In
just a few days, it's flying time again for America's space shuttle.
The
last shuttle trek, Discovery's July 2005 mission, marked both a return to
flight and then a grounding of the fleet to grapple with problems of falling
foam from the shuttle's huge external fuel tank--the issue that was flagged as
leading to the tragic loss of Columbia and its crew in 2003.
But
even before Discovery on its STS-121 mission roars skyward, this next flight
finds itself in a swirl of controversy--with NASA and its contractor team still dogged
by technical issues of dealing with foam loss.
Furthermore,
NASA's
own director of Safety and Mission Assurance and the space agency' chief
engineer voted no-go for the July 1 launch. While they called for a delay to make
further design changes to the shuttle system, they also stated that the
still-unresolved issues do not represent a threat to safe return of the shuttle
crew.
In
a press briefing earlier this month, NASA's chief, Mike Griffin, noted the
high-stakes in play with Discovery's imminent liftoff.
"If
we were to lose another vehicle, I would tell you right now that I would be
moving to figure out a way to shut the program down," Griffin said. "I think at
that point, we're done. I'm sorry if that sounds too blunt for some, but that's
where I am. We're trying to navigate some very difficult waters ... to get the
station assembled. I think that's worth doing. I've stated that on multiple
occasions, but it's not easy."
Glass spacecraft
There
is no doubt the shuttle system is an engineering marvel. Still, given its
delicate nature--thousands of easily damaged ceramic tiles--the space plane has
been dubbed the "glass spacecraft", said Scott Hubbard a former member of the
Columbia Accident Investigation Board (CAIB) and past director of NASA's Ames
Research Center. He is now a visiting scholar at Stanford University and Carl
Sagan chair at the SETI Institute.
And
being the aging, exceedingly complicated space ship it is, the shuttle is also
a troubled craft.
"I
think the concern by many members of the CAIB, myself included, is that there
are other failure mechanisms ... other types of aging going on that may appear at
any time," he told SPACE.com. "You have this uneasy feeling of what else
might show up in such an incredibly complex vehicle ... any vehicle that is that
complex has failure modes that are difficult to predict or anticipate."
Every
shuttle launch "is a holding of the breath," Hubbard said.
Meanwhile,
the clock is ticking on the aging fleet of three remaining shuttles--with the
hands of that clock sweeping toward retirement of the vehicles in 2010, and
with 16
more shuttle liftoffs to go.
Going-out-of-business trajectory
"NASA
has laid out a schedule for the space shuttle between now and 2010 that is
certainly achievable ... if the shuttle can be operated safely over its remaining
16 or so flights," said John Logsdon, Director of the Space Policy Institute in
the Elliott School of International Affairs at George Washington University in Washington, D.C.
All the changes that have been introduced since 2003 are intended to make this possible, he added "so it is reasonable to plan for such
success." Also a member of the CAIB, Logsdon said the space shuttle remains a risky
vehicle. So at any point between STS-121 and its final flight "there is a
possibility of a major problem, one that could lead to permanent grounding of
the remaining shuttle fleet," he told SPACE.com.
The
ripple effect from such the grounding would have major impacts in the short
term, meaning that the International Space Station (ISS) could not be
completely assembled, Logsdon explained. For the long term, the shuttle is on a
"going-out-of-business trajectory," he added, with the development of its replacement--the
Crew Exploration Vehicle and its Crew Launch Vehicle--soon underway.
"So
it makes sense to me to make a best effort to fly the shuttle to assemble ISS,
while recognizing that a decision that this cannot be done with acceptable risk
could come at any point in the next four years," Logsdon noted. "Whenever the
shuttle program ends, there will be a replacement means for taking Americans to
space on the near horizon."
Good news/bad news
The
soon-to-depart shuttle mission evokes a good news/bad news comeback from Joseph
Pelton, a research professor with the Institute for Applied Space Research at George Washington University.
"The
good news is that the shuttle is still a relatively safe experimental space
vehicle with a 1-in-60 to 1-in-100 chance of a category one failure--loss of
vehicle, loss of crew. The bad news is that after $2 billion in expenditures
for the reflight effort--and now many years after the Columbia failure--critical
objectives set by the CAIB have not been accomplished," Pelton told SPACE.com.
