The Japan Aerospace Exploration Agency (JAXA) has some Earth observation programs such as disaster and crisis monitoring, investigation of the Earth resources, global environmental to contribute to a safe and secure society. Presently, there are many global issues such as shortage of water resources, desertification, increase in natural disasters, which inflict a serious impact on our community. To overcome such problems and take appropriate measures against them, it is necessary to cooperate among many countries and ensure the establishment of a comprehensive, coordinated, and sustained Earth observation. The 2nd Earth Observation Summit was held in April 2004 and adopted the framework for the 10-year implementation plan, aimed at the establishment of an integrated earth observation system of systems, so called Global Earth Observation System of Systems (GEOSS). JAXA has been developping a future Earth observation program to contribute the GEOSS in cooperate with other space agencies. JAXA committed the contribution to GEOSS using satellites such as ALOS, GPM/DPR and GOSAT mainly focused on observations of global warming and water cycle at the 2nd Summit. In addition, JAXA will propose a series of satellites for establishing GEOSS to monitor climate change. JAXA is studying the Global Change Observation Mission (GCOM) to contribute to process study, prediction of the global change phenomena and the preservation of the global environments.

The Japan Aerospace Exploration Agency (JAXA) is developing a high-speed, high capacity and low-power-consumption solid-state recorder (SSR) for space-use. The aim was to develop an SSR for installation on Earth-observation (EO) satellites that could store and process large amounts of data. A prototype of the SSR was completed in the spring of 2004, and an engineering model is currently being constructed. The main features of the SSR are 200GBytes capacity, total 2.5Gbps (four channels) data transmission speed, low weight (25Kg) and low power consumption (120W). A 512Mbit synchronous dynamic random access memory (SDRAM) with an on-board multi-bit error detection and correction (EDAC) mechanism, as well as a CompactPCI bus for fast data exchange, are used to improve the efficiency of data collection and storage capabilities. The results of a flight experiment were demonstrated using an older generation SSR on JAXA's Mission Demonstration test Satellite-1 (MDS-1 or "Tsubasa"). This experiment sought to demonstrate a practical solid-state recorder in the space environment, with reliability and stability to withstand vibration at launch (by H-IIA rocket), the ability to endure high levels of space radiation (e.g., single-event upsets (SEUs) or total ionizing doze (TID)) effects, and the thermal environment. This paper, describes the main features of the SSR system, it's developmental and manufacturing technologies, an application for high-data-rate EO sensors, and the simulation results assuming various observation and operation modes.

The Atmospheric Neutral Density Experiment (ANDE) is a series of four microsatellites that will study the atmosphere of the Earth from low earth orbit. Each microsatellite is based on a common design; however, each differs in the instrument payloads and the associated science and mission requirements. The primary mission objective is to provide total neutral density along the orbit for improved orbit determination of resident space objects. Each ANDE microsatellite has several secondary goals. It is the unique design of the microsatellites that allows this task to be accomplished. Each microsatellite is a compact, near perfect sphere; this reduces shape and drag errors so that the local density of the atmosphere can be determined by instantaneous tracking variations detected by very high accuracy laser and radar ranging whereby the spacecrafts themselves are the primary sensing instrument. The accuracy of the atmospheric density measurements inferred from the orbital tracking of ANDE microsatellites will be much greater than that achieved by similar experiments in the past or from any currently proposed. Many unique design challenges had to be overcome to achieve the necessary science, mission, and operational requirements as well as severe cost constraints. New methods for parts and assembly fabrication were sought out and implemented. These new methods allowed similar parts to function in each of the microsatellites despite the differences between them. In addition, the command and telemetry links used inexpensive COTS Ham radio transceivers while meeting all the International requirements for operations in the Amateur Satellite Service.

