NASA: Undocked shuttle to use robotic arm to inspect heat shield

Now undocked from the space station, Discovery begins two days of safety inspections

After undocking from the International Space Station this afternoon, the crew of the space shuttle Discovery quickly began two days of inspections to make sure it can survive the trip home. The astronauts leave after installing the S6 truss and attached 5,000-pound solar arrays last week.

After being docked together for 7 days, 22 hours and 34 minutes, the two spacecraft parted at 3:53 p.m. EDT today. About a half an hour after the undocking, the shuttle and station began an hour-long process of taking pictures of each other. The images will be sent to NASA engineers on the ground who will study them as part of an effort to determine whether the shuttle suffered any damage to its thermal protection system, which protects the craft and its seven-person crew from blazingly high temperatures that come during reentry into the Earth's atmosphere.

The shuttle inspection continues Thursday morning when the crew will use Discovery's onboard robotic arm, dubbed Canadarm, and an attached laser imager to inspect the external tiles that make up shuttle's heat shield, along with its nose cone and the edges of its wings. Again, engineers on the ground will examine the images and data to check Discovery's thermal protection system.

Discovery is scheduled to land at 1:43 p.m. EDT Saturday at the Kennedy Space Center in Florida.

NASA has been especially diligent about studying the heat shields since the space shuttle Columbia broke apart on reentry on Feb. 1, 2003. According to NASA, an investigation found that the disaster was caused by a hole in the heat-resistant panels that protected the wing from the high temperatures of reentry. The hole allowed superheated air into the wing, which was destroyed by it, sending the shuttle spinning out of control before it broke apart.

While the Canadarm 2 will be critical to inspecting the space shuttle on Thursday, it was also a key part of work that was done to the space station during this mission.

NASA reported last week that two robotic arms played critical roles in the installation of what essentially is the last piece of the backbone of the International Space Station. Canadarm, the robotic arm aboard the space shuttle, and a robotic arm on the space station dubbed, in turn, Canadarm 2, were used to unload the truss from the space shuttle's cargo bay. Then the robotic arm on the space station maneuvered the truss into place while the space walkers watched to make sure it was aligned exactly. Then the astronauts screwed in the bolts while Canadarm 2 held the truss in place.

This past Monday, two NASA astronauts spent part of their last spacewalk of this mission lubricating the robotic arm on the space station. The astronauts oiled up the wire snares in the arm's gripper mechanism, which had been sticking.

Copyright © 2009 IDG Communications, Inc.

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