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Old July 8th 03, 09:16 PM
Rusty Barton
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Default NASA: Gases Breached Wing of Shuttle Atlantis in 2000

NASA: Gases Breached Shuttle Wing in 2000

Associated Press - 08 July, 2003

By TED BRIDIS, Associated Press Writer

WASHINGTON - Superheated gases breached the left wing of shuttle
Atlantis during its fiery return to earth in hauntingly similar fashion
to the demise of Columbia nearly three years later, according to
internal NASA documents.

Unlike Columbia, Atlantis suffered no irreparable damage during the May
2000 episode and, after repairs, returned to flight just four months
later. NASA ordered fleetwide changes in how employees install
protective wing panels and sealant materials.

The small leak through a seam in Atlantis' wing during its return from
the International Space Station as disclosed in documents sought by The
Associated Press under the Freedom of Information Act. The mission
commander was James Halsell, a shuttle veteran who is coordinating
NASA's effort to return the shuttles to flight.

One of the seven Atlantis astronauts, Mary Ellen Weber, said NASA never
told her about the breach, which was not discovered until the shuttle
had landed.

"There are thousands and thousands of things that can go wrong, and the
crew is very much aware this can happen," Weber said. "Certainly, when
you learn about this, if it had progressed, it could have been much more
dire."

Weber operated the robotic arm aboard Atlantis and flew aboard Discovery
in July 1995. She said NASA may have reported the wing damage to other
crew members. Attempts by AP to reach the other astronauts by telephone
through family members and NASA offices in Houston and Washington were
unsuccessful; one Atlantis crewman was a Russian cosmonaut and another
has left NASA to return to the Air Force.

NASA spokesman James Hartsfield said crews and engineers generally
participate in two months of meetings to discuss their experiences and
spacecraft conditions. He could not say whether the shuttle's commander
or pilot was told about the wing breach, which NASA blamed on
incorrectly installed sealant material.

Some experts expressed surprise that superheated gases ever had leaked
inside a shuttle's wing. Although protective wing panels have been found
damaged, even cracked, the Columbia disaster was widely believed outside
NASA to have been the first such breach.

"Very little information about the flaws of the tile system ever make it
into the open literature, so those of us who work on this ... seldom
hear much about serious problems such as this one," said Steven P.
Schneider, an associate professor at Purdue University's Aerospace
Sciences Lab. "I've never heard this sort of leak occurred."

NASA said it later determined Atlantis' exterior wing panels were not
damaged by the overheating despite being discolored from the high
temperatures. Aluminum structures inside the wing "looked outstanding,"
NASA said. Other parts immediately behind the wing panels were covered
with a glassy material, apparently from melted insulating tile and other
sealant material.

Hartsfield said all damaged parts were replaced.

The space agency formally reported the damage to its Program
Requirements Control Board, an internal safety oversight body, which
ordered fleetwide improvements in the installation of sealant materials
before Atlantis was allowed to launch for its mission in September 2000.
Atlantis is expected to be the next shuttle into space when NASA is
cleared to resume flights.

Weber, now an associate vice president at the University of Texas
Southwestern Medical Center in Dallas, described Atlantis' return to
Earth as mostly routine and remembered seeing an orange glow from hot
gases dancing outside the shuttle windows.

Although damage inside Atlantis' left wing was detected post-flight,
NASA worried about the shuttle's return even before the discovery.

During liftoff, a 6-inch chunk of ice had smashed against the back edge
of the right wing; so experts deemed it prudent to adjust Atlantis'
flight to rapidly cool its wings prior to the fiery trip through the
atmosphere, NASA documents showed.

It was impossible to know whether this cooling technique, called a
thermal conditioning maneuver, also helped minimize heat damage inside
Atlantis' defective left wing. NASA later determined damage on the right
wing was relatively minor.

The board investigating Columbia's Feb. 1 breakup determined that
superheated gases penetrated protective wing panels that had been
loosened by insulating foam that broke off its external fuel tank on
liftoff and smashed against the shuttle. Investigators believe searing
re-entry temperatures melted key structures inside until Columbia
tumbled out of control and broke apart at close to 13,000 miles per
hour, killing its seven astronauts.

NASA did not consider ordering the thermal conditioning maneuver on
Columbia because it believed such a move would have interfered with
efforts to warm Columbia's landing gear tires for a safe landing.

NASA blamed the Atlantis damage on improper installation of a seal
between two protective panels on the shuttle's left wing, "called a
butterfly gap filler," at the Boeing Co. plant in Palmdale, Calif.,
during an overhaul of Atlantis in late 1997. The mistake went unnoticed
during subsequent inspections because the part could not be seen without
removing protective panels, NASA said.

Engineers found the damage on Atlantis while investigating the mystery
of a partially melted insulating tile. Removing two protective wing
panels nearby and peering inside the wing structure, they determined the
dislodged seal had created "a substantial flow path," according to
NASA's internal reports. The gap measured just over one-quarter inch,
about the width of a paperclip or a No. 2 pencil.

The protective panels, insulators and other hardware inside the left
wing "shows various signs of overheating," NASA reported. Photographs
showed charred and scorched components, including parts made from
titanium and inconel, two of the most heat-resistant materials on the
shuttle. Titanium melts about 3,000 degrees; inconel melts about 2,550
degrees.

Investigators examining Columbia's breakup remain uncertain over the
size of the gap that permitted hot gases to penetrate that shuttle's
wing. But they believe it was as small as a one-inch slit running
vertically up the wing for nearly 30 inches. In a test Monday, a chunk
of foam blew open a dramatic 16-inch hole in parts of a mock-up of a
shuttle wing.

Temperatures during a shuttle's return can climb to almost 3,000 degrees
— nearly one-third as hot as the surface of the sun — along parts of the
spacecraft, especially the leading edges of its wings. Damage there is
considerably more likely to doom a shuttle than anywhere else. NASA
requires immediate repairs when damage to the wing's protective panels
exceeds four-hundredths of an inch, about the thickness of a dime.

http://story.news.yahoo.com/news?tmp...624&e=1&u=/ap/
20030708/ap_on_sc/shuttle_earlier_breach
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