The Earth Science Enterprise distinguishes three types of space flight missions: systematic observation missions, exploratory missions, and operational precursor or technology demonstration missions. All three types of missions are represented at the Goddard Space Flight Center, and we will discuss them in turn. Systematic Observation Missions provide long-term continuity of critical earth observations; at GSFC they include Landsat 7 and Terra, which were launched in 1999 and are now operational and returning data; the Aqua and Icesat missions are scheduled for launch later in the year, the SORCE mission in 2002 and the Aura mission in 2003. Exploratory missions are expected to be one-time missions that address a focused set of scientific questions. Exploratory missions at GSFC include QuikTOMS, VCL, CloudSat, ESSP3-CENA, and Grace. Finally, operational precursor and technology development missions are intended to lead to future operational deployment in low Earth orbit or geostationary orbit (within the framework of the NPOESS and GOES programs). The first technology development mission, EO-1 was launched last year. The NPOESS Preparatory Project, or NPP, is currently in formulation. We briefly introduce each of these missions, outlining the major characteristics and anticipating their data products. The overall development schedule is shown.

The National Aeronautics and Space Administration (NASA) is studying options for future space-based missions for the EOS Follow-on Era (post 2003), building upon the measurements made by Pre-EOS and EOS First Series Missions. One mission under consideration is the Global Precipitation Measurement (GPM), a cooperative venture of NASA, Japan, and other international partners. GPM will capitalize on the experience of the highly successful Tropical Rainfall Measurement Mission (TRMM). Its goal is to extend the measurement of rainfall to high latitudes with high temporal frequency, providing a global data set every three hours. A reference concept has been developed consisting of an improved TRMM-like primary satellite with precipitation radar and microwave radiometer to make detailed and accurate estimates of the precipitation structure and a constellation of small satellites flying compact microwave radiometers to provide the required temporal sampling of highly variable precipitation systems. Considering that DMSP spacecraft equipped with SSMIS microwave radiometers, successor NPOESS spacecraft equipped with CMIS microwave radiometers, and other relevant international systems are expected to be in operation during the timeframe of the reference concept, the total number of small satellites required to complete the constellation will be reduced. A nominal plan is to begin implementation in FY'03 with launches in 2007. NASA is presently engaged in advanced mission studies and advanced instrument technology development related to the mission.

The High Resolution Dynamics Limb Sounder (HIRDLS) mission has particularly demanding scientific goals which represent especially challenging engineering technologies, assembly and calibration strategies. These goals include the measurement of various atmospheric species and associated geophysical parameters that have spatial resolutions and absolute accuracies that are at the same time commensurate with the resolution of current global general circulation models and with the observed fine structure of processes important in the upper troposphere and lower stratosphere (UTLS) and polar vortex mixing. The performance of the HIRDLS instrument and the pre-launch calibration equipment and procedures are essential to the achievement of these goals. The results of tests of the equipment to-date are described. These results and the procedures and equipment that are in place for the pre-launch calibration suggest that HIRDLS will be well capable of meeting the science requirements.

The ASTER system is flying on the Terra spacecraft since December 18, 1999. After the instrument check, multispectral images ranging from visible to thermal infrared have been provided using three subsystems, i.e., VNIR, SWIR and TIR. To deliver data products with high quality from the viewpoint of the geolocation and band-to-band registration performance, the fundamental program called the Level-1 processing has been developed. On December 1, 2000, the official data products (Version 1.0) were released, where the band-to-band registration accuracy in the subsystem was better than 0.3 pixels and that between subsystems was better than 0.5 pixels. On May 1, 2001, the validated data products have been released by improving the geometric performance, where the band-to-band registration in the subsystem is better than 0.1 pixels and that between subsystems is better than 0.2 pixels. In this paper, the characteristics of the images and the effect of geometric parameters on the image quality of the ASTER system, which consists of four telescopes and a cross-track pointing function, are analyzed by image matching method based on a cross-correlation function.

ASTER instrument on NASA Terra spacecraft has an along-track stereoscopic capability using one of the near infrared spectral bands. To acquire the stereo data, ASTER has two telescopes, one for nadir and another for backward viewing, with a base-to-height ratio of 0.6. The spatial resolution is 15 m in horizontal plane. Parameters such as the line-of- sight vectors and the pointing axis were adjusted during initial operation period to generate the Level-1 data products with the high quality stereo system performance. The accuracy of the stereo data generated from the Level-1A data is better than 10 m without GCP correction for individual scenes. Geolocation accuracy that is important for the DEM data sets is better than 50 m. This seems to be limited by the spacecraft position accuracy. The stereo system configuration, the method of parameter adjustment, DEM generation algorithm, and the final performance are described.

The Landsat 7 spacecraft and its Enhanced Thematic Mapper Plus (ETM+) were launched on April 15, 1999. Pre-launch modeling of the ETM+ optical system predicted that modulation transfer function (MTF) performance would change on-orbit. A method was developed to monitor the along-scan MTF performance of the ETM+ sensor system using on-orbit data of the Lake Pontchartrain Causeway in Louisiana. ETM+ image scan lines crossing the bridge were treated as multiple measurements of the target taken at varying sampling phases. These line measurements were interleaved to construct an over-sampled target profile for each ETM+ system transfer function. Model parameters were adjusted to achieve the best fit between the simulated profiles and the image measurements. The ETM+ modulation at the Nyquist frequency and the full width at half maximum of the point spread function were computed from the best-fit system transfer function model. Trending these parameters over time revealed apparent MTF performance degradation, observed mainly in the 15-meter resolution ETM+ panchromatic band. This confirmed the pre-launch model prediction that the panchromatic band was the most sensitive to changes in ETM+ optical performance.

As one of three ENVISAT instruments dedicated for atmospheric chemistry research, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), a high-resolution Fourier Transform Infrared (FTIR) limb sounding spectrometer, will measure the Earth's limb emission in the infrared range (685 - 2410 cm-1, 14.6 - 4.15 micrometers ) on a global scale over a period of several years. The systematic processing of MIPAS scene and calibration data up to fully calibrated, geo-located limb radiance data and vertical profiles of atomospheric pressure, temperature and volume- mixing-ratios (VMR) of several atmospheric species requires a stable data acquisition and ground processing scenario and a number of calibration and characterization activities prior and after launch. After completion of the Flight Model FM test campaign and subsequent integration and test on the ENVISAT platform, MIPAS is now ready for launch by an ARIANE-5 launcher into an 800 km polar orbit. This paper gives an overview of the MIPAS instrument design, recalls the performance as measured in the instrument ground test campaigns and presents the preparations for the commissioning phase, comprising of an initial switch-on and data acquisition phase (SODAP) and a subsequent calibration/validation (CAL/VAL) phase preparing MIPAS for routine operation.

Desertification has become a major environmental issue in scientific, political and public circles. Notwithstanding the many inaccurate statements concerning the extension and dynamics of desertification, the fact that dry ecosystems are by nature fragile and susceptible to degradation, and that desertification is to be considered a serious problem, there is now large agreement that the phenomenon is related to particular geographic and physical conditions. The processes are context specific and climate sensitive, and the probability or onset of desertification is a function of biotic and abiotic exchanges at the regional level, and human activity at the local level . While standard methods for identifying and monitoring environmental change in drylands are imperfect or expensive, remote sensing approaches to degradation monitoring can characterize surface properties in terms of physical, bio- and geo- chemical components with indicator function and linkages into appropriate process models. Repeated and, by force, standardized observations over longer time periods are indispensable to assess significant changes. The concept of hyperspectral imaging or imaging spectrometry, i.e. the acquisition of surface spectral signatures in a wide wavelength range with numerous narrow and contiguously spaced spectral bands, has meanwhile provided the user community with a range of powerful, yet experimental airborne sensor systems. Considerable efforts have been taken to construct hyperspectral imaging systems which are able to observe the Earth from space orbits. Encouraging results are delivered from the Hyperion senso r on board EOS-1. Nevertheless, none of the existing sesors will allow a long term monitoring of dry ecosystems. In this view, the paper ill discuss a concept for developing a hyperspectral satellite mission named 'Spectral Analyses for Dryland Degradation (SAND)' dedicated to the assessment of land degradation in arid and semi-arid areas that attempts to combine characteristics of operational earth observation and particular advantages of high spectral resolution systems.

