Eos: The earth observing system of the 1990s

In this paper the recent considerations of NASA's Earth Observing System Science and Mission Requirements Working Group are summarized. The Working Group was chartered to consider the broad Earth Science objectives that could be addressed from a low-earth orbital perspective in the 1990s, together with consideration of the specific observations and instrument packages that would be needed to meet the science objectives. The concept that was developed diverges somewhat from past practices in that the Working Group chose to consider Eos as an information system, where mission operations, Eos databases, and information about other relevant data sets are tied together by an information network. The network would link users with mission data repositories, with Eos and non-Eos data archives, and with subsets of Eos and related data maintained as active research databases. Three Eos instrument packages were chosen on the basis of synergistic groupings of instruments to make simultaneous observations of selected phenomena over a variety of wavelengths. The suggested packages are: 1) a surface-imaging and-sounding package, with two imaging spectrometers, a high-resolution multifrequency microwave radiometer, and a Lidar atmospheric sounder and altimeter; 2) an active microwave package, with a synthetic-aperture radar, an altimeter, and a scatterometer; and 3) an atmospheric physical and chemical monitoring package, with a variety of instruments to measure atmospheric chemistry, winds, and energy balances. The significant observing capabilities offered by the Eos instrument packages, if implemented in the proposed information system environment, will allow significant increases in our understanding of global processes operating above, on, and beneath the earth's surface.