Over the weekend, a data relay box on the International Space Station failed, causing NASA to green light a spacewalk for the two American astronauts on-board. Expedition 51 Commander Peggy Whitson and her colleague Jack Fischer will venture outside the station for an extra-vehicular activity, better known as a spacewalk, to repair the box.
NASA’s official name for the data relay box is multiplexer-demultiplexer, or MDM. There’s two of them in the truss of the ISS, which are the arms that extend off either side where the large solar panels are connected. According to NASA, the MDM’s are responsible for controlling “the functionality of radiators, solar arrays, cooling loops and other station hardware.”
Essentially, that means they’re the brains behind controlling the power and heat management both inside and outside the station. So it’s an important job. That’s why Whitson and Fischer are replacing the faulty one as soon as possible. NASA built two into the system to maintain redundancy, and one is still functioning.
The spacewalk is set for May 23, and Whitson and Fischer are scheduled to leave the station around 7 AM CDT. If the duo can get in their suits and be ready earlier, it could start earlier.