Mon, Jun 16, 2003 page7

• Shuttle disaster report might be full of holes

  UNANSWERED QUESTIONS Comments by the panel suggest that no unsolvable problems have been identified, but have some profound issues been mentioned?

  • NY TIMES NEWS SERVICE
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  The report by the independent commission investigating the Columbia shuttle disaster promises to be wide and deep, but it will also most likely have some gaping holes.

  A month before the anticipated completion of the inquiry, the panel's chairman, Admiral Harold Gehman Jr., has often referred to the idea that there are "no showstoppers" to resuming flight with the three surviving orbiters, meaning all of the problems the board has identified so far are solvable.

  The implication of that unofficial conclusion, though, means that some profound questions could remain unanswered and even unmentioned.

  That conclusion endorses NASA's finding in the 1970s, at the end of the Apollo program, and was supported by President Richard Nixon. It is the very basis of the shuttle program: that a reusable orbiter strapped to booster rockets and an external tank can be reliably operated. And comments by the investigative panel strongly suggest that that concept will remain unchallenged.

  Yet it is the nature of the design that brought on two shuttle disasters and the early deaths of 14 astronauts. Leaky O-rings in the boosters ignited the external tank of the Challenger in 1986. And foam falling from the external tank almost certainly fatally damaged the Columbia this year.

  Falling foam has been a frequent phenomenon on rockets, but there is usually nothing for the foam to hit besides the rocket itself; likewise, without a shuttle attached, there is nothing for a tongue of flame to burn if one escapes around a seal.

  The endorsements for the shuttle concept, in the 1970s and today, have had two additional, more subtle effects: freezing the technology and allowing time for age-related problems to develop in reusable parts.

  The shuttle's planners thought they were building a vehicle for 20 years, but it has already lasted that long, and NASA may stick with the design for 20 more.

  In contrast, the first three programs to carry astronauts -- Mercury, Gemini and Apollo -- took only 11 years combined. With disposable rockets, new and improved technology was rapidly incorporated.

  The reuse concept behind the shuttles, of course, allows the three main engines, 21 tons of high-precision machinery, to fly over and over. But the shuttle program is the only one to reuse engines that run on cryogenic fuel, according to experts. This appears to allow damage, like cracks in components of the fuel lines, known as flowliners, to develop slowly. The shuttle program was shut down for months last year after cracks were found, almost by accident.

  Similarly, metal balls that support the orbiter's liquid oxygen lines developed problems, and numerous internal e-mail messages between engineers discussed the deterioration of the so-called Stoody balls, named after their manufacturer. The investigative board may now focus new light on these devices.

  Reuse is also accompanied by a loss of proficiency. The shuttles fly so seldom that technicians have told members of the investigating commission that they have lost proficiency in some tasks, which they perform only a few times a year.

  General Duane Deal of the Air Force, a member of the commission, said at a recent briefing that NASA had tried to adhere to quality standards used worldwide in industry. But, he said, in most industries a technician "does something dozens of times a week."

  If NASA technicians prepare only a few launchings a year, he said, "it's kind of a stretch to say that some of those principles apply."

  In contrast, it is the launchings of disposable rockets that are routine. And the cost to put a pound of cargo in orbit is still US$10,000, 10 times what NASA wants to spend. Unmanned launchings for the cargo that the shuttle now carries to the International Space Station would probably be cheaper, some analysts say, because the rockets do not have special features to assure that they are safe enough for launching people.

  Some of them, however, are statistically more reliable than the shuttle.

  Sean O'Keefe, the NASA administrator, told reporters on Wednesday that NASA would "comply fully without any equivocation" with whatever recommendations the board made. But if it eliminates the foam hazard, as it previously eliminated the O-ring hazard, then it will have reduced the number of hazards by two.

  Gehman repeatedly muses in public about the "unknown unknowns," the future foams and O-rings, and while the Gehman board may find a few in its investigation, all that can definitively be said about the two shuttle disasters is that they will have reduced the number of unknown unknowns by two.

  The number remaining is, of course, unknown.

  To judge from the public comments of board members, the report is likely to be an unusually public and frank discussion of risk in human spaceflight.
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