TIME: Almanac 1990/1990 Time Magazine Compact Almanac, The (1991)(Time).iso/time/caps/86/86capts.3

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                WÅ                                                      Y««Looking for What Went Wrong

February 10, 1986

NASA begins an arduous search for clues to the disaster

It may take weeks or even months for federal investigators to be
certain of the answer, and perhaps they will never know for sure.  At
least ten separate teams of investigators are now probing every
aspect of the mystery of why Challenger exploded; and Acting NASA
Administrator William Graham vowed they would "provide the best
national capability to study this, to analyze it, to find out how to
correct it, and to ensure that it will never happen again."

Although attention at week's end was focusing on a possible burn-
through of the casing on one of the shuttle's two solid-fuel booster
rockets, Space Flight Director Jesse Moore warned against premature
speculation, saying "it will take all the data and a careful review
of those data before we can draw any conclusions."

The first step was to gather every scrap of evidence that could be
found, including the remains of Challenger.  A fleet of 13 vessels,
four planes and nine helicopters began searching an area that
eventually grew to 6,000 sq. mi. of Atlantic coastal waters, picking
up thousands of pounds of wreckage, including a large section of the
shuttle's fuselage and the nose of a booster rocket.

Then there were all those pictures that the whole nation had seen,
over and over again, and that the experts now had to study, in slow
motion and with computer enhancements, over and over again.  NASA not
only had 80 of its own cameras filming the Challenger launch, but it
impounded all the film in 90 remote-control cameras that various news
organizations (including TIME) had installed near the launch pad.

Finally, there were the billions of signals sent between the doomed
shuttle and NASA computers at Cape Canaveral's Launch Control and in
Houston's Mission Control before and during the 73 seconds of its
flight.  The shuttle contained an extraordinary array of monitoring
devices (sensors to detect pressures, temperatures, fuel flow, and
so on), which reported their findings thousands of times a second.
This flow of information, or telemetry, was so constant and so
enormous that a lot of it was not sent either to the shuttle cockpit
or to the consoles at Launch and Mission controls.  Instead, the data
that were non-operational--that neither controllers nor crew could
have done anything about--were simply stored away in computers.  Thus
while controllers at Cape Canaveral and in Houston apparently noticed
nothing abnormal on their consoles until telemetry from Challenger
abruptly stopped, the stored data could contain the clue that the
space agency is seeking.

Though NASA experts repeatedly objected to all public guessing about
what caused the explosion--all employees of the agency were ordered
not to speculate--it was virtually impossible to prevent people from
doing just that.  But the space agency promptly took issue with some
of the early theories.

One was that ice, which had formed on Launch Pad 39-B during Cape
Canaveral's 27 degree F weather the night before the lift-off, had
somehow damaged the shuttle.  In fact, engineers at Rockwell
International, the prime contractor for the shuttle, saw the ice in
televised shots of Pad 39-B and telephoned NASA to urge a delay in
the launch.  But Space Flight Director Moore said that an "ice team"
had just inspected the shuttle.  "We checked just 20 minutes prior to
launch, and the consensus of the reports was good," he said.  "It was
decided that very low risk would be involved."

Another theory was that the external fuel tank's insulation had been
damaged during a minor accident Saturday, when a derrick arm
supposedly scraped the tank.  But Moore insisted that the derrick had
not touched the tank, only part of the launch-pad equipment.  "It was
a small box," he said, "a heater box that had about a quarter of an
inch of insulation, out of five inches, scraped.  It was a very minor
scrape, and it was repaired."

Since the videotapes played early in the week seemed to show a small
ball of fire suddenly appearing between one of the solid rocket
boosters and the large external tank, most of the speculation
centered on the possibility of a failure in either the tank of one of
the boosters.  Either situation could have caused the uncontrolled
ignition of hydrogen gas, which needs only a spark and the presence
of oxygen to explode violently.  When the flame first appeared, a bit
more than a minute after blast-off, the shuttle had just experienced
its maximum aerodynamic stress, which a few experts thought might
have caused some flawed part to crack.