The Advanced Land Observing Satellite (ALOS) is required to achieve stringent attitude determination accuracy (3.0×10^-4deg on-board and 1.4×10^-4deg ground-based), position determination accuracy (1m ground-based), and attitude stability (3.9 × 10^-4deg/5sec) in order to provide precise geometric accuracy for high-resolution images without ground control points. It is designed to yield the geolocation determination accuracy of 6m from attitude and position estimates and that of 3m with an additional high-bandwidth measurement. Presented in this paper are ALOS's platform and ground systems technologies developed for achieving the attitude determination accuracy and the position determination accuracy. They include a precision star tracker, optimal attitude estimation algorithms (real-time and off-line), an alignment change reduction, a jitter sensor, a precision GPS receiver, and a ground-based position estimation algorithm. The star tracker provides the best star position accuracy (random error: 9.0arcsec, and bias error: 0.74arcsec). The on-board attitude determination algorithm estimates attitude quaternion by applying an extended Kalman filter. The off-line attitude estimation introduced an extended-Kalman-filter-based smoother. To minimize the alignment change, the sensors are placed on the optical bench subject to precise temperature control. The jitter sensor provides precise angular information (0.010arcsec) from 2Hz to 500Hz and extends the attitude determination bandwidth. The dual-frequency GPS receiver capable of measuring pseudoranges and carrier phases allows the ground-based position determination with sub-meter accuracy.

NASA's Jet Propulsion Laboratory is currently implementing a reconfigurable polarimetric L-band synthetic aperture radar (SAR), specifically designed to acquire airborne repeat track interferometric (RTI) SAR data, also know as differential interferometric measurements. Differential interferometry can provide key displacement measurements, important for the scientific studies of Earthquakes and volcanoes1. Using precision real-time GPS and a sensor controlled flight management system, the system will be able to fly predefined paths with great precision. The radar will be designed to operate on a UAV (Unmanned Arial Vehicle) but will initially be demonstrated on a minimally piloted vehicle (MPV), such as the Proteus build by Scaled Composites. The application requires control of the flight path to within a 10 m tube to support repeat track and formation flying measurements. The design is fully polarimetric with an 80 MHz bandwidth (2 m range resolution) and 16 km range swath. The antenna is an electronically steered array to assure that the actual antenna pointing can be controlled independent of the wind direction and speed. The system will nominally operate at 45,000 ft. The program started out as a Instrument Incubator Project (IIP) funded by NASA Earth Science and Technology Office (ESTO).

In conjunction with the implementation of spaceborne atmospheric radar flight missions, NASA is developing advanced instrument concepts and technologies for future spaceborne atmospheric radars, with the over-arching objectives of making such instruments more capable in supporting future science needs, and more cost effective. Two such examples are the Second-Generation Precipitation Radar (PR-2) and the Nexrad-In-Space (NIS). PR-2 is a 14/35-GHz dual-frequency rain radar with a deployable 5-meter, wide-swath scanned membrane antenna, a dual-polarized/dual-frequency receiver, and a real-time digital signal processor. It is intended for Low Earth Orbit (LEO) operations to provide greatly enhanced rainfall profile retrieval accuracy while using only a fraction of the mass of the current TRMM PR. NIS is designed to be a 35-GHz Geostationary Earth Orbiting (GEO) radar with the intent of providing hourly monitoring of the life cycle of hurricanes and tropical storms. It uses a 35-m, spherical, lightweight membrane antenna and Doppler processing to acquire 3-dimensional information on the intensity and vertical motion of hurricane rainfall. Technologies for NIS are synergistic with those for PR-2. During the last two years, several of the technology items associated with these notional instruments have also been prototyped. This paper will give an overview of these instrument design concepts and their associated technologies.

Global warming has become a very serious issue for human beings. In 1997, the Kyoto Protocol was adopted at the Third Session of the Conference of the Parties to the United Nations Framework Convention on Climate Change (COP3), making it mandatory for developed nations to reduce carbon dioxide emissions by six (6) to eight (8) per cent of their total emissions in 1990, and to meet this goal sometime between 2008 and 2012. The Greenhouse gases Observing SATellite (GOSAT) is designed to monitor the global distribution of carbon dioxide (CO2) from the space. GOSAT is a joint project of Japan Aerospace Exploration Agency (JAXA), the Ministry of Environment (MOE), and the National Institute for Environmental Studies (NIES). JAXA is responsible for the satellite and instrument development, MOE is involved in the instrument development, and NIES is responsible for the satellite data retrieval. The satellite is scheduled to be launched in 2008. In order to detect the CO2 variation of boundary layers, both the technique to measure the column density and the retrieval algorithm to remove cloud and aerosol contamination are investigated. Main mission sensor of the GOSAT is a Fourier Transform Spectrometer with high optical throughput, spectral resolution and wide spectral coverage, and a cloud-aerosol detecting imager attached to the satellite. The paper presents the mission sensor system of the GOSAT together with the results of performance demonstration with proto-type instrument aboard an aircraft.

