How to Build Space Station-Saving Cuff Links
Cobbled Cuff link: An improvised fix, such as this 'cuff link' built from spare parts, may stabilize a torn power-providing solar array on the International Space Station during the joint STS-120-Expedition 16 mission.
In 1970, the solution involved duct tape, a flight manual's cover, a plastic bag and a sock.
Three years later, it was a nylon and mylar umbrella that was assembled with a sewing machine. In 1985, although unsuccessful, the answer was two makeshift flyswatters.
And on Saturday, should NASA proceed as planned, the success of its current mission will rely on six cuff links.
But it's not like the 10 astronauts in space can rent the fasteners from the local tuxedo shop. To save the space station on which they all currently inhabit, they needed to assemble their repair tools from the spare parts launched for just such an occasion.
A rip in an array
Earlier this week, after successfully repositioning a truss and solar array assembly to its permanent berth on the International Space Station (ISS), the crew of shuttle Discovery and the outpost's own residents set about deploying the segments' pair of power-generating wings. The first array extended without issue, but as the second was almost at its full length, the station's commander halted the deploy after observing a tear that was forming mid-way along its 110-foot (33 meter) length.
The damage, which upon closer inspection was found to be two tears -- a 2.5-foot (0.7-meter) rip and another about one-third the size -- was a serious concern. The ISS was already at a power handicap as a faulty joint was preventing one set of its arrays from rotating to track the Sun. Now, with the second set of arrays unable to extend completely, it too would be unable to follow the power-providing rays of our nearest star. Although there was enough electricity to support its current configuration, without repair, the torn wing was threatening future expansion, including the long awaited launch of European and Japanese science labs.
Flights controllers quickly went to work around the clock to develop a daring plan: using a 50-foot (15-meter) boom designed to inspect the shuttle for damage and the station's own 50-foot robotic arm, an astronaut will be positioned at the site of the tear, where he will attempt to clear a snagged guide wire believed to be the source of the damage, and then repair the torn hinge by inserting splints, referred to as cuff links, to stabilize the array such that it can be fully extended. Were it not enough that the boom has never been used for such a purpose, or that the astronauts were never trained for such a maneuver, the array, though torn, will still be running a current such that it poses a low but real risk of shocking the spacewalker.
Well before Discovery launched to space on Oct. 23, STS-120 commander Pam Melroy dubbed one of her six crewmates as the astronaut version of the resourceful TV character MacGyver. Speaking of her mission specialist from the European Space Agency, Melroy recalled telling Paolo Nespoli to take all his tools with him to space.
"I encouraged him to take one of everything because I am sure he's going to build something in space with it."
As chance would have it, Melroy would be partially right. Though Nespoli will support Scott Parazynski and Doug Wheelock during the spacewalk from his vantage point inside, it was Discovery's pilot George Zamka along with ISS Expedition 16 commander Peggy Whitson who were called upon on Thursday to exhibit their inner-MacGyver.
Using strips of aluminum, a hole punch, a bolt connector and 66 feet (20 meters) of wire, along with detailed instructions sent by mission control, the duo assembled half a dozen space station-saving cuff link contraptions. If all proceeds as planned, Parazynski, suspended at the end of the boom-arm assembly, will slip the cuff link-like tabs through holes in the array's blanket, enabling it to support the tension exerted when the solar wing is fully extended.
Like the sock/duct tape/plastic bag solution that allowed a square-shaped carbon dioxide scrubber to fit in a round hole aboard Apollo 13, the success of the cuff links won't be known until they are installed, but those who worked to devise the fix are optimistic that failure is not an option.
"We're faced with a difficult situation," said experienced spacewalker David Wolf. "I think we're onto a solution that should work and get us pretty close to a permanently acceptable situation."
How exactly does one assemble a space station saving cufflink from spare parts? Very carefully, as appears to be the case in the seven-part instructions that were uplinked to the astronauts, complete with illustrations for key steps.
SPACE.com's live coverage of the spacewalk begins Saturday morning at 5:00 a.m. EDT (0900 GMT).
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