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SPAS (Shuttle Pallet Satellite)

A reusable free-flying vehicle built by Messerschmitt-Bolkow-Blohm which can be deployed and retrieved by the Space Shuttle's Remote Manipulator System (RMS). The original SPAS, with materials processing and SDI ("Star Wars")-related sensor payloads, was carried on three missions but not deployed on the second of these because of an electrical problem with the RMS.

ORFEUS (Orbiting and Retrievable Far and Extreme Ultraviolet Spectrometer), was a German astronomical payload that flew twice aboard SPAS. The main instrument was a 1-meter telescope with extreme ultraviolet and far ultraviolet spectrometers of high spectral resolution. Also carried was the Princeton Interstellar Medium Absorption Profile Spectrograph which studied the fine structure of UV absorption lines in stellar spectra caused by interstellar gas, and several non-astronomy payloads.

CRISTA, equipped for observation of the Earth's atmosphere, also flew on two SPAS missions.

spacecraft shuttle deployment retrieval mission orbit mass
SPAS-I Jun. 18, 1983   STS-7 228 × 947 km  
SPAS-1A Feb. 3, 1984   STS-11 not deployed  
SPAS-II Apr. 28, 1991   STS-39 248 × 263 km × 57.0°  
ORFEUS-SPAS I Sep. 13, 1993 Sep. 18, 1993 STS-51 301 × 331 km × 28.5° 3,202 kg
CRISTA-SPAS I Nov. 4, 1994 Nov. 12, 1994 STS-66    
ORFEUS-SPAS II Nov. 19, 1996 Dec. 4, 1996 STS-80    
CRISTA -SPAS II Aug. 7, 1997 Aug. 16, 1994   282 × 296 km × 57.0°  

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