The primary payload on a small-satellite, MightySat II.1, is a spatially modulated Fourier transform hyperspectral imager designed for terrain classification. This imager is the first hyperspectral imager to be successfully operated from space. As part of its year long mission, images have been taken of the Earth's limb and the moon. Analysis of the limb data have shown the presence of large scale structure in the limb while the moon imagery is being used to determine the suitability of using the moon as a vicarious calibration source. The paper briefly describes the satellite and hyperspectral instrument and presents examples of the limb and moon observations and data.

The Waves Michelson Interferometer (WAMI) is designed to provide simultaneous measurements of dynamical and constituent signatures in the upper stratosphere, mesosphere and lower thermosphere. It is being included as part of the Waves Explorer mission (G. Swenson, P.I. being proposed for NASA's MIDEX program. It is a field-widened Michelson interferometer based on the same design principle as the successful Wind Imaging Interferometer (WINDII). WAMI includes visible and near-IR channels, a segmented interferometer mirror for simultaneous fringe sampling at different optical paths and views the atmosphere in six distinct directions. Use of the segmented mirrors minimizes the aliasing of atmospheric intensity variations into the fringe parameter determinations. This technique also allows two emissions to be viewed simultaneously through the same optical channel. The emissions chosen include lines in the molecular oxygen IR-atmospheric band, a doublet in the hydroxyl Meinel bands and the oxygen green line. The daytime coverage includes winds from 45 to 180 km, and rotational temperature and ozone density from 45 to 95 km. The nighttime coverage is restricted to the airglow layer centered near 90 km where atomic oxygen, horizontal wind and rotational temperature measurements are provided. These measurements provide a rich data set from which dynamics, energetics and constituent budgets can be determined.

Static interferometers are imaging devices, which produce electromagnetic interference for each propagation direction of the accepted light beam. The fundamental component of this type of interferometers is a beam-splitter semi- transparent plate that provides phase-delay between the two interfering rays. The phase-delay changes with varying the incidence angle of the entering ray, thus producing the entire interference pattern while moving the device over the surface of the observed target. Due to their technical characteristics these interferometers can reliably be adapted for aerospace remote sensing applications. This paper describes the result coming from numerical simulations executed in order to investigate the possible use of the static interferometers for remote sensing purposes. The principal objectives are: a deep investigation about interferometers and novel detector technologies, the study of its performance as compared with that of dispersing sensors and the study of a laboratory prototype of the interferometric hyperspectral imager.

The Ozone Monitoring Instrument (OMI) is a nadir viewing wide field imaging spectrometer for ozone monitoring. The instrument is the Dutch/Finnish contribution to the NASA EOS-AURA mission. OMI observes earth's back scattered radiation in two spectral channels: the UV channel (270 nm - 350 nm) and the VIS channel (350 nm - 500 nm). Each channel employs a CCD detector (576 X 780 px). The extreme wide field of view of 114 degrees, equal to a swath wide of 2600 km, is obtained by an all reflective telecentric telescope and enables global ozone coverage in one day. Other key features are the spectral range (270 nm - 500 nm) and resolution (spectral sampling distance 0.15 - 0.32 nm/px), the application of a polarization scrambler and its compact design (400 X 300 X 500 mm). Excellent stray light performance in the UV channel is obtained by an elegant opto-mechanical design of the UV optics where the UV wavelength range is split in two parts with separate optical paths and the separate spectra are imaged on one CCD. Onboard calibration includes a white light source, LEDs, and multi-surface solar-calibration diffuser. The OMI-EOS project follows a Proto-Flight approach, supported by breadboards and engineering qualification models on parts and sub-system level. In order to increase confidence in the design, the instrument development model was built. During intensive testing critical performance parameters were checked , e.g. UV stray light behavior, polarization sensitivity, distortion, spatial and spectral ranges and resolutions.

The paper focuses on the aliasing phenomenon that may produce distortions on remotely sensed images acquired by hyper-spectral push-broom sensors and that arises because of its sampling rate. The analysis is performed on images recorded over different targets at a resolution that is high for the sensor under investigation. A model for the system modulation transfer function of PRISM hyper-spectral push- broom sensor is developed by taking into account the different contributions due to optical layout, electronics, detector, satellite motion. By using the sensor model, the high resolution images are pre-filtered and spatially re- sampled in order to obtain simulated images of the sensor. Such images are compared with those obtained by an ideal pre-filtering and re-sampling process in order to evidence possible aliasing effects. Quantitative indexes are adopted in order to assess the presence of aliasing. Filtering procedures are utilized to mitigate aliasing effects; to this aim multi-resolution filtering and a fuzzy filtering scheme are evaluated by means of the adopted indexes and by visual inspection. Quantitative and qualitative results show that, due to the efficacy of the proposed filters, aliasing mitigation is obtained with negligible penalties on spatial resolution.

The Officine Galileo (OG) Hyperspectral Camera (HYC) (currently under development in the frame of the Hypseo ASI program) consists of an high spatial resolution (20 m) imaging spectrometer working in the visible and SWIR bands, to be embarked on future low earth orbit operational satellites. The mission requirements include monitoring of vegetation, coastal/internal waters and geology/hydrology. The instrument works with a swath of 20 Km and steering capability within 500-Km across-track. It operates in about 210 spectral bands of 10 nm of resolution. The objective of the present work is the evaluation of application performances of the HYC camera compared to those of multi- spectral sensors (e.g. ETM+/Landsat 7), carried out by means of images and products simulations. For this scope some airborne campaigns have been performed with hyper- spectral sensors (VIRS, MIVIS) in a test area of Tuscany region (1), with contemporaneous collection of ground/sea truth data. HYC and ETM+ radiance images have been simulated by means of surface reflectance maps obtained from the airborne sensors, applying the MODTRAN atmospheric code and the HYC (and ETM+) instrumental models (spatial, spectral and noise degradation). The retrieval of surface reflectance has been performed by means of an atmospheric correction algorithm based on the dark pixel method. Next, two test products (forest classification and river plumes analysis) have been simulated; the first based on a maximum likelihood classification method and the second based on multivariate regression analysis. The results have been validated with ground truth data for different atmospheric conditions. Classification error decreases from 22% (ETM+) to 13% (HYC), whereas suspended sediments accuracy error decreases from 24% (ETM+) to 15% (HYC) in the tested conditions. The implemented methodology has allowed studying the better trade-off between product accuracy and instrumental requirements.

The Advanced Technology Microwave Sounder (ATMS) is a new generation of microwave instrument for measuring atmospheric temperature and humidity profiles from satellites. It is being developed in the U.S. for the future operational weather satellite systems, called the National Polar- orbiting Operational Environment Satellite System (NPOESS). This paper presents some key design features of the ATMS, its essential characteristics, the expected performance, and program status.

The Norwegian Defence Research Establishment and industry partners develop a new sensor concept for maritime surveillance by passive detection of X-band navigation radars from a micro-satellite in polar LEO. The Phase-A study was finished June 2001. According to the International Convention for the Safety Of Life At Sea (SOLAS), all vessels longer than 45 m are required to be equipped with X- band navigation radar. The proposed localization of vessels is based on in-orbit detection and processing of navigation radar signals, using precise direction-finding techniques for geolocation. The optimum sensor configuration is side viewing towards the horizon, giving an approximately 1200 km wide swath for detection of the radar's main lobe signal. From polar LEO, the sensor can cover Norwegian waters more than four times per day. This exceeds the coverage of existing SAR systems by more than a factor of four, and at a much lower price. An orthogonal microwave antenna array and a multi-channel receiver are used for acquisition of the radar signals. Utilizing advanced signal processing, the angle of arrival of individual pulses is determined with a precision that corresponds to an error smaller than 1 km in the geographic position. The orbit and attitude determination systems of the platform are high performance and closely connected to the payload, to give satellite position and orientation with knowledge or 15 m and 0.001 degree(s), respectively. A high degree of on-board autonomy is required to process the radar signals to user-data packets. The satellite provides a dedicated downlink channel to broadcast the vessel traffic data to compact user terminals in near real time.

