NASA pleased with tank; shuttle blanket examined
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: June 9, 2007
The Atlantis astronauts late today used the shuttle's robot arm and a powerful camera on the end of a heat-shield inspection boom to take a close-up look at a pulled up insulation blanket on one of the ship's aft rocket pods.
A preliminary assessment of ground video and imagery from Atlantis indicates the ship's repaired external fuel tank performed well during the climb to space, with only minor instances of foam shedding and nothing apparent above NASA's critical threshold for causing damage to the shuttle's heat shield.
"As you remember, there was a lot of concern pre-flight when we had the hail storm in February and it put well over 2,000 divots in the upper part of the tank," Shannon told reporters. "The crew was able to image that very well after the orbiter separated from the tank. The external tank team is looking at that very closely, but from what we can tell so far, we did not lose any of the repairs, everything looked exactly like it should look, it looks like everything stayed in place."
The only obvious bit of foam loss occurred near a 17-inch-wide liquid oxygen feed line near the top of the tank's hydrogen section.
"We saw a little 6-inch by 3-inch divot by that big feed line that takes oxygen to the main engines," Shannon said. "That is very similar to foam losses we've seen in previous flights. We expect that it will give us some data on the mechanics of why the foam comes off in that area and we can work on improvements in future tanks. This is not any kind of a threat to the vehicle at all, it's just good engineering data."
Analysis of data from C-band and KU-band radars near the launch pad is on-going as is an assessment of data from impact sensors mounted behind the reinforced carbon carbon panels making up the leading edges of Atlantis' wings. Cameras mounted in the shuttle's twin booster rockets will be recovered and assessed after the spent casings are towed back to Port Canaveral on Sunday.
Shannon said those cameras may have captured the moment the foam separated from near the feedline and they may show whether a paper rocket nozzle cover or any other sort of debris hit the protruding insulation blanket on the left OMS pod. The blanket was installed in January and engineers think it is more likely that a corner simply pulled away in the airflow.
"There's an area on the OMS pod that (is protected by) tile, it has more aerodynamic forces on it, a little bit more heating, then that transitions in a lower-heating area to the blankets and at that transition point, it looks like one corner of one of those thick blankets pulled up a little bit," Shannon said. "It looks like some of the stitching ripped and a corner of that peeled up."
Engineers are assessing the blanket to determine what, if anything, might need to be done. On the first shuttle flight in 1981, several tiles on each of Columbia's OMS pods were cracked or missing, but no problems were seen after landing. Likewise, a blanket lost during another early shuttle flight caused no problems.
But in the post-Columbia world, NASA takes no chances and Shannon said the protruding blanket seen on Atlantis' port OMS pod will get a thorough engineering analysis to make sure it doesn't pose a threat to the ship or its crew.
"We have flight history of damage to these OMS pods," Shannon said. "Early in the program, STS-1, we lost some tile material, STS-6, we lost at least one blanket in that area. And for all of those, we do not believe we had any damage at all to the OMS pods.
Even so, he said. "we're going to go and characterize it and go through our analysis. Every flight, I feel like I'm a broken record. I come in and say 'there's this thing, it doesn't look like a big deal, we're going go do our assessment and see how it turns out.' We'll do the exact same thing on this flight."
The Atlantis astronauts already plan to carry out three spacewalks, Monday, Wednesday and Friday, to connect and activate a new space station solar array, retract another solar panel so it can be moved later and perform a variety of other assembly tasks.
Shannon said if necessary, the astronauts could work on the protruding blanket, possibly tucking the material back in and pinning it down or even using a viscous, heat-resistant tile-repair material to fill in the exposed underlying area."
But nothing like that will be planned until engineers complete their assessment of the damage and the likely effects of re-entry aerodynamics and heating on surrounding blankets and the underlying structure of the rocket pod.
The Atlantis astronauts, meanwhile, are continuing to close in on the international space station, on track for docking Sunday afternoon. During final approach, the station astronauts will photograph the shuttle's belly to look for any signs of impact damage, a routine part of post-Columbia rendezvous procedures.