Astronauts Christina Koch and Jessica Meir will venture outside the International Space Station late this week to replace a power controller that failed during the weekend. The spacewalk, the first ever that will be conducted by two women, is planned for Thursday or Friday.
Station managers decided to postpone previously planned spacewalks that had been set to install new batteries this week and next in order to replace the faulty power unit, called a Battery Charge/Discharge Unit (BCDU). The station’s overall power supply, which is fed by four sets of batteries and solar arrays, remains sufficient for all operations, and the failed unit has no impact on the crew’s safety or ongoing laboratory experiments. However, the failed power unit does prevent a new lithium-ion battery installed earlier this month from providing additional station power.
The battery charge/discharge units regulate the amount of charge put into the batteries that collect energy from the station’s solar arrays to power station systems during periods when the complex orbits during nighttime passes around the Earth. Two other charge/discharge units on the affected 2B power channel did activate as planned and are providing power to station systems.