The far-infrared spectroscopy of the troposphere (FIRST) project is under development by NASA through its Instrument Incubator Program (IIP) administered by the Earth Science Technology Office. The objective of the FIRST project is to develop and demonstrate the technology needed to routinely observe from space the far-infrared spectrum between 15 and 100 micrometers in wavelength. This spectral region contains about half of the outgoing longwave radiation from the Earth and its atmosphere and is responsible for about half of the natural greenhouse effect. Radiative cooling of the free troposphere occurs almost exclusively in the far-infrared. The far-infrared emission is modulated almost entirely by water vapor, the main greenhouse gas. Cirrus clouds exhibit significant climate forcing in the far-infrared. Despite this fundamental science, the far-infrared has remained almost unobserved directly, primarily due to technological limitations. The FIRST project is advancing technology in the areas of high throughput interferometers, broad bandpass beamsplitters, and detector focal planes to enable routine measurement of the far-infrared from space. FIRST will conduct a technology demonstration on a high altitude balloon platform in Spring 2005.

Techniques for passive remote sensing of aerosol optical and microphysical properties from space include visible, near- and shortwave-infrared imaging (e.g., from MODIS), multiangle intensity imaging (e.g., ATSR-2, AATSR, MISR), near-ultraviolet mapping (e.g., TOMS/OMI), and polarimetry (e.g., POLDER, APS). Each of these methods has unique strengths. In this paper, we present a concept for integrating these approaches into a unified sensor. Design goals include spectral coverage from the near-UV to the shortwave infrared; intensity and polarimetric imaging simultaneously at multiple view angles; global coverage within a few days; kilometer to sub-kilometer spatial resolution; and measurement of the degree of linear polarization (DOLP) for a subset of the spectral complement with an uncertainty of 0.5% or less. This high polarimetric accuracy is the most challenging aspect of the design, and is specified in order to achieve climate-quality uncertainties in optical depth, refractive index, and other microphysical properties. Based upon MISR heritage, a pushbroom multi-camera architecture is envisioned, using separate line arrays to collect imagery within each camera in the different spectral bands and in different polarization orientations. For the polarimetric data, accurate cross-calibration of the individual line arrays is essential. An electro-optic polarization "scrambler", activated periodically during calibration sequences, is proposed as a means of providing this cross-calibration. The enabling component is a rapid retardance modulator. Candidate technologies include liquid crystals, rotating waveplates, and photoelastic modulators (PEMs). The PEM, which uses a piezoelectric transducer to induce rapid time-varying stress birefringence in a glass bar, appears to be the most suitable approach. An alternative measurement approach, also making use of a PEM, involves synchronous demodulation of the oscillating signal to reconstruct the polarization state. The latter method is potentially more accurate, but requires a significantly more complex detector architecture.

Lessons learned from the Atmospheric Infrared Sounder (AIRS) and the Moderate Resolution Imaging Spectroradiometer (MODIS) projects highlight areas where further technology development is needed to address future land, ocean and atmospheric measurement needs. Although not established as requirements at this time, it is anticipated that scientists will expect improvements in the areas of spatial, spectral, radiometric, polarimetric, temporal and calibration performance for future instruments. This paper addresses each of these performance areas and provides lessons learned from MODIS and AIRS. We also present expectations in performance of a Medium Earth Orbit (MEO) Infrared Imaging Spectrometer based on information from the NASA Instrument Incubator Program and industry reports. Tradeoffs are presented vs orbit altitude (LEO, MEO and GEO) and provide a "systems" perspective to future measurement concepts.

Wide-Angle Multi-band Sensor - Thermal Infrared (WAMS-TIR), one of the three sensors aboard the station-keeping test airship (SPF-II) for the stratospheric platform project, is a thermal infrared multi-band radiometer designed to observe land surface temperature. WAMS-TIR consists of very wide field-of-view (over 100 deg) optics and an uncooled microbolometer array detector. It has band-pass filters mounted on a rotating wheel to select spectral bands in the range of 7 to 12 microns. A blackbody calibrator is also mounted on the same rotating wheel to calibrate sensor performance in the operation. Results of pre-flight performance tests suggest that WAMS-TIR has the predicted image quality and high radiometric performance. This paper describes the instrument design and the performance tests results of WAMS-TIR.

