A Much Better (IASA) Safety Idea - for Leading Edge Holes
June 18, 2004

NASA Lags in Shuttle Patch Development



CAPE CANAVERAL, Fla. (AP) - When space shuttle flights resume, the astronauts will have putty and other filler to repair cracks and small gashes in the wings, but they will not be able to patch a hole as big as the one that doomed Columbia, NASA said Friday.

Michael Kostelnik, deputy associate administrator, said it is taking longer than expected to come up with a

 technique for wrapping a crater as big as the one gouged in Columbia's wing by a chunk of foam last year.

Engineers also are behind in designing a boom for inspecting the belly of orbiting shuttles and the undersides of the wings, Kostelnik said. NASA hopes to have the boom ready for the first post-Columbia flight, still on track for next March. Kostelnik said NASA has yet to decide what it will do if the boom is not ready by then.

Discovery is scheduled to fly to the international space station and drop off badly needed supplies and replacement parts. The latest crew - an American and a Russian - has been aboard the space station since April.

The inspection boom would provide a 50-foot extension to the shuttle's 50-foot robot arm, and hold a set of sensors and lasers for finding holes. It could reach most if not all of the thermal protective layer on the ship's underside and possibly even support a spacewalking astronaut.

Discovery will be equipped with a puttylike material for filling any cracks in the wings, as well as plugs for holes up to 4 inches in size. But its crew will not be able to fix anything bigger than that in the leading edges of the

wings, NASA said.

Columbia was brought down by a hole 6 to 10 inches in size in the leading edge of the left wing. The searing gases of re-entry entered the gash and melted the wing from the inside out, leading to the breakup of the shuttle over Texas on Feb. 1, 2003, and the deaths of all seven astronauts.

The task force overseeing NASA's flight preparations has yet to approve the decision by top space agency managers to skip the wrap repair for now.

Shuttle program director Bill Parsons stressed that NASA is not giving up on the wrap concept and that engineers will press ahead in coming up with a solution for holes over 4 inches.

But Kostelnik and Parsons said the main emphasis is on reducing the possibility of foam insulation coming off the external fuel tank during launch. NASA already has removed the foam from the area of the tank that shed a big piece during Columbia's launch.

Kostelnik said NASA will not resume shuttle flights "unless we can assure ourselves that we will not shed a piece of debris that can damage the orbiter."

The backup plan, at least for the first two flights, is to have a second shuttle ready to blast off for an emergency rescue. The crew of the damaged ship could wait at the space station for up to three months.

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On the Net:

NASA: http://spaceflight.nasa.gov


  The Solution To Shuttle Wing Leading Edge Holes

NASA didn't acknowledge (or decide to investigate) the IASA suggested sacrificial glove "fix" for the Shuttle leading edge (that was sent along to them). However, it appears that they are now going to fly the Shuttle without any fix - (or more logically, without any avoidance measures). How typical of NASA bravado....

Maybe a short ASW comment on this "missed opportunity" might be appropriate. I never really believed that they were going to read any of the public input emails that they solicited on the www.caib.us site. But someone might bring an ASW comment to their attention.

I did get an email reply back from RTV about a suitable material for the job (rubberised silicone or Silastic) - which as you may know, comes in many different formulations, depending upon the environment and the task. Wonder why they're being so thick about it at NASA?? I think it's the exact solution that they're still looking for....for those largish holes that are going to burn you up on re-entry.

 Instead of A Sacrificial Leading Edge  NASA Struggling with Back to Flight
 The Flat Plate Effect  Orbiter Break-up TimeLine
 The Story of Reinforced Carbon Carbon  CAIB Shuttle Accident Conclusions
 The Distinctive Clues  The Early Clues
 NASA Agrees that it was a Leading Edge Event  Data Shows Heat Hurt Wing Early in Re-Entry
 Evidence points to a wing leading-edge failure  NASA Pondering Shuttle Changes
  What are some of the solutions that NASA is seeking to the problem with the space shuttle?  They should be looking at a sacrificial shield (or "glove") around the innermost RCC panel sections on the port and starboard wings. This would protect the brittle reinforced carbon-carbon

