Holy, there going for it. I can't wait to see the video on this.
Shuttle Repairs to Be Tried in Spacewalk.
By JOHN SCHWARTZ and WARREN E. LEARY
Published: August 2, 2005.
HOUSTON, Aug. 1 - Astronauts will perform a landmark spacewalk on Wednesday morning to remove or clip two tiny strips of stiff cloth that are protruding from the belly of the shuttle Discovery and could cause dangerous heating during the craft's fiery re-entry into the atmosphere, officials said Monday.
Astronauts have never ventured to the underside of a shuttle during orbit or performed a safety-oriented repair during a mission.
At a briefing for reporters on Monday evening, mission managers said they were unsure whether the protruding strips of the cloth, known as gap fillers, were the kind of minor annoyance the shuttles had endured many times or whether they could severely damage the vehicle by disturbing the flow of superheated plasma that surrounds the craft in re-entry.
The decision to try the repairs was made Monday afternoon by members of the mission management team, after they reviewed three days of research and analysis by engineers and scientists from around the nation. It required balancing the substantial risks of conducting a spacewalk, or extravehicular activity, with doing nothing on the assumption that all is well.
"When you go E.V.A.," said N. Wayne Hale, the deputy manager of the shuttle program and chairman of the mission management team, "you always take risks." He added, however, that "it was prudent to take action."
Under some of the calculations, Mr. Hale said, the heat caused by one of the strips could expose panels on the leading edge of a wing to more heat than they were designed to resist. By comparison, he said, "the remedy is easy."
The spacewalk, Mr. Hale said, is straightforward, even though it will take astronauts to a part of the shuttle never visited during a mission and even though incidental damage could occur during the work.
Tools have been selected and gathered for the repairs, which will take place during a previously scheduled spacewalk to install a tool cabinet on the outside of the International Space Station.
The first strategy will be for the astronaut, Stephen K. Robinson, to simply grasp the two gap fillers with his thumb and forefinger and try to pluck them out. If that proves impossible, Mr. Hale said, Dr. Robinson will try to cut them with a blade that has been taped on the ends to prevent it from nicking thermal protection tiles. If that does not work, he will trim them to a quarter of an inch with special scissors designed for use in space.
The underside of the shuttle has thousands of gap fillers. As their name implies, they fill the gaps left between the shuttle's heat-resistant tiles so they do not grind against one another when the shuttle's body flexes under extreme temperatures.
Dangling gap fillers have been found before, and they are generally not considered a serious hazard. For that reason, Mr. Hale said, he did not initially encourage the repairs.
But the two gap fillers, one protruding 1.1 inches and the other 0.6 inches, are the longest ones ever measured so close to the shuttle's nose, where they can do the greatest amount of damage downstream. In 1995, the shuttle Columbia returned from a mission with a gap filler that was 0.9 inches long, or 1.4 inches when it was stretched out, and was 10 feet farther back on the bottom of the craft.
Under the safety-conscious environment at the National Aeronautics and Space Administration since the Columbia disaster in 2003, Mr. Hale said, "if we cannot prove that it's safe, then we don't want to go there."
The shuttle can return to Earth without either of these two gap fillers in place, mission managers said, because their chief purpose is to keep tiles from hitting each other during ascent.
The areas of uncertainty are enormous, mission managers said, because the physics of atmospheric entry are numbingly complex and the data on the way materials perform is limited to the 113 previous shuttle flights.
"Nobody else flies Mach 22 at 216,000 feet," said Chuck Campbell, a NASA manager in aerothermodynamics. "The only data that we've got comes from the shuttle."