Wide-Angle Multi-Band Sensor-Visible and Near Infrared (WAMS-VNIR) has been developed as an Earth-observation mission instrument for SPF-II. SPF-II is a step toward the realization of Stratospheric Platform (SPF) using airships; it is capable of station-keeping flight at an altitude of 4km. WAMS-VNIR is a STARING multi-spectral imaging radiometer and polarimeter with five bands in wavelengths of 500 to 1000nm. WAMS-VNIR has optics of a 110° FOV, two rotating filter wheels, and a 1280 × 1024 pixel Si-CCD FPA. The wide field-of-view optics enable observing an 8km area even from an altitude of 4km. Five narrow-band spectral filters are installed on a rotating wheel, and two polarizers are installed on another rotating wheel. The polarizers rotate around the optical axis separately from the rotation of the wheel, providing several advantages in polarization measurement. The sensor system was completed and performance checks are being conducted. This paper introduces the sensor system and its performance.

This paper presents the results of the analysis and experimental characterization of a narrow bandpass optical filter based on the Fabry-Perot interferometer configuration with a variable spacing between the mirrors allowing for a relatively wide spectral tunability. Such a filter with a high-throughput bandpass and sufficiently large aperture and acceptance angle is of practical interest for a high-resolution spectral measurements and remote sensing in the visible and infrared spectral regions. The Fabry-Perot filter (FPF) can be designed in a compact single-assembly architecture that can be accommodated within existing instruments and should provide a stable performance under variable thermal and mechanical conditions, including space and airborne platforms. Possible applications of the filter include high-resolution multi-spectral imaging, terrain mapping, atmosphere and surface parameters measurements, and detection of chemical and biological agents.

Newly developed high-strength reaction-sintered silicon carbide, called New-Technology Silicon Carbide (NT-SiC) is an attractive material for lightweight optical mirror with two times higher bending strength than other SiC materials. The material has advantages in its fabrication process. The sintering temperature is significantly lower than that of pure silicon carbide ceramics and its sintering shrinkage is smaller than one percent. These advantages will provide rapid progress to fabricate large structures. The characteristics of the material are also investigated. The polish of the test piece demonstrated that the polished surface has no pore and is suited to visible region as well as infrared without CVD SiC coating. It is concluded that NT-SiC has potential to provide large lightweight optical mirror.

Tropospheric chemistry is considered to be the next frontier of atmospheric chemistry, and understanding and predicting the global influence of natural and human-induced effects on tropospheric chemistry will be the next challenge for atmospheric research over the foreseeable future. A geostationary Earth orbit (GEO) vantage point provides an ideal location for measuring spatially and temporally resolved distributions of trace gas species. One powerful technique for making this measurement is LIght Detection And Ranging (lidar) using solid-state lasers. Presently, NASA has a notional plan for using lidars for tropospheric chemistry measurements, but from low Earth orbit (LEO). While permitting high spatially resolved measurements, LEO measurements, however, lack the temporal resolution required to monitor important atmospheric processes and transport. A GEO instrument will require a more energetic and efficient lidar system in order to permit accurate measurements. In this study, we investigated the capability of a lidar for tropospheric profiling of chemical species and we develop a roadmap for the requisite technologies.

Space-based laser and lidar instruments play an important role in NASA's plans for meeting its objectives in both Earth Science and Space Exploration areas. Almost all the lidar instrument concepts being considered by NASA scientist utilize moderate to high power diode-pumped solid state lasers as their transmitter source. Perhaps the most critical component of any solid state laser system is its pump laser diode array which essentially dictates instrument efficiency, reliability and lifetime. For this reason, premature failures and rapid degradation of high power laser diode arrays that have been experienced by laser system designers are of major concern to NASA. This work addresses these reliability and lifetime issues by attempting to eliminate the causes of failures and developing methods for screening laser diode arrays and qualifying them for operation in space.

