Shuttle Discovery might have avoided serious damage from the foam insulation that flew off the external fuel tank during liftoff, escaping the ill fate of Columbia, US space agency NASA said on Thursday.

A big chunk of foam insulation flew off the shuttle Discovery 's fuel tank during its liftoff Tuesday. NASA decided to ground all future space shuttle missions because foam debris that brought down the shuttle Columbia is still a risk.

Keeping an alert eye on Discovery, NASA managers said that foam loss did not hit the orbiter. "It looks extremely good and we don't have anything to worry about on Discovery," said flight operations manager John Shannon.

NASA Administrator Michael Griffin also confirmed that Discovery appeared to be healthy by now. "There was no indication the piece of foam sighted Tuesday caused any damage to Discovery," he said in a statement.

The shuttle did a somersault maneuver to allow the astronauts on the International Space Station (ISS) to photograph the shuttle 's belly for signs of damage. Discovery later docked with the station to deliver long-awaited supplies and replacement parts, NASA said.

Engineers said the foam might be 50 to 60 centimeters long, 20 to 30 centimeters wide, and just a few centimeters thick, very similar to the chunk that hit Columbia's left wing during liftoff in January 2003.

The Shuttle will undergo further inspection beginning Thursday to check for any significant damage to the orbiter, according to Griffin. He noted that the space agency may never be able to prevent threatening chunks of insulation foam from breaking off the shuttle's fuel tank during launch.

"As with any unexpected occurrence, we will closely and thoroughly evaluate this event and make any needed modifications to the Shuttle before we launch again," Griffin said.

"This is a test flight. Among the things we are testing are the integrity of the foam insulation and the performance of new camera equipment installed to detect problems. The cameras worked well. The foam did not."

In addition to the big chunk of foam, several smaller pieces broke off during the launch. Thermal tile was also damaged on Discovery's belly soon after liftoff; one tile lost a 3-centimeter piece right next to the set of doors for the nose landing gear, a particularly vulnerable spot.

But deputy shuttle manager Wayne Hale said none of the tile damage looked serious and likely would not require repairs in orbit.

Source: Xinhua