Francesco Bordi

Contribution of EOS Terra to Earth science

NASAs first Earth Observing System (EOS) satellite, Terra (formerly known as EOS AM-1), is scheduled for launch in the fall of 1999. This launch will begin a comprehensive monitoring program of solar radiation, the atmosphere, the oceans, and the Earths continents from a single space-based platform. Specific scientific objectives of Terra include providing the first state distribution of the main Earth- atmosphere coupled parameters; improving our ability to detect human impacts on climate and predicting climate change; providing observations for improving forecasts of the timing and geographical extent of transient climatic anomalies; improving seasonal and interannual predictions; developing technologies for disaster prediction, characterization, and risk reduction from wild-fires, volcanoes, floods, and droughts; and starting long-term monitoring of the change in global climate and environmental change. These objectives are supported by data from five scientific instruments: the Advanced Spaceborne Thermal Emission Radiometer (ASTER), the Clouds and Earths Radiant Energy System (CERES), the Multi- angle Imaging SpectroRadiometer (MISR), the Moderate Resolution Imaging Spectroradiometer (MODIS), and the Measurements of Pollution in the Troposphere (MOPITT) instrument. The raw instrument data will be archived and distributed to the scientific community after capture on the ground and processing to generate scientific data products. The nature of these science data products and their relevance to Earth science will be discussed along with Terras current status. Terra is managed by Goddard Space Flight Center.

A spacecraft for the Earth observing system

Abstract The space segment of NASAs Earth observing system (EOS) includes three series of intermediate-sized spacecraft, plus two smaller spacecraft. The EOS-AM spacecraft is the first of the intermediate-sized spacecraft. EOS-AM accommodates sensors that measure cloud and aerosol radiative properties, and that provide data to study the water and energy cycles. Scheduled for launch in the late 1990s, the EOS-AM spacecraft is designed for a 5-year mission. The spacecraft will be launched from the Western Space and Missile Center (California) into a polar, Sun-synchronous, low-Earth orbit with a 16-day repeat cycle. In its flight configuration, the spacecraft is almost 20 ft long (including instruments mounted at the fore end of the spacecraft) and 6 ft wide (in its widest dimension), has a mass of about 13,000 Ibs and uses about 3000 W of electrical power. The spacecraft is compatible with the Atlas IIAS launch vehicle. EOS-AM has on-board storage for at least two orbits of science data. These data will be transmitted to the ground via the tracking and data relay satellite system (using data structures and protocols in compliance with the recommendations of the Consultative Committee for Space Data Systems). A direct downlink system to support distributed users will also be available.

EOS-AM1: current status

EOS-AM1 is the first element of NASAs Earth Observing System (EOS). The primary goal of EOS, which serves as the centerpiece of Mission to Planet Earth (MTPE), is to provide satellite observations to determine the extent, causes, and regional consequences of global climate change. The EOS series of spacecraft will provide continuous, well calibrated data sets over a period of fifteen years. The EOS-AM1 instrument complement is tailored to the characterization of terrestrial and oceanic surfaces; clouds, radiation, and aerosols; and the earths radiative balance. In addition, vertical profiles of important tropospheric greenhouse gases, the contribution of volcanoes to climate, and ocean primary productivity will be measured. The payload consists of five advanced facility and principal investigator (PI) instruments: advanced spaceborne thermal emission and reflection radiometer (ASTER), clouds and earths radiant energy system (CERES), multi-angle imaging spectroradiometer (MISR), moderate resolution imaging spectroradiometer (MODIS), and measurements of pollution in the troposphere (MOPITT). These instruments are being provided by the Ministry of International Trade and Industry of Japan, Langley Research Center, Jet Propulsion Laboratory, Goddard Space Flight Center, and the Canadian Space Agency, respectively. The project is currently in its C/D phase and is on-track in its development for a June 1998 launch. The EOS-AM project is managed by Goddard Space Flight Center.

