Shuttle undergoes thorough exam

Astronauts inspect possible damage to Discovery with robotic arm.

CAPE CANAVERAL, Fla. -- Astronauts orbiting Earth aboard Discovery spent Wednesday using a robotic arm to inspect their space shuttle's heat shield for any damage it might have incurred during its thunderous launch from Florida one day earlier.

Pilot Jim Kelly and mission specialists Andy Thomas and Charlie Camarda used the arm to wave a boom, equipped with a laser scanner, over Discovery's wings and underbelly to look for cracks or holes as small as a quarter-inch.

The tedious examination, just one of numerous safety improvements NASA has instituted since another space shuttle suffered catastrophic damage in January 2003, offered ground controllers two- and three-dimensional views of regions they could not examine before.

At Mission Control in Houston, NASA officials didn't immediately offer an analysis of the flickering black-and-white images from space. But they continued to express vague concern about other video that shows at least two pieces of debris peeling away from the Discovery and its redesigned external fuel tank about two minutes after the shuttle bolted skyward from Kennedy Space Center on Tuesday.

One piece of debris has been identified as a small chip of thermal tile from the black-coated underbelly of the orbiter, near a critical seal protecting its nose landing gear door. The larger piece, which has not been identified, came off the shuttle's redesigned rust-colored external fuel tank.

Engineers analyzing launch photography "found some things that they are concerned about on the tank," lead flight director Paul Hill said during a news conference Wednesday. He told reporters that he had not been involved in the analysis and couldn't provide details. Mission managers met later in the day to review the ongoing analysis and were scheduled to update the media after the meeting.

They informed the astronauts of their concerns, although mission management team leader Wayne Hale said there was no indication so far that the problem was serious. "We are paying very serious attention to this," Hale told reporters. "This is something that we have spent the last two years preparing for."

Discovery's 12-day mission is the first since the space shuttle Columbia disaster. Columbia's left wing took a hit from a chunk of insulating foam that popped off its fuel tank during launch. The debris poked a hole that went unnoticed, leading to the shuttle's destruction - and the deaths of seven astronauts -- during atmospheric re-entry on Feb. 1, 2003.

NASA redesigned the tank and changed the way foam is applied in an effort to keep it from coming loose, but wasn't able to eliminate every debris hazard. A key objective of Discovery's mission is to test new tools and techniques for inspecting the heat shield in flight and repairing it, if necessary.

The tools include the laser scanner, mounted on the end of a 50-foot-long boom that serves to double the length of the shuttle's robotic arm. The astronauts operated it from a workstation in Discovery's cockpit. Their methodic survey took about five hours, and will be repeated Friday.

Mission managers are using the two scans -- along with new views from dozens of cameras on the ground, on airplanes and on Discovery itself - to gauge their success in improving shuttle safety since the tragedy.

Columbia accident investigators required NASA to enhance launch photography before it returned shuttles to flight. Additional pictures will be taken later this week by an astronaut and a cosmonaut aboard the International Space Station as Discovery pulls up to dock and deliver supplies.

Mission managers expect to complete their exhaustive analysis - and determine whether the shuttle sustained damage that must be repaired before re-entry - by Sunday.