As part of the Advanced Targeting FLIR (ATFLIR) program for the United States Navy, Raytheon has designed and developed a compact and rugged diode-pumped solid-state laser for high-altitude airborne targeting systems. This laser is based on the relatively mature Nd:YAG technology. In the laser pump head, 168 diode bars are stacked into 24 arrays, which, in turn, are packed around the laser rod to provide 4-sided optical pumping. These standard 20°C operating temperature diode bars and the laser rod are conductively cooled to fins located in the air flow circulating in the pod housing. The laser operates with very low variation in output energy or beam divergence at laser pulse rates from 8 to 20 Hertz and ambient temperatures from -54 to +71°C. The optical to optical efficiency of the pump head is better than 25%. Eye safe laser wavelengths are achieved thorough the use of an Optical Parametric Oscillator. This compact and rugged diode-pumped solid-state laser with proven performance and reliability on high altitude aircrafts can also be modified to serve as transmitters for a variety of airborne laser remote sensing applications. It also has the potential to serve as laser transmitters for spaceborne applications with some design changes and space qualifications.

Advances in Earth observing technologies are required to fulfill NASA's long-term vision for Earth system prediction in the years 2010 to 2020. The observing system during these years will include satellites in a variety of orbits including smaller, smarter ones in low Earth orbit, large aperture sensors in medium Earth orbit and geostationary orbit to provide enhanced temporal coverage and perhaps sentinel satellites at Lagrange points L1 and L2 to provide synoptic views of the entire globe. These higher vistas can meet pending science challenges in a variety of areas directly relevant to NASA’s plans. They include, among others, meeting high temporal and spatial resolutions to observe rapidly evolving chemical events in the global atmosphere, meeting the requirements of increased spatial and temporal sensing of varying precipitation events over portions of the globe, and the increased temporal coverage necessary to see clear skies over coastal regions for coastal process monitoring. A set of technology tradeoffs and needs that meet the above science challenges can be identified. They include an increase in collecting aperture for passive measurements, increased transmitted power for active measurements, and improved on-board processing coupled with enhanced bandwidth communications as data collection increases. The technologies will involve differentiating filled versus sparse aperture collection systems, developing advanced scanning capabilities and large array detectors, as well as large structure pointing control and metrology. This talk will examine these issues for a range of NASA Earth science measurements.

The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new microwave atmospheric sounder under development. It will bring capabilities similar to those now available on low-earth orbiting environmental satellites to geostationary orbit - where such capabilities have not been available. GeoSTAR will synthesize the multi-meter aperture needed to achieve the required spatial resolution, which will overcome the obstacle that has prevented a GEO microwave sounder from being implemented until now. The synthetic aperture approach has until recently not been feasible, due to the high power needed to operate the on-board high-speed massively parallel processing system required for 2D-synthesis, as well as a number of system and calibration obstacles. The development effort under way at JPL, with important contributions from the Goddard Space Flight Center and the University of Michigan, is intended to demonstrate the measurement concept and retire much of the technology risk. To that purpose a small ground based demo version of GeoSTAR is being constructed, which will be used to characterize system performance and test various calibration methods. This prototype development, which is being sponsored by NASA through its Instrument Incubator Program, will be completed in 2005. A GeoSTAR space mission can then be initiated. In parallel with the technology development, mission architecture studies are also under way in collaboration with the NOAA Office of System Development. In particular, the feasibility of incorporating GeoSTAR on the next generation of the geostationary weather satellites, GOES-R, is being closely examined. That would fill a long standing gap in the national weather monitoring capabilities.

The area accessible from a spaceborne imaging radar, e.g. a synthetic aperture radar (SAR), generally increases with the elevation of the satellite while the map coverage rate is a more complicated function of platform velocity and beam agility. The coverage of a low Earth orbit (LEO) satellite is basically given by the ground velocity times the relatively narrow swath width. The instantaneously accessible area will be limited to some hundreds of kilometers away from the sub-satellite point. In the other extreme, the sub-satellite point of a SAR in geosynchronous orbit will move relatively slowly, while the area which can be accessed at any given time is very large, reaching thousands of kilometers from the sub-satellite point. To effectively use the accessibility provided by a high vantage point, very large antennas with electronically steered beams are required. Interestingly, medium Earth orbits (MEO) will enable powerful observational systems which provide large instantaneous reach and high mapping rates, while pushing technology less than alternative systems at higher altitudes. Using interferometric SAR techniques which can reveal centimeter-level (potentially sub-centimeter) surface displacements, frequent and targeted observations might be key to developing such elusive applications as earthquake forecasting. This paper discusses the basic characteristics of a SAR observational system as a function of the platform altitude and the technologies being developed to make such systems feasible.

