In the Vehicle Assembly Building at Kennedy Space Center, workers are constructing a scaffolding around a section of the external fuel tank that shuttle Discovery is supposed to use for a planned launch next month. Late today, technicians in High Bay No. 1 will begin pulling plugs of foam from the 154-foot tank's intertank area to see if it is properly adhered to the metal surface, or if might be prone to the unusual shedding seen during Endeavour's ascent Wednesday.
The intertank is an unpressurized cylindrical connection that joins liquid hydrogen and liquid oxygen reservoirs, roughly parallel with the orbiter's nose on the launch pad. The intertank measures more than 22 feet long and 27 feet in diameter, and weighs 12,100 pounds.
Foam loss is not usually seen there, but up to a dozen pieces tore away from Endeavour's intertank, some in strips (shown above).
Inspections determined that dings to Endeavour's heat shields were not significant enough to require repairs, but NASA began to inspect its other tanks to make sure the problem doesn't reoccur. A Lockheed Martin team from NASA's Michoud Assembly Facility in New Orleans, where tanks are manufactured, was on site at KSC over the weekend helping develop a tool for the plug work. Personnel from Marshall Spaceflight Center in Alabama are also assisting the inspection effort.
By Tuesday morning, a total of 26 foam plugs measuring up to 1.5 inches in diameter are expected to have been removed from a full circle around the intertank. They will be sent back to Michoud for analysis that should be complete withing a couple of days, NASA says.
Discovery's rollover to the VAB from a processing hangar to be mated with the tank and solid rocket boosters, once planned last week, is now planned no earlier than Thursday.
The shuttle would typically roll out to launch pad 39A a week after the orbiter enters the VAB.
The delays mean Discovery's targeted Aug. 18 launch is certain to move to the right.
In a weekend briefing on Endeavour's mission, Shuttle Program Manager John Shannon said he didn't expect the tank work to prevent a "late August" launch.
Aug. 18 was already iffy because the Air Force's Eastern Range is unavailable that day, assuming a planned Aug. 17 launch of a Delta II rocket and GPS satellite from Cape Canaveral Air Force Station proceeds on schedule.
The STS-128 mission crew, which had been scheduled to fly to KSC for pre-launch training this coming Sunday, July 26, is now tentatively expected in the first week of August.
Also subject to change is a program-level flight readiness review planned Aug. 4-5.
Work at pad 39A to repair two damaged areas of the flame trench's main flame deflector is expected to be completed by the end of this week. The areas measured 7 feet by 12 feet and 3 feet by 4 feet.
IMAGE NOTE: Above, a picture showing foam loss from Endeavour's external tank. Credit: NASA. Below, External Tank-132, slated for use by Discovery on STS-128, is rolled out of NASA's Michoud Assembly in New Orleans on May 1. Credit: Lockheed Martin.
3 comments:
Going back to this foam situation with the external tank for just a second and I'm by no means an engineer or anything nor do I pretend to be, but this time around, could this have been a product of being outside in the florida ocean side elements for what almost 4 months?? And being rolled out to launch pad 39b and around to launch pad 39a and tanking what 7 times??
Hey Matt:
I think you might be onto something there. Shuttles certainly have been out on the pad, in the elements, for just as long before and NASA insists the closed-cell foam doesn't absorb water, although there is evidence otherwise. But we have seen situations post-Columbia that indicate foam can crack during the expansion and contraction seen during the loading and draining of cryogenic propellants. So I would not be surprised if the number of cycles on Endeavoiur's tank is found to be at least a contributing cause to the foam loss seen on the way uphill.
http://www.nasaspaceflight.com/2009/07/sts-128-initial-et-132-intertank-pull-tests-show-positive-results/
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