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ISS Crew Prepares for Final Spacewalk

The third EVA will be the last for STS-119

Mar 23, 2009 14:08 GMT  ·  By
Astronaut Steve Swanson is seen here loosening the screws that affix a battery set on the ISS. The move will make it easier for another mission to change them
   Astronaut Steve Swanson is seen here loosening the screws that affix a battery set on the ISS. The move will make it easier for another mission to change them

At this time, the third spacewalk of the STS-119 shuttle mission to the International Space Station is already underway, as astronauts are attempting to fix a loose pin that has hindered the deployment of the station's cargo holders, located on the exterior walls of the orbital lab. During today's extra-vehicular activity (EVA), Discovery astronauts Joseph Acaba and Richard Arnold II, both former school teachers, will attempt to fix the problem and restore the ISS to its full functionality.

The jammed cargo platform on the lab's truss rod is of paramount importance for the $100-billion international project, as it's the place where all the back-up components of the ISS will be stored for the five years between 2010 and 2015, when the space shuttle will be retired, and there will be no other similar vehicle capable of delivering the payloads that Discovery, Atlantis and Endeavor can. Re-supplying will be left to the Russian Soyuz craft and the European Verne ATV.

The astronauts will exit the International Space Station airlock at 11:43 am EDT (1543 GMT), in a mission that is expected to last well over 6 hours. In addition to having to fix the jammed pin, the two astronauts will also have to deploy similar cargo containers at the other end of the ISS as well, which is definitely going to take a lot of time to do. “The fix for it may be as simple as simply pulling on in harder. But this is only a theory. We won't really know until we get the spacewalker at the site,” Kwatsi Alibaruho, lead space station flight director for the Discovery mission, said on Sunday.

In addition to deploying the two platforms, Acaba and Arnold will also have to add a little grease to the ISS' robotic arm (Canadarm2) in order to make sure that its “grasp” is in perfect order. Then, they will rearrange a cargo cart from one side of the facility's Mobile Transporter to the other, in order to make more room for the robotic arm. This will help future missions, which will benefit from more mobility and versatility in the robotic mechanism.