Essentially, therefore, the Satcom launched by Columbia on STS-61C was her last fully commercial payload. It was also, as Hoot Gibson remembered years later, the ''end of innocence'' for the Shuttle. After deploying Satcom, he and his crewmates settled down to what should have been five days of experiments and observations of Halley's Comet, which was making its closest approach to Earth since 1910. The Comet Halley Active Monitoring Programme (CHAMP) was a camera which involved astronomer Pinky Nelson burying himself under a black shroud to eliminate cabin-light interference, before shooting a number of high-resolution pictures of the comet.
The camera failed due to a battery problem and did not return even one good image of the famous comet. Another attempt was scheduled during Challenger's mission and then, during Columbia's ASTRO-1 flight in March, the most detailed observations would be conducted, utilising a battery of ultraviolet telescopes in the payload bay. The loss of Challenger and stalling of the Shuttle until September 1988 meant that NASA had lost its chance to see Halley's Comet from space. Although
Nelson and his colleagues tried to fix CHAMP, their efforts were in vain and by 14 January they were told to press on.
Franklin Chang-Diaz, on the other hand, was having more luck with the experiments under his watchful eye. The 35-year-old physicist was making his first flight and had been given responsibility for running three experiments on MSL-2, a bridge-like structure that straddled Columbia's payload bay. It was a reflight of a similar facility that had flown on Challenger during the STS-7 mission in June 1983 and carried an Electromagnetic Levitator (EML), an Advanced Directional Solidification Furnace (ADSF) and a Three-Axis Acoustic Levitator (3AAL). All three were dedicated to materials processing in space.
EML examined material flow during the solidification of melted materials. Six samples were suspended in the electromagnetic field of a cusp coil and melted by induction heating from its electromagnetic field. ADSF used four furnaces to melt and solidify several materials. Lastly, 3AAL carried 12 liquids suspended in sound pressure waves, which were rotated and oscillated to study bubble behaviour in microgravity. All three were up and running by the end of 12 January and 3AAL activities were completed the next day. The other two experiments encountered problems, however; they did not power-up properly and were terminated earlier than intended.
The second bridge in the payload bay was hidden behind Satcom's Pacman cradle, but was the first time that as many as 12 GAS canisters had been flown on a single Shuttle mission. An extra canister was also attached to the payload bay wall. The decision to fly the so-called 'GAS bridge' came about following the cancellation of one of two satellites originally assigned to the mission. The US Navy's Leasat-5 military communications satellite was supposed to fly on Hoot Gibson's mission along with Satcom Ku-1 and MSL-2, but it was withdrawn for inspections following the failure of its predecessor after reaching its orbital slot, and shifted onto Columbia's STS-61L mission, scheduled for November 1986. NASA then opted to
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