Videotapes of Challenger's brief flight, and shuttle debris recovered from the Atlantic, finally began to yield some sketchy information over the weekend. National Aeronautics and Space Administration (NASA) pictures released Saturday night showing a plume of flame from a booster rocket, beginning about 10 seconds before the Challenger exploded, offered the first public evidence that something was indeed wrong before the abrupt disaster.
Yet the Coast Guard recovered small unfired rockets used to separate the shuttle's boosters, indicating that Challenger's commander, Francis Scobee, had no warning of the problem -- at least, says a NASA spokesman, not enough warning to pull the ``ditch'' switch.
The focus of the inquiry into the mishap, still in its early stages, remains on the millions of bits of data from the shuttle's more than 2,000 sensing instruments.
Mission Control operators in Houston had no warning whatsoever when the Challenger exploded last Wednesday. But their video screens monitor only about one-tenth of the shuttle's sensors.
NASA teams at Kennedy Space Center at Cape Canaveral, Johnson Space Center at Houston, and Marshall Space Center in Huntsville, Ala., have already begun the meticulous work of piecing the data into a history of the 74-second flight.
What they find may determine the middle-range future of the US space program.
By the end of last week, White House officials were discussing creation of a panel to study the future of the space program in light of last week's explosion.
Even before the disaster, there had been fresh stirrings over US space policy -- over how best to use the shuttle and whether the US needed to develop other, unmanned, launch vehicles as well.
Another presidential commission, headed by former NASA director Thomas Paine, is already looking 50 years ahead at the long-term future of the US in space. The Challenger investigation and what it uncovers, says the commission's director of planning, Ted Simpson, is not likely to change that distant picture.
But the findings could heavily sway US directions in space in the next decade or two, some observers say. ``If the disaster was due to a bad engineering design or something, that's one thing, '' says Lou Friedman, director of the Planetary Society, based in Pasadena, Calif. ``But if it's something wrong with the basic technology of the shuttle, that could be a much more troubling problem.''
It could determine whether NASA builds a shuttle to replace Challenger and whether the US branches out into building other kinds of launch vehicles, Dr. Friedman says.
NASA's search for what happened Tuesday is proceeding largely out of public view. The key to this probe, according to the agency, will lie in piecing together the telemetry data from the shuttle.
``Then we'll know what to look for in the debris and the pictures,'' says NASA spokesman Jim Mizell. ``I'm confident, as a systems engineer, that we will find the accident's signature in the telemetry data.''
A fundamental starting point in NASA probes, says John Atkins, a former safety director at Kennedy, is working from what is known to have happened, not from how the mishap may have occurred. He acknowledges that this philosophy has been frustrating to the press, who are eager to make sense of the tragedy.
Mr. Atkins, a veteran of many NASA accident investigations, including the 1967 Apollo fire that killed three astronauts, says the teams conducting the probe are under tremendous public pressure to come up with reasons -- where reasons may never be entirely clear-cut.
When a disaster as serious as the Challenger explosion hits, says Atkins, everyone involved in the program from top NASA staffers to subcontractors asks himself: ``Did I do something wrong?''
``Your gut's shot the first couple of days,'' he says. ``Then you've got a job to do. . . . Once you get to the point of trying to find out what happened, it's a whole different ballgame. It's an intellectual challenge.''
Another working principle of NASA probes, says Atkins, is that the team is not interested in placing blame. ``Otherwise your efficiency factor goes to nil.''
When does work return to a sense of normalcy for the shuttle team? ``After the next launch,'' Atkins says. Until then, ``you're looking at yourself and looking at three other guys and saying, `Are you sure?' You'll look at something on a chart for 20 minutes that before you would have glanced over once and checked off.''