A series of low-cost, short-duration payloads launched from the space shuttle, which were retrievable, reusable, and operated autonomously. Spartan 201 flew five times - on its first two trips, Spartan 201-01 and 02, it carried telescopes to study the Suns extremely hot atmosphere, the corona. Spartan 201-03 carried X-ray, far ultraviolet, and visible-light instruments to study the corona. Spartan 201-04 had to be retrieved during a spacewalk, after a computer glitch made it spin. Data from Spartan 201-05 helped re-calibrate NASAs Solar and Heliospheric Observatory (SOHO).