Frits Westra segnala: http://spaceflightnow.com/shuttle/sts107/030208

NASA studies telemetry for signs of orbital impact

BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE"
http://cbsnews.cbs.com/network/news/space/current.html

Posted: February 8, 2003

A military radar system shows indications that an object might have
separated from the shuttle Columbia in orbit, prompting a review of
telemetry by NASA flight controllers to look for signs of anything -
including impact by high-velocity space debris - that might have
contributed to the shuttle's breakup Feb. 1 during re-entry.

NASA sources said the radar data apparently shows a small object
suddenly separating from the shuttle at about five meters per second, or
roughly 11.2 mph, on Jan. 17, about 24 hours after Columbia's launch
from the Kennedy Space Center.

NASA officials late Saturday confirmed shuttle engineers are reviewing
telemetry from the ship to determine if any sort of propulsive or other
event might have happened that could explain such radar observations.

Shuttle crews routinely dump waste water overboard, which instantly
turns into a rapidly expanding cloud of ice crystals. It's not yet known
whether a routine water dump could have resulted in the observed radar
"signature."

Occasionally, large plugs of ice develop on the water dump nozzles.
Whether such an ice plug might have been blown off during an otherwise
routine water dump - showing up on radar as an object moving away from
the orbiter - is not yet known.

It's also possible some piece of non-critical hardware was somehow
released or ejected from the shuttle without the crew's knowledge,
something that would not have played a role in Columbia's re-entry
breakup Feb. 1 over Texas.

Columbia was destroyed 16 minutes from landing when it veered out of
control. Telemetry from the shuttle shows elevated temperatures in a
landing gear wheel well and along the left side of the fuselage during
the final eight minutes of flight.

Telemetry also shows an unusual aerodynamic drag on the left wing, which
tended to force the ship to pull to the left. Columbia's flight control
system attempt to correct for this drag by adjusting the craft's trim.
Moments later, contact was lost.

What might have caused problems for the left wing is not yet known.

During launch Jan. 16, foam debris from the shuttle's external tank hit
the underside of the wing and outside analysts have speculated that
impact might have weakened the shuttle's thermal protection system tiles
enough to trigger the catastrophe during re-entry.

But it's also possible impact by space debris could have damaged the
heat shield tile or the carbon-carbon panels protecting the leading edge
of the wing by knocking a piece off the shuttle. While a tile would be
visible to a powerful radar, NASA engineers have not yet confirmed such
an impact took place. Agency officials stress they are investigating
those possibilities and many others.

In east Texas, meanwhile, a large section of the shuttle Columbia's
lower fuselage - possibly part of its rear body flap or a piece of a
landing gear door - was recovered today near Nacogdoches. But NASA
engineers have not yet determined whether debris found earlier near Fort
Worth is part of the ship's left or right wing.

The debris found near Nacogdoches appears to have curved hinge
components on each side, indicating it was moveable hardware. Heavily
damaged black heat shield tiles on the debris show it came from the
bottom of the spacecraft.

The only large hinged panels on the shuttle's fuselage are the nose and
main landing gear doors, the external tank umbilical attachment covers
and a large "body flap" at the rear of the shuttle that shields the main
engines from heat during re-entry.

The debris found today appeared to be part of the body flap, but
television views were not conclusive. While its shape was roughly
correct, it was smaller than a complete body flap, indicating a large
piece is still missing.

NASA officials, meanwhile, said work continues to establish a reliable
timeline showing when various sensors failed during re-entry or detected
higher-than-normal temperatures on the left side of the shuttle. The
timeline is not yet complete, but officials hope to finalize the details
over the next few days.

NASA officials also dismissed media reports earlier today that raised
the possibility precautions could have been taken before Columbia's
return to Earth that might have helped minimize left-wing heating during
re-entry.

During a flight in 2000, engineers studying launch video were concerned
a six-inch piece of ice falling away from the ship's external fuel tank
might have hit and damaged protective tiles on one of the wings. Playing
it safe, flight controllers re-oriented the shuttle just before
re-entry, "shadowing" the area in question to help lower its
temperature. The idea was to slow the onset of entry heating.

In Columbia's case, officials said today, the shuttle's orientation, or
attitude, during the mission resulted in lower-than-normal temperatures
across the lower fuselage. As a result, Columbia was re-oriented to warm
the belly slightly, part of a routine procedure to properly control main
landing gear tire pressure.

NASA spokesman Kyle Herring said the re-entry flight profile was normal
and dismissed speculation flight controllers could have re-oriented the
shuttle during its descent through the atmosphere to ease the effects of
heating.

"There is no protected, secret attitude we can fly," he said. "We
already fly the most benign entry possible."

Shuttle program manager Ron Dittemore said much the same thing last
week, pointing out that any attempt to favor one wing would subject the
other wing to extreme, inherently hazardous conditions.