MEMS technology now makes possible to produce active microdevices combining detection, signal processing, and data storage with accuracy and compactness. In view of their characteristics, it can be expected that such microsensors will be used extensively in space applications dedicated to micro and nano satellites. The advanced architecture of a MicroInfraRedEarthSensor generic system based on a Vo_x microbolometer array associated with optics and electronics 'on the shelves' for signal processing and depointing computation, used to control the attitude of satellites in low earth orbits, has been completely developed, through the design of a virtual prototype combined with a breadboard implementation of an IR camera (called MST, and has been developed by EADS-SODERN, in the frame of IASI project). The correlation of the virtual prototyping approach, has allowed to build one complete optical head part of the instrument with efficient and optimized parameters where the performances are consistent with the main mission specifications (pointing accuracy <EQ 0.1 degree(s), measurement frequency > 10 Hz, aperture angle: > 36 degree(s), volume <EQ 250cm³, self contained measurement system able to operate self-calibration, should operate 24 hours a day). In addition, this standard and compactness electronics is very generic, which means that the system can be adapted to any kind of microbolometer, for LEO and also GEO (by the way of a new software) ADCS control and be used even in other fields of remote sensing.

An Acousto-Optical Spectrometer (AOS) features the submillimeter-wave limb-emission sounder (SMILES) to be aboard the Japanese Experiment Module (JEM) of International space station (ISS). The Japanese space agency (NASDA) has contracted ASTRIUM for the development of the AOS. Acousto- Optical Spectrometers are well adapted for analyzing in real time with high resolution a wide band and faint signal embedded in radiometric noise. Their usefulness for instantaneous detection and mapping of multi-species emission was first demonstrated in the field of radio astronomy in 1970s and thanks to their compactness and low power consumption, they are highly well adapted to space application. Several technical concerns related to important instrumental characteristics of AOS are discussed and performances are overviewed.

This paper reports on a space-qualified cooling system for submillimeter SIS mixer receiver (SIS: superconductor- insulator-superconductor). Designed cooling capacity of the system is 20 mW at 4.5 K, 200 mW at 20 K, and 1000 mW at 100 K. The combination of two-stage Stirling cooler and Joule- Thomson one has demonstrated the capacity with a power consumption of less than 300 W, including losses of drive electronics. The cryostat has a thermal insulation structure of S2-GFRP straps to fasten its 100 K stage. 20 K stage of the cryostat is held with GFRP pipes on the 100 K stage, while 4 K stage is supported with CFRP pipes on the 20 K stage. The cooling system accommodates two SIS mixers at 4.5 K, two IF amplifiers at 20 K, and two more IF amplifiers at 100 K. The mass of the cooling system is 40 kg for the mechanical cooler itself, 26 kg for the cryostat, and 24 kg for the driver electronics. The system has been developed for a 640 GHz receiver for an atmospheric limb-emission sounder SMILES, which is to be aboard the International Space Station in 2005. The engineering model of the system has been built and tested successfully.

A submillimeter wave limb emission sounder, that is to be aboard the Japanese Experiment Module (JEM, dubbed as 'KIBO') at the International Space Station, has been designed. This payload, Superconducting Submillimeter-wave Limb Emission Sounder (SMILES), is aimed at global mappings of stratospheric trace gasses by means of the most sensitive submillimeter receiver ever operated in space. Such sensitivity is ascribed to a Superconductor-Insulator- Superconductor (SIS) mixer, which is operated at 4.5 K in a dedicated cryostat combined with a mechanical cooler. SMILES will observe ozone-depletion-related molecules such as ClO, HCl, HO₂, HNO₃, BrO and O₃ in the frequency bands at 624.32 - 626.32 GHz, and 649.12 - 650.32 GHz. A scanning antenna will cover tangent altitudes from 10 to 60 km in every 53 seconds, while tracing latitudes from 38S to 65N along its orbit. This global coverage makes SMILES a useful tool of observing the low- and mid-latitudinal areas as well as the Arctic peripheral region. The molecular emissions will be detected by two units of acousto-optic spectrometers (AOS), each of which has coverage of 1.2 GHz with a resolution of 1.8 MHz. This high-resolution spectroscopy will allow us to detect weal emission lines attributing to less-abundant species.

MARSCHALS (Millimeter-wave Airborne Receivers for Spectroscopic CHaracterization in Atmospheric Limb Sounding) is being developed with funding from the European Space Agency as a simulator of MASTER (Millimeter-wave Acquisitions for Stratosphere Troposphere Exchange Research), a limb sounding instrument in a proposed future ESA Earth Explorer Core Mission. The principal and most innovative objective of MARSCHALS is to simulate MASTER's capability for sounding O₃, H₂O and CO at high vertical resolution in the upper troposphere (UT) using millimeter wave receivers at 300, 325, and 345 GHz. Spectra are recorded in these bands with 200 MHz resolution. As such, MARSCHALs is the first limb-sounder to be explicitly designed and built for the purpose of sounding the composition of the UT, in addition to the Lower Stratosphere (LS) where HNO₃, N₂O and additional trace gases will also be measured. A particular attribute of millimeter-wave measurements is their comparative insensitivity to ice clouds. However, to assess the impact on the measurements of cirrus in the UT, MARSCHALs has a near-IR digital video camera aligned in azimuth with the 235 mm limb-scanning antenna. In addition to UT and LS aircraft measurements, MARSCHALs is capable of making mid-stratospheric measurements from a balloon platform when fitted with a 400 mm antenna. Provision has been made to add further receiver channels and a high resolution spectrometer.

In this paper, the U.S. Air Force's Research Laboratory Space-Time Adaptive Processing (RLSTAP) tool is used to demonstrate the impact of large sidelobe discretes on modern Synthetic Aperture Radar (SAR) signal and image processing. Sidelobe discretes ay mask or even completely obscure weak target returns of interest in the immediate vicinity of these strong returns. Adaptive processing offers the potential to mitigate the effects of strong sidelobe discretes on image formation. In this paper, we characterize the severity of the problems caused by these discretes. RLSTAP can simulate high-fidelity airborne, spaceborne, or ground based multi-channel radar data in jamming and clutter environments, develop and evaluate new signal and image processing algorithms, and assess the performance of advanced radar systems. RLSTAP is a time domain simulation, updating object positions for every radar pulse and allowing modeling of realistic effects such as returns 'walking' across range bins and Doppler filters. The site-specific clutter model uses terrain elevation and cover data to derive the line-of-site visibility, grazing angle, and clutter type for each range-angle cell. Spatial and temporal clutter statistics are applied to each cell and the signal strength at the receiver is calculated as a function of the backscatter coefficient, range, atmospheric attenuation, antenna gain, and system gains/losses. The scene generation capability in RLSTAP is unique in that it exploits Defense Terrain Elevation Data (DTED) and Land Use Land Cover Data (LULC) to create realistic clutter scenes (data cubes) for any given geographic location. As such, the application of adaptive multi-channel/multi-pulse processing to radar data that is characteristic of the area being imaged is now possible. Furthermore, the selection of waveform parameters, signal and image processing techniques, and associated radar parameters may be improved upon.

In recent years the Italian Space Agency has been proceeding to the definition and launch of small missions. In this ambit, the BISSAT mission was proposed and selected along with five other missions for a competitive Phase A study. BISSAT mission concept consists in flying a passive SAR on board a small satellite, which observes the area illuminated by an active SAR, operating on an already existing large platform. Several scientific applications of bistatic measurements can be envisaged: improvement of image classification and pattern recognition, derivation of medium-resolution digital elevation models, velocity measurements, measurements of sea-wave spectra. BISSAT payload is developed on the basis of the X-band SAR of the COSMO/SkyMed mission, while BISSAT bus is based on an upgrade of MITA. Orbit design has been performed, leading to the same orbit parameters apart from the ascending node right ascension (5.24 degree(s) shift) and the time of the passage on the ascending node (1.17s shift). A minimum distance at the passage of the orbit crossing point of about 42 km (5.7s) is computed. To maintain adequate swath overlap along the orbit, attitude maneuver or antenna electronic steering must be envisaged and traded-off taking into account radar performance and cost of hardware upgrade.