A review of the history and current state of atmospheric sensing lidar from Earth orbit was conducted and it was found that space based earth remote sensing is still in its infancy with only one limited success extended duration autonomous mission to date. An analysis of the basic requirements for some candidate geo-stationary lidar concepts was completed and it was concluded that significant basic work is required in all areas of lidar development.

The National Polar-orbiting Operational Environmental Satellite System (NPOESS) spacecraft design is based on the Northrop Grumman T430 that has legacy to the Earth Observing System (EOS) Aqua and Aura. The EOS conceived and was structured to achieve cost/schedule savings over multiple builds by adhering to rigorous requirements and minimizing changes to accommodate instruments. The larger sized NPOESS bus has been enhanced to support 14 or more sensors in common locations for the 3 NPOESS orbit planes. Spacecraft deck space and other spacecraft resources such as mass, power and data accommodation have been reserved for "Instruments of Opportunity" that may be selected and inserted into the baseline mission schedule at later dates. This poster will examine the EOS lessons learned from Aqua and Aura and report on the progress of the pre-planned product improvement (P3I) payload accommodations for NPOESS.

A recently completed two-year NASA-sponsored study on Advanced Weather Forecasting Technologies envisions that given the opportunity to realize key technological advances over the next quarter century, and with judicious infrastructure and technology investments, it may be possible to significantly extend the skill range of model based weather forecasting via real-time two-way feedbacks between computer forecast models and highly networked, intelligent observing systems (Sensor Webs). Through this linkage, the observing system will have access to information about the present and evolving state of the atmosphere and, most importantly, have the intelligence to act on information about the future states of the atmosphere derived from the forecast model. An ultimate aim is full dynamic situation-driven observing system reconfigurability. The system is conceived to enable operational expression of optimized targeted observing. Ideas are presented on how the entire system might be designed and operated from the perspectives of the underlying science, technology evolution, and system engineering in order to provide the needed coordination between and among space- and ground-based observing and forecast model operations. The greatest challenges lay with the development of the large scale deep infrastructure on which the more advanced proposed forecast system functionality depends.

A key feature of the National Polar-orbiting Operational Environmental Satellite System (NPOESS) is the Northrop Grumman Space Technology patent-pending innovative data routing and retrieval architecture called SafetyNet^TM. The SafetyNet^TM ground system architecture for the National Polar-orbiting Operational Environmental Satellite System (NPOESS), combined with the Interface Data Processing Segment (IDPS), will together provide low data latency and high data availability to its customers. The NPOESS will cut the time between observation and delivery by a factor of four when compared with today's space-based weather systems, the Defense Meteorological Satellite Program (DMSP) and NOAA's Polar-orbiting Operational Environmental Satellites (POES). SafetyNet^TM will be a key element of the NPOESS architecture, delivering near real-time data over commercial telecommunications networks. Scattered around the globe, the 15 unmanned ground receptors are linked by fiber-optic systems to four central data processing centers in the U. S. known as Weather Centrals. The National Environmental Satellite, Data and Information Service; Air Force Weather Agency; Fleet Numerical Meteorology and Oceanography Center, and the Naval Oceanographic Office operate the Centrals. In addition, this ground system architecture will have unused capacity attendant with an infrastructure that can accommodate additional users.

This is a companion paper to "Architecture Vision and Technologies for post-NPOESS Weather Prediction System: Two-way Interactive Observing and Modeling". Our recently completed two-year NASA-sponsored study on Advanced Weather Forecasting Technologies concluded that it may be possible in the future to significantly extend the skill range of model based weather forecasting via a direct real-time two-way feedback between computer forecast models and highly networked, intelligent observing systems (Sensor Webs). The study group developed a high-level Weather Architecture to describe the system (see the companion paper). This paper describes application of the proposed Weather Architecture to a particular weather scenario-the US east coast Blizzard of January 24 and 25, 2000. The objective of the scenario exercise was to help clarify thinking on the architecture functions in light of realistic, tractable (1 to 5 day) forecast situations, and infrastructure and technologies that might be reasonably projected for 2015.

