STS-51-F Abort-to-Orbit (1985)

STS-51-F was a 1985 Space Shuttle Challenger flight that suffered an in-flight main-engine anomaly but still completed a science-rich Spacelab mission. A pad abort at T−3 seconds delayed the first attempt; on the successful July 29 launch a failure of high-pressure turbopump temperature sensors led to an automatic shutdown of the center RS-25 engine about six minutes into ascent. Quick action by ground engineers to inhibit further automatic shutdowns prevented additional engine cutoffs and a probable loss-of-vehicle scenario, but the shuttle flew an Abort-to-Orbit (ATO) profile, reaching a lower-than-planned orbit (~265 km vs. ~385 km). The seven-person crew operated in two 12-hour “Red” and “Blue” shifts and carried two EMUs for contingency extravehicular activity.

Payloads were centered on Spacelab 2 and a broad suite of experiments in astronomy, plasma physics, life sciences and technology. The European Instrument Pointing System was flight-tested and brought to nominal performance after software fixes; the 15.2 cm helium-cooled Spacelab Infrared Telescope recorded useful data across 1.7-118 μm and covered about 60% of the galactic plane despite thermal contamination and stray mylar. A Plasma Diagnostics Package was deployed and returned using the Canadarm during proximity operations. A highly publicized consumer experiment compared Coca-Cola and Pepsi dispensing in microgravity (Coke’s system performed better); crew tastes favored Tang for practical reasons. Overall, mission replanning accommodated the ATO and the science objectives were met.