NASA: Astronauts on spacewalk oiling up sticky robotic arm

Outer space maintenance -- shuttle astronauts fix latch and grease up Canadarm 2

On their third and final spacewalk in the latest NASA shuttle mission, two astronauts are trying to fix a broken latch and lubricate the robotic arm on the International Space Station.

NASA Astronauts Joseph Acaba and Richard Arnold began today's spacewalk at 11:37 a.m. Eastern time. They're not expected to wrap it up and reenter the space shuttle Discovery until 6:13 p.m. A fourth spacewalk was initially planned for this shuttle mission, but was cut when the launch was delayed earlier this month because of a gas leak in an external fuel tank.

The astronauts took the first two spacewalks last week mostly to unload and set up the S6 truss, which is the last piece of the backbone of the space station. NASA said last week that after installing the truss, which has a 5,000-lb. set of solar arrays attached to it, work on the space station now is 81% complete.

The solar arrays already are generating power for the space station. The arrays are designed to produce enough energy to power 42 2,800-square-foot homes. That will double the amount of power -- from 15 kilowatts to 30 kilowatts -- that goes to science experiments on board the station.

It also means that the space station can now support a crew of six to eight astronauts. Right now, there is a crew of three aboard the station, but that number is expected to be bumped up to six this May because of the extra energy capacity.

Today's spacewalk, though, will focus on several smaller jobs.

Kelly Humphries, a NASA spokeswoman, said that Acaba and Arnold will be trying to fix a latch on an external payload attachment grid. The grid is a platform that could hold experiments or anything else that needs to be held outside the space station. The lock on the latch wasn't working right. Humphries added that a bolt appears to be the problem.

Among other jobs, the astronauts will also be lubing the gripper on Canadarm 2, which is a robotic arm designed for big, heavy jobs -- like lifting the truss and solar arrays out of the shuttle's cargo bay last week. The robotic arm has a series of wire snares that are part of the gripper mechanism. Humphries said the wires have been sticking so the spacewalkers will inject grease all around them to nothing gets hung up in the future.

Copyright © 2009 IDG Communications, Inc.

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