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Astronauts Complete Short Spacewalk To Replace Backup Computer

April 23, 2014
Image Caption: Steve Swanson works on a rack inside the Kibo laboratory. Credit: NASA TV

[ Watch the Video: Astronauts Replace Backup Computer During Spacewalk ]

NASA

UPDATE: April 23, 2014 (10:35AM CDT)

NASA Astronauts Steve Swanson and Rick Mastracchio have completed a short spacewalk to replace a failed Multiplexer/Demultiplexer (MDM) back up computer. They began the re-pressurization of the Quest airlock at 11:32 a.m. EDT signifying the excursion’s end time.

The backup computer failed April 11 after a routine health check by the Mission Control team in Houston. While the primary computer continues operating flawlessly NASA managers ordered the spacewalk repair to ensure redundancy on critical

The duo worked on the S0 truss which is where the backup MDM is located. The truss is located above the Destiny laboratory module and forms the center of the station’s Integrated Truss Structure, or backbone. The MDM provides telemetry and commands to truss systems, solar alpha rotary joints and the Mobile Transporter rail car which rides along the truss structure.

Swanson and Mastracchio installed a spare MDM that was housed inside the Destiny lab since April 2001 when it was delivered aboard space shuttle Endeavour. They removed the failed MDM from the S0 truss where it has been located since the truss was delivered with the MDM already inside in April 2002. The station houses 45 MDMs, 24 internally and 21 externally.

Station and SpaceX managers decided the computer failure wouldn’t impact Sunday’s arrival of the Dragon commercial cargo craft on the SpaceX-3 mission. After an engineering review of the station’s systems it was determined the station had enough redundancy for SpaceX-3 to begin its mission when it launched Friday afternoon aboard a Falcon 9 rocket.

A few hours earlier today an ISS Progress 53 resupply ship undocked from the Zvezda service module. It will back up about 311 miles from the space station so Russian mission controllers can test its upgraded Kurs automated rendezvous system. The Progress will redock again Friday at 8:15 a.m. to the Zvezda service module after the Kurs tests are complete.

UPDATE: April 23, 2014 (9:25AM CDT)

NASA Astronauts Steve Swanson and Rick Mastracchio have stepped outside the International Space Station for a short spacewalk to replace a failed Multiplexer/Demultiplexer (MDM) back up computer. They set their spacesuits to battery power at 9:56 a.m. EDT signifying the excursion’s official beginning time.

The backup computer failed April 11 after a routine health check by the Mission Control team in Houston. While the primary computer continues operating flawlessly NASA managers ordered today’s spacewalk repair to ensure redundancy on critical systems. The computer outage did not pose a risk to the six crew members aboard the space station.

The duo is working on the S0 truss which is where the backup MDM is located. The truss is located above the Destiny laboratory module and forms the center of the station’s Integrated Truss Structure, or backbone. The MDM provides telemetry and commands to truss systems, solar alpha rotary joints and the Mobile Transporter rail car which rides along the truss structure.

Swanson and Mastracchio are installing a spare MDM that was housed inside the Destiny lab since April 2001 when it was delivered aboard space shuttle Endeavour. They will remove the failed MDM from the S0 truss where it has been located since the truss was delivered with the MDM already inside in April 2002. The station houses 45 MDMs, 24 internally and 21 externally.

Station and SpaceX managers decided the computer failure wouldn’t impact Sunday’s arrival of the Dragon commercial cargo craft on the SpaceX-3 mission. After an engineering review of the station’s systems it was determined the station had enough redundancy for SpaceX-3 to begin its mission when it launched Friday afternoon aboard a Falcon 9 rocket.

A few hours earlier today an ISS Progress 53 resupply ship undocked from the Zvezda service module. It will back up about 311 miles from the space station so Russian mission controllers can test its upgraded Kurs automated rendezvous system. The Progress will redock again Friday at 8:15 a.m. to the Zvezda service module after the Kurs tests are complete.

ORIGINAL: April 23, 2014 (5:30AM CDT)

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.


Source: NASA



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