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Newsday June 28, 2006

Ready to rise again

By Bryn Nelson

Nearly one year since the last shuttle launch and 3 1/2 years after the Columbia disaster, NASA is primed to return to human space flight Saturday with the liftoff of the Discovery orbiter and its crew of seven.

After months of redesigns and analysis, space agency officials hope to prove they have learned from past mistakes even as they eye an ambitious slate of missions aimed at completing the International Space Station before the shuttle fleet retires in 2010. But lingering concerns about the external fuel tank and shuttles' notorious tendency to shed foam debris have underscored the delicate balance NASA has struck between pursuing major safety upgrades and resuming inherently dangerous missions.

Diane Vaughan, a professor of sociology and international and public affairs at Columbia University, said NASA's space shuttle program has always operated under the premise that some risk is inevitable.

"It's not like you go out into your car every day and it's the same piece of equipment," said Vaughan, a staff member of the investigation board that probed the Columbia shuttle disaster. The shuttle changes after every flight, she said, "and every mission is an experiment."

Foam remains an issue

The main sources of foam shed from the thermos-like fuel tank during the ascent of the doomed Columbia in 2003 and of the more fortunate Discovery last July have now been removed, though engineers have repeatedly acknowledged that smaller pieces of foam will likely still fall off.

A spate of new cameras, grouped under the cheekily named Enhanced Launch Vehicle Imaging System, or ELVIS, will provide many more high-resolution images - particularly in the critical two minutes between the launch and separation of the orbiter from its external tank. Another round of scrutiny will begin late in the 12-day mission to look for any damage from space debris.

New thermal tiles developed by Boeing have replaced old ones around the landing gear door on the shuttle's heat-sensitive belly. And thousands of gap fillers between the shuttle tiles have been replaced and more securely fastened in the hopes of preventing a replay of some tense moments during last July's mission, when astronaut Steve Robinson plucked a protruding gap filler from the Discovery's underside during an impromptu space walk.

But will it all be enough?

John Logsdon, director of the Space Policy Institute at George Washington University, said NASA's flight readiness review process - in which engineers and managers must collectively sign off on all aspects of a launch - has opened up considerably since the Columbia broke apart during its return to Earth in 2003, killing its crew of seven. As an example, he pointed to the spirited debate within NASA about whether to fly the shuttle with the external tank's existing ice-frost ramps, pieces of foam that cover metal clips charged with securing cables and fuel lines.

"It was not an easy decision," conceded John Chapman, manager of NASA's external tank program, at a televised news conference earlier this month.

Exposed to the extreme cold of the tank's liquid fuel, the clips could collect condensation in Florida's humid air and lead to a catastrophic buildup of ice. The solution has been to cover the clips with foam, but foam debris can pose its own hazards to the shuttle, as the Columbia disaster revealed.

NASA recorded a worrisome amount of foam loss from some ice-frost ramps during last July's shuttle ascent as well as from larger ramps that have since been removed. Initial efforts at redesigning the ice-frost ramps failed, as the new foam parts broke apart in wind tunnel experiments. In the end, a majority of the engineers agreed to fly the shuttle with the existing foam configuration, reasoning that one major change to the tank at a time was the best way forward and that minor extensions could be added to the ramps' exposed portions to preserve their aerodynamics.

A redesign effort, they concluded, would be a top priority for the program in the coming months, likely incorporating a new material for the clips.

Concerns but no objection

Although two top NASA officials recommended a launch delay, they did not ultimately object to Saturday's attempt. Other NASA officials said the seemingly contradictory decision, while unprecedented, is evidence of an agency that now takes seriously the idea of open debate. Both officials later clarified their positions publicly, voicing confidence that the space station could harbor the Shuttle crew in the event of an emergency.

Vaughan agreed that the open dissent is a step forward, though she remains concerned over NASA's tendency to get bogged down in details and lose sight of the bigger picture.

"We can only hope that's not happening now," she said.

NASA is still hoping to squeeze 16 shuttle missions into the next four years, with the next one slated for Aug. 28. Logsdon said he believes the remaining schedule is realistic, giving the looming retirement of the fleet and the goal of finishing the space station.

"It's success oriented," he said. "That's the way you have to go in."

But John Pike, a veteran space policy analyst and director of GlobalSecurity.org, said NASA faces the dilemma of having limited time and money to devote to a system that engineers don't fully understand but must soon retire.

"They thought they understood it a year ago, and they didn't," he said. "They thought they understood it back at the beginning of the decade and they didn't."

And this flight?

"Well, we'll see," Pike said.


Copyright 2006, Newsday Inc.