Processes Research by an Imaging Space Mission (PRISM)

Abstract

PRISM is a spaceborne hyperspectral imager for a future land surface research mission, whose prime objective is the observation of biophysical processes at a local to regional scale. PRISM is designed for a dedicated medium-size satellite in a polar sun-synchronous 11:00 h orbit, and will provide coregistered spectral images in tow spectral regions: from the visible to short-wave IR range with a spectral resolution of about 10 nm and two bands in the thermal IR from 10.3 micrometers to 12.3 micrometers . The presented instrument concept comprises four modules with separate interfaces to the platform: the optical, calibration, cooler and electronics modules. The optics module design is based on a pushbroom type of imaging spectrometer in which the entire field of view is imaged on four detector arrays. The long-wavelength arrays are cooled by tow pairs of Stirling cycle coolers. The instrument layout and platform accommodation are optimized to meet the high radiometric accuracy requirement. The key element of the instrument is the pointing unit, whose mirror is protruding over the platform edge for a wide across track coverage and or access to the three on-board characterization units and to cold space. The pointing unit will provide global accessibility in 3 days. A platform rotation in pitch will enable BRDF measurements of ground test sites by varying along track pointing angles.