Calibration is critical for useful long-term data records, as well as independent data quality control. However, in the context of Earth observation sensors, post-launch calibration and the associated quality assurance perspective are far from operational. This paper explores the possibility of establishing a global instrumented and automated network of test sites (GIANTS) for post-launch radiometric calibration of Earth observation sensors. It is proposed that a small number of well-instrumented benchmark test sites and data sets for calibration be supported. A core set of sensors, measurements, and protocols would be standardized across all participating test sites and the measurement data sets would undergo identical processing at a central secretariat. The network would provide calibration information to supplement or substitute for on-board calibration, would reduce the effort required by individual agencies, and would provide consistency for cross-platform studies. Central to the GIANTS concept is the use of automation, communication, coordination, visibility, and education, all of which can be facilitated by greater use of advanced in-situ sensor and telecommunication technologies. The goal is to help ensure that the resources devoted to remote sensing calibration benefit the intended user community and facilitate the development of new calibration methodologies (research and development) and future specialists (education and training).

Calibration of the five EOS ASTER instrument emission bands (90 m pixels at surface) is being checked during the operational life of the mission using field measurements simultaneous with the image acquisition. For water targets, radiometers, temperature measuring buoys and local radiosonde atmospheric profiles are used to determine the average water surface kinetic temperature over areas roughly 3 X 3 pixels in size. The in-band surface leaving radiance is then projected through the atmosphere using the MODTRAN radiation transfer code allowing an at sensor radiance comparison. The instrument at sensor radiance is also projected to the water surface allowing a comparison in terms of water surface kinetic temperature. Over the first year of operation, the field measurement derived at sensor radiance agrees with the image derived radiance to better than plus/minus 1% for all five bands indicating both stable and accurate operation.

Recent work by the Remote Sensing Group at the University of Arizona has focused on the calibration and radiance validation of numerous sensors that are part of NASA's Earth Observation System and Earth Sciences Enterprise. The unique orbital combination of many of these sensors, both from formation flying as well as from multi-sensor platforms, provides an unprecedented opportunity with which to cross- compare results from these sensors. This work presents the results of cross-comparisons between the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), the Moderate Resolution Imaging Spectroradiometer (MODIS), the Enhanced Thematic Mapper Plus (ETM+) sensor, the MODIS- ASTER Simulator (MASTER), and the Advanced Land Imager (ALI). Differences in the cross-comparison between these sensors can be attributed to numerous causes, including spatial registration effects, spectral differences in the sensors, and temporal changes in the atmosphere and surface between sensor collections. One aspect of cross-comparison studies that is often overlooked is the solar spectral irradiance that is used by each sensor's calibration and validation teams, and with the advent of onboard diffusers the selection of the solar irradiance values becomes even more critical. This work describes the differences between typical solar irradiance spectra that are being used for the above-listed sensors and the effect of these spectra on the intercomparison of at-sensor radiances from earth-observing sensors.

The Ozone Monitoring Instrument (OMI) is a UV/VISible spectrograph (270 - 500 nm). It employs two-dimensional arrays of CCD detectors for simultaneous registration of numerous spectra from ground pixels in the swath perpendicular to the flight direction. As a result, OMI provides (almost) daily global coverage in combination with small ground pixel sizes (nominally 13 X 24 km² at nadir, minimum 13 X 12 km² at nadir). The small ground pixels allow retrieval of tropospheric constituents. The OMI Flight Model is currently being integrated and will be launched on the Aura satellite in2003 as part of NASA's Earth Observing System. This paper discusses relationships between and the details of the on-ground calibration approach of OMI, the data processing of level 0 data (raw data) to level 1b data (geophysical data) and the foreseen activities for in-flight calibration.

JPL has implemented advances in CMOS APS visible sensors well suited for the development of ultra-low power, miniature, highly integrated image sensor systems. Applications for these low cost, modular, high performance 'camera-on-a-chip' sensors include: remote earth and planetary visible science cameras, wireless payload deployment monitors for large mirrors, solar panels, booms and antennas, and FPAs for star trackers, sun sensors and high bandwidth multi-window optical communication beacon tracker. This paper reports on the newest generation of CMOS APS dubbed the Versatile Integrated Digital Imager or VIDI APS 'camera-on-a-chip.' VIDI is an integrated, digital 'chip-camera' with a 512 X 512 format, 12-um pixels, utilizing a single 3.3 V supply, with analog or 10-bit digital output, fabricated on a standard 0.5 um CMOS process. The chip size is 10 mm X 15.5 mm. Features include a simple, all digital 'five-wire' interface, on-chip timing, control, four five-bit DACs for bias generation, and 512 column parallel ADCs, VIDI offers programmable exposure, resolution, data efficient 'smart' area-of-interest windowed high speed readout, no blooming, while continuing to operate with approximately 20 mW of power in the on-state and approximately 40 uW in the 'sleep' state and has a maximum data rate of 20 Mbits/sec.

The NASA Mars Exploration Rover mission will launch two scientific spacecraft to Mars in 2003. The primary goal of the mission is to obtain knowledge of ancient water and climate on the red planet. Each spacecraft will carry one rover with a mass of approximately 150 kg and a design lifetime of about 90 days to the surface of Mars. The rovers are intended to travel up to 100 meters per day. The scientific payloads of the rovers will include a stereo pair of Panoramic cameras and a Microscopic Imager. The Panoramic cameras also support the engineering functions of high gain antenna pointing and navigation by solar imaging. The rovers have six additional cameras that will be used, exclusively, for engineering. All nine cameras share a common design, except for their optics. The focal plane of each camera is a 1024 X 1024-pixel frame transfer CCD. A stereo pair of Navigation cameras is mounted on a gimbal with the Panoramic camera pair. The Navigation camera pair is used for traverse planning and general imaging. Finally, one stereo pair of wide-angle Hazard Avoidance cameras will be mounted on the front (and one pair on the back) of each rover to autonomously generate range maps of the surrounding area for obstacle detection and avoidance.

The FUEGO system is a remote sensing satellite constellation aimed at providing early fire alarms throughout the forest fire risk area of Europe and other temperate areas. An excellent revisit time (<16 min.) can be achieved from a low earth orbit constellation of 12 mini-satellites. Each mini-satellite carries infrared sensors in MIR, TIR, and VIS/NIR bands operating in push-broom mode and a depointing mirror to cover a large swath. This can ensure early detection of fire outbreaks with a 2500 km swath. This paper presents the thermal infrared (TIR) camera characteristics. The main purposes of the TIR channels are the discrimination of clouds and detection of forest fire false alarms during low light or night operation. The main requirements for the TIR camera are: spectral range 8 - 12 micrometers ; FOV equals +/- 7.2 degree(s) (177 km on ground); ground resolution 369 m; NETD < 0.4 K 300 K (blackbody temperature); large dynamic range of radiance (equivalent blackbody temperature 240 K to 380 K). The TIR pushbroom camera is built around an off-the- shelf SOFRADIR microbolometer FPA of 320 X 240 elements with a pitch of 45 micrometers . The focal plane is uncooled and operates at T equals 303 K. The paper details the tests performed on the engineering model of the camera. More particularly, radiometric characterization and MTF measurement are described. The demonstrated camera performance together with the low cost and complexity of the camera offer a large field of opportunities for future space applications.

The PLEIADES-HR Earth Observation satellites will combine a high resolution panchromatic channel -- 0.7 m at nadir -- and a multispectral channel allowing a 2.8 m resolution. This paper presents the main specifications, design and performances of a 52 microns pitch quadrilinear CCD sensor developed by ATMEL under CNES contract, for the multispectral channel of the PLEIADES-HR instrument. The monolithic CCD device includes four lines of 1500 pixels, each line dedicated to a narrow spectral band within blue to near infra red spectrum. The design of the photodiodes and CCD registers, with larger size than those developed up to now for CNES spaceborne imagers, needed some specific structures to break the large equipotential areas where charge do not flow properly. Results are presented on the options which were experimented to improve sensitivity, maintain transfer efficiency and reduce power dissipation. The four spectral bands are achieved by four stripe filters made by SAGEM-REOSC PRODUCTS on a glass substrate, to be assembled on the sensor window. Line to line spacing on the silicon die takes into account the results of straylight analysis. A mineral layer, with high optical absorption performances is deposited between photosensitive lines to further reduce straylight.

