NASA hopes to test a thermal tile patch on the next space shuttle mission that could have been used to fix the gouge that was carved into the bottom of Endeavour during last month's launch.
The repair — a squirt of goo — was one of three methods NASA considered using before deciding the damaged tiles didn't need to be fixed in flight.
Shuttle program manager Wayne Hale said Friday he also plans to expand the flight readiness review for Discovery's mission next month to encourage more people to speak up about safety concerns, an ongoing culture problem for NASA, and indicated the space shuttle Atlantis might not retire next year after all.
Once the tile-repair demonstration is formally approved Monday, a fifth spacewalk will be added to Discovery's two-week flight to the international space station. Two shuttle astronauts will use a caulk-like gun to squirt the goo into deliberately damaged tile samples, and small foam brushes to tap down and smooth the material. The tiles will be returned for analysis.
Hale called the demonstration — which was moved up by more than a year — "a confidence builder." The salmon-colored goo, the consistency of peanut butter, has been tested extensively on the ground, but never in space. It has a tendency to bubble on Earth, and NASA wants to see if that happens in space.
NASA concluded last month there was no need to apply this goo to a 3 1/2-inch-long gouge on Endeavour's belly that was caused by a piece of foam insulation and possibly ice that broke off the external fuel tank during liftoff. But the episode reminded NASA it needs to sharpen its repair skills, Hale said.
The astronaut who will do the repair demo, Dr. Scott Parazynski, said the delicate work on fragile tiles will be like surgery.
"This is a very exciting time for us to finally get the ground truth if you will — or the space truth — on how this material behaves," he said.
Parazynski said he was confident the goo would have worked for Endeavour's damage, given how small it was.
Developed in the wake of the 2003 Columbia disaster, the goo was not tested sooner in orbit because of toxicity concerns and unwieldy tools. A caulk-line gun has replaced the much larger applicator, and the smaller amount of goo made it safer to handle, Hale said.
The fuel tank for Discovery's Oct. 23 launch has been modified to reduce the possibility of foam coming off the latest problem area, brackets that support the liquid-oxygen feed line.
At a news conference, Hale said the flight readiness review before Discovery's launch will be more thorough and extensive. The two extra days of informal discussions hopefully will encourage more lower-level engineers to speak up, he said.
A reluctance by space program employees to openly bring up safety concerns contributed to both shuttle accidents.
"I would like to say that everybody feels comfortable coming to a board, standing up in front of the management and presenting their case, but apparently that's not so," Hale said.
He noted that safety concerns are still being reported anonymously for fear of retribution.
Just this summer, an independent review of astronaut medical issues criticized NASA for failing to heed the concerns of flight surgeons regarding the health of flight crew members. The panel also noted that astronauts were reluctant to disclose improper behavior by colleagues for fear of being ostracized.
Hale said Atlantis' 2008 retirement will be put off if NASA can't complete the international space station by 2010 with only two shuttles. NASA wants to retire Atlantis to save money and use its parts for the other two shuttles, Hale said.