Japanese satellite for climate change observation, named ADEOS-II, was lost in October 2003. A quick concept study to compensate the loss of ADEOS-II was made. Regarding climate change study, we found the importance to monitor human activity effect for climate change is important as well as to study the natural climate system and variation by global observation. Moreover, the results from previous satellite ADEOS-II suggests the possibility of global observation and human activity monitoring, which requires certain resolution to distinguish regional change. Thus, the concept of the mission objectives is focusing human activity effect on climate change. The new system, named Global Change Observation Mission: GCOM, consists of two satellites. One satellite carrying microwave radiometer: AMSR2 and a scattarometer, and another satellite carrying multi-spectral imaging radiometer: SGLI. These satellites are named GCOM-winds: GCOM-W and GCOM-climate: GCOM-C, respectively. This system will be continued for over 13 years to observe climate change together with other specific Japanese or Japanese joined satellites, namely, Greenhouse gas observation satellites: GOSAT, Global precipitation measurement: GPM with NASA and Earth cloud aerosol and radiation explorer: EarthCARE with ESA. GCOM-W and GCOM-C are proposed to be launched in 2009 and 2010, respectively.

Today most operational Earth observing satellites reside in low Earth orbits (LEO) at less than 1,000 km altitude, and in geostationary Earth orbits (GEO) at ~35,800 km altitude. These orbits have been the venues of choice for observations, albeit for very different reasons. LEO provides high spatial resolution with low temporal resolution while GEO provides for low spatial resolution, but high temporal resolution. NOAA utilizes both venues for their environmental satellites. The NOAA Polar-orbiting Operational Environmental Satellites (POES) reside in LEO Sun synchronous orbits at approximately 830 km in altitude, as do the Defense Meteorological Satellite Program (DMSP) satellites of the Department of Defense. In the near future the POES and DMSP satellites will be merged into a new satellite system referred to as the National Polar-orbiting Operational Environmental Satellite System (NPOESS). The NOAA Geostationary Operational Environmental Satellite (GOES) system, as the name specifies, resides at the other preferred observational venue of GEO. The Jet Propulsion Laboratory (JPL), under contract to NOAA, has been studying the characteristics of medium Earth orbits (MEO), at altitudes between 1000 and 35,800 km, as an observation venue to answer the question as to whether MEO might capture the attributes of the two traditional venues. This on-going study initially focused on determining the optimal altitude for MEO observations, through numerous trade studies involving altitude, instrument complexity, coverage, radiation environment, data temporality, revisit time, data rates, downlink requirements and other parameters including cost and launch complexity. Once the optimal altitude of 10,400 km had been determined the study proceeded to explore single through multiple MEO satellite constellation performance capabilities using two instrument types, a visible through infrared (IR) imager and IR sounder as the satellites’ payload. The MEO performance capabilities were compared to comparable LEO and GEO satellite constellation capabilities. This portion of the study concluded that indeed for global coverage a constellation of satellites operating in the MEO venue could capture the attributes of those operating in the LEO and GEO venues. Three 8-satellite constellations configurations - Walker, ICO, and Equatorial-Polar (EP) - then were studied to develop more constellation coverage statistics including robustness to individual satellite failure. That study phase concluded that the EP constellation was superior to both the ICO and Walker configurations. The study is presently examining if, and to what extent, the equatorial portion of the EP constellation might provide substantive supplemental data to that collected by the NPOESS and GOES satellite constellations.

Architecture-level studies have assessed the merits of a Distributed architecture for NOAA's next-generation Geostationary Operational Environmental Satellites, the GOES-R series. In contrast with the historical Consolidated architecture, which aggregates all GOES instruments on a single platform at each of the 75 and 135 W operating locations, the proposed Distributed architectures split up the GOES instrument suites onto multiple platforms, with sets of platforms located at each longitude. Analyses demonstrate significant advantages to distributing GOES instruments across multiple platforms, including superior deployment options and significantly increased system-level reliability. These benefits can substantially lower overall risk exposure and increase the on-orbit constellation life. In addition, the properties of Distributed architectures permit several features that provide substantial benefit for GOES-R and follow-on systems. These features include enhanced measurements and better requirements allocation, enabling performance and cost advantages for future pre-planned instrument enhancements. Distributed architectures also enable superior upgrade paths through better options for demonstrating and validating new technologies, inserting new technologies (such as microwave sensors) into existing constellations, and refreshing on-orbit instruments.

