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 6:30 a.m. EDT 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.