During the last 10 years, research about CMOS image sensors (also called APS - Active Pixel Sensors) has been intensively carried out, in order to offer an alternative to CCDs as image sensors. This is particularly the case for space applications as CMOS image sensors feature characteristics which are obviously of interest for flight hardware: parallel or semi-parallel architecture, on chip control and processing electronics, low power dissipation, high level of radiation tolerance... Many image sensor companies, institutes and laboratories have demonstrated the compatibility of CMOS image sensors with consumer applications: micro-cameras, video-conferencing, digital- still cameras. And recent designs have shown that APS is getting closer to the CCD in terms of performance level. However, he large majority of the existing products do not offer the specific features which are required for many space applications. ASTRIUM and SUPAERO/CIMI have decided to work together in view of developing CMOS image sensors dedicated to space business. After a brief presentation of the team organization for space image sensor design and production, the latest results of a high performances 512 X 512 pixels CMOS device characterization are presented with emphasis on the achieved electro-optical performance. Finally, the on going and short-term coming activities of the team are discussed.

In the frame of the development of infrared sensors for space applications, Sofradir and the European Space Agency (ESA) have undertaken detector breadboarding activities dedicated for short wave band infrared (SWIR) hyperspectral imagers to be implemented on future earth observation satellites. Based on previous breadboarding activities, a development of a 1000 X 256 SWIR focal plane array has been launched. This focal plane array has a format of 1000 X 256 with a pitch of 30 micrometers . It operates in the 1 to 2.5 micrometers waveband at an operating temperature compatible with passive cooling largely used in satellites. The retina of the detector is based on a photovoltaic HgCdTe array hybridized to a full custom silicon CMOS readout circuit. The readout circuit is versatile so that it answers several system requirements for hyperspectral applications. In this paper, major trade-offs regarding detector design and performances are presented with a particular emphasis on the capability of the retina in terms of noise and dynamic range. Then, the SWIR focal plane array performances are described including different applications requirements needs analysis.

Most of devices used for controlling a system are composed of four main parts: a sensor that 'senses' the system, generally converting a physical quantity in electric signal, a control electronics that analyses this signal, an actuator that re-converts the electric signal to the physical quantity and finally a power supply unit that provides the general supplying of the device. The global effect is the control of the physical quantity through a feedback chain. In particular, for mechanical systems, the electronics and the power supply units make the device complex and expensive, increasing in many cases the time response. The device presented in this work, conceived for controlling a mechanical quantity (force, pressure, deformation, etc.), utilizes piezoelectric for both the actuator and sensor parts. The electrical signal generated by the sensor is directly supplied to the piezoelectric actuator without any additional intermediate electronics, realizing a fully self- supplied sensing-actuating device. Without control electronics and power supply unit the device becomes inexpensive, simple and fast no matter the distance in between the sensor and the actuator. An original configuration of the piezoelectric sensor-actuator control device is presented, together with a theoretical interpretation. Experimental trials, also illustrated, show clearly that the proposed solution can be a smart and inexpensive alternative to the traditional control devices.

Recent improvements in CCD technology make hexagonal sampling attractive for practical applications and bring a new interest on this topic. In the following the performances of hexagonal sampling are analyzed under general assumptions and compared with the performances of conventional rectangular sampling. This analysis will take into account both the lattice form (squared, rectangular, hexagonal, and regular hexagonal), and the pixel shape. The analyzed hexagonal grid will not based a-priori on a regular hexagon tessellation, i.e., no constraints will be made on the ratio between the sampling frequencies in the two spatial directions. By assuming an elliptic support for the spectrum of the signal being sampled, sampling conditions will be expressed for a generic hexagonal sampling grid, and a comaprison with the well-known sampling conditions for a comparable rectangular lattice will be performed. Further, by considering for sake of clarity a spectrum with a circular support, the comparison will be performed under the assumption of same number of pixels for unity of surface, and the particular case of regular hexagonal sampling grid will also be considered. Regular hexagonal lattice with regular hexagonal sensitivity shape of the detector elements will result as the best trade-off between the proposed sampling requirement. Concerning the detector shape, the hexagonal is more advantageous than the rectangular. To show that a figure of merit is defined which takes into account that the MTF (modulation transfer function) of a hexagonal detector is not separable, conversely from that of a rectangular detector. As a final result, octagonal shape detectors are compared to those with rectangular and hexagonal shape in the two hypotheses of equal and ideal fill factor, respectively.

In a previous effort the authors developed a methodology for describing uncertainty in thermal radiation Monte Carlo ray- trace (MCRT) analyses. An application to radiometric channels used in space-based observations such as those provided by NASA's Clouds and the Earth's Radiant Energy System (CERES) was reported.. In the previous study preliminary attempts were presented to confirm the theory. In the current effort extension and modifications of the previous theory are formulated and new examples are presented to confirm the extended theory. A generic MCRT- based computational environment that simulates radiative exchange among surfaces in enclosures is used to obtain performance estimates of a simple cavity-type thermal radiation detector. Standard statistical methods are used to interpret the results as uncertainties and their related confidence intervals. The example problem is used as a vehicle to verify the modified theory. The authors then demonstrate the theory in a more complex situation that of a high-level numerical model used to predict the dynamic opto- electro thermal behavior of the CERES radiometric channels.

This paper briefly introduces the operation principle and configuration of distributed optical fiber sensor (DOFS) system. A new demodulation method that uses Rayleigh back scattering photon flux to demodulate Raman back scattering photon flux is put forward, and the advantages of this new method are discussed. Methods to measure temperature, strain and pressure at the same time are researched. The performance of DOFS is following: fiber length: 10.2 km; temperature uncertainty: +/- 2 degree(s)C: temperature resolution: 0.1 degree(s)C; spatial resolution: 4m: measurement time: 5 min; Main unit operation temperature range: 0 - 40 degree(s)C. The DOFS system have been applied to coal mine.

This paper describes the simulation of the earth radiation budget (ERB) as viewed by Triana and the development of correction models for converting Triana-viewed radiances in to a complete ERB. A full range of Triana views and global radiation fields are simulated using data from the Earth Radiation Budget Experiment (ERBE) and analyzed with a set of empirical correction factors specific to the Triana views. The results show that the accuracy of global correction factors to estimate ERB from Triana radiances is a function of the Triana position from Lagrange-1 (L1) or the Sun position. Spectral analysis of the global correction factor indicates that both shortwave (SW) and longwave (LW) parameters undergo seasonal and diurnal cycles that dominate the periodic fluctuations. The diurnal cycle, especially its amplitude, is also strongly dependent on the seasonal cycle. Based on these results, models are developed to correct the radiances for unviewed areas and anisotropic emission and reflection. A preliminary assessment indicates that these correction models can be applied to Triana radiances to produce the most accurate global ERB to date.

The international community agrees that the new technology based on the use of Unmanned Air Vehicles High Altitude Very long Endurance (UAV-HAVE) could play an important role for the development of remote sensing and telecommunication applications. A UAV-HAVE vehicle can be described as a low- cost flying infrastructure (compared with satellites) optimized for long endurance operations at an altitude of about 20 km. Due to such features, its role is similar to satellites, with the major advantages of being less expensive, more flexible, movable on demand, and suitable for a larger class of applications. According to this background, Politecnico di Torino is involved as coordinator in an important project named HeliNet, that represent one of the main activities in Europe in the field of stratospheric platforms, and is concerned with the development of a network of UAV-HAVE aircraft. A key point of this project is the feasibility study for the provision of several services, namely traffic monitoring, environmental surveillance, broadband communications and navigation. This paper reports preliminary results on the HeliNet imaging system and its remote sensing applications. In fact, many environmental surveillance services (e.g. regional public services for agriculture, hydrology, fire protection, and more) require very high-resolution imaging, and can be offered at a lower cost if operated by a shared platform. The philosophy behind the HeliNet project seems to be particularly suitable to manage such missions. In particular, we present a system- level study of possible imaging payloads to be mounted on- board of a stratospheric platform to collect Earth observation data. Firstly, we address optical payloads such as multispectral and/or hyperspectral ones, which are a very short-term objective of the project. Secondly, as an example of mid-term on-board payload, we examine the possibility to carry on the platform a light-SAR system. For both types of payload, we show how intelligent processing algorithms for environmental data can be run on-board in real-time, in order to make data analysis and transmission more effective, and designed to match the constrains imposed by a UAV-HAVE platform. The results of the study lead to the conclusion that the stratospheric technology seems to be a competitive infrastructure (with respect to the satellites) in the remote sensing scenarios described above.

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, 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 geo-coded 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.

