Shuttle crew is ready to repair
Astronauts are poised to become mechanics when Discovery launches. If needed, Atlantis will become a rescue ship.
By CURTIS KRUEGER
Published April 18, 2005
CAPE CANAVERAL - Thirty-nine miles above Earth, as the space shuttle Columbia was melting, cracking and breaking into smoldering bits, the seven men and women on board had no way of knowing exactly what was happening to them.
The astronauts also had no chance of saving themselves.
They spent 16 days in orbit, but never saw the hole or holes that had gouged into Columbia 's left wing during launch.
If they had gotten a good look at their damaged wing - and realized that it might doom them - the astronauts still couldn't have done much. NASA had no plan for rescuing the crew of an orbiting shuttle.
And years earlier, NASA had discarded the thought of making in-flight repairs to the tiles and panels that shield the shuttle from fierce 3,000-degree heat while re-entering Earth's atmosphere.
"The old heads at NASA told us that they tried to do that in the early '80s and had to give up; it was an unattainable goal," said Wayne Hale, deputy manager of the space shuttle program for NASA.
All that changes next month.
NASA hopes to launch Discovery between May 15 and June 3, on a mission that will take it to the international space station. It will be the first flight since the Columbia tragedy more than two years ago. In many ways this mission will be unlike any of NASA's previous 113 space shuttle flights.
When Discovery lifts off from Launch Pad 39B, it will mark the first time astronauts have ever carried repair kits into space to fix the kind of damage that destroyed Columbia . Space travelers will become space mechanics, eventually capable of performing body work on their own ship.
"Historically that has not been part of the space program, so this is very new," said Howard McCurdy, a space historian at American University in Washington, D.C.
And in another first: "If we get into a situation we cannot fix, we will have the option to try to rescue the crew," Hale said in a recent briefing at Johnson Space Center in Houston.
Once Discovery launches, crew members of Atlantis will go on alert, ready to follow their fellow astronauts into space and offer a lifeline if necessary.
* * *
Not long after the charred wreckage of Columbia smashed down in February 2003 along a stretch of Texas and Louisiana, flak started hitting NASA too.
An independent board and NASA's own engineers investigated what went wrong, and the story that came out was not pretty.
Engineers ultimately showed that a 1.6-pound chunk of foam fell from a spot near a strut that attaches the space shuttle vehicle, called the orbiter, to the huge orangish torpedo shape called the external tank. The foam struck the leading edge of the orbiter's left wing, puncturing it.
Perhaps more disturbing was how NASA responded to it, or failed to.
Some officials were alarmed from the first sight of the foam strike, not long after launch. They discussed it in e-mails and even tried to get a military spy satellite to photograph any possible damage.
But as an independent board later concluded, NASA's corporate culture discouraged dissent and making too much of what seemed to be small problems. The concerns were never fully debated before the top brass, even as Columbia continued to orbit.
All this weighs on NASA now. The agency faces a slew of challenging goals, above and beyond the already daunting task of launching a complex spacecraft and returning it home.
Among them: Redesigning the external tank, so big chunks of foam won't peel off. Inventing new ways of looking for the kind of damage Columbia's astronauts never saw. Developing the in-flight repairs. Preparing for rescues.
And above all, making sure the most pressing questions do not get squelched.
"I was part of this program maybe when the culture was a little different," Bill Parsons, NASA's space shuttle program manager, said this month as Discovery rolled out of the giant Vehicle Assembly Building toward the launch pad at the Kennedy Space Center. "I've been a part of it now when it's changing. It's still evolving. But ... people are coming forward now with opinions."
It's essential for NASA officials to speak up and disagree with each other when necessary, says McCurdy, chairman of American University's department of public administration. "They're supposed to be yelling at each other."
He believes "NASA has restored a lot of checks and balances" to encourage such debate.
In June 2003, NASA appointed an outside task force led by two former astronauts to evaluate if the agency has implemented all safety improvements recommended after Columbia's crash. Although Discovery could launch less than a month from now, the task force still has not signed off on all the safety measures.
McCurdy said it remains to be seen whether NASA has changed the underlying assumptions that form its bedrock management culture.
And now, McCurdy said, NASA has contracted out so much work to outside companies that he wonders something else: Will NASA's in-house mission managers have enough high-level technical expertise to make informed decisions about flight safety?
"That really worries me," he said.
* * *
As the launch date approaches, it's hard to imagine NASA facing any decision more difficult than what to do if Discovery sustains damage on liftoff, as Columbia did. The risks of not fixing the damage are now obvious. But the repair techniques are experimental, so no one knows yet if the methods might actually create more dangers.
Debating whether to launch a rescue mission could be just as vexing, because it would put more astronauts at risk.