EOS-AM1: project update

EOS-AM1 is the initial component of NASAs Earth Observing System (EOS). EOS serves as the centerpiece for Mission to Planet Earth (MTPE) and is to provide satellite observations to determine extent, causes, and regional consequences of global climate change. EOS-AM1 is specifically focused on the characterization of terrestrial and oceanic surfaces; clouds, radiation, and aerosols; and the earths radiative balance. It carries five advanced instruments: advanced spaceborne thermal emission and reflection radiometer (ASTER), clouds and earths radiant energy system (CERES), multi-angle imaging spectroradiometer (MISR), moderate resolution imaging spectroradiometer (MODIS), and measurements of pollution in the troposphere (MOPITT). They are provided by the Ministry of International Trade and Industry of Japan, NASAs Langley Research Center, Jet Propulsion Laboratory, NASAs Goddard Space Flight Center, and the Canadian Space Agency, respectively. The project is currently in its C/D phase and is maintaining schedule for a June 1998 launch. During the past year all of the instruments and the spacecraft successfully completed their critical design reviews (CDRs) and engineering model fabrication, integration, and testing. Fabrication and integration of flight model hardware is underway. Results of these activities and the current development status are discussed. The EOS-AM1 project is managed by Goddard Space Flight Center.

EOS AM-1

The payload of the EOS AM-1 spacecraft consists of five scientific instruments: the Advanced Spaceborne Thermal Emission Radiometer (ASTER), the Clouds and the Earth Radiant Energy System (CERES), the Multi-Angle Imaging Spectroradiometer (MISR), the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Measurements of Pollution in the Troposphere (MOPITT) instrument. The EOS AM-1 instruments will collect data on the physical and radiative properties of clouds (ASTER, CERES, MISR, MODIS); on air-land and air-sea exchanges of energy, carbon, and water (ASTER, MISR, MODIS); and on vertical profiles of greenhouse gases (MOPITT). The EOS AM-1 spacecraft and its instruments are fully integrated and launch is expected in mid-1999.

EOS follow-on missions (near-term)

Next June NASA will launch the EOS AM-1 mission, followed in July by the Landsat 7 mission. Since some of the scientific objectives require long-term observation, beyond the six-year lifetime of Landsat 7 and EOS AM-1, NASA has started initial planning of near-term EOS follow-on missions. To guide the planning of these missions, five science themes have been identified: land cover and land use change; seasonal to interannual climate prediction; natural hazards; long-term climate variability; and atmospheric ozone. Planning for near- term follow-on missions focuses on acquiring data within the land cover and land use change theme, providing broad continuity with EOS AM-1 and Landsat 7, but not mechanically replicating the measurements taken by those missions. Strawman measurements for the EOS follow-on missions include radiation budget; polarization; bi-directional reflectance distribution function; global land and atmosphere imaging; global ocean imaging; and high resolution imaging.

EOS AM-1: launch-9 months

EOS AM-1 is the first element of NASAs Earth observing system (EOS). EOS, the centerpiece to Mission to Planet Earth (MTPE), will provide long-term well-calibrated satellite observations to determine the extent, causes, and regional consequences of global climate change. EOS AM-1 will obtain information about the physical and radiative properties of clouds; air-land and air-sea exchanges of energy, carbon, and atmosphere; and volcanology. It carries five advanced instruments: advanced spaceborne thermal emission and reflection radiometer (ASTER) provided by the Ministry of International Trade and Industry of Japan, clouds and Earths radiant energy system (CERES) provided by NASAs Langley Research Center, multi-angle imaging spectroradiometer (MISR) provided by the Jet Propulsion Laboratory, moderate resolution imaging spectroradiometer (MODIS) provided by NASAs Goddard Space Flight Center, and measurements of pollution in the troposphere (MOPITT) provided by the Canadian Space Agency. The project is currently in its D (development) phase and is scheduled for a June 1998 launch. All flight model instruments have been delivered and integrated with the spacecraft. The process of functional, compatibility, comprehensive performance, and environmental testing at the spacecraft-level is currently underway. During the next six months, this will be completed and the spacecraft will be prepared for shipment to the launch site. Results of these activities and the current development status are discussed. The EOS AM-1 project is managed by Goddard Space Flight Center.

