatic images with a ground sample distance (GSD) of 6.6 m and a swath width of 17 km by pushbroom scanning. We generated the RPC from a physical sensor model of KOMPSAT-1 and aerial photography. The iterative least square solution based on Levenberg-Marquardt algorithm is used to estimate the RPC. In addition, data normalization and regularization are applied to improve the accuracy and minimize noise. And the accuracy of the test was evaluated based on the 2-D image coordinates. From this test, we were able to find that the RPC model is suitable for both KOMPSAT-1 and aerial photography.

Pushbroom Hyperspectral Imaging technology is a new method to acquire the imaging spectrum data. Based on the area CCD technology, pushbroom imager can provide the higher SNR and more bands. Since 1995, Shanghai Institute of Technical Physics was developing the Pushbroom Hyperspectral Imager. In the paper, two generation of pushbroom hyperspectral imager (PHI) and the principle of instrument are introduced. The method and result of spectral calibration and radiation calibration are written in detail. PHI had been used in remote sensing of environment monitoring, geology study, oil and gas prospecting, vegetation, ocean observation, city layout, fine agriculture, forest fireproofing at home and abroad.

Contamination monitoring of spacecrafts during ground processing operations is essential to maintain performance of optical systems. The cleanliness level of spacecrafts is usually evaluated by counting particles fall on collector plates, but the manual counting is taken a considerable time and subject to human errors. Computer-aided counting of particles was performed on silicon wafers with various cleanliness levels using a scanning laser microscope. It was possible to detect particles larger than 1μm. Number of deposited particles, μparticle size distribution, and area coverage were measured and the correlation between the surface cleanliness level and the area coverage was obtained within the range of cleanliness level from 250 to 800. Concurrently with laboratory measurement, the contamination monitoring of storage environment of ADEOS-II at Tanegashima Space Center was performed with collector plates. The area coverage of collector plates agreed very well with the results of the laboratory experiments. The chemical component analysis was also carried out to the particles accreted on the collector plates set in the ADEOS-II storage clean room by an electron probe micro-analyzer. It found that a maximum of 70% of the particles on collector plates were organic and these were thought to come from human sources. Fibrous particles accounted for 11% of measured particles. Moreover, the percentage of particles containing heavy metals was significantly higher than in outdoor environment.

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), one of five sensors on Terra, has five bands (10 to 14) in the thermal infrared (TIR) region. These TIR bands are radiometrically calibrated by one onboard blackbody with the function of changing temperature between 270 and 340 K. In normal operation the blackbody is set up at 270 K, and a constant coefficient in a quadratic radiometric calibration equation for each detector is adjusted at that temperature before each Earth observation, but the gain coefficient cannot be adjusted at this time, while it can periodically be updated by long term calibration in which the blackbody is measured at 270, 300, 320, and 340 K. On the other hand the sensor response of all bands (particularly band 12) has been degrading since the launch, and periodical updating of the gain coefficient does not fully follow the degradation, so that the calibration error on level-1 (L1) products is often unacceptable. We therefore have developed a recalibration method which is easily applied to L1 products by a general user. By using this method, the calibration error will mostly be reduced below the level of NEDT.

CO.RI.S.T.A. is involved in a research project funded by ASI (Italian Space Agency), named MITAR, to realise a very compact, lightweight deployable telescope in visible wavelength range to get earth images from microsatellite. The satellite considered for the study is SMART, an Italian academic multi-mission microsatellite operating on circular sun-synchronous orbits. The telescope has a Cassegrain configuration with a parabolic primary mirror and an hyperbolic secondary mirror. This configuration guaranties the best aberrations corrections and the best compactness. The primary and the secondary mirror are 40 cm and 10 cm in diameter respectively, while their relative distance is 52cm. Mirrors will be realised with innovative composite material to obtain lightweight optical elements. Thanks to its limited size and light weight, the system can be easily deployed. The deployable structure will keep the secondary mirror close to the primary one during launch phases. Once in orbit, a system of lenticular tape springs and dumpers will extend the structure. The structure will be enclosed in multilayer blankets that will shield the sensor from light and will thermally stabilize the structure, preventing excessive thermal deformation. The images will be detected by a very high resolution CCD camera installed onboard the satellite.

The near-infrared spectrometer, SIR, is a flexible, compact and low mass (2 kg) instrument designed to measure reflectance spectra in the wavelength range between 935 and 2390 nm with a resolution of 6 nm per pixel. In its current implementation it is part of ESA’s technology mission SMART-1, which will be launched in 2003 and tested in an orbit around the Moon. The SIR spectrometer uses a reflection grating and an InGaAs detector. Its design is optimized to operate under extreme temperature and to withstand extreme vibrational conditions. For the SMART-1 mission its capabilities are of particular importance for the study of features like maria, craters, and fracture ridges that will provide deeper insights into crust and mantel material and therefore, into the development of the Moon and the Earth-Moon system.

