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Out of space? NASA delays relaunching of shuttle flights
By Patrick Martin
4 May 2005
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The announcement April 29 of a two-month delay in the resumption
of space shuttle flights is a warning sign of a deeper crisis
in the US space program. While NASA Administrator Michael D. Griffin
said the flight of Discovery would be rescheduled for mid-July,
the problems that caused the delay could lead to an indefinite
grounding of the shuttle fleet.
It has become increasingly clear in the two years since the
destruction of the Columbia during reentry on February 1, 2003,
that the US space program suffers from technical and organizational
flaws so severe as to foreclose any possibility of a safe return
to manned space shuttle launches in the foreseeable future.
Last Fridays announcement was the third time that NASA
has pushed back the launch of Discovery, the first space shuttle
flight since the Columbia disaster. Shuttle program officials
blamed the latest delay on re-engineering required to prevent
ice buildup on the outside of the line leading into the shuttle
booster rockets huge fuel tank, which stores liquid hydrogen
at temperatures several hundred degrees below zero.
Testing suggested that large ice chunks could shake loose from
the fuel line during launch and slam into the skin of the shuttle,
resulting in damage analogous to that caused by the piece of foam
insulation that broke off during the launch of Columbia. That
damage to the leading edge of the Columbias wing is believed
to have caused the disintegration of the shuttle during reentry.
Shuttle engineers are now working to rig up a heater for the
outside of the fuel tank to prevent ice buildup, with installation
and troubleshooting expected to take several weeks. As a result,
the shuttle would not be ready to launch during the next time
window, from May 22 to June 3, forcing a postponement to the next
available slot, July 13 to 31.
There are several constraints that limit the launch dates.
These include the Discoverys mission to the International
Space Station, which requires a trajectory placing it in high
Earth orbit, and NASAs decision to launch only in the daytime
rather than at night, to insure maximum visibility in assessing
damage to the spacecraft during launch. The Columbia investigation
was hampered because the launch was at night, reducing the quality
of the videotape used to monitor the shuttles skin.
NASA engineers have been especially concerned about joints
in the fuel line, which allow the fuel line to contract without
damage as the super-cold liquid flows through it. (The fuel tank
contains liquid oxygen at a temperature of minus 297 degrees Fahrenheit
and liquid hydrogen at minus 423 degrees.) Ice can form on the
outside, and chunks as large as five inches by two inches broke
loose during testing. Deputy shuttle program director N. Wayne
Hale said that during launch, A piece of ice that big going
three times the speed of sound can do some serious damage.
In his comments to the press, Hale tried to minimize the significance
of the delay. After a great deal of testing and analysis,
we have been able to cross about 175 potential debris sources
off our concerned list, he said. There are still three
or four more items to work on. Well take a few more weeks
to deal with them.
Behind this effort to present the delay as routine, there are
troubling indications of the kind of systemic failure that produced
the Columbia tragedy. Lower-level engineers at NASA were so concerned
about the internal procedures for handling safety concerns that
they leaked documents to the New York Times last week showing
that top officials were relaxing safety standards previously established
as requirements for a return to space.
A lengthy article in the April 22 edition of the Times
cited internal documents showing that NASA officials have
loosened the standards for what constitutes an acceptable risk
of damage from the kind of debris that led to the disintegration
of the shuttle Columbia as it was returning from space two years
ago.
The Times said that among experts who reviewed the documents,
a small but forceful minority say they worry that NASA is
repeating a practice that contributed to the Columbia disaster:
playing down risks to continue sending humans into space
Specifically, the documents suggest that NASA was seeking to
justify a return to space shuttle flights even though it could
not fully meet the safety goals set by the independent board that
investigated the Columbia accident. The agency made at least three
changes in statistical methods used to assess the risks of debris,
according to one document, because we cannot meet
the previous standards.
The piece of foam that struck the left wing of the Columbia
during its liftoff is estimated to have weighed 1.67 pounds. Since
then, tests have shown that a fragment as small as 0.023 pounds
could cause catastrophic damage. NASAs goal is to insure
that no fragment larger than 0.01 pounds, about one sixth of an
ounce, strikes the shuttle skin.
One of the internal documents leaked to the Times, co-authored
by John Muratore, the manager of systems engineering and integration
for the shuttle program, suggests shifting from traditional worst-case
situation estimates to our best estimate of actual conditions,
or relaxing safety margins outright, from about 1-in-800 chance
of failure to an estimated 1-in-40.
NASA officials responded to the Times report by denying
they were moving the goal posts on safety standards
to insure a favorable launch decision. At the same time, they
postponed the scheduled May 15 launch of Discovery to May 22,
the prelude to the subsequent two-month postponement.
The space shuttle engineers who leaked the documents to the
press demanded their names be withheld, in fear of retribution.
The Columbia investigation board found that NASA executives maintained
an internal regime that suppressed criticism and the voicing of
safety concerns. In the week between the launching of Columbia
and its fiery breakup, several lower-ranking engineers expressed
concern about damage from the foam impact during liftoff, but
their input was ignored, and top officials rejected a request
that US spy satellites be used to inspect the shuttles underside.
In the wake of the report of the board investigating the Columbia
disaster, NASA appointed a task force headed by Richard Covey
and Thomas Stafford, both former astronauts, to monitor progress
in compliance with the reports 15 major recommendations.
The seven astronauts scheduled to fly aboard Discovery said
they wanted assurances from the task force before going ahead
with the launch. At a press conference last month at the Johnson
Space Center, mission commander Eileen Collins said, If
we ever get to the point where a recommendation is not fulfilled
in anyones mind, we are not going to fly until we are ready
to fly. She added, We learn more by taking risks [but]
we dont want to take silly risks.
But by mid-April, the Covey-Stafford group said that only eight
of the major safety recommendations had been implemented. They
canceled a public hearing scheduled for March because NASA had
not supplied the required data. Last week, a final session of
the task force with NASA officials, scheduled for May 4-6, was
postponed indefinitely.
In his first news conference after being installed as NASA
administrator, Michael Griffin said the Discovery might take place
without final approval by the Covey-Stafford task force. I
dont believe that technical decisions are a voting matter,
he said. Stafford-Covey will have their criteria; the line
managers in charge of the program will have theirs.
The real issue, however, is political. The Bush administration
has placed considerable pressure on NASA to resume space shuttle
flights, as part of its emphasis on space as the high ground
in military operations. The enormous lifting capacity of the space
shuttle has been utilized primarily for placing sophisticated
satellites in orbit to provide military surveillance and intelligence.
This is what underlies the grandiose White House proclamations
about resuming manned space flight operations to the Moon and
ultimately Mars: scientific exploration for its own sake, which
can be accomplished far more effectively by instruments carried
on unmanned probes, is being downgraded in favor of the manned
flights required to make use of space for military purposes.
See Also:
Bush administration
cancels maintenance of Hubble Space Telescope
[13 March 2004]
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