Griffin doesn't rule out quick resumption of flights
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: July 29, 2005
Griffin fielded questions from a small group of reporters, starting off by joking about "late-breaking" news that had not made it into news reports.
"This is the cleanest flight practically that we've ever seen," he said. "The flight control team is executing above flawlessly, they haven't flown a shuttle for two-and-a-half years and the control team is doing better than perfect. The astronauts on orbit are executing better than perfect. (Commander) Eileen Collins performed a minimum-propellant rendezvous yesterday, did a perfect docking, all the equipment is in great shape. The orbiter has had, I think, one minor flaw, maybe a tape recorder (problem).
"Almost everything we did on the external tank to get it ready for flight has worked," Griffin said. "We expected and we have seen a dramatic reduction in the amount of debris that was generated. Looking at the photography we've seen so far on Discovery, we've had about 25 dings as opposed to a mission average of about 145 (in earlier flights). So the engineering work we did on the external tank has reduced scarring on the orbiter by a factor of about six. I thought all that was really kind of nice and you should know it."
During Discovery's launching, a large piece of foam peeled away from one of two so-called protuberance air load - PAL - ramps on the side of the tank. The ramps are in place to smooth the flow of air over pressurization lines and a cable tray when the spacecraft goes supersonic.
Two other larger-than-allowable chunks of foam separated from the area of the tank near the struts that support the nose of the shuttle. One of those divots came in an area where post-Columbia improvements had been implemented. The other came from an area that, like the PAL ramps, was unchanged.
The PAL ramp foam is sprayed in place by hand and engineers have long recognized it represents a potential source of debris. In the wake of Columbia's demise, managers considered ordering changes but in the end, decided it was safe to fly them as is. That rationale was based in part on flight history - only two early missions experienced known instances of PAL ramp foam loss - and because of non-destructive testing capable of finding the internal voids thought to contribut to shedding.
But given orbital lighting constraints, NASA only has post-launch photographic documentation of less than half the tanks launched to date and additional PAL ramp foam shedding might have gone undetected.
Richard Covey, co-chairman of a panel that assessed NASA's implementation of an accident board's return-to-flight recommendations, said early on, NASA identified the PAL ramps as "a potential source of large debris."
"They early on identified that and we, during the course of our subsequent fact finding, followed the agency through the extensive process they went through of analyzing the causes of foam loss, studying the flight histories that they had and looking at the non-destructive inspection techniques they could use to eventually develop rationale that said that changes to the PAL ramps were not required in order to eliminate critical debris.
"Now, we accepted that rationale and so when we talked in our report about the fact that critical debris itself had not been eliminated and we would expect debris to be liberated from the external tank, that led to me not being surprised that foam would come off the external tank. We fully expected that foam would. ... That being said, I am surprised as are other members of the task group that foam from the PAL ramp separated during this launch. We were surprised at both the fact that it was PAL ramp foam and the size of it."
He said NASA now will have to re-examine the physics behind foam loss and perhaps re-think the theory that voids in the foam are primarily responsible for separation in flight.
"The idea that voids were primarily the cause of separation, that you can see these voids in non-destructive inspection, has all been challenged by what happened on the launch," Covey said.
Griffin agreed NASA "missed" the threat posed by the PAL ramp foam, "but to extrapolate from that fact and say that we can't fix it, I think is just a bridge too far. I think we're going to fix it, I think we're going to fix it in short order, we're going to get back flying. All we ever said the other day was that we are not going to fly again until we fix it. And I think that's the right thing to do. But we don't expect this to be a long, drawn-out affair, to be honest with you. If that changes, we'll tell you, but that's what we're looking at now."
The PAL ramp issue is only part of NASA's problem. Foam also broke away from two other areas and "we clearly need to fix those," Griffin said.
"Now if we compare that performance to prior performances of the external tank, I don't need to tell you that the difference is huge," he said, coming back to his central point. "And that's what I was alluding to earlier. Almost everything we did to improve the external tank worked. We said at the start this was a test flight, we said that ... without putting this machine into flight, we said we would not be able to evaluate how well we'd done. Now we have some real flight data and we can go figure out what we need to do next."
NASA had hoped to launch the shuttle Atlantis by around Sept. 9 on another mission to resupply the international space station. Because of delays getting Discovery off that ground, Atlantis's launch target was expected to slip several days. Asked about the impact of a much longer delay, Griffin said "you've gone into speculation by saying we won't be able to fly the shuttle until early next year. At this point, we don't know that, we're not conceding that.
"We're putting together a NASA tiger team to look at foam remedies with emphasis on those that have not previously been considered or what we need to do to address the PAL ramp and the couple of other areas where we need to do better."
Asked how NASA could get another launch off this year with all the testing that now must be done, Griffin said "by being smart and working hard. If we can do those and are successful, then we'll capture one of those flight opportunities and if not, it will move. But we don't start out by assuming that we can't succeed."
Finally, Griffin was asked if the media had over-reacted to the foam problems experienced during Discovery's launch.
"I started out with what I thought was at least a little bit of humor, pointing out all the things that are going well on this mission precisely because I believe folks really have over reacted just a bit," he said. "There's no question that NASA's goal was to eliminate all significant foam shedding, debris shedding of any kind, from the tank. There is no question that we always said that while that was a goal, that perfection would be unattainable. So we had a size limit that we wanted to be below.
"There's no question that in maybe four places on the tank, pieces of foam bigger than what we wanted to see came off. So we weren't perfect. We said this was a test flight, we said that we because of the physics involved, the nature of the problem, we could not test this tank on the ground in a wind tunnel or in any other kind of facility, we had to put it back into flight to see how well we have done. So we did that.
"But this was a test flight," Griffin said. "It now has provided data that we can use going forward. The bad news is there were three or four things we didn't get. The good news is we hugely reduced, by a factor of six or more, we hugely reduced any damage to the orbiter through the engineering measures we took to improve the tank. We specifically said the return to flight test sequence was two test flights. I love it when stuff goes well and I know you guys do, too. We plan for the worst and we hope for the best and that's how we conduct business."
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