lawyerlee
08-02-2005, 08:17 AM
Astronaut to make first in-flight repair[/b] (]CNN
JOHNSON SPACE CENTER, Texas (CNN) -- Discovery astronauts were gearing up Tuesday for a history-making repair Wednesday to remove filler material sticking out from between heat-resistant tiles in two places on the shuttle's underbelly.
"It's conceptually very simple, but has to be done very, very carefully," said Steve Robinson, the astronaut who will be dangled from a robotic arm on the international space station and maneuvered to the bottom of Discovery to remove the gap fillers -- thin fabric stiffened with a ceramic material that is used to plug gaps between tiles on the orbiter.
NASA managers decided Monday to attempt the repair after an analysis showed the protrusions might produce excessive heat during re-entry and threaten the spacecraft.
"It was prudent to take action so that we wouldn't have to worry about some of the worst consequences," said Wayne Hale, NASA's deputy shuttle program manager, at a news conference Monday. "If we can't prove that it's safe, then we don't want to go there."
Robinson's assignment will mark the first time NASA has ever tried to repair the exterior of a shuttle in orbit, a capability developed in the wake of the 2003 Columbia disaster.
The Columbia shuttle disintegrated over Texas, killing all seven crew members, as it returned from space.
Andy Thomas, another member of the Discovery crew, acknowledged that the crew had initial "misgivings" about the repair, scheduled to take place during Wednesday's scheduled spacewalk. "We were concerned about the implications of it and what was motivating it," he said. "However, it's a lot better...(to) remove this material."
Discovery commander Eileen Collins agreed. "This situation, I believe, will certainly be safer for entry. I'm actually not that worried about it," she when asked how she felt about returning to Earth in a repaired shuttle.
The removal of the gap fillers is being added to the list of tasks set out for the spacewalk, during which astronauts will also install an external storage platform to the space station.
Robinson will first try to pull out the gap fillers, which are glued between the tiles. "It'll be a gentle pull with my hand," Robinson said of the repair, which will last approximately 90 minutes. "If that doesn't work I have some forceps, I'll give a slightly more than a gentle pull." If that doesn't work, he said he will use a saw to remove the fillers. There will be "no yanking," he said.
During the procedure, Robinson will only be visible to the other members of Discovery's crew via a camera on the space shuttle's boom. A second astronaut, Soichi Noguchi, will be spacewalking at the same time, but he will be working on other tasks.
President Bush called the crew Tuesday and expressed his support for the mission and the space program.
He thanked the astronauts for being "risk takers for the sake of exploration."
"We look forward to the successful completion of this mission," he said.
The protruding gap fillers were discovered during an extensive inspection of Discovery's exterior, carried out by cameras and lasers on a new boom on the space shuttle. The crew of the space station also photographed the underbelly of the shuttle before it docked last Thursday, part of a new inspection regime put in place after the Columbia disaster.
Hale said NASA managers are satisfied that appropriate safeguards are in place to prevent Robinson from damaging the tiles during the repair operation, which could make Discovery's re-entry even more problematic.
Calculations by NASA experts showed that the protrusions could increase the re-entry temperature by 10 percent to 30 percent, possibly exceeding NASA's safety guidelines for how much heat the shuttle's thermal protection system should be allowed to endure, Hale said.
While the protrusions might not pose any threat to Discovery, the "large uncertainty" about their possible effect in the aerodynamics of the shuttle convinced NASA officials to try to fix the problem in space, he said.
Hale said there is no data to show whether previous shuttle missions have managed to return safely with similar protrusions. While extended gap fillers have been found before, they were only discovered after landing, leaving NASA experts with no way to know whether the material shifted before or after re-entry.
Discovery can return safely without either of the gap fillers in place, Hale said. One of them keeps tiles from vibrating against each other during liftoff and has no purpose for re-entry; the other is designed to prevent repeated overheating of a gap between two tiles, but not having it in place during a single re-entry would still be "well within our safety margins," Hale said.
On Monday, Robinson and Noguchi completed their second spacewalk of the mission, during which they replaced a faulty gyroscope on the space station.