Described in this paper are technical ways to improve the temperature stability of fiber optic gyroscopes. The fiber optic gyroscope consists of a super luminescent diode, an integrated optical circuit, a fiber coupler, a polarizing optical fiber coil, a detector and a signal-processing device. The peak wavelength of SLD is 1.3 micrometers . The multifunctional integrated optical circuit that includes a polarizater, a Y type junction coupler and a phase modulator, is manufactured with annealed proton exchange process. The polarizing optical fiber coil is fabricated by applying quadrupolar winding technology. The fiber optic gyroscope can work in high/low temperature, large acceleration, vibration, shock and other harsh environments. It is applied in strapdown inertial navigation systems, directional measuring system in oil-rigs and automobile positioning and guidance.

Strap-down inertial navigation system is a low cost and high precision inertial navigation system. With the fast development of fiber optic gyros, FOG strap-down inertial navigation system is taking place of traditional electro- mechanic gyros inertial navigation system of. Discussed in this paper are fiber optic gyros used in a strap-down inertial navigation system and strap-down inertial navigation system consisting of three-axis FOGs.

The linear polarization sensitivity of scanning system is comparatively high or changes with the scanning angle. Due to these shortcomings of scanning system, a new design of scanning subsystem is given in this paper. It can overcome the effect of the scanning angle on the linear polarization sensitivity while keeping on the low linear polarization sensitivity.

We describe a phenomenon in which a macroscopic superconducting probe, as large as 2 - 6 cm, is chaotically and magnetically levitated. We have found that, when feedback is used, the probe chaotically moves near an equilibrium state. The global optimization approach to highly sensitive measurement of weak signal is considered. Furthermore an accurate mathematical model of asymptotically stable estimation of a limiting weak noisy signal using the stochastic measurement model is considered.

The sol-gel derived metal oxide semiconductor films have been used as sensing medium in the opto-chemical sensor based on SPR for the first time. Data simulation shows that the sensitivity of this scheme to refractive index of the films is predicted to be more than 10⁵. By adding an intermediate layer between the metal films and the sensing films, optimizing the optical parameters, the sensitivity of this sensor with optimal optical parameters can increase by 40% over that of only sensing films. Experimentally, we have selected SnO₂ and SiO₂ films as sensing and intermediate layers, and made the gas sensing tests to NH₃, C₂H₅OH and C₃H₈. The sensor with optimized structure has a higher sensitivity, and the detection limits for these gases are available to 10^-1 ppm.

The intense global competition to produce quality products at a low cost has led many industrial nations to consider tolerances as a key factor to bring about cost as well as to remain competitive. In actually, Tolerance allocation stays widely applied on the Mechanic System. It is known that to study the tolerances in an electronic domain, Monte-Carlo method well be used. But the later method spends a long time. This paper reviews several methods (Worst-case, Statistical Method, Least Cost Allocation by Optimization methods) that can be used for treating the tolerancing problem for an Electronic System and explains their advantages and their limitations. Then, it proposes an efficient method based on the Neural Networks associated with Monte-Carlo method as basis data. The network is trained using the Error Back Propagation Algorithm to predict the individual part tolerances, minimizing the total cost of the system by a method of optimization. This proposed approach has been applied on Small-Signal Amplifier Circuit as an example. This method can be easily extended to a complex system of n-components.

A monitoring system using both visible (VIS) and infrared (IR) images has been developed for the measurement of reflectance characteristics of land surface and buildings. An uncooled infrared detector array of monolithic 320 X 240 bolometers is used for the observation in thermal infrared region in the wavelength of 8 - 12 micrometers . Two images from a visible camera and an infrared camera, which are co-aligned on the same optical axis, are registered using an image processing board in real time. The registration error among images obtained at the same time is investigated. Using the system, temperature distributionof ground objects put out of doors is estimated, where the real-time identification between VIS and IR images is important.

Concept of a multi-channel system installed at the International Space Station is considered. A strategy of multi-channel synchronized observations in the IR, sub-mm and mm wavelengths is proposed.

About twenty Saharian desert regions have been selected a few years ago in order to carry out in-flight calibration of the different instruments operating in the visible and near- infrared spectral domain. Since then, CNES has collected an important number of measurements acquired by these instruments of interest (SPOT, AVHRR, SeaWiFS, Polder, Vegetation, MODIS, MISR) over the selected desert areas (SADE database). The present work fits into a global assimilation approach which aims to improve both the characterization of the calibration sites and the cross- calibration of optical satellite sensors. This work is particularly devoted to the spectral characterization of the selected site using the SADE database. The method is based on the use of a spectral model of ground surface reflectance at global scale. It is assumed that this model can be derived from laboratory reflectance measurement (i.e. 'Small scale' measurement). Then, instead of reversing the top of atmosphere measurement into ground reflectance, the ground reflectance model is transported at the top of atmosphere for comparison to available measurement, and the parameters adjustment is done at this level. A top of atmosphere simulated reflectance dataset (corresponding to various usual multispectral sensors) is used in a first step to assess for the relevancy of the proposed method.

The Stratospheric Wind Interferometer For Transport studies (SWIFT) is a passive sensor designed to measure winds in the stratosphere from a satellite. It is a field-widened Michelson interferometer very similar to the WINDII instrument on UARS but operates in the mid-IR, where it detects the Doppler shifts of atmospheric thermal emission lines of ozone. SWIFT uses a HgCdTe array detector to view the emission at the Earth's limb. Measurements are subsequently inverted by computer to obtain true vertical profiles of the stratospheric wind in the altitude range 20 to 40 km. Two orthogonal fields of view allow wind vectors to be obtained by combining the components observed from different directions a few minutes apart. Prototype Ge wafer etalon filters and a field-widened Michelson interferometer for the Mid-IR have been built and tested, with good results. Modeling studies indicate that a measurement precision of 5 m/s can be obtained throughout the altitude range of interest. In addition to the winds, SWIFT will measure ozone densities in the stratosphere. SWIFT has been selected for flight on NASDA's GCOM-A1 satellite and a Phase A study is being supported by ESA and the Canadian Space Agency.

With this paper we present new 3D sensing technique based on the novel Photonic Mixer Device (PMD), a new generation of smart 3D sensor, which provides a brilliant interface between the world of incoherent light and the world of electronic signal processing. As a new semiconductor device, it combines fast optical sensing and mixing in one component of pixel size by its unique and powerful principle of operation. Based on standard CMOS-technology, it can be easily integrated into PMD sensing arrays, providing both 3D depth and intensity information of the scene. The presented 3D TOF ranging system based on PMD measures the phase and time delay of the back scattered optical signal. The RF- modulated light reflected from the 3D-scene represents the total 3D depth information within the aperture of the PMD receiver. Since the whole 3D-scene is illuminated simultaneously by using intensity-modulated light, the PMD- array on the receiver side performs parallel electro-optical mixing and correlation and delivers an optimal evaluation of time-of-flight and the optical power for each PMD pixel. So there is no scanner required in contrast to the conventional 3D-laser radar systems. The introduction of the PMD into the 3D range sensing technique offers very attractive solutions for the realization of flexible, extremely fast and robust low-cost 3D solid-state smart ranging systems.

This paper deals with the simulation of very high spatial resolution images in the thermal infrared range, from 3 to 14 micrometers . It focuses on the conceptual architecture of a simulator of 3-D landscapes; its specifications are described and discussed. A new methodology is proposed for the simulation to best reproduce the properties of the infrared imagery. Particularly, this methodology enables a very accurate simulation of the signal coming from each object constituting the landscape. The interactions between the radiations and objects and between objects themselves are considered. Their changes in time, and the recent past of the temperature and the humidity for each object, are taken into account. To reproduce these physical phenomena, the computation is performed on elements, which are defined as homogeneous entities with respect to the physical processes. This concept of element leads to a new methodology in design and realization of simulators. It permits to reproduce efficiently the behavior of the landscape in this spectral range at very high spatial resolution.

The Eppley pyranometer is widely used to measure broadband shortwave irradiances on the earth's surface. Measurements obtained using these instruments are known to be influenced by infrared radiation that produces an offset from the signal that would result solely from the incident shortwave radiation. Described is an effort to model the energy exchanges within the instrument to describe the measurement error as a function of external conditions. A finite element method (FEM) analysis simulates heat diffusion in the instrument, and a Monte Carlo ray-trace (MCRT) code models radiative exchange in the instrument. An FEM analysis models heat diffusion in the outer dome of the instrument and produces the dome temperature distribution resulting from specified external boundary conditions. An MCRT code is used to model the influence of radiative exchanges between the domes and the sensor surface on the sensor signal. The code confirms offsets expected from a variety of ambient conditions. The goal of the effort is to create a working MCRT model of the pyranometer that will be combined with the existing FEM model. The completed tool will allow an accurate study of the signal sensitivity to various external conditions.

