Contingency EVA Set For Tuesday
Astronauts Prepare For Contingency Spacewalk
“Astronauts Peggy Whitson and Jack Fischer are getting ready for a contingency spacewalk Tuesday morning. Whitson and Fischer are set to begin the spacewalk at 8 a.m. Tuesday for about two hours of maintenance work. The spacewalk’s primary task is the removal and replacement of a data relay box, known as a Multiplexer-Demultiplexer (MDM), which failed Saturday morning. The MDM controls the functionality of station components such as the solar arrays, radiators, cooling loops and other systems.”
These MDMs do not seem very reliable. This one was just installed. I would be curious to know why they are failing. My guess would be inadequate micro meteor or radiation protection. An electronics product should not fail so quickly.
I’d bet on radiation over micrometeorites. The multiplexers I’m familiar with are inherently less radiation hard than other sorts of microelectronics. But even that doesn’t seem likely. This a known problem with known solutions, and in a known radiation environment.