JOHNSON SPACE CENTER, Texas (CNN) -- Discovery astronauts were gearing up Tuesday for a history-making repair Wednesday to remove filler material sticking out from between heat-resistant tiles in two places on the shuttle's underbelly.
"It's conceptually very simple, but has to be done very, very carefully," said Steve Robinson, the astronaut who will be dangled from a robotic arm on the international space station and maneuvered to the bottom of Discovery to remove the gap fillers -- thin fabric stiffened with a ceramic material that is used to plug gaps between tiles on the orbiter.
NASA managers decided Monday to attempt the repair after an analysis showed the protrusions might produce excessive heat during re-entry and threaten the spacecraft.
"It was prudent to take action so that we wouldn't have to worry about some of the worst consequences," said Wayne Hale, NASA's deputy shuttle program manager, at a news conference Monday. "If we can't prove that it's safe, then we don't want to go there."
Robinson's assignment will mark the first time NASA has ever tried to repair the exterior of a shuttle in orbit, a capability developed in the wake of the 2003 Columbia disaster.
The Columbia shuttle disintegrated over Texas, killing all seven crew members, as it returned from space.
Andy Thomas, another member of the Discovery crew, acknowledged that the crew had initial "misgivings" about the repair, scheduled to take place during Wednesday's scheduled spacewalk. "We were concerned about the implications of it and what was motivating it," he said. "However, it's a lot better...(to) remove this material."
Discovery commander Eileen Collins agreed. "This situation, I believe, will certainly be safer for entry. I'm actually not that worried about it," she when asked how she felt about returning to Earth in a repaired shuttle.
The removal of the gap fillers is being added to the list of tasks set out for the spacewalk, during which astronauts will also install an external storage platform to the space station.
Robinson will first try to pull out the gap fillers, which are glued between the tiles. "It'll be a gentle pull with my hand," Robinson said of the repair, which will last approximately 90 minutes. "If that doesn't work I have some forceps, I'll give a slightly more than a gentle pull." If that doesn't work, he said he will use a saw to remove the fillers. There will be "no yanking," he said.
During the procedure, Robinson will only be visible to the other members of Discovery's crew via a camera on the space shuttle's boom. A second astronaut, Soichi Noguchi, will be spacewalking at the same time, but he will be working on other tasks.
President Bush called the crew Tuesday and expressed his support for the mission and the space program.
He thanked the astronauts for being "risk takers for the sake of exploration."
"We look forward to the successful completion of this mission," he said.
The protruding gap fillers were discovered during an extensive inspection of Discovery's exterior, carried out by cameras and lasers on a new boom on the space shuttle. The crew of the space station also photographed the underbelly of the shuttle before it docked last Thursday, part of a new inspection regime put in place after the Columbia disaster.
Hale said NASA managers are satisfied that appropriate safeguards are in place to prevent Robinson from damaging the tiles during the repair operation, which could make Discovery's re-entry even more problematic.
Calculations by NASA experts showed that the protrusions could increase the re-entry temperature by 10 percent to 30 percent, possibly exceeding NASA's safety guidelines for how much heat the shuttle's thermal protection system should be allowed to endure, Hale said.
While the protrusions might not pose any threat to Discovery, the "large uncertainty" about their possible effect in the aerodynamics of the shuttle convinced NASA officials to try to fix the problem in space, he said.
Hale said there is no data to show whether previous shuttle missions have managed to return safely with similar protrusions. While extended gap fillers have been found before, they were only discovered after landing, leaving NASA experts with no way to know whether the material shifted before or after re-entry.
Discovery can return safely without either of the gap fillers in place, Hale said. One of them keeps tiles from vibrating against each other during liftoff and has no purpose for re-entry; the other is designed to prevent repeated overheating of a gap between two tiles, but not having it in place during a single re-entry would still be "well within our safety margins," Hale said.
On Monday, Robinson and Noguchi completed their second spacewalk of the mission, during which they replaced a faulty gyroscope on the space station.