fly the GAS bridge instead to help to clear the backlog of small experiments awaiting launch. The Challenger disaster kept Leasat-5 grounded for longer than planned, but it finally reached space in 1990. The GAS canisters were activated by 14 January and included an ultraviolet instrument, a US Air Force payload, numerous student experiments looking at materials processing, fluid physics, crystal growth and brine-shrimp behaviour and an amateur radio package.
Other experiments, in what Bolden, like Hawley, described as ''a year-end clearance sale'', included the first of NASA's Hitchhikers. Unlike GAS payloads, Hitchhikers were controlled from the Goddard Space Flight Center in Greenbelt, Maryland, and allowed experimenters to actively interact with their investigations. The mounting hardware for the Hitchhikers also allowed them to draw on some of the Shuttle's power supply. At the time of STS-61C, two versions of the Hitchhiker were under development: one, called 'Hitchhiker-G', was attached to the payload bay wall and another, called 'Hitchhiker-M', consisted of a cross-bay bridge.
For its first flight, the Hitchhiker-G carried three experiments: a US Air Force package to record particle distribution in Columbia's payload bay, as part of preparations to fly sensitive infrared detectors on future Department of Defense missions, together with an investigation to examine the Shuttle's effects on a set of coated mirrors and a test of a capillary pumped-loop experiment for heat transport purposes. All three Hitchhiker experiments were successfully activated within the first four hours of the mission and performed satisfactorily.
Other activities included Chang-Diaz conducting a live televised broadcast in Spanish, in which he gave Latin American audiences a guided tour of Columbia. Meanwhile, Bill Nelson operated the Hand-held Protein Crystal Growth (HPCG) experiment, which 'grew' large crystals of sufficient purity to permit scientists to analyse their structure through X-ray diffraction (crystals grown on Earth tend to be irregular and difficult to study). He also participated in several medical tests which observed bodily fluid shifts, electrolyte changes and pharmacokinetics. Each of these tests helped to build a clearer picture of the effects of microgravity exposure on the human body.
Was this article helpful?