EOS-AM1: L-2

EOS-AM1 is the first component of NASAs Earth Observing System (EOS). As centerpiece to Mission to Planet Earth, EOS will provide satellite observations to determine the extent, causes, and regional consequences of global climate change. EOS-AM1 is intended to obtain information about the physical and radiative properties of clouds; air-land and air-sea exchanges of energy, carbon, and water; measurements of important trace gases in the atmosphere; and volcanology. It carries five advanced instruments: advanced spaceborne thermal emission and reflection radiometer (ASTER) provided by the Ministry of International Trade and Industry of Japan, Clouds and Earths Radiant Energy System provided by NASAs Langley Research Center, Multi-angle Imaging SpectroRadiometer provided by the Jet Propulsion Laboratory, Moderate Resolution Imaging SpectroRadiometer provided by NASAs Goddard Space Flight Center, and Measurements of Pollution in the Troposphere provided by the Canadian Space Agency. The project is currently in its D Phase and is maintaining schedule for a June 1998 launch. Fabrication of Flight Model hardware is being completed and integration and subsystems testing is underway. During the next six months, all instruments will be delivered to the spacecraft contractor for integration with the spacecraft bus. System- level compatibility, performance, and environmental testing will follow. The ambitious science objectives, associated data quality and instrument/spacecraft technology considerations, and the current development status will be discussed. The EOS-AM1 project is managed by Goddard Space Flight Center.

EOS-AM2: a design update

EOS AM-2, scheduled to launch in 2004, is the second mission in the EOS AM series within NASAs Mission to Planet Earth program. The EOS AM-2 mission will measure the Earths radiation budget and atmospheric radiation, global land use, land cover change, local-scale ecological and biogeochemical processes, global aerosol distribution and cloud properties, top-of-atmosphere, cloud, and surface angular reflectance functions, surface albedo, aerosol, and vegetation properties, as well as biological and physical processes on land and the ocean. The baseline instrument complement for the EOS AM-2 mission includes five instruments: the Landsat Advanced Technology Instrument, which will continue the Landsat series of measurements; advanced versions of three instrument that will have flown on the EOS AM-1 mission: the Advanced Moderate Resolution Imaging SpectroRadiometer, the Advanced Multi-angle Imaging SpectroRadiometer, and the clouds and the earth radiant energy system; and a new instrument, the Earth Observing Scanning Polarimeter. Several options are being explored to deploy this instrument complement, including several single spacecraft configurations as well as multiple spacecraft configurations. The driving requirements contributing to the choice of a spacecraft configuration include measurement continuity, coverage, resolution, geolocation, co- registration, repeat cycle, and calibration; important constraints are cost and launch vehicle availability.

Land remote-sensing mission design process: EOS-AM2--a case study

The Mission to Planet Earth will provide long term measurements of the Earth as a global system; the first series of missions is already under development. The second series of missions will continue the measurement baseline while evolving beyond todays technology. The EOS-AM2 mission is the second in the EOS-AM series of remote sensing spacecraft and is scheduled to launch in 2004. The measurements being considered for the EOS-AM2 mission include the Earths radiation budget and atmospheric radiation, global land use, and land cover change, local-scale ecological and biogeochemical processes, global aerosol distribution and cloud properties, top-of-atmosphere, cloud, and surface angular reflectance functions, surface albedo, aerosol, and vegetation properties, as well as biological and physical processes on land and the ocean. Several options are being explored to deploy the set of instruments to carry out these measurements, including single spacecraft as well as multiple spacecraft configurations. The driving requirements contributing to the choice of a spacecraft configuration include measurement continuity, coverage, resolution, repeat cycle, and calibration.