 (RCC) leading-edge wing tiles from blunt-force or pointy direct hits by foam, ice and other debris while it's parked on the launchpad (for weeks) - or damaging impacts on launch itself. The "sacrificial" means that it would burn away very early on re-entry as the Shuttle leading edge heats up - because the sacrificial shield would be made from siliconised rubber. Unfortunately NASA hasn't seen any merit in that IASA suggestion and their solution leaves the RCC leading edge wide open to further pre-launch and on-launch damage. The 100% integrity of the RCC inboard leading edge tiles is critical because of the electrical, cooling and hydraulic systems lying immediately behind them (including the landing gear bays and tires). They have instead opted for a robot camera inspection of the RCC tiles once in orbit and a rescue mission to the ISS (or by another Shuttle) should the damaged Orbiter be unrecoverable - or the hole too large to putty over. That is quite frankly putting the cart before the horse.

The objective should be to preclude Orbiter wing damage. The most vulnerable area of the Orbiter airframe is the brittle leading edge and it just cries out for some silicone rubber "wedge" protection during launch. Quite frankly, because the Orbiter's aerodynamics are almost inconsequential during launch and whilst in orbit, you wouldn't even have to pay too much attention to making the silicone rubber (RTV) protection too cosmetically perfect (i.e. you could just daub it on in two inch thick layers over the inboard sections). No foam or detaching bolts would penetrate that.

The Columbia Tragedy
Image: Shuttle Repairs
A simple brush just might fix shuttle damage
NASA looks into low-tech method for orbital repairs
NASA Administrator Sean O'Keefe uses a common foam brush to illustrate one of the thermal tile repair options being considered for emergency repairs to the space shuttle.
The Associated Press

WASHINGTON, Oct. 9, 2003 - Repairing the space shuttle heat shield in orbit may be simpler than NASA once thought, requiring one of the most basic of home repair items — a foam paint brush.

NASA administrator Sean O’Keefe said that engineers studying ways for spacewalking astronauts to fix a hole in the panels that protect the space shuttle from re-entry heat have found that an ordinary foam paint brush could be used to spread a special compound while the craft is in orbit. 

Designing and testing such a repair kit is a key part of NASA’s efforts to return the space shuttle to orbit in the wake of the Feb. 1 accident that destroyed Columbia and killed seven astronauts. The Columbia Accident Investigation Board determined that the shuttle was destroyed when superheated air entered a hole in the heat shield on the leading edge of the left wing and melted internal aluminum supports.

The CAIB called for the space agency to develop a way for spacewalking astronauts to repair such heat shield damage.

Astronauts on Columbia and engineers in Mission Control were not aware of the extent of damage to the shuttle wing, but officials said that, in any case, there was no equipment on board the orbiting shuttle to patch the wing even if the problem was recognized.

From high-tech to low-tech
O’Keefe, at a news conference on Wednesday, said that engineers had looked at the problem prior to the Columbia accident and concluded that it would require highly technical tools and a very difficult spacewalk. For that reason, no repair kit was ever flown on the shuttle.

But with a fresh look at the problem, he said, engineers have determined that patching a heat shield hole may be “elegantly simple.”

He said experts have developed an applicator that would squirt two compounds into a heat shield hole. The compounds would chemically combine to make a strong patch that would expand when heated by the friction of re-entry, O’Keefe said.

“The easiest way to spread the compound without having it stick to the instrument turns out to be a simple thing — a foam brush,” he said. Such a brush is commonly available at hardware and paint stores and is routinely used by millions of homeowners when painting their houses.

For spacecraft repair, said O’Keefe, the foam brush is “an elegant piece of hardware.”

Tested in zero-gravity
O’Keefe said the compound, which he did not identify, has been tested with an electrical arc at 3,000 degrees Fahrenheit, the temperature encountered during shuttle re-entry. Space-suited astronauts, he said, are testing application of the compound in a zero-gravity airplane, a KC-135 that can be flown in a way to give a few seconds of relative weightlessness.

The administrator said the patching technique is still being refined, but the early studies show the problem may be relatively easy to solve.

© 2004 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.



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