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MICAS Instrument Cryo/Thermal Design

The Miniature Integrated Camera and Spectrometer (MICAS) instrument (pictured above) is an integrated camera and spectrometer with four channels covering the wavelength range from 80 nm in the ultraviolet to 2.4 Ám in the infrared. It was developed by a team of engineers and scientists from JPL, USGS/Flagstaff, University of Arizona, Boston University, SSG, Inc, and Rockwell Science Center for use on deep-space missions; it was launched aboard DS-1 in October 1998.

The optics and structure, which make up the majority of the instrument, are designed to run at a temperature of 140 K, while the infrared detector assembly runs at approximately 90 K. To yield an instrument that maintains optical alignment from room temperature down to these cryogenic temperatures, the optics and structure are made from highly stable silicon carbide (SiC), which has a near-zero coefficient of thermal expansion. This high dimensional stability enables the instrument to be made with no moving parts such as complex focusing mechanisms.

The cryo/thermal design of the MICAS instrument is unique in its simplicity and low cost. With a focus on deep-space missions, the cooling is based entirely on two passive cryo-radiators, one at 140 K attached to the optical bench, and the second at 88 K for the infrared focal plane assembly.

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