NASA’s Earth Science Enterprise (ESE) is changing focus from single satellite missions to measurement oriented programs. An example of this paradigm shift is the Global Precipitation Measurement (GPM) project. GPM is conceptualized as a rolling-wave of measurement possibilities all focused on the key precipitation parameter. In response to this shift to measurement programs and also integral to the ESE’s new strategy for processing and management its data, a measurement based approach is also critical for data processing system that support measurement programs like GPM. This paper provides an overview of the paradigm shift from mission to measurement. It also presents a summary of the ESE’s new strategy for its data systems. Building on this background the paper details the architectural, design and implementation aspects of the Precipitation Processing System (PPS). The PPS is an evolution of a single point system developed for the Tropical Rainfall Measurement Mission to a generic precipitation data system. The paper provides the context within which PPS will support the GPM program.

Use of satellite images has been of great help for studies of landuse distribution in different places at different conditions. Landsat images have been one of the best ones due to their great spectral resolution (Landsat TM-7 with 7 bands), but their limited spatial resolution of 30m has been of the biggest disadvantages for detailed landuse studies. In the other hand Radarsat images have one of the best spatial resolution (6 m) but poor spectral resolution (pancromatic mode). Besides their good spatial resolution Radar images have other advantages over other images like their capacity to operate under any climatic conditions and at any time (day or night). Radar images are able to get information even in cloudy conditions and this characteristic make them perfect for studies of coastal zones and specially on tropical areas, where most part of the year are covered by clouds. The study area in this case was located at a tropical area (09°33’45” N and 75°23’45”W) so it was absolutely necessary to find a solution to perform the best detailed landuse distribution in order to actualize coastal zone management plans for the area. Nowadays techniques have been able to overcome these disadvantages. Applications of fusion techniques were able to solve these limitations, by the combination of the best characteristics of these two types of images. In this specific case the good multiespectral resolution of Landsat images and the good spatial resolution of Radarsat images were combined in order to obtain a completely new image, but only with 20 m of spatial resolution since Radarsat resolution was decreased due to the exaggerated difference in spatial resolution between the two images (6m and 30m). This is very much recommended to decrease errors created during the pixel to pixel fusion. With this new image obtained a good and detailed landuse distribution was performed by the application of supervised classifications in the study area. The results obtained were of good percentage of reliability and then used for new coastal zone plans.

Criteria for selecting the appropriate combination of sensors when searching for cultural features within an archaeological site are poorly developed and sorely needed for the economic application of remote sensing in archaeology. The Hollywood Mounds, a late prehistoric ceremonial center in the lower Mississippi alluvial valley of the southeastern United State, has been the subject of a large number of remote sensing experiments using a wide variety of both digital airborne and geophysical sensors. In addition, two seasons of ground truth excavations have been carried out at the site. Multivariate statistical analyses, beginning with a map of the known locations of house and mound remnants, allow us to derive quantitative measures of the relative value of the various instruments in this specific but fairly typical context.

With EO-1 Hyperion in orbit NASA is showing their continued commitment to hyperspectral imaging (HSI). As HSI sensor technology continues to mature, the ever-increasing amounts of sensor data generated will result in a need for more cost effective communication and data handling systems. Lockheed Martin, with considerable experience in spacecraft design and developing special purpose onboard processors, has teamed with Applied Signal & Image Technology (ASIT), who has an extensive heritage in HSI spectral compression and Mapping Science (MSI) for JPEG 2000 spatial compression expertise, to develop a real-time and intelligent onboard processing (OBP) system to reduce HSI sensor downlink requirements. Our goal is to reduce the downlink requirement by a factor > 100, while retaining the necessary spectral and spatial fidelity of the sensor data needed to satisfy the many science, military, and intelligence goals of these systems. Our compression algorithms leverage commercial-off-the-shelf (COTS) spectral and spatial exploitation algorithms. We are currently in the process of evaluating these compression algorithms using statistical analysis and NASA scientists. We are also developing special purpose processors for executing these algorithms onboard a spacecraft.

