Space shuttle Challenger (Mission 41-G, 5-13 October 1984) showing Astronauts David C. Leestma & Kathryn D. Sullivan working on the orbital refuelling system (ORS) in the aft section of the Earth- orbiting spacecraft's cargo bay. The ORS was an experiment for refuelling orbiting satellites (such as the Landsat series): part of the task was to transfer 550lb of cold, toxic hydrazine fuel from one tank to another. Astronaut Kathryn Sullivan became America's first woman to work outside an orbiting spacecraft.