A rupture of a seam in the external fuel tank is another possibility.
But the inner hydrogen tank would also have to break for the hydrogen
to escape, and that would be hard to explain.  Then, too, a leak
would have lowered the tank pressure, a change that should have
showed up in readings on the controllers' consoles.  Charles Donlan,
a former NASA official who is now an aerospace consultant, suspects
that something may have gone wrong in the fuel lines connecting the
external tank to the orbiter's engines.  Former Astronaut Frank
Curtis Michel, now a professor of astrophysics at Rice University,
speculates that trouble may have started "in the rear of the orbiter,
where all of the action is going on.  There's a lot of plumbing
there, all of which has to be leakproof."   Even though the
videotapes seem to show fire breaking out in the forward part of the
craft, he notes, it could have quickly reached there by moving
through pipes or even the payload bay.

Technicians at the Cape thought that the forward attachment, or
strut, connecting the orbiter to the external tank might have broken
and severed fuel lines.  Or, they say, a failure might have occurred
in the barrier between the liquid hydrogen and liquid oxygen
containers within the big external tank.

At NASA's Jet Propulsion Laboratory in Pasadena, Calif., however,
some rocket experts suggested at midweek that the explosion had been
caused by a burnthrough in the 3/8-in.-thick steel casing of the
solid-fuel boosters.  After watching replays of network tape of the
Challenger disaster at J.P.L., officials said it looked "very much
like films we've seen of burnthroughs during tests at Thiokol."
(Morton Thiokol Inc., which manufactures the booster rockets at its
plant in Utah, has since the 1970s been conducting tests in which the
boosters are deliberately overpressurized to see how much stress they
can take."

The J.P.L. experts interpret the tape as showing a bright sphere of
flame appearing well above one of the boosters' lower skirts.  It is
on the interior side, facing the external tank and pointing away from
the orbiter.  A fraction of a second later, the sphere of flame
becomes a cone-shaped jet of fire.  The pointed end of the cone
emerges from the booster, and its rounded end seems to aim at the
fuel tank, apparently burning a hole in its side.  The next thing to
be seen is the huge fireball, engulfing everything.

Indeed, a near burnthrough at a different side on a booster occurred
on an earlier Challenger flight, during the summer of 1983.  In that
case, the insulating material on the interior of the nozzle's throat
was scorched away to within half an inch of the nozzle's outer skin.

Still, the way the boosters continued flying after the explosion
prompted some experts to reject the likelihood of a burnthrough in
either one.  Hurled away from the exploding external tank, both
rockets appeared to be moving rather stably, producing the awesome Y-
shaped pattern that millions of Americans will never forget.  A
burnthrough on the side of the casing, several rocket specialists
say,would have sent the booster cartwheeling wildly through space.
Bob Truax, a retired engineer who directed the Thor missile program
in the 1950s, agrees.  "After the explosion, they were continuing on
a fairly normal trajectory," he says.  "Even if you get a small leak,
that hole would get bigger in a matter of seconds, and you'd have
hell in a handbasket very quickly."

But at week's end the New York Times reported that NASA technicians
had found evidence amid the reams of telemetry that seemed to support
the burnthrough theory.  According to the unnamed source, the date
show that the right solid-fuel booster had a pressure drop of nearly
30 lbs. per sq. in. and a loss of 100,000 lbs., or about 4%, of
normal thrust about 10 sec. before the explosion--the kind of
decrease of burnthrough would have caused.  Later the same day, NASA
released new pictures and a videotape showing what it called "an
unusual plume" of flame streaking from an apparently enlarging gap in
the side of the right booster immediately before the explosion.  That
seemed to be strong evidence.

But NASA still refused to jump to any conclusions.  The agency named
an interim investigative panel to take charge of the search and
called upon two aircraft "crash detectives" from the National
Transportation Safety Board for help.  The NTSB experts, more
experienced than the space agency in reconstructing accidents, will
assist in building a "fault tree":  a split-second, item-by-item
analysis of the flight's progress, as portrayed by telemetry, voice
recordings, eyewitnesses, photographs and videotape.  With NASA and
industry engineers, the NTSB investigators, like paleontologists
trying to reconstruct a dinosaur, will piece together every available
scrap of Challenger debris--the same procedure they follow in
investigating an aircraft crash.  Says one former NASA scientist:  "I
just hope there's enough evidence to find the smoking gun."

--By Otto Friedrich.
 Reported by Jay Branegan/Washington and Jerry Hannifin/Cape Canaveral