RocketSTEM Issue #2 - April 2013 | Page 41

of its four folded arms did not swing out properly and Kerwin expressed dismay when he saw it had only deployed to cover two-thirds of its required area. “It’s not laid out the way it’s supposed to be,” a dejected Conrad told Mission Control, as it became clear that the parasol was askew and somewhat crinkled. Nevertheless, the ground team in Houston assured the astronauts that the wrinkles had probably set in during the coldness of the lengthy deployment, which took place during orbital ‘night-time’, and, as the material heated up in sunlight, it would spread out fully. “I think the ground noticed the temperatures coming down,” Weitz recalled. “Within an hour, they could tell.” Indeed, overnight on 26/27 May, the temperature on the exterior of the workshop dropped by 55°C and its interior by 11°C. Eventually, the interior temperature stabilised at around 30°C. However, for the mission to survive and succeed, it was necessary to release the jammed array, and soon, and plans were set in motion for an EVA on 7 June. Since the airlock was right in the middle of the Skylab cluster, with the hatch to the workshop at its aft end and a hatch to the station’s multiple docking adaptor and the command module at its forward end, a fully-suited Weitz had to make sure that Conrad and Kerwin had all of their tools and tethers before he depressurised them. Weitz then retreated into the multiple docking adaptor. The hatch was opened at 10:23 a.m., just before the workshop entered the dark portion of its orbit. Conrad assembled the tools – six 1.5 m rods were screwed together, the cable cutter was fitted and several metres of rope from the backup SEVA sail were tied to the cutter’s pull rope – and then he and Kerwin moved into position alongside the antenna boom. The unlikely contraption thus enabled them to operate the cutter from 8-9 m away… just far enough from the airlock to the jammed array. As Kerwin tried to close the cut- www.RocketSTEM.org ters against the debris, it became apparent that he was ‘slipping’, because he was unable to establish a secure position for himself. For half an hour or more, with one hand steadying himself and the other trying to close the cutters, he struggled fruitlessly to complete the work. As his pulse rate began to climb, he decided on an alternative course of action and shortened his own tether, in an effort to steady himself against the edge of the workshop. It worked and after ten minutes or so he was able to tell ground controllers in Houston that the cutters were now securely fastened to the debris. Next, he pulled on the lanyard to operate them… and nothing happened. Conrad made his way, handover-hand, along the length of the beam to see what was amiss, and precisely as he reached the cutter ‘end’, the jaws snapped shut, freeing some of the metal strap at 2:01 p.m. and hurling the commander into space. Fortunately, his tether restrained him from moving far from Skylab, and the jammed array now stood at 20-degrees-open. The frozen damper, however, still resisted normal deployment and the holes on the solar array were smaller than on the ground model. The two men heaved, without success, until Conrad placed his feet on the frozen hinge, stooped to fit the tether over his shoulder and ‘stood up’. Kerwin pulled on the tether and, this time, the solar array suddenly released and sprang into its full, 90-degrees-open position. Both astronauts were flung outwards by the catapult-like effect and arrested by their tethers. Inside Skylab, the needles of the electricity meters dramatically jumped, signalling success. By the next day, 8 June, solar heating had fully extended the array and it was generating no less than 7 kW of much-needed power. From just 40 percent power, the station’s output suddenly increased to around 70 percent. Against all the odds, Skylab’s fortunes had been snatched from the gaping jaws of defeat. The mission was underway. MISSIONS continued from page 37 to the point of exhaustion, the mission was enormously successful, performing observations of Comet Kohoutek and several spacewalks. Skylab 5 At one stage, it was possible that a fourth crew of Vance Brand (Commander), Bill Lenoir (Science Pilot) and Don Lind (Pilot) may have flown a short, 21-day mission to finish up some final experiments aboard Skylab. However, when Skylab 4 was extended from 56 to 84 days, this mission became unnecessary. STS-3 One of the early plans for the Shuttle was to visit and re-boost Skylab into a higher orbit. On the third Shuttle mission, astronauts Fred Haise (Commander) and Jack Lousma (Pilot) would have transported a system to dock with Skylab and save it from a fiery re-entry. It was hoped that the Shuttle might enable a new series of Skylab missions in the 1980s. However, solar activity caused Skylab to descend to Earth faster than expected, the Shuttle was delayed and the mission was cancelled. Skylab burned up in the atmosphere in July 1979. 39 39