The objective of the current research is to minimize the theoretical uncertainty of the CERES ERBE-like level 1 instantaneous filtered and unfiltered radiance data products. The instrument's measured digital counts are converted to a filtered radiance by means of instrument calibration coefficients. The filtered radiance is then converted to an unfiltered radiance with an algorithm that utilizes the instrument's spectral response function. Uncertainties in the calibration sources and the spectral response function of the instrument can negatively affect the quality of the final data products. To reduce this effect, we are seeking to increase our understanding of the relative impact that various instrument and calibration parameters have on the level-1 filtered and unfiltered data products. Results of a statistical study of data products sensitivity to various instrument and calibration parameters are presented. The sensitivity of the level-1 data products to the spectral response of the instrument when viewing non- Planck Earth scenes is also discussed.

Microwave remote sensing is a good tool for topsoil moisture monitoring due to the large difference between dielectric properties of dry soil and water. The aim of this work is to exploit microwave remote sensing techniques to collect data on soil water content of large areas rapidly and without direct soil samples analysis. To this purpose, a frequency modulated - continuous wave C-band microwave polarimetric radar has been built. The device has two transmitting channels that illuminate the soil with orthogonal linearly polarized electromagnetic waves. Two receiving channels detect the linearly polarized waves backscattered from the same target. This scatterometer can measure the module of the soil electromagnetic scattering matrix elements. The knowledge of this matrix permits the computation of all the possible polarization combinations of backscattering normalized Radar Cross Section (RCS) through a polarization synthesis approach. A Fourier analysis of this signal extracts the scattering matrix values of 'different-in- range' resolution cells. The height and the incidence angle of this microwave sensor can be varied within large intervals; this allows the measurements of the RCS in various configurations that should give insights on soil moisture parameter extraction under different conditions.

Commercial satellite remote sensing is a rapidly growing market, some projections indicating revenues from the sale of data and GIS products totaling over $12B by 2003. Though commercial remote sensing may be promising, there have been some limiters to the growth of the market over the past few years, including the costs per image, the not-so-timely acquisition of data and delivery to the customer, and others. One current inhibitor to the growth of the market is the cost of commercial images. Most commercially provided data range from $1,500 to $4,000 per scene, depending on the resolution and size of the image, with more integrated GIS products costing as high as $10,000 for one image. A second inhibitor is the difficulty in translating spectral signatures into useful and accurate information without weeks of ground research. Another potential inhibitor is the timeliness in acquiring satellite images. At present, it takes anywhere from two days to well over four weeks before customers receive imagery from vendors. This time lapse can be a problem for users of imagery with rigid time constraints (e.g., agricultural or media interests). Due to these inhibitors, the success of a remote sensing system depends not just on the spectrum and resolution of the data, but also on other factors important to customers such as image cost, speedy access to data, service reliability, and other figures of merit relevant to a customers needs. ELOP has examined how these various figures of merit become beneficial to different applications as they vary in performance. Applications such as Agriculture, Forestry, Geology, Coastal & Water and many other, were compared with variations in spatial resolution, spectral resolution, spectral range, revisit rate, data delivery speed, and others. A condensed version for varying figures of merit evaluated with some expected applications will be presented and the various parameters analyzed for variable revisit rate with a conclusive approach for the optimal solution.

The Republic of Korea KOMPSAT-I satellite has been in operation for over one year. The 6.6 meter resolution panchromatic Electro-Optical Camera (EOC) has shown a high degree of stability and fidelity in its digital signature, including its radiometric and Modulation Transfer Function (MTF) characteristics. The presentation will discuss the methods used in modeling these characteristics prior to launch, measurements after launch of the KOMPSAT-I, characterizations of the long-term stability and current image processing results.

Remote sensing satellite operators throughout the world are starting to require an increasing number of proprietary hardware and software components as a prerequisite to the collection, processing and distribution of their satellite's data. This assessment investigates the technical, economic and political impetus for these proprietary requirements. This assessment concludes with an overview of the potential impact on ground receiving stations and the remote sensing community.

An investigation has been carried out, concerning remote sensing techniques, in order to assess their potential application to the energy system business: the most interesting results concern a new approach, based on digital data from remote sensing, to infrastructures with a large territorial distribution: in particular OverHead Transmission Lines, for the high voltage transmission and distribution of electricity on large distances. Remote sensing could in principle be applied to all the phases of the system lifetime, from planning to design, to construction, management, monitoring and maintenance. In this article, a remote sensing based approach is presented, targeted to the line planning: optimization of OHTLs path and layout, according to different parameters (technical, environmental and industrial). Planning new OHTLs is of particular interest in emerging markets, where typically the cartography is missing or available only on low accuracy scale (1:50.000 and lower), often not updated. Multi- spectral images can be used to generate thematic maps of the region of interest for the planning (soil coverage). Digital Elevation Models (DEMs), allow the planners to easily access the morphologic information of the surface. Other auxiliary information from local laws, environmental instances, international (IEC) standards can be integrated in order to perform an accurate optimized path choice and preliminary spotting of the OHTLs. This operation is carried out by an ABB proprietary optimization algorithm: the output is a preliminary path that bests fits the optimization parameters of the line in a life cycle approach.

The work describes an innovative technique to automatically extract and manage remote sensing image-content. Simple but very flexible numeric recognition methodologies allow the content-based retrieval from huge remotely sensed image database. The most important result of this methodology is a tool for the information retrieval based on example. In order to properly characterize remotely sensed images and improve retrieval performance, many factors, such as the image resolution, the scale, the sensor features, have been taken into account. Kingfisher is the content-based database management system, developed at DIBE laboratories, that exploits these methodologies.

The demand for remote sensing data has increased dramatically mainly due to the large number of possible applications capable to exploit remotely sensed data and images. As in many other fields, along with the increase of market potential and product diffusion, the need arises for some sort of protection of the image products from unauthorized use. Such a need is a very crucial one even because the Internet and other public/private networks have become preferred and effective means of data exchange. An important issue arising when dealing with digital image distribution is copyright protection. Such a problem has been largely addressed by resorting to watermarking technology. Before applying watermarking techniques developed for multimedia applications to remote sensing applications, it is important that the requirements imposed by remote sensing imagery are carefully analyzed to investigate whether they are compatible with existing watermarking techniques. On the basis of these motivations, the contribution of this work is twofold: (1) assessment of the requirements imposed by the characteristics of remotely sensed images on watermark-based copyright protection; (2) discussion of a case study where the performance of two popular, state-of-the-art watermarking techniques are evaluated by the light of the requirements at the previous point.

Use of modern techniques like remote sensing has been without doubts one of the main factors to take a forward step towards the achievement of serious plans regarding Coastal Management. A multi-temporal analysis of the land- use, in some areas of the Colombian Caribbean Coast, was done mainly focused in environmental impacts caused by anthropogenic activities like deforestation of mangroves due to shrimp farming. Selection of sensitive areas, percentage of destroyed mangroves, possible endangered areas, etc. have been some of the results of this analysis as well as some advises for a coastal management plan in the area. Some other consequences of the deforestation of mangroves in the coastal zone and the construction of shrimp ponds were also analyzed like increase of erosion problems in these areas and water pollution among others. The increase of erosion in these areas has also changed part of their morphology, which has also been studied by the analysis of SPOT images in different years. A serious concern exists about the future of these areas, for this reason new techniques like satellite images (SPOT) have been applied with good results and in this way a more effective control and coastal management in the area is taking place. The use of SPOT images to study changes in the land-use of the area was a useful technique in order to determine patterns of human activities and suggest solutions for severe problems in these areas.

