Performance of the AIRS Pulse Tube Coolers and Instrument-A First Year in Space

• Published in: Advances in Cryogenic Engineering; Volume 49B Vol. 710; pp. 1293 - 1300
• Main Authors: Ross Jr, R G, Rodriguez, J I
• Format: Journal Article
• Language: English
• Published: 23.06.2004
• ISBN: 9780735403840; 0735403848
• ISSN: 0094-243X
• DOI: 10.1063/1.1774817

Launched on NASA's Aqua platform on May 4, 2002, JPL's Atmospheric Infrared Sounder (AIRS) instrument has completed a successful first year in space and captured a number of important lessons. AIRS is designed to make precision measurements of air temperature over the surface of the Earth and uses a redundant pair of TRW 55 K pulse tube cryocoolers to cool its sensitive IR focal plane. Soon after the instrument went cold, contamination of cryogenic surfaces led to increased cooler loads and the need for decontamination cycles. In addition, single event transients occurred while passing through the South Atlantic Anomaly (SAA) necessitating corrective actions. In November 2002 the fundamental operating strategy of the AIRS instrument was changed from the original strategy of running a single cooler and having the second cooler as a non-operating backup. Instead, based on a new system-level reliability analysis, both coolers began operation simultaneously. This change resolved the contamination and SAA driven interruptions and has enabled unprecedented levels of continuous science measurements. A review of the AIRS instrument cryogenic performance over the past year is presented including its contamination buildup and interrupt history. The reliability analysis conducted to justify two-cooler operation is also reviewed.