May 22, 2017 – NASA astronauts Peggy Whitson and Jack Fischer are preparing for an unscheduled spacewalk outside the International Space Station Tuesday, May 23. Live coverage will begin at 4:30 a.m. MDT on NASA Television and the agency’s website.
Whitson, Expedition 51 commander, and Fischer, flight engineer, will replace a critical computer relay box that failed May 20. The relay box, known as a multiplexer-demultiplexer (MDM), is one of two units that regulate the operation of radiators, solar arrays and cooling loops. They also route commands to other vital station systems.
Because each MDM is capable of performing the critical station functions, the crew on the station is in no danger and station operations are not affected.
The failed relay box was installed in the space station truss March 30 during a spacewalk by Whitson and Expedition 50 commander Shane Kimbrough. Whitson prepared a spare data relay box May 21, and tested components installed in the replacement. She reported the spare MDM is ready to be brought outside to replace the failed unit.
The spacewalk to replace the failed box is planned to last about 2.5 hours. While Whitson is replacing the MDM, Fischer will install a pair of antennas on the U.S. Destiny Laboratory module to enhance wireless communication capability for future spacewalks.
The spacewalk will be the 201st in support of space station assembly and maintenance, the sixth spacewalk conducted from the Quest airlock this year, the 10th for Whitson and the second for Fischer.
Whitson, who already is the leading female spacewalker in history, will be designated extravehicular crew member 1 (EV-1) wearing a suit with red stripes. Fischer will be designated as EV-2, wearing a suit with no stripes.
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