The Solar Imaging Radio Array (SIRA) is a mission to perform aperture synthesis imaging of low frequency solar, magnetospheric, and astrophysical radio bursts. The primary science targets are coronal mass ejections (CMEs), which drive shock waves that may produce radio emission. A space-based interferometer is required, because the frequencies of observation (<15 MHz) are cutoff by the ionosphere. SIRA will require a 12 to 16 microsatellite constellation to establish a sufficient number of baselines with separations on the order of kilometers. The microsats will be located quasi-randomly on a spherical shell, initially of diameter 10 km or less. The baseline microsat, as presented here, is 3-axis stabilized with a body-mounted, earth-directed high gain antenna and an articulated solar array; this design was developed by the Integrated Mission Design Center (IMDC) at NASA Goddard Space Flight Center (GSFC). A retrograde orbit at a distance of ~500,000 km from Earth was selected as the preferred orbit because the 8 Mbps downlink requirement is easy to meet, while keeping the constellation sufficiently distant from terrestrial radio interference. Also, the retrograde orbit permits imaging of terrestrial magnetospheric radio sources from varied perspectives. The SIRA mission serves as a pathfinder for space-based satellite constellations and for spacecraft interferometry at shorter wavelengths. It will be proposed to the NASA MIDEX proposal opportunity in mid-2005.

Next-generation science and exploration systems will employ new observation strategies that will use multiple sensors in a dynamic environment to provide high quality monitoring, self-consistent analyses and informed decision making. The Science Goal Monitor (SGM) is a prototype software tool being developed to explore the nature of automation necessary to enable dynamic observing of earth phenomenon. The tools being developed in SGM improve our ability to autonomously monitor multiple independent sensors and coordinate reactions to better observe the dynamic phenomena. The SGM system enables users to specify events of interest and how to react when an event is detected. The system monitors streams of data to identify occurrences of key events previously specified by the scientist/user. When an event occurs, the system autonomously coordinates the execution of the users' desired reactions between different sensors. The information can be used to rapidly respond to a variety of fast temporal events. Investigators will no longer have to rely on after-the-fact data analysis to determine what happened. This paper describes a series of prototype demonstrations that we have developed using SGM and NASA's Earth Observing-1 (EO-1) satellite and Earth Observing Systems' Aqua/Terra spacecrafts' MODIS instrument. Our demonstrations show the promise of coordinating data from different sources, analyzing the data for a relevant event, autonomously updating and rapidly obtaining a follow-on relevant image. SGM is being used to investigate forest fires, floods and volcanic eruptions. We are now identifying new earth science scenarios that will have more complex SGM reasoning. By developing and testing a prototype in an operational environment, we are also establishing and gathering metrics to gauge the success of automating science campaigns.

As more assets are placed in orbit, opportunities emerge to combine various sets of satellites in temporary constellations to perform collaborative image collections. Often, new operations concepts for a satellite or set of satellites emerge after launch. To the degree with which new space assets can be inexpensively and rapidly integrated into temporary or "ad hoc" constellations, will determine whether these new ideas will be implemented or not. On the Earth Observing 1 (EO-1) satellite, a New Millennium Program mission, a number of experiments were conducted and are being conducted to demonstrate various aspects of an architecture that, when taken as a whole, will enable progressive mission autonomy. In particular, the target architecture will use adaptive ground antenna arrays to form, as close as possible, the equivalent of wireless access points for low earth orbiting satellites. Coupled with various ground and flight software and the Internet, the architecture enables progressive mission autonomy. Thus, new collaborative sensing techniques can be implemented post-launch. This paper will outline the overall operations concept and highlight details of both the research effort being conducted in the area of adaptive antenna arrays and some of the related successful autonomy software that has been implemented using EO-1 and other operational satellites.

Distributed spacecraft flying in formation can overcome the resolution limitations of monolithic, Earth-sensing systems. However, formation spacecraft must now expend fuel to counteract disturbances and the gravity gradients between spacecraft. We consider three different formation architectures and determine the delta-v required to maintain relative positions at accuracies ranging from 0.1 to 10 m (1 sigma). The three architectures considered are: (i) Leader/Follower, in which individual spacecraft controllers track with respect to a passive, leader spacecraft, (ii) Center of Formation, in which individual spacecraft controllers track with respect to the geometric center of the formation, and (iii) Iterated Virtual Structure, in which a formation template is fit each timestep and individual spacecraft controllers track with respect to the fitted template. We show that in the presence of relative and inertial sensor noise and disturbances (e.g., Earth oblateness and aerodynamic drag) relative positions can be maintained to the 10 m level for 4 mm/s/orbit.