CAPE CANAVERAL - NASA next
week will try to free a knob stuck between the dashboard and a cockpit window
on shuttle Atlantis - a problem that some fear could trigger lengthy launch
delays or even an early retirement for the orbiter.
But NASA shuttle program
officials effectively are saying, "Not so fast."
"I think it's too
early to know whether it's a big deal or not," said Kyle Herring, a
spokesman for NASA's Johnson Space Center in Houston.
"This is just kind of
a new issue, and there's a lot of creativity, I'd say, that engineers have, and
they'll probably exhaust every option that they have to try to free it,"
he said. "It's a little premature to say that an orbiter is finished
flying because of this."
Here's the situation:
A notched rotary knob from
a lighting bracket somehow got wedged between the orbiter's cockpit instrument
panel and one of six forward windows during NASA's fifth and final
Hubble Space Telescope mission in May. The knob is designed to mount a work
light to a bracket.
Somehow, it floated into a
recess in the corner of the cockpit, and two edges of one of its
crescent-shaped notches are pressing against the inside of the triple-pane
window, which is a little more than 2 1/2 inches thick.
Small gouges already have
been detected. Engineers are concerned that efforts to extract the knob might
exacerbate the damage.
Flying "as-is" is
not an option. NASA cannot adequately evaluate the structural integrity of the
window with the knob wedged against it.
Another fear is that the
effort to free the knob might be so invasive that it could cause serious delays
in future Atlantis flights. The next one is scheduled
for Nov. 12.
Any disassembly of the
dashboard likely would involve the removal of cockpit instrumentation. That
could take months to complete.
With shuttle fleet
retirement set for the end of 2010, NASA could decide to sideline Atlantis and
fly eight remaining missions on Discovery and Endeavour.
Atlantis at one time had
been set to retire after the Hubble servicing mission, then serve as a donor of
spare parts. As it stands, Atlantis is scheduled to fly two more International
Space Station assembly
missions. The second is set for May 2010.
Technicians
have been unable to free the jammed knob.
Dry ice was applied to it
in an attempt to shrink the knob enough to retrieve it. That didn't work, so
engineers are examining options that include drilling or cutting it out.
"Your primary goal is not to damage the window," Herring said.
On Monday, NASA will
pressurize the crew cabin to just less than 18 pounds per square inch - higher
than normal pressure at sea level. The hope is that the space between the
dashboard and the window will expand enough to free the knob.
An assessment then would be
carried out to see if the innermost pane of the window would have to be
replaced.
Technicians at Kennedy
Space Center routinely swap the outermost panes of cockpit windows - panes that
get dinged by micrometeorite or space debris.
But the innermost panes had
been changed at a California assembly facility that was shuttered years ago.
Herring said the
consequences of such a swap on Atlantis at KSC is not clear.
"There may be other
ways to get around changing it out," he said. "But until they get
there, it's hard to tell how the schedule will play out. So whether that would
be an impact to a November flight is" to be determined.
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