Cryogenic testing of several parts of the meteosat second generation payload

Abstract

The first Meteosat Second Generation (MSG) satellite is planned to be launched in 2000. As the first generation of the Meteosat satellites, it is mainly an Infra-Red and Visible Imager. The cooling of the experiment is provided by a passive radiator facing the deep cold space. In the frame of this program, CSL is in charge of the testing of four different parts of the payload, with different thermal environments and cooling systems. For SFIM-ODS REOSC, the I/R detectors are calibrated at 85 and 95 K, before and after cycling them from 333 down to 70 K. The visible detectors are calibrated at 248 K and cycled from 333 down to 228 K. They are cooled by conduction. For Fokker Space b.v., the Passive Cooler Assembly, including the sunshield and the two-stage radiator, is tested with regards to its mechanical stability and thermal performances. As in space, it is cooled radiatively by means of a helium plate. The main specifications for this plate are a total hemispherical emittance greater than 0.95 at 20 K, and a temperature lower than 25 K with a heat load of 200 W. Liquid nitrogen shrouds surround the set-up. For Matra Marconi Space, the Passive Cooler Assembly and the detectors are calibrated at their nominal temperature. The cooling power is provided by the same helium plate simulating the deep cold space. Again for Matra Marconi Space, the whole payload, called SEVIRI, is thermally and optically calibrated. Up to 19 temperature regulated channels are used, and the space is once again simulated by the helium plate. Three of these tests have already been performed successfully. From the facility point of view, we present here the relevant testing philosophies used to meet the specifications, the related problems, solutions and results.