The increasing availability of high-resolution satellite imagery is one of several factors that is renewing interest in teaching photo interpretation skills both in academia and in the workplace. The Aerial Photointerpretation Course, developed by the NASA-funded Geospatial Workforce Development Project at the University of Mississippi, presents an unusual opportunity to remedy the neglect of photointerpretation in many university curricula in past years. Course development in Remote Sensing and GIS within the geospatial curriculum in recent decades has diverted attention from development of original teaching materials devoted specifically to photointerpretation. This newly developed course provides the opportunity to offer students with materials that can present basic concepts in the context of current technology and resources, and current workforce needs. Course content is presented in four units: (1) History and Significance, (2) Photographic Systems, (3) The Human Dimension to Photointerpretation, and (4) Applications. The applications unit consists of several components encompassing a broad range of subject areas, from Agriculture and Forestry, to Geology and Geomorphology, and to History and Archeology. The on-line format offers opportunity to deliver a high density of visual content to students, and to increase opportunities for students to acquire first-hand experience in photointerpretation. The on-line format also offers opportunities to use a wide range of sources and activities not normally available for conventional classroom presentation.

Computer based teaching has become common place as the demand for specialists continues to increase in view of continuously evolving remote sensing technologies. Moreover, content accessibility via the internet makes anytime, anywhere teaching possible while reaching a larger audience. The majority of computer based courses however, continue to use the static text model and present the student mainly with the same material found in a textbook. Student computer based learning experiences could be much more rewarding if the curriculum included more interaction and practice. It is with these goals in mind that the development of a virtual experiment and game were devised. Herschel's experiment was the first to show the existence of infrared (IR) light. This virtual experiment requires the student to set up the experiment and record data in order to prove the existence of IR light. The 'Field Experiment' game requires the student to plan and execute a field collection campaign with the use of a field spectrometer. These 'beyond the book' experiences hopefully encourage and stimulate students in the subject at hand as well as provide more 'practical' experience that is not available through viewing static text and graphics.

Over the last 25 years, a tremendous progress has been made in the Earth science space-based remote sensing observations, technologies and algorithms. Such advancements have improved the predictability by providing lead-time and accuracy of forecast in weather, climate, natural hazards, and natural resources. It has further reduced or bounded the overall uncertainties by partially improving our understanding of planet Earth as an integrated system that is governed by non-linear and chaotic behavior. Many countries such US, European Community, Japan, China and others have invested billions of dollars in developing and launching space-based assets in the low earth (LEO) and geostationary (GEO) orbits. However, the wealth of this scientific knowledge that has potential of extracting monumental socio-economic benefits from such large investments have been slow in reaching the public and decision makers. For instance, there are a number of areas such as energy forecasting, aviation safety, agricultural competitiveness, disaster management, homeland security, air quality and public health, which can directly take advantage. Nevertheless, we all live in a global economy that depends on access to the best available Earth Science information for all inhabitants of this planet. This paper surveys and examines a number such applications in terms of their architecture, maturity and economic applicability as they apply to the societal needs. A detailed analysis is also presented of various challenges and issues that pertain to a number of areas such as: (1) difficulties in making a speedy transition of data and information from observations and models to relevant Decision Support Systems (DSS) or tools, (2) data and models inter-operability issues, (3) limitations of spatial, spectral and temporal resolution,(4) communication limitations as dictated by the availability of image processing and data compression techniques. Additionally, the most critical element amongst all is the organizational and management boundaries that must be resolved at local, state, national and international levels to implement and realize free flow of such vital information. This paper also makes attempts to address this topic and discuss possible approaches to deal with this quandary.

NASA/GSFC has developed with other groups a Land Data Assimilation System (LDAS) to output water and energy budgets for the primary purpose of improving weather and climate prediction. However, LDAS water and energy cycle outputs also may be coupled with other information to help with a wide range of water resources applications. For example, LDAS results may be used for water availability and quality, agricultural management and forecasting, assessment and prediction of snowmelt runoff, and flood and drought impact and prediction. Specifically, LDAS uses various satellites and ground based observations within a land surface modeling and data assimilation framework to produce optimal output fields of terrestrial energy, water and carbon fluxes. Current land surface outputs are gridded at 1/4° resolution globally and 1/8° for North America with work in progress to convert to a 1-km global grid. Integrated modeling, observations and data assimilation at various spatial and temporal scales helps LDAS to quantify terrestrial water, energy and biogeochemical processes. LDAS applications described in this paper are aimed at improving weather and seasonal forecasts. In addition, we also summarize the use of LDAS data to assist critical needs specified by the U.S. Bureau of Reclamation water resources management for selected basins in the western U.S.

Digital elevation models (DEMs) are important tools in the planning, design and maintenance of mobile communication networks. This research paper proposes a method for generating high accuracy DEMs based on SPOT satellite 1A stereo pair images, ground control points (GCP) and Erdas OrthoBASE Pro image processing software. DEMs with 0.2911 m mean error were achieved for the hilly and heavily populated city of Amman. The generated DEM was used to design a mobile communication network resulted in a minimum number of radio base transceiver stations, maximum number of covered regions and less than 2% of dead zones.