Re: GO FEVER IS WELL ENTRENTCHED:(
- From: "Bob Haller" <hallerb@xxxxxxx>
- Date: 26 Mar 2006 06:42:39 -0800
http://www.floridatoday.com/apps/pbcs.dll/article?AID=/20060326/NEWS02/603260312/1007/news02
Schedule pressure propels NASA
Foam danger is unresolved, but agency moves ahead with launch plans
BY JOHN KELLY
and TODD HALVORSON
CAPE CANAVERAL - Three months before the planned launch of shuttle
Discovery and seven astronauts, NASA again is under dangerous pressure
to fly so it can finish the International Space Station by 2010.
Once again, NASA has delivered a revamped external fuel tank to Kennedy
Space Center before finishing tests to prove whether it is safe to fly.
This time, decisions will be colored by that mortifying moment last
July when Discovery's right wing was almost struck by another chunk of
orange foam insulation from the tank, a piece similar to the debris
that doomed Columbia three years ago.
Managers insist they will delay the launch if tests show conditions
could lead to another disaster, which would prompt an early shutdown of
the shuttle program and the loss of thousands of jobs in Brevard
County.
"Is there a potential that you would fly something that you have less
than full confidence in just because you're already going down the path
toward flight?" said John Chapman, manager of the external tank project
at Marshall Space Flight Center in Alabama. "The answer to that is
absolutely not.
"There is absolutely zero intent to fly that tank before that work is
complete. . . . It's as simple as that."
However, a FLORIDA TODAY review of NASA documents shows that agency
managers bowed to schedule pressure during NASA's attempt to return the
shuttle fleet to service after the Columbia accident. The records show
that some engineers argued for changes to the part of the tank that
shed foam on Discovery's flight, but were overruled by managers.
The review also showed:
Discovery was cleared for flight last year even though a redesigned
external tank failed to meet stricter safety standards set after the
2003 Columbia catastrophe.
NASA managers changed ground rules of crucial engineering analyses,
avoiding further modifications to a tank already at KSC.
Discovery's fragile heat shield suffered more debris hits than orbiters
on prior flights, but the damage was less severe.
In February 2003, Columbia's seven astronauts died when their shuttle
disintegrated over Texas during atmospheric re-entry. Investigators
blamed a hole in the heat shield, caused when a piece of tank
insulation broke free during launch and struck the left wing at high
speed.
Today, this much is clear: NASA never will be able to completely stop
the foam insulation from breaking free from external tanks in flight.
But the agency has made significant progress in preventing debris large
enough to cause catastrophic damage to an orbiter.
"You guys ought to be aware, and we have got to make it clear to
everybody we talk to, when we launch the next flight, there is still
going to be foam come off the tank," shuttle program manager Wayne Hale
told KSC workers in a meeting last month.
"We have not got a plan in place that is going to eliminate all foam
loss off the tank," he said. "That is a big goal, and we don't think we
are going to get there in the life of the program."
Near-hit
NASA concedes the near-hit on Discovery averted the kind of damage that
could have triggered a risky rescue mission. Astronauts would have
docked at the space station and waited while NASA scrambled to launch a
second shuttle.
With Discovery, a 3-foot slab of foam broke away from a long wedge of
insulation -- dubbed a Protuberance Air Load ramp, or PAL ramp --
designed to provide a wind shield for critical fuel pressurization
lines and electrical cables that run along the outside of the tank.
Two independent review teams said schedule pressure played a role in
decisions about the extent of safety modifications the agency would
attempt before Discovery's flight last summer.
Lower-level engineers flagged the 38-foot PAL ramp for removal,
modification or extra inspections. They knew the handcrafted wedge was
susceptible to shedding large chunks of debris.
It now appears their suggested changes could have made a difference.
NASA removed and replaced 10 feet of the ramp to make other changes in
the area. On that section, workers used a new and improved process to
reapply the foam. The debris later shed during Discovery's launch came
from the 28-foot part of the ramp that had not been replaced.
At the time, managers planned to fly two more missions while engineers
completed the analyses.
Changing rules
Discovery was on the launch pad at KSC last spring before NASA finished
analyses aimed at showing whether the redesigned tank met stricter new
requirements for reducing launch debris. The reviews ultimately showed
the tank did not meet standards.
But rather than change the tank itself, managers changed the ground
rules for the debris analyses. Several members of an independent
oversight group took exception with that approach.
"The middle of a design review does not seem an appropriate time to be
changing the rules," they said in comments added to the Return To
Flight Task Group's final report. A NASA manager told them, "That's why
we're changing the models, so we don't have to change the tank."
Ultimately, NASA conceded foam or ice debris large enough to cause
catastrophic damage still could come off parts of the modified tank.
A post-flight inspection report shows that Discovery was battered by
debris during last July's flight.
A total of 176 dings and gouges were counted on fragile heat-shielding
materials designed to protect the orbiter and its crews from the
intense heat of re-entry. The average on previous flights: 144.
Armando Oliu, the head of NASA's ice and debris inspection team at KSC,
said the majority of the damage was minor. That's a sign that the
agency is making progress toward eliminating the worst debris.
"We know the external tank is producing the majority of those debris
hits, but it's from small particles," he said. "What we've reduced is
the potential for a major hit."
Modifications
NASA managers decided late last year to remove PAL ramp foam from the
tank now being readied for the next shuttle flight. Engineers think it
will be safe to fly the tank without the ramp, but conclusive tests and
analyses are ongoing.
"Your gut says it's probably an OK thing to do, but you don't want to
bet the safety of the vehicle on intuition," Hale said.
Wind tunnel tests are under way in California and Ohio. Additional
tests are scheduled in Tennessee in June. Discovery is set to launch
July 1.
Hale says he would postpone the launch if the tests prove fuel
pressurization lines or electrical cables might be ripped off in flight
without the PAL ramp to protect them.
"You don't want to fool around with that because you can't stand for
those things to come loose when you go Mach 4. That would be a bad
thing," Hale said. "If the answer comes back and says the cable tray
will come off, then that's not something we're going to fly with."
Contact Kelly at 242-3660 or jkelly@xxxxxxxxxxxx
.
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