In this image released by NASA TV, a camera attached to the space shuttle Discovery's robotic arm shows astronaut Steve Robinson going under the underside of the Discovery to remove gap fillers in this view from television Wednesday, Aug. 3, 2005

Crewmembers of the space shuttle Discovery say they are impressed by technology and procedures used to make the mission a success.

With the shadow of the Columbia disaster never far from their minds, Discovery's astronauts discussed the chunk of foam insulation that broke away from the external fuel tank during launch of the shuttle two weeks ago.

A similar incident doomed the Columbia two and a half years ago when a larger piece of hard foam struck the space shuttle's wing, causing the vehicle to burn up during reentry into the earth's atmosphere, killing all seven astronauts.

This time around, the foam did not strike the shuttle.  But Discovery's many cameras showed the exterior fabric used to fill in gaps between the heat tiles was sticking out.  NASA engineers worried that if the strips were not removed, they could cause dangerous overheating during reentry.

NASA devised a plan for astronaut Steve Robinson to make an unprecedented external repair of the space shuttle to remove the gap fillers.  Attached to the end of a robotic arm operated by astronaut Wendy Lawrence, Mr. Robinson gave a gentle tug and the gap fillers came out.

Mr. Robinson says the operation proved it may be possible to make other external repairs in the future.

Steve Robinson pulls out a protruding piece of filler fabric from between heat tiles on the underside of the Discovery orbiter

"I felt like I could have performed various types of repair.  I felt very well stabilized.  The lighting was very good," said Mr. Robinson.

The Discovery did sustain some minor damage to heat tiles from launch debris.  Crewmember Charlie Camarda says photographs taken of Discovery during the mission proved to be extremely accurate on the ground.

"The first thing I noticed when I looked at the vehicle, walked under the vehicle, looked at the leading edges, I was amazed at how clean the vehicle was," said Mr. Camarda.  "And so a lot of people have hypothesized that, when we hit the ground, when we land, we incur some damage.  So, I think the damage we see in orbit, we see on the ground.  That damage was minimal."

The Discovery crewmembers agree the problem with the insulating foam has to be taken care of before any future shuttle flights.  But they believe the technology and procedures adopted in the wake of the Columbia disaster will help ensure the safety of future missions.