Posted on 08/04/2005 9:19:47 AM PDT by anymouse
Discovery's external fuel tank was the first to fly with a new insulating foam custom-made to satisfy environmental bans on chemicals suspected of depleting the Earth's ozone layer.
NASA is investigating why a 1-pound chunk of the foam peeled off Discovery's tank two minutes after launch July 26, missing the shuttle's right wing as it climbed toward orbit.
The incident prompted NASA to ground the shuttle fleet even as Discovery was on its way to the International Space Station.
"We are treating this very seriously. We are going to fix this before we go fly," said John Shannon, a senior shuttle manager at Johnson Space Center.
Indeed, Discovery's tank shed four pieces of foam large enough to cripple the shuttle if the pieces had hit it, and NASA records show at least two of those pieces were applied manually using the new formula of foam.
NASA officials will not discuss any emerging theories about why the foam continues to come off the tank. A team of experts from NASA and tank-builder Lockheed Martin are studying possible reasons.
The main focus is on a pillow-sized piece of foam that broke free from a ramp that runs next to fuel pipes and cables, protecting them from turbulent airflow on the violent ride to space. Alterations or repairs made to that ramp are being looked at as a possible contributor to the foam loss, as is is every other change made to the tank.
The change in the chemical make-up of the foam is unrelated to the redesign ordered by the Accident Investigation Board in the wake of the fatal 2003 Columbia accident. Instead, NASA made the change as part of an ongoing bid to meet U.S. and international environmental bans dating to the 1990s.
That's when the federal government started trying to ban ozone- depleting types of freon present in the chemicals used to spray and mold plastic foam for everything from refrigerators to furniture to rockets.
Most of the inch-thick orange foam that covers the tank is sprayed on by robots at a sprawling factory east of New Orleans.
A freon-based chemical is used in that process. For robot-sprayed portions of the tank, NASA's contractor originally used a formula called CFC-11, long since banned. By 1996, NASA had switched to a more acceptable chemical, HCFC-141b, for all but one of the four kinds of foam it was using on the tank at the time.
Then, on three flights in the late 1990s, popcorn-sized bits of the new, environmentally safe foam flaked off in record amounts. A frightening number of dings and gouges on the orbiters' heat shields got NASA's attention.
The freon-free foam was blamed. NASA found a quick fix, changing the way the new foam was applied to the tank to reduce -- but not eliminate -- the popcorning. It's unclear whether the environmentally friendly foam remained a factor in the continuing loss of small fragments of foam on subsequent missions, but NASA records show the agency knew it did not stick to the tank as well as the original foam.
Unwarranted blame
When Columbia disintegrated over Texas in 2003, some blamed the environmental change. That wasn't the case. The big piece of foam that smashed the hole in Columbia's wing was made from the old foam containing the long-banned freon blowing agent. The old substance was called BX-250.
NASA and its contractors were trying to develop a freon-free version of that foam, which workers used to manually craft the aerodynamic ramps and hand-made patches of foam applied once the robots are done spraying that initial layer.
The space agency was still flying the old foam because it had won exemptions to the EPA rules and was making only progressive steps in changing the foam.
Cautious pace
In records obtained by FLORIDA TODAY under the Freedom of Information Act, NASA told the EPA that it could not switch the foam formula faster "without jeopardizing the safety of NASA's human spaceflight program." Years of tests were needed on promising new formulas because "qualification testing must be performed to ensure that the material meets all of the requirements for mission success and human flight safety." The records note the agency's struggle with the initial change, and the resulting damage, as evidence it needed more time.
In 2003, as investigators were reviewing the Columbia accident, NASA did certify a replacement for the BX-250 foam that did not include the freon-based agent. The new foam, called BX-265, was ready for the fuel tanks for NASA's first two post-Columbia shuttle missions and is the foam under investigation.
Engineers ultimately might find that the change was inconsequential. Foam loss is not a new problem. Foam hit orbiters on at least 75 of the flights to date. Overall, Discovery appears to have come through its test flight relatively unscathed, indicating NASA's redesign reduced the foam shedding. The heat-shield tiles have taken a record-low number of hits, according to extensive inspections on orbit.
Not a new idea but these tanks can be the basis for a tank farm in orbit to fuel the Earth/Lunar FEDEX truck, (privately owned inter orbit vehicle) which will usher in the true conquest of space since the likes of Rutan will fill the void that NASA has not occupied!
The tank burns up upon reentry. The tank stays with the Shuttle nearly all the way to orbit, as it must supply the fuel to the Shuttle main engines.
They are bold face liars, whose lies have caused deaths, therefore they are murderers.
The tank's pretty light, when empty - I think it slows down pretty fast and doesn't completely burn.
Actually, I think I saw a video once 'way back during the earliest launches where they showed the boosters being recovered in the Atlantic and the tank/pieces splashing in the Indian.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.