In spite of the success of the mission so far, STS-80 will be remembered as the flight on which both planned spacewalks were cancelled because of a faulty airlock hatch. When Jernigan and Jones were assigned to the crew in January 1996, they eagerly anticipated the chance to perform two excursions, each lasting around six hours, to prepare for the kind of procedures and equipment-handling that would prove so vital when building the International Space Station. Their spacewalks were part of a series of EVA Development Flight Tests (EDFTs), which also served to build spacewalking experience among NASA's astronaut corps.
''Of all the space station assembly missions coming up, probably more than 80% of them [require spacewalks],'' Jones told journalists before the flight. ''They're going to depend on these concepts that we think we've gotten right, but we've got to prove.'' While Jones and Jernigan were outside in the payload bay - becoming the first astronauts to perform a spacewalk from Columbia - Musgrave would have choreographed their every move from the flight deck, while Rominger would have handled the RMS for several key tests.
During their first spacewalk, planned for 28 November, they were to conduct an 'end-to-end' demonstration to replace an International Space Station battery, using a 1.8-m-tall, 70-kg crane. This was anticipated to take three hours. They would then have tested the crane's ability to lift and move a small 'cable caddy', previously used on the previous EDFT spacewalks in January 1996. Jernigan and Jones' second excursion on 30 November would involve each of them spending two hours working with the battery while standing on a mobile work platform affixed to the RMS.
"A little more elbow grease" 289
Other activities would have included evaluating a Body Restraint Tether (BRT), which offered a kind of stabilising bar for spacewalking astronauts, and a Multi-Use Tether (MUT), capable of fitting square Russian handrails and round American ones. The crane, meanwhile, included a boom capable of telescoping out to between one and five metres in length and could move payloads as massive as 270 kg to various locations on the International Space Station's truss structure.
In anticipation of their first spacewalk, on 21 November, Jernigan and Jones, with assistance from Musgrave, began checking out their suits in Columbia's middeck. Then, late on the 27th, the cabin pressure was lowered from 14.7 psi to 10.2 psi, thus reducing the amount of time that the two spacewalkers would need to pre-breathe pure oxygen before venturing outside. Ironically, as it would turn out, the five astronauts were awakened that evening by Robert Palmer's 'Some Guys Have All The Luck', although Jernigan and Jones' fortunes were bad for that day when the outermost airlock hatch refused to open.
''Initially, I thought we just had a sticky hatch and the fact that Tammy's initial rotation wasn't able to free it up was just an indication that we'd have to put a little more elbow grease into it,'' Jones told CNN on 2 December. ''Certainly, we are feeling some combination of disappointment at the failure of the hatch, but yet pleasure in being part of this mission that's been in every other way very successful,'' added Jernigan. Both astronauts remarked that spaceflight was a complex business, but remained upbeat, adding: ''We'll learn from this experience and go on.''
The hatch's handle apparently stopped after about 30 degrees of rotation, making it unable to release a series of latches around its circumference. An engineering team was quickly established to determine the most likely cause of the mishap and Mission Control frantically adjusted the astronauts' schedules in anticipation of a hoped-for second try on 29 November. A minor problem was also noted with a signal conditioner in Jones' spacesuit and it was decided to replace it should the spacewalk go ahead. ''We've got high hopes'', said Cockrell optimistically, ''[for] the rest of the flight.''
By the evening of the 29th, however, Mission Operations representative Jeff Bantle was telling journalists that engineering analyses thus far suggested a misalignment of the hatch against the airlock seal. Meanwhile, engineers worked feverishly to assess emergency procedures to open the hatch - which might still be needed if a contingency spacewalk to manually close the payload bay doors became necessary - including warming it by orienting Columbia's topside towards the Sun and having Jernigan and Jones apply pressure from inside the airlock.
"It [takes] fairly light forces overall [to open the hatch]," said Jerry Ross, himself a veteran of four spacewalks. "That's what was a little bit surprising to us." The force needed to open the hatch in normal circumstances, he added, is "certainly not as high as a lug wrench on a bolt''. Awakened by David Bowie's song, 'Changes', on 29 November, the crew underwent another day in limbo, working with their many onboard experiments, until finally the Mission Management Team, chaired by Loren Shriver, decided that a conclusive cause could not be pinpointed.
Capcom Dom Gorie relayed the bad news to the five astronauts on 30 November, telling them that both spacewalks would be cancelled. Nevertheless, the following day, Jernigan and Jones conducted a demonstration on Columbia's middeck of a 'pistol-grip' power tool which they would have used during their excursions. They successfully loosened and tightened bolts and screws on floor panels. Ultimately, both astronauts would fly again and perform their 'missed' spacewalks, albeit next time outside the 'real' International Space Station: Jernigan on STS-96 in mid-1999 and Jones on STS-98 in February 2001.
After landing, inspections would reveal a small screw had apparently come loose from an internal assembly and lodged in an 'actuator' - a gearbox-like mechanism which operates linkages that secure the hatch of the airlock - that had subsequently made all of Jernigan and Jones' efforts in vain. When the actuator was replaced, the hatch opened normally.
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