A Statement of Task

ANALYSIS OF SMALL SATELLITE CAPABILITIES IN LIGHT OF SCIENCE REQUIREMENTS FOR CORE OBSERVATIONAL NEEDS IN EARTH STUDIES

Background In recent years, "faster, better, cheaper" has become the National Aeronautics and Space Administration's (NASA's) motto for future missions. New technologies have evolved in the Department of Defense (through the Strategic Defense Initiative and other defense activities) and to enable constellations of low-altitude communication satellites. In addition small, commercial launch vehicles are being developed. Proponents now assert that these advances offer new means for the conduct of Earth observations that offer lower costs and enhanced capabilities. They also assert that the technologies are applicable to the National Oceanic and Atmospheric Administration's (NOAA's) Geostationary Operational Environmental Satellites (GOES). Furthermore, pressures on the federal budget have produced calls for a complete revamping of the Mission to Planet Earth (MTPE) [now called Earth Science Enterprise—ESE] and its ground data processing element (both in the pre-2000 era that was targeted in earlier restructurings and more recently in a new reexamination of post-2000 plans) and in the annual cost of NOAA's operational satellites. In both instances, the issue of the small satellite capabilities and applicability arises.

NASA's MTPE and NOAA's Polar-orbiting Operational Environmental Satellites (POES) have evolved in an era in which launch vehicle costs were a major driver in overall mission costs. The POES are in the process of being merged with the Air Force's Defense Meteorological Satellite Program (DMSP). The DMSP satellites evolved in the same era and with the same underlying assumption of high launch costs. This was also an era in which the available launch vehicles did not pose a serious limit on payload and spacecraft mass or volume. As a result, both MTPE and POES/DMSP found the most economical overall design to be one in which several sensors were flown on the same spacecraft. This configuration also offered the advantage of multiple Earth sensors simultaneously observing some atmospheric and surface parameters. It is time to reassess whether earlier assumptions and technical approaches should now be changed due to new technology and the changed environment.

Plan The study will address the following questions:

  1. What are the core observational needs for NASA and NOAA/DMSP?

  2. Are there simultaneity of measurement requirements that necessitate that particular sensors are orbited on the same spacecraft or on two or more spacecraft that orbit in close proximity to one another (e.g., in a satellite constellation)?



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OCR for page 67
The Role of Small Satellites in NASA and NOAA Earth Observation Programs A Statement of Task ANALYSIS OF SMALL SATELLITE CAPABILITIES IN LIGHT OF SCIENCE REQUIREMENTS FOR CORE OBSERVATIONAL NEEDS IN EARTH STUDIES Background In recent years, "faster, better, cheaper" has become the National Aeronautics and Space Administration's (NASA's) motto for future missions. New technologies have evolved in the Department of Defense (through the Strategic Defense Initiative and other defense activities) and to enable constellations of low-altitude communication satellites. In addition small, commercial launch vehicles are being developed. Proponents now assert that these advances offer new means for the conduct of Earth observations that offer lower costs and enhanced capabilities. They also assert that the technologies are applicable to the National Oceanic and Atmospheric Administration's (NOAA's) Geostationary Operational Environmental Satellites (GOES). Furthermore, pressures on the federal budget have produced calls for a complete revamping of the Mission to Planet Earth (MTPE) [now called Earth Science Enterprise—ESE] and its ground data processing element (both in the pre-2000 era that was targeted in earlier restructurings and more recently in a new reexamination of post-2000 plans) and in the annual cost of NOAA's operational satellites. In both instances, the issue of the small satellite capabilities and applicability arises. NASA's MTPE and NOAA's Polar-orbiting Operational Environmental Satellites (POES) have evolved in an era in which launch vehicle costs were a major driver in overall mission costs. The POES are in the process of being merged with the Air Force's Defense Meteorological Satellite Program (DMSP). The DMSP satellites evolved in the same era and with the same underlying assumption of high launch costs. This was also an era in which the available launch vehicles did not pose a serious limit on payload and spacecraft mass or volume. As a result, both MTPE and POES/DMSP found the most economical overall design to be one in which several sensors were flown on the same spacecraft. This configuration also offered the advantage of multiple Earth sensors simultaneously observing some atmospheric and surface parameters. It is time to reassess whether earlier assumptions and technical approaches should now be changed due to new technology and the changed environment. Plan The study will address the following questions: What are the core observational needs for NASA and NOAA/DMSP? Are there simultaneity of measurement requirements that necessitate that particular sensors are orbited on the same spacecraft or on two or more spacecraft that orbit in close proximity to one another (e.g., in a satellite constellation)?

OCR for page 67
The Role of Small Satellites in NASA and NOAA Earth Observation Programs What instrument technologies are currently planned for the conduct of these observations? Have new payload technologies emerged that can reduce cost, payload mass, power requirements, other interface needs (views of cold space for radiative cooling, views of celestial objects for calibration, thermal dissipation, etc.), and/or data communications needs with respect to those that are planned? Have new spacecraft technologies emerged that can enhance payload mass, power, and volume fractions or reduce overall system costs? As a result of technological advances, are there new ways of aggregating or parsing sensor systems (including satellite constellations) that can offer advantages in the cost or effectiveness of Earth observations? If such ways exist, what are their implications for the future of MTPE, POES/DMSP, and GOES in terms of both spacecraft and ground system configurations?