(Photo/Chinanews.com)

NASA astronauts Jack Fischer and Peggy Whitson completed urgent repairs at the International Space Station during a two and a half-hour spacewalk, replacing a critical computer relay box that failed on May 20, the Associated Press reported on May 23.

The box, known as a multiplexer-demultiplexer, or MDM, is one of the two MDMs that regulate the station’s radiators, solar arrays and cooling loops. The failed relay box was installed on March 30 by Whitson and Shane Kimbrough.

(Photo/Chinanews.com)

The spacewalk lasted less than three hours, which was longer than expected. The operation was ultimately successful, concluding after Whitson screwed the bolts into place. The spacewalk - Whitson's 10th and Fischer's second - was the 201st space station maintenance operation.