Spacewalk Planned to Change Out Failed Relay Box – NASA https://www.nasa.gov/blogs/spacestation/2017/05/21/spacewalk-planned-to-change-out-failed-relay-box/
International Space Station Program managers met Sunday and gave approval for a contingency spacewalk no earlier than Tuesday by two Expedition 51 crewmembers to change out a multiplexer-demultiplexer (MDM) data relay box on the S0 truss that failed on Saturday morning. The cause of the MDM failure is not known. A final decision on a …
The crew has never been in any danger and the MDM failure, believed to be internal