Astronauts prepare for unprecedented shuttle repairs
Discovery’s astronauts are preparing for a high-stakes task that’s never before been attempted: sending a spacewalker beneath the craft to repair filler sticking out from ship’s thermal tile belly.
Nasa says the protruding material could cause dangerous overheating during re-entry and lead to another Columbia-type disaster.
The agency will put astronaut Stephen Robinson on the space station’s 58-foot robotic arm tomorrow as part of an unrehearsed manoeuvre. The arm will be operated by astronauts inside the station, who will bend and wrap Robinson around so he can reach the shuttle’s belly.
Once there, he’ll tug out the ceramic-fabric filler with his gloved hands. If that doesn’t work, he’ll cut away the material, which is sticking out about an inch from two spots near Discovery’s nose.
Deputy shuttle program manager Wayne Hale said if the proposed methods did not work, there would likely be some head-scratching for a day. However, he said the agency would find another method and try the repair again on Thursday or Friday.
Engineers simply don’t know enough about any potential problem that could be caused by the protruding gap fillers, some of which protect tiles from htting one another during launch.
Hale said the decision to attempt the repairs was simple and a way “to set our minds at rest”.
“The bottom line is there is large uncertainty because nobody has a very good handle on the aerodynamics at those altitudes and at those speeds,” Hale said. “Given that large degree of uncertainty, life could be normal during entry or some bad things could happen.”
Discovery Commander Eileen Collins told Mission Control early today that her crew would reschedule its joint meal with the space station’s crew and instead focus on procedures for the mission’s third spacewalk, expected to take seven hours.
Robinson and his spacewalking partner, Soichi Noguchi, will still install a tool platform onto the space station. But once the installation is complete, the spacewalk will alter from the way it was carefully choreographed before last week’s launch.
Mission Control told Collins that spacewalk trainers would be in early today to discuss the repairs with Robinson, who along with Noguchi spent more than 300 hours training in a pool where they were weighted down to simulate the zero gravity environment in space.
Spacewalk instructor Cindy Begley said Robinson was going to have to be careful not to cause any additional damage while under Discovery. He’ll have to secure his safety tethers behind him and leave any tools he won’t need for the repair behind.
“The first attempt is going to be to pull it out,” Begley said of the filler. “We don’t expect that to take a lot of force. If it seems to be taking a lot of force, then we are going to look at cutting it off.”
Aboard Discovery today, astronaut Andy Thomas prepared Noguchi’s and Robinson’s spacesuits for tomorrow’s early morning outing. He also assisted the spacewalking pair in constructing a makeshift hacksaw for gap-filler repair.
Astronauts James Kelly and Wendy Lawrence, meanwhile, were aboard the space station reviewing how they would operate the station’s arm so Robinson’s hands would be close enough to make the repairs, but his feet far enough away not to cause any additional damage
Kelly and Lawrence seemed pleased with the plan.
“We wouldn’t change a thing,” Kelly radioed Mission Control. “We think it is great. We will be ready to fly tomorrow.”
Discovery will remain docked at the station until Saturday. The shuttle is set return to Earth early on Monday.
