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."
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.
"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.
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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- STS-121 Launch Dissent Stemmed From Risk to Shuttle, Not Astronauts
- Return to Flight: NASA's Road to STS-121
- The Great Space Quiz: Space Shuttle Countdown