Spartan Halley

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Spartan Halley was a short-lived NASA mission to study the ultraviolet light from comet 1P/Halley for about 48 hours. The small satellite, also known as Spartan 203 or HCED (Halley’s Comet Experiment Deployable), was part of the Space Shuttle Challenger’s STS-51-L mission, which ended in disaster at launch. The mission’s principal scientist was Alan Stern, and the autonomous sub-satellite was designed by the University of Colorado. It carried two ultraviolet spectrometers with an angular resolution of about 1 arcminute by 80 arcminutes, covering wavelengths from 1,250 to 3,200 angstroms. A Nikon camera with an f-number of 3 would help determine the instruments’ orientation. The craft navigated autonomously using solar sensors, a star tracker, three-axis gyroscopes, and dual microprocessors. The main goal was to measure emissions from atomic oxygen and hydroxyl produced when water in the comet’s coma is photodissociated. Other possible signals included nitric oxide, carbon monoxide, carbon dioxide, and carbon monosulfide—i.e., other carbon-, nitrogen-, and sulfur-bearing species. The plan was to observe Halley during its 1986 approach, deploying the Spartan Halley satellite with Ron McNair and Judy Resnik using the Canadarm and retrieving it about two days later.