Space Forum / Shuttle / November 2005

Cause of foam loss eludes NASA

Agency hopes for May launch of shuttle

BY TODD HALVORSON
FLORIDA TODAY
Examination. Steve Poulos, orbital project manager, holds up a sample
of a shuttle gap filler at a news conference Tuesday at Johnson Space
Center in Houston. AP
Enlarge this image

CAPE CANAVERAL - NASA still has not zeroed in on the cause of a
dangerous foam loss on its first post-Columbia shuttle mission, but the
agency is working toward launching another test flight in May,
officials said Tuesday.

Four months after the July 26 launch of Discovery, the officials also
said NASA will not let schedule pressure affect its foam loss
investigation or the timing of the shuttle's return to service.

"We have not set a launch date," NASA shuttle program manager Wayne
Hale said.

"We are not driving to a date on a calendar that was set arbitrarily.
We are not allowing ourselves to be driven to do something stupid
because of some schedule date," he said. "And the only people, quite
frankly, that I get pressure from on launch schedules is the media."

Accident investigators cited schedule pressure as a contributing cause
of both the 1986 Challenger explosion and the February 2003 Columbia
disaster. Fourteen astronauts were killed in the accidents.

NASA put shuttle flights on hold when a one-pound piece of foam
insulation broke free from Discovery's external tank two minutes into
flight, barely missing the ship's right wing.

The Columbia accident was blamed on a 1.67-pound piece of external tank
foam that blasted a hole in that shuttle's left wing. The damage went
undetected and allowed hot gasses to rip the ship apart during
atmospheric re-entry.

NASA spent $205 million and two-and-a-half years trying to fix the foam
loss problem before clearing Discovery for flight.

The foam that doomed the Columbia crew was a large piece of
hand-crafted insulation around metal struts that connect the nose of
the shuttle orbiter to the tank, which is filled with supercold
propellant prior to launch.

A heater designed to keep ice from building up and potentially breaking
off in flight replaced the foam.

The foam that endangered Discovery's crew also was a large handcrafted
piece of insulation but it came from a different area of the tank.

It broke free from a 38-foot-long ramp designed to ensure smooth
airflow over pressurization lines and electrical cables that run along
the outside of the tank.

John Chapman, manager of NASA's external tank project office, said
engineers still don't know why the foam fell off Discovery's tank.

"We haven't found any eureka, or smoking gun, so far," he said.

Small defects, hairline cracks, the foam application process and
inadvertent damage by workers all could be factors, he said. NASA has
found tiny cracks in foam applied on unflown shuttle tanks.

NASA ultimately aims to remove the ramp.

Wind tunnel tests and computer analyses are under way to make certain
the cables and pressurization lines it is designed to protect would not
be damaged in flight.

Hale said there is a chance the tests could be complete by May. The
plan otherwise is to replace ramps on tanks to be used on NASA's next
two flights using a new application process aimed at preventing foam
loss.