Storage and transmission requirements for hyperspectral data sets are significant. In order to reduce hardware costs, well-designed compression techniques are needed to preserve information content while maximizing compression ratios. Lossless compression techniques maintain data integrity, but yield small compression ratios. This paper presents three lossy compression algorithms that use the noise statistics of the data to preserve information content while maximizing compression ratios. The Spectral Compression and Noise Suppression (SCANS) algorithm adapts a noise estimation technique to exploit band-to-band correlation for optimizing linear prediction for data compression. The Adaptive Spectral Image Compression (ASIC) algorithm uses an iterative adaptive linear unmixing compression method, constrained by the noise statistics of the hypercube. By dynamically optimizing the end-members for each pixel this method minimizes the number of components required to represent the spectrum of any given pixel, yielding high compression ratios with minimal information content loss. The Adaptive Principal Components Analysis (APCA) algorithm uses noise statistics to determine the number of significant principal components and selects only those that are required to represent each pixel to within the noise level. We demonstrate the effectiveness of these methods with AVIRIS and HYMAP datasets.

The purpose of this research study is to evaluate the effectiveness of atmospheric correction and radiometric calibration techniques by measuring the differences of corrected data and ground truth spectra. Several atmospheric correction methods have been performed utilizing the ATREM and ACORN software packages. A variety of different settings (14 for ATREM and 5 for ACORN) have been tested and evaluated. The Spectral Similarity Scale (SSS) developed by BAE SYSTEMS is a measure of spectral similarity based on spectral magnitude and shape. The SSS-based spectral comparison process indicates that the default settings for iron rich soils are the best ATREM inputs for the Shelton, NEAVIRIS scene. The SSS comparison of the ACORN results with the spectral ground truth revealed that ACORN with the artifact type 1 was the best correction setting available for both ATREM and ACORN. For atmospheric water we find that ACORN is superior to ATREM. ATREM does correct for gain offsets that ACORN does not correct for with default settings. When used incorrectly, it is possible to severely reduce the spectral accuracy with either software package.

This paper addresses the issue of spatial diversity in radar applications. The has been an increased need for information via radio frequency (RF) detection of airborne and ground targets while at the same time the electromagnetic spectrum available for commercial and military applications has been eroding. Typically, information concerning ground and air targets is obtained via monostatic radar. Increased information is often equated with increased bandwidth in these monostatic radar systems. However, geometric diversity obtained through multistatic radar operation also affords the user the opportunity to obtain additional information concerning these targets. With the appropriate signal processing, this translates directly into increased probability of detection and reduced probability of false alarm. In the extreme case, only discrete Ultra Narrow Band (UNB) frequencies of operation may be available for both commercial and military applications. As such, the need for geometric diversity becomes imperative.

We focus on three applications of high-resolution imagery in the littorals: mapping bathymetry, monitoring the health of coral reefs, and taking censuses of marine mammals. All three applications show the importance and potential benefits of higher-resolution imagery. Increased radiometric sensitivity and the simultaneous collection of panchromatic and multispectral imagery are also important. An Ikonos image of Maui is used to demonstrate these applications. We also briefly explain some important differences between multispectral remote sensing over water and land.

We present an application of our framework for 3-D object- centered change detection to combined satellite and aerial imagery. In this framework, geometry is compared to geometry, allowing us to compare image sets with different acquisition conditions and even different sensors. By working in this framework, we do not encounter the restrictions and short-comings of conventional image-based change detection, which requires that the images being compared have similar acquisition geometry, photometry, scene illumination, and so forth. The contributions of our framework are: (1) using a geometric basis for change detection, allowing image sets acquired under different conditions to be compared; (2) explicit modeling of image geometry to be able to numerically characterize significant and insignificant change. The contributions of this paper are: (1) the algorithms are embedded in an integrated cartographic modeling and image processing system, which can ingest and make use of a variety of government and commercial imagery and geospatial data products; (2) experimentation with a variety of imagery and scene content. Modifications to the algorithm specific to their use with satellite imagery are discussed and the results from several experiments with both aerial and satellite images urban domains are described and analyzed.

The worldwide demand for accurate, up-to-date cartographic information has never been greater than it is today. Driven by applications as diverse as telecommunications siting, in- car navigation, and environmental assessment of change, this is an area of rapid growth for commercial remote sensing technology. As new sensor systems, both satellite and airborne, come online, they will address the demand with a range of new types of data. One factor limiting our ability to meet this demand is the lack of automation in extracting information and building datasets. We now have the first of a generation of commercial high resolution multispectral satellites. This contemporaneous, closely co-registered, multispectral and panchromatic imagery will provide a rich source for the development of automation. Imagery with a high degree of radiometric and geometric accuracy and consistency, previously available only in limited areas, will be available worldwide. In this paper, we discuss properties of the new satellite imagery that support the development of automated processes. We look at two examples using imagery from the IKONOS satellite for GIS applications, building large image mosaics and automated road vector updating.

The guideline series VDI 3786 'Environmental meteorology; Meteorological measurements' is organized into several parts. The present guideline VDI 3786 Part 14 describes the determination of the three-dimensional wind vector using Doppler LIDAR ('LIght Detection and Ranging' or 'Light Identificaiton, Detection and Ranging'). The guideline refers to guideline VDI 3786 Part 2 with regard to the definition of the measurement variable wind and goes back to the guideline VDI 3786 Part 1 in considering the averaging time. Use is also made of the guideline VDI 3786 Part 8. Safety problems are not treated; reference may be made here to relevant Standards [VBG 93, DIN EN 60825-1]. Wind profiles in the atmospheric boundary layer yield a very important contribution also to the investigation of atmospheric exchange processes. The wind field in the atmospheric boundary layer is highly variable in spatial and temporal scales. For a few applications a more frequeent wind sensing is necessary, i.e. (1) on airports located in low level jet areas, (2) near chemical plants to get information of the transport of toxic gases from leakages, (3) for metrology in general to improve the weather forecast, (4) for environment protection purposes like dispersion studies. The following statements are valid for visibility measurements [visual range LIDAR (VDI 3786 Part 15)]: (1) Lidar can provide the same information of the visibility as conventional sensors, but in addition lidar will provide range resolved measurements. (2) It is possible to shrink a lidar down to the size of binoculars. (3) It is possible to measure local visibility with an eye- safe (class 1) lidar. (4) Layers can be detected up to 250 m distance in approximately 2 s even with a small size instrument.

The photoconductor detector arrays for the PACS instrument (Photoconductor Array Camera and Spectrometer) aboard the future ESA telescope Herschel have been developed during the engineering phase in 1999. In early 2000 the construction of the qualification models began for both, the highly and low stressed Ge:Ga arrays, which consist of 12 linear modules each. These two types of photoconductor arrays are dedicated for different wavelengths bands in the spectrometer section of the instrument. While the performance of a few engineering arrays has been studied and presented earlier, additional data are meanwhile available on the absolute responsivity and quantum efficiency of the detectors. Furthermore, experience has been obtained during manufacture of a larger series of arrays giving better statistics on performance aspects, such as uniformity of the cutoff wavelengths and of the responsivity or the maximum stress obtainable within such arrays. Considerable progress has also been made in the development and manufacture of the 4 Kelvin Cold Read-out Electronics (CRE), which will integrate and multiplex the signals generated in each linear array with its 16 detector pixels. Manufacture of the detector arrays for the qualification model is scheduled to be completed by this summer, and manufacture of the flight model has already started. The qualification model will be delivered to the test facilities, where absolute spectral performance of the 24 linear modules will be determined. In this paper we give a summary of the related activities and results as obtained during manufacturing and testing.

The MODerate Resolution Imaging Spectroradiometer (MODIS) has 36 spectral bands with wavelength ranging from 0.41(mu) to 14.5(mu) and spatial resolution of 0.25 km (2 bands), 0.5 km (5 bands), and 1.0 km (29 bands) at Nadir. Its ProtoFlight Model (PFM) on the NASA EOS Terra spacecraft has been providing global coverage of the Land, Ocean, and Atmosphere for the science community since the instrument opened its Nadir door on 24 February 2000. The MODIS optical system includes a 2-sided paddle wheel scan mirror, a fold mirror, and a primary mirror. The sensor's 20 reflective solar bands (RSB) from 0.41(mu) to 2.1(mu) are calibrated on- orbit by a solar diffuser (SD) and a solar diffuser stability monitor (SDSM). In addition to the SD, degradation of the MODIS optics in the reflective solar bands has been observed, including variations in degradation between the two sides of the MODIS scan mirror. During MODIS first year of on-orbit operation, the overall degradation at the shortest wavelength of 0.41(mu) is about 2.5% for the SD, and in excess of 8% for the MODIS system. In this paper, we present our degradation analysis results and discuss their impact on the RSB on-orbit calibration.