Ricor K506B cryocooler performance during the Clementine mission and ground testing: A status report

摘要

Two Ricor K506B Stirling cycle cryocoolers with H-10 control electronics were used on the Clementine spacecraft, one cooling a 256 x 256 InSb infrared detector for the near-infrared (NIR) camera and the other cooling a 128 x 128 HgCdTe focal plane array on the longwave infrared (LWIR) camera. This is the first use of these Ricor Stirling cryocoolers in a space environment. This mission has demonstrated the use of these Clementine lightweight imaging sensors in the demanding environment of space, and has space-qualified this Ricor cryocooler. Moreover, nearly the entire 38 million square kilometers of the Moon's surface was mapped in 11 spectral bands, six in the near-infrared, during the 71 days of lunar mapping. The more than 1.6 million digital images collected are providing-mineral typing scientific data to the international civilian scientific community. The NIR cryocooler operated successfully for a total of 840 hours with 361 on/off cycles. The H-10 electronics provided good focal plane array (FPA) temperature control with a typical operating FPA temperature of 70.3 K and a one-sigma variation of 0.46 K. The thermal environment for the cooler ranged from -23.7(degrees)C to 38.2(degrees)C. The Ricor cryocooler used on the LWIR camera performed the same during the Clementine mission as it did on the ground. This cryocooler ran for a total of 670 hours with 359 on/off cycles. The H-10 electronics were not able to provide FPA temperature control. This inability to operate at a fixed set point is believed to be caused by a ground difference between the H-10 controller electronics and the FPA temperature sense diode. The FPA temperature varied in proportion to the cryocooler (heat reject) temperature. The FPA temperature during imaging varied from 66.9 K to > 85 K. The thermal environment for this cooler ranged from -22.1(degrees)C to 41.0(degrees)C.