Expedition 39 US-EVA 26 Spacewalk

After the success of US-EVA 26 spacewalk by Expedition 39 astronauts, I’m presenting the sequence of the EVA with the ISS model.
Astronauts Rick Mastracchio and Steve Swanson replaced a failed computer on the ISS’s power truss on April 23, 2014, efficiently racing through a short spacewalk to restore full functionality to a critical control network.
Mastracchio was designated EV-1 with red stripes suit and Swanson was EV-2 with solid white spacesuit, and their task was to swap a failed computer called the External 2 Multiplexer-demultiplexer (MDM). The MDM relays commands between computers and systems outside the space station, such as the solar array rotary joints, thermal coolant loops, the robotic arms’s mobile transporter, and other functions. The failed MDM was launched inside the S0 truss back in April 2002. It was in backup mode when it failed on April 11.

This photo shows the big picture where the EVA took place.


The EVA started when the astronauts exited the Space Station’s Quest Airlock.


The astronauts then climbed the Airlock Spur (1) towards the S0 truss segment at the center of the station’s structural backbone.



This is the area on the S0 truss where the failed MDM is located.



This is a closeup view of the working area. The failed MDM is the small box shown here.


Less than an hour into the spacewalk, Mastracchio had removed the failed MDM and driven three bolts to affix a new unit that was brought by Swanson. Swanson carried the bag containing a fresh EXT MDM.
The new computer was affixed in its housing on the S0 truss. An initial test of the new computer showed it was healthy.

The replacement of the MDM ensures space station ground controllers have full insight and command capability for several key systems on the station’s truss.
The EVA was completed when the astronauts returned to the Quest Airlock.

This reference was obtained from Spaceflightnow.com website.
In regards to the ISS paper model, this EVA has no effect on making changes to the model.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s