Advanced Geosynchronous Studies Imager: instrument system design

Abstract

The Advanced Geosynchronous Studies Imager (AGSI) system design combines the latest available technologies into an instrument design concept which could deliver the improved performance sought by the National Weather Service at NOAA and meet NASA earth system science goals in a joint program. The instrument could cover the Earth disk eveiy 15 minutes with subsatellite point resolution from 1/2 kilometer in the visible to 2 kilometers in the long wave infrared. Simultaneously, it could provide coverage of a 3000 x 5000 kilometer region in 5 minute intervals and 30 second updates of a 1000 kilometer square region containing a weather system of interest. We found that performance margins could be improved even as we drove the design iterations with emphasis on reducing the mass. Scan speed was chosen by maximizing perfonnance while trading off the acceptable impact on the total system. The resulting 18-channel design could deliver vastly improved performance over the present GOES without great increases in mass or volume, while still paying close attention to control of development costs and impact on the host spacecraft. The design could be adapted to changed requirements or descoped to have lower data rates and fewer channels.

Thermal Analysis of Radiometer Onboard a Geostationary Satellite

“…The radiometer is required to operate 24 h a day in a very harsh thermal environment. During a single diurnal period, the optics are exposed to the direct view of the sun for approximately 4 h during the day and the deep space during the remaining periods [1][2][3][4]. Even with the highly reflective optical surfaces, the scan mirrors still experience large temperature excursions during the heating and cooling periods [5].…”