HOUSTON (Reuters) - Shuttle Atlantis astronauts used cameras on a robot arm to inspect their spacecraft on Wednesday to see if a mystery object seen falling near the ship posed a threat to its safety.
The scan was the third of the mission and had not been scheduled until the object was spotted on Tuesday, creating concern that a key component, such as a piece of the heat shield that protects the shuttle during its fiery descent to Earth, had broken off.
Atlantis was supposed to land at Kennedy Space Center in Florida on Wednesday, but the mystery object and a forecast of bad weather led NASA to postpone the shuttle's return until at least Thursday.
The previous inspections, on Sept. 10 and 18, revealed no damage. NASA managers said the unidentified object was most likely harmless debris, but they ordered the latest survey just to be sure.
The U.S. space agency operates under much stricter safety rules since shuttle Columbia broke apart while landing on Feb. 1, 2003, due to heat shield damage that went undetected.
The accident killed Columbia's seven astronauts and caused NASA to ground the shuttle program for 2 1/2 years.
The Atlantis mission follows two test flights to refine post-Columbia safety upgrades and was the first of at least 15 flights to complete the half-finished International Space Station by 2010, when shuttles will be retired.
Atlantis was on its way back from the station, where its crew installed a $372 million solar power unit and truss structure, when the dark object was seen during television shots from Atlantis.
PIECE OF PLASTIC
Shuttle program manager Wayne Hale said in a Tuesday evening briefing that the object could be ice or perhaps a small piece of plastic that came loose when the Atlantis crew tested flight controls on Tuesday morning.
The plastic piece, a spacer between heat shield tiles, was seen hanging out during an earlier survey and deemed non-threatening.
"That could be what we saw," he said. "It's not held in there by anything but friction. By the shock (of the tests), it could have floated away."
A second smaller object was spotted later on Tuesday by Atlantis flight engineer Dan Burbank, but Hale said it appeared to be "just a plastic bag that came from somewhere (in the shuttle) and got loose."
Should the inspection turn up something worrisome, the shuttle could go back to the space station for further assessments or to wait for a rescue mission for its crew.
A return to the station would make things crowded there because a Russian Soyuz spacecraft carrying cosmonaut Mikhail Tyurin, U.S. astronaut Michael Lopez-Alegria, and American tourist Anousheh Ansari arrived early on Wednesday after launch on Monday from Kazakhstan.
With the station's newly-installed 73-metres solar-power array in the background, Soyuz could be seen in television shots creeping toward the space outpost 352 km above Earth before docking with a gentle bump.
"We have arrived," Tyurin said.
He and Lopez-Alegria will replace Jeff Williams and Pavel Vinogradov, who have been on the station for six months and are scheduled to return to Earth with Ansari on Sept. 28.
German astronaut Thomas Reiter will stay aboard with the new station crew until his replacement arrives during the next shuttle mission, currently scheduled for December.
Did you find this article insightful?