Discovery Patched up in Historic Spacewalk

US astronaut Stephen Robinson carried out a risky repair to Discovery on Wednesday pulling out two ceramic fibers that experts feared could have caused the shuttle to overheat when it returns to Earth. But experts have still not decided what to do about a thermal blanket below the cockpit that is also causing concern.

Dangling at the end of a 17.7 meter (58 feet) long robotic arm with a hacksaw and forceps, Robinson became the first astronaut to carry out a spacewalk beneath the shuttle during orbit. He easily pulled out the two problematic protruding pieces of ceramic fiber under the nose of Discovery within minutes of each other. Robinson was accompanied on the six hour and one minute walk outside the shuttle by Japanese astronaut Soichi Noguchi.

While the removal of the protruding gap fillers took only about 40 minutes, Robinson and Noguchi stayed outside the ISS for several hours to work on other planned maintenance jobs.

Concerns alleviated by repairs to ceramic fibers

The operation lifted one of the doubts about Discovery's safety as it prepares to Earth on August 8. Engineers had feared that the gap fillers between the thermal ceramic tiles could upset the stability of the shuttle as it re-enters the Earth's atmosphere and cause it to overheat in a similar way to the Columbia disaster on February 1, 2003.

The shuttle travels at about 26,500 kilometers per hour (16,700 mph) into the atmosphere, pushing temperatures on the shuttle skin to 1,370 degrees Celsius (2,500 Fahrenheit) during reentry. The contour of the vessel's belly has to be smooth to make sure it does not overheat.

A crack in the Columbia shuttle's thermal shield caused by a piece of foam that hit the wing during liftoff was blamed for its destruction, which killed all seven crew on board. Discovery is the first shuttle mission since the Columbia tragedy.

The images of falling debris after the Discovery's launch on July 26 (photo) were reminiscent of the Columbia disaster.

But Professor Berndt Feuerbacher from the German Aerospace Center in Cologne says the Discovery launch was successful and hopes that flights will resume soon.

"In the past, when the shuttle was up there, there were always about 50 tiles missing when it was back and they were refurbished and put back on for the next flight," Feuerbacher said. "Now we are much more careful and even if a single tile is missing we are trying to repair it because this tragic accident has happened. And I think that's the right way of looking we shouldn't take any risk when we send up people up to space."

German astronaut's big chance in the balance

Germany has a lot riding on the success of the Discovery mission with their astronaut, Thomas Reiter (photo). He is one of many astronauts waiting for the return to flight.

"Yes, we were expecting Thomas to fly on Sept. 9. This has now been delayed. We don't know how long but we still count on him being up there in the near future," Feuerbacher added.

ESA projects facing unknown delays

The problems now will probably delay further space projects, including the German one involving Reiter and the implementation of the European Space Agency's (ESA) Columbus laboratory on the International Space Station (ISS). The laboratory should be brought into space in late 2005, a date which is now in question.

The science module Columbus is ESA's biggest single contribution to the ISS. The 4.5-meter cylindrical module should give a boost to the station's research capabilities.

In future, earth-based researchers, with help from the ISS-crew, should be able to conduct thousands of experiments in life sciences, materials science, fluid physics and a whole host of other disciplines, all in the weightlessness of orbit. For ESA, bringing the laboratory into space is essential.

"We would like to make the best use of what we have without endangering the crew. I think this is the policy that we are following," said Feuerbacher. "In Europe we have built the Columbus laboratory, we want to have the Columbus laboratory attached to the space station and we want to make use of it in terms of scientific and commercial activities on board."

A full assessment of images taken of Discovery is underway and further assessments will take a few more days.