Two astronauts armed with a toothbrush, a wire cleaner and some nitrogen air boldly took their second spacewalk in less than a week. A faulty bolt was preventing the installation of a power station unit on the International Space Station, which was discovered after a marathon eight-hour spacewalk on August 30.
The unit that astronauts Sunita Williams and Akihiko Hoshide, of NASA and JAXA, respectively, were trying to replace was a main bus switching unit (MBSU). While the duo was able to remove the faulty unit during their first spacewalk, they were unable to get the new system in place because one of the bolts was unable to be driven into its housing.
After a lengthy attempt at installation, Williams and Hoshide finally had to tie down the MBSU with a tether and began the process of troubleshooting with NASA on how to get the unit installed. Success was critical as the MBSUs are responsible for diverting the power collected by the ISS solar array into the station itself.
The troubleshooting process was not unlike what happened with the fateful Apollo 13 mission when problems with the space capsule required the astronauts and the entire ground control team to tackle the problem of dwindling breathable air with only the objects they had available to them in space.
On their second attempt yesterday, the duo undid the bolts to the MSBU again and, when they looked inside the receptacle, they found there were indeed small metal shavings and debris inside, which is what the team had expected might be the problem.
After the spare toothbrush, the wire cleaner and nitrogen gas dispersed the shavings, Williams and Hoshide lubricated a spare bolt (if there was a spare toothbrush on the space station, of course there was a spare bolt, right?) and it was eventually driven in.
While the mission is a significant lesson in always carrying a spare, there are some other reasons why this mission will stand out. The first spacewalk lasted eight hours and 17 minutes, making it the third longest in history and the longest by a space station crew.
The second outing yesterday was also lengthy — six hours and 28 minutes. Two hours into the spacewalk Astronaut Williams became the record holder for the female with the most time spent working in the vacuum of space.