NASA spacewalkers Peggy Whitson and Jack Fischer replaced a faulty computer relay box on the International Space Station today, but not before dealing with a problem all too familiar to home fixer-uppers.
The box, about the size of a microwave oven, is known as a multiplexer-demultiplexer or MDM. It’s one of two MDMs that regulate the operation of the station’s radiators, solar arrays and cooling loops. The component failed on Saturday, but because each box can handle all essential functions, operations on the station weren’t affected.
NASA decided to go ahead with a rapid-response spacewalk today to preserve the system’s redundancy, and Whitson made quick work of uninstalling the failed equipment. However, when it came time to install the replacement, she found she couldn’t secure the primary bolt that was supposed to hold it in place.
She reported that it looked as if there were metal shavings inside the bolt hole. The problem was resolved when Fischer came over and sprayed compressed nitrogen gas into three of the unit’s bolt holes, dislodging the debris. “I think all three look clean as a whistle,” Fischer declared.
Whitson then successfully screwed the bolts into place.
"Victory" as @AstroPeggy installs data relay box. Ground controllers will power up box now. https://t.co/yuOTrZ4Jut pic.twitter.com/u2RDqff17r
— Intl. Space Station (@Space_Station) May 23, 2017
“We have a good install, everybody’s happy with those,” Mission Control reported. NASA engineers checked out the MDM’s connections from the ground and found that everything was working normally. NASA hasn’t yet determined why the faulty box failed less than two months after it was installed.
During today’s two-hour, 46-minute spacewalk, Fischer also installed a pair of antennas to enhance the station’s wireless communications.
The outing boosted Whitson to No. 3 on the list for cumulative spacewalk time, with 60 hours and 21 minutes of extravehicular activity. The only other spacewalkers with more time are Russia’s Anatoly Solovyev (78 hours) and NASA’s Michael Lopez-Alegria (67 hours). Whitson already holds the U.S. record for cumulative time in space (564 days) and the world record as the oldest woman in space (57 years old).
