NASA says Discovery's heat shield in good shape
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: October 25, 2007
The shuttle Discovery appears to have come through its launch and climb to space in good shape with no major heat shield problems and no need for any additional, "focused" inspections before undocking, NASA managers said today.
"Oh man, that is fantastic news!" shuttle commander Pam Melroy replied.
"Just to be clear, that is an initial report, they've still got a few things to look at so you'll get more in the MMT summaries (overnight), but just wanted to pass that along."
"We sure appreciate it," Melroy said. "Obviously, it's been a question, it's very much on our minds. So we're pretty excited to hear about that because it will give us more time with Node 2, which is just great. We can't wait to get inside."
Node 2, a multi-hatch module recently named Harmony, will be pulled out of Discovery's cargo bay Friday, during the first of five planned spacewalks, and temporarily mounted on the left side of the central Unity module. Harmony's installation is a major milestone for the space station project because it will serve as the connecting point for long-awaited European and Japanese research modules scheduled for launches in December, February and April.
The crew's flight plan included time for an additional heat shield inspection Saturday, if necessary, a time-consuming procedure using a 50-foot-long boom attached to the shuttle's robot arm. While analysis is not yet complete, laser scans of the shuttle's critical wing leading edge panels show no signs of trouble and close-up photography of heat shield tiles on the shuttle's belly, taken today during final approach to the space station, show only minimal damage.
"It's a pretty clean vehicle," said John Shannon, chairman of NASA's Mission Management Team. "Overall, we are not working ay issues. The imagery team is taking a close look at all the data but they have not seen anything that would cause them any concern at this time. So we'll go ahead and go through that process and report out on it just like we have for every mission."
Mission managers opted to launch on schedule based on the past history of the panels - the degradation has been relatively stable over the past two mission - and the crew's post-Columbia ability to detect and repair minor heat shield damage.
"We haven't seen anything on the three panels that were brought up by the NESC (NASA Engineering and Safety Center)," Shannon said.
In an overnight message to the astronauts, the MMT mentioned a piece of ice that formed before launch and shook off during main engine ignition. The ice fell, lightly grazing one of the propellant feedline doors on the belly of the shuttle as the ship began its ascent. Shannon said today the umbilical doors appeared to be in excellent condition and that the ice did not fall far enough or hit at a steep enough angle to cause any damage.
Footage from cameras mounted on Discovery's solid-fuel boosters will be examined this weekend, but based on live views from a camera mounted on the external tank, engineers do not expect any major surprises.
All in all, Shannon said, "we are extremely lucky that we have a vehicle that is in such incredible shape. If I had to pick a mission where the vehicle would give us no problems and we'd just be able to concentrate on the mission and the assembly sequence, this would be the one. So we've really gotten lucky."
Discovery's mission is considered by many to be the most complex station assembly flight yet attempted. After getting Harmony attached to the station, the astronauts will stage two spacewalks and use two robot arms on the shuttle and the station to move a 35,000-pound solar array segment to the far left end of the lab's main power truss. Another spacewalk is planned to test a new heat shield repair technique and a fifth is on tap to complete preparations to move Harmony to the front of the space station as required after Discovery undocks.
Given the complexity of all that work, Shannon said NASA does not want to extend Discovery's mission unless problems require additional time to resolve.
"If we can get all of our work done and leave (on time) that would be really good for the ISS team," he said. "They have a very highly thought-out timeline that gets them on track for STS-122 and the Columbus module, launching on Dec. 6, and really, if we extended this mission a day or two like we've done in the past, that would impact that timeline. So there is a premium on getting our work done on this flight and getting undocked from the space station and letting them carry on with their stage work. Even though we have a lot of (power), I would expect that unless we run into some significant problems we would not be talking about extending this mission. But of course, we have to see how that goes."
One open item that may affect one of the crew's spacewalks is an unusual vibration in one of the rotary joints that turns the station's right-side solar arrays to keep them face on to the sun. Shannon said a quick inspection of the starboard solar alpha rotary joint, or SARJ, might be requested if it can be worked into the spacewalk timeline.
"There's some vibration," he said. "I don't think they really have a good idea yet exactly what's causing it. There was some discussion today (about) is there anything they want to go look at on one of the EVAs to maybe go narrow down what the issue might be? From a shuttle standpoint, (the issue is) no impact to us at all. We can undock, we can do all of our activities and it's no impact. ... But I don't think they have a real good handle on exactly what the problem is. I wouldn't be surprised if they came in and asked on EVA 2 to go look at something and we'll have the EVA team go and assess that and make sure it's something we can safely do."
Asked about the critical nature of Discovery's mission, Shannon said "I told my team before we started this mission, this is the kind of mission we all came to NASA for. This is why we're here. ... We've got the infrastructure built, now we're kind of putting the living space on. And it's extremely exciting, it's very gratifying. Especially after the hiatus we went through after Columbia. You know, we all kind of thought jeez, can we get this done? To see the team step up to improve the vehicle and improve our operations and pick up where we left off is just a wonderful thing to see."