So for NASA, the ideal scenario is: no rescue, no repairs.
That's why the space agency has redesigned the shuttle's external tank so less of the insulating foam will fall off. Foam has been removed from the area around the strut where it fell on Columbia's last flight.
Asked what it would take to prompt NASA to actually make repairs on this shuttle flight in orbit, Parsons said, "the kind of damage we don't expect to see."
This time, they will have several new ways of checking for it.
NASA will station more than 100 cameras, including dozens of new ones, on the ground, aboard airplanes near Kennedy Space Center and even aboard Discovery, to document the launch. Also, new sensors have been placed in the crucial RCC panels, the heat shields lining the leading wing edges. If a large chunk of foam hits an RCC panel on this flight, the sensors should feel it.
In space, astronauts also will use a new extension to the existing shuttle arm, with a camera and two lasers on its end. They and Mission Control will be able to look under Discovery for the kind of damage that Columbia's astronauts never were able to see.
* * *
The big problem remains friction. The friction of air.
Walk to your mailbox, and you won't even feel the air passing around you on both sides.
But things are different when a 212,000-pound spacecraft rages into the atmosphere at 17,000 mph. The orbiter blasts into the thin upper reaches of the atmosphere so forcefully that it splits air molecules apart. Friction heats the underbelly like a frying pan, raising its temperature to 3,000 degrees, hot enough to melt steel. Astronauts looking out the window see air glowing red.
To protect the shuttle from these forces, the orbiter is surrounded by a thermal protection system. This includes ceramic tiles and, for the most critical areas, panels made from material called reinforced carbon carbon, or RCC.
A hole in these can cause havoc. Superheated air can shoot inside a hole like a giant blowtorch, with roughly the same effect. That's what happened to Columbia.
"If something breaks or comes off at a critical high-temperature spot, you're doomed," said Chuck Eastlake, an aerospace engineering professor at Embry-Riddle Aeronautical University.
Any repairs on future flights would be designed to keep the protective covering intact, to save the orbiter from the destructive power outside.
Discovery's crew will carry five repair kits aboard, with some tools that look like high-tech versions of what you might buy at Lowe's or Home Depot.
The kits include a sort of caulk gun to repair cracks in RCC panels, and a different version for tiles; another device that would dab a tarlike substance onto cracked or pockmarked tiles; a plug with an expansion bolt to cover holes in RCC panels; and insulating bags that would be held in place by augers and a cover plate over tiles.
The plan now is to test two of these procedures - the tarlike substance, called "emittance wash," and the RCC crack repair - on samples. On the fifth day of the mission, two astronauts will conduct a spacewalk to the payload bay, the orbiter's large storage space. There, in the vacuum of space, they will try out the repairs on intentionally damaged tiles and panels that are not attached to the orbiter. Back on Earth, scientists will subject the samples to intense heat, to see how they would hold up on re-entry.
Inside the orbiter, astronauts will put together the RCC plug repair, so they can get the feel of it during weightlessness. The crew won't demonstrate the other two methods on this flight, but will carry the materials along just in case.
If these repair methods hold up during tests, NASA could eventually approve them for use on future flights. At the moment, they remain experimental. Astronauts have expressed reservations about using them until they have seen more results.
* * *
NASA also worries about a rescue.
If Discovery sustains damage that is considered irreparable, the seven-member crew would begin a last-ditch scenario to save themselves that would involve throwing Discovery away.
They would get into the international space station, joining two astronauts already there. The nine of them would wait for as long as 45 days. That's not an attractive option, says Parsons.
"The life support on the international space station isn't set up for that many people. I mean it's really designed for three people, as many as six when you get certain other pieces together. We would be really kind of stressing the system."
Atlantis would then launch with a small crew of no more than four. Meanwhile, Discovery would be jettisoned, burning up in Earth's atmosphere and then dropping into the Pacific Ocean.
Considering the pitfalls, it's easy to see why NASA hopes for neither rescue nor in-flight repairs.
But Parsons, the shuttle manager, said that in spite of past critiques of NASA's corporate culture, he believes his colleagues would fully debate such agonizing choices, and ultimately make the best call.
"You know, we had an example on Columbia that was a bad example, it didn't work out the way it should have. What we need to do is just open up, and be open to listening to other people give us their opinions," he said.
Parsons said the public may consider engineering "a precise, dead-on kind of science, but it isn't. It requires a lot of judgment, it requires people to have opinions ... you can do all the calculations you want to. But sometimes you have to have that good engineering judgment."
--Curtis Krueger can be reached at firstname.lastname@example.org or at 727 893-8232.
[Last modified April 18, 2005, 02:47:13]
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