Expedition 39 is finalizing preparations for a 2.5 hour spacewalk scheduled to begin 9:20 a.m. EDT Wednesday. The station crew is also getting ready to send off a Russian space freighter for two days of tests before it redocks again Friday morning.
Spacewalkers Steve Swanson and Rick Mastracchio will install a spare backup computer on the S0 truss located on top of the Destiny laboratory module Wednesday morning. They will remove the old computer which failed April 11 after being shut down then restarted for a periodic health check.
The duo was joined by Commander Koichi Wakata for a short spacewalk procedure conference. The trio also set up the Quest airlock, where they will stage their excursion, and readied spacewalk tools.
Known as a Multiplexer/Demultiplexer (MDM), the backup computer provides telemetry and commands to truss systems, solar alpha rotary joints and the Mobile Transporter rail car which rides along the truss structure. Both MDMs have been at the International Space Station for over 10 years.
There are 45 MDMs throughout the space station. There are 24 inside the orbital laboratory and 21 located externally.
Before Wednesday’s spacewalk, an ISS Progress 53 resupply ship will undock from the Zvezda service module at 4:58 a.m. It will back away about 311 miles from the space station. It will return back to the Zvezda docking port Friday morning after Russian flight controllers have tested its new Kurs automated rendezvous system.
Flight Engineer Mikhail Tyurin closed the hatches to the Progress Tuesday morning and conducted leak checks. He also set up video gear to record its undocking, separation and eventual re-rendezvous and redocking to the station.
The last time a Progress cargo freighter pulled away from the station and redocked was in July 2012. The ISS Progress 47 space freighter undocked from the Pirs docking compartment for eight days of testing before redocking to the same port. Russian flight controllers were also testing its new Kurs automated rendezvous system.
Cosmonauts Alexander Skvortsov and Oleg Artemyev worked throughout the station’s Russian segment on a host of science and maintenance tasks Tuesday. They performed light plumbing work, checked air ducts and adjusted a gas analyzer. Science work included observing the veins of a crew member’s legs, studying macroparticles in a magnetic field and Earth observations.