Sorption cooling of astrophysics science instruments

The current status of continuous and periodic operation sorption cryocooler development for astrophysics missions requiring refrigeration to 4 K and below, is reviewed. These coolers are suited for the cooling of detectors in planned astrophysics missions such as the exploration of neighboring planetary systems planet finder array (ExNPS PFA). The cooler requirements imposed by these missions include a ten-year life, zero vibration, zero electromagnetic interference and electromagnetic charging operation, and the ability to scale designs to provide low refrigeration capability with low power consumption. Spaceflight test results are summarized for the brilliant eyes 10 K sorption cryocooler experiment. This experiment successfully validated flight cooler performance and provided characterization of all sorption cooler design parameters which may have shown sensitivity to microgravity effects. Ground test results from a continuous 25 K cooler planned for use in a long duration airborne balloon experiment are presented. A NASA program to develop 30 K, 10 K and 4 K vibration-free coolers for astrophysics missions is outlined.