NASA astronauts Peggy Whitson and Jack Fischer conducted an emergency spacewalk Tuesday morning, May 23, to replace a malfunctioning external computer and install a pair of antennas on the International Space Station (ISS).
The spacewalk, which lasted two hours and 46 minutes, was Whitson’s tenth. She now holds a new record, having spent a total of 60 hours and 21 minutes in extravehicular activity (EVA), bringing her to third in the world in time spent on spacewalks.
When a multiplexer-demultiplexer (MDM) external computer, used to control various systems on the ISS, malfunctioned on Saturday, May 20, NASA ordered an emergency spacewalk to replace it.
Redundancy is built into the system, with two external computers capable of controlling the same systems. Although a single computer can do the job on its own, NASA sought to restore the redundancy as quickly as possible.
One of two second-tier computers that relay commands to the space station’s control system, guidance, navigation, cooling system, stabilizing gyros, and environmental control, the MDM was installed along with its companion during a late-March spacewalk.
Whitson inspected the malfunctioning computer after removing it but found no damage to its electrical connectors and was unable to determine the cause of its failure.
Working on the space station’s Earth-facing side, she expressed amazement upon viewing the planet 250 miles below her.
“Oh my gosh, so beautiful!” she exclaimed.
Fischer, who successfully installed the wireless antennas designed to improve wireless communications on future missions, came to Whitson’s aid with a cleaning tool when, in installing the replacement computer, she discovered the primary bolt to be less secure than expected.
To remove debris from the primary bolt hole and secondary fittings for the computer, the astronauts sprayed the openings with compressed nitrogen.
Once tests showed the replacement computer to be functioning normally, Whitson and Fischer concluded the spacewalk.