Pelton
was lead investigator for Space Safety Report: Vulnerabilities and Risk
Reduction In U.S. Human Space Flight Programs an
independent assessment prepared and released last year by the Space and
Advanced Communications Research Institute (SACRI) of George Washington University.
Pelton
singled out several remaining key issues: the stiffening of the shuttle outer
hull; the ability perform repairs to the shuttle's thermal protection system in
space; and correction of the foam-shedding problem.
"The
mantra that NASA developed after Columbia that said 'find it, fix it and fly
safely again' rings hollow after so much time and money has been spent with
such limited results," Pelton explained.
NASA credibility and space funding
"In
truth, the problems that NASA continues to experience with its shuttle and the
International Space Station program--really the only reason the shuttle is still
flying--goes back at least to the Challenger disaster in 1986," Pelton said.
Two
major national space commissions back then--one looking into the Challenger
accident, the other delving into the future of the American space program--noted
that the shuttle was indeed becoming "obsolescent" and that it had to be
replaced by another vehicle within at least 15 years, or 2001, Pelton noted.
"Instead
of developing alternative plans for the launch of International Space Station
components in smaller and more modular parts at that time," Pelton said, "NASA
pushed ahead without developing a new vehicle, nor developing a back-up plan.
Now,
not only is NASA's credibility and space funding at risk, Pelton continued, but
also at risk are the agency's international partners that are engaged in the
$100 billion station program. "The now 'tar baby-like tandem' of the ISS and
the space shuttle has done great harm to space programs around the world."
NASA
has over-invested in both the shuttle and station initiatives, Pelton said, taking
away money from programs that truly matter to the United States and indeed the
world.
Never too late to start over
"The
truth of the matter is that the shuttle program--an experimental program when
designed in the 1970s--should have been grounded years ago. It should be
replaced by better, safer, and more cost efficient programs. The development of
private space vehicles that are human-rated, something that NASA is currently
actively supporting, is clearly the right step forward," Pelton advised.
Ultimately,
it is not NASA that is at fault here, Pelton said, pointing to national
leadership that has often overruled the space agency on where and how to spend
their limited resources. It is never too late to start over, he said, and
develop a NASA program that makes sense, balances expenditures, and set
priorities that matter to the person in the street.
"The
question is not whether NASA should be grounding the space shuttle and putting
them in museums," Pelton concluded, "but what are its backup plans and how can
it restore balance to its overall space programs and give new focus to its
various NASA centers?"
Level of success
Indeed,
there is a lot riding on the next shuttle liftoff, beyond technology.
"This
is one of the most significant missions of the shuttle program because of the
policy implications that it presents," said Roger Launius, Chair, Division of
Space History at the Smithsonian Institution's National Air and Space Museum in Washington, D.C.
Launius
underscored the fact that Griffin has stated clearly that if NASA does not fly
successfully this time it would mean the end of the program. "That, of course,
begs the question [as to] what defines a successful mission?"
The
last mission, for all of its challenges, was successful by most measures. It
launched, flew, and returned safely; it delivered its supplies and equipment to
the ISS; it undertook several safety tests and repairs.
That
being the case, several questions percolate to the surface, Launius said.
"Is
a level of success commensurate with the last mission sufficient to conclude
that the program will continue? If that is not where the bar is set, is it
higher or lower? I confess that I have no idea. I also confess that I hope and
pray that this mission is a rousing success, by any standard that one might
want to apply," Launius told SPACE.com.
Honorable retirement
Launius
also senses there is something present with the forthcoming shuttle flight that
he hasn't necessarily experienced before.
"A
sustained and underlying depression seems present among those working in the
program, some of them for their entire careers," Launius explained. "There is a
sense of ending--as well as an ever-present perception of loss and failure--present
among many members of the space shuttle team."
Without
question, Launius said, the space shuttle will be retired within something less
than a decade, whether it is after this next mission or 2010 or sometime a bit
later.
"As
the space shuttle enters its home stretch, it should be remembered with both
praises for its many accomplishments and criticisms for its shortcomings,"
Launius suggested. "I am in favor of giving the shuttle an honorable retirement
and to give a full measure of respect and thanks to those charged with its
operations over the years for their efforts."
In
the process of retiring the space shuttle, "I hope NASA will ensure that the
knowledge and expertise gained in the shuttle program is preserved and used for
the future," Launius concluded.
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