The return to flight mission of space shuttle Discovery - and subsequent grounding of the shuttle fleet - has spurred anxiety regarding the future of NASA's human spaceflight programs.
A falling chunk of insulating foam from the shuttle external tank, as well as dings of its patchwork of fragile reentry protective tiles, are haunting replays of problems that led to the destruction of shuttle Columbia and loss of its crew in 2003.
After years of costly post-Columbia work, there are those who caution that the space shuttle system remains a circa 1970's jerry-rigged approach to 21st century space travel. Moreover, how NASA and its confab of contractors can speed up any move to a shuttle-replacement - the Crew Exploration Vehicle - is but one of a myriad of bewildering issues still to tackle.
Shuttle system: creature of compromise
"I'm quite pessimistic today about the future of the space shuttle program, and I'm also pessimistic about the future of the human spaceflight effort of the United States," said Roger Launius, Chair, Division of Space History at the Smithsonian Institution's National Air and Space Museum in Washington, D.C.
Launius said that the policy questions posed by the latest "grounding" of the shuttle fleet have conceivably enormous implications for the future.
"First, for many people the failure to resolve the external tank foam debris problem --despite more than two years of effort and more than a billion dollars -- calls into question the capability of NASA to manage critical technical challenges," Launius said.
A second point, Launius continued, involves a dash of irony.
"While the U.S. is going to retire the shuttle by 2010, perhaps sooner now, the irony is that most of the Crew Exploration Vehicle (CEV) concepts I have seen use a shuttle-derived launch system. What is actually being retired is the orbiter, which has not been the problem...but the launch system that has been problematic will be continued," Launius explained.
The shuttle launch system was "a creature of compromise" struck by political and NASA leaders during the early 1970s, Launius added.
Foam collides with the future
Compromises of the past are catching up with NASA's future - specifically for trekking back to the Moon, onward to Mars and beyond.
Shuttle foam troubles portend larger issues, suggested Howard McCurdy, a space policy expert and professor of public affairs and chair of the public administration department at American University in Washington, D.C.
"The foam may have missed the [shuttle] orbiter, but it might have collided with the Vision for Space Exploration," McCurdy said.
"Given the lack of money for the Crew Exploration Vehicle, the assumption regarding the launcher is that it will be something derived from the current shuttle," McCurdy said. In his view, if NASA and its contractors cannot fix and test new approaches to foam application "that in turn confounds the cost assumptions underlying the whole vision."
The current shuttle flight, McCurdy said, is the beginning of the end for the space shuttle and eventually the International Space Station (ISS). "The vision for space exploration calls for NASA to get out of the business of operating both. The space shuttle is needed to complete construction of the International Space Station and possibly extend the life of the Hubble Space Telescope, but it is not the future vehicle of choice for missions beyond."
McCurdy said he recalls the liftoff language blared out as Discovery rose skyward, the "to the Moon and Mars and beyond."
"It sort of reminds me of the Concorde [supersonic aircraft] accident. When that vehicle was grounded, it ended the whole supersonic transport industry. Not a pleasant thought," McCurdy said.
"I'm more pessimistic today," McCurdy said, "but perhaps it will pass."
Unwise risks
NASA is faced with no alternative but to fix and fly.
"As painful as this situation is...NASA has no choice but to take whatever time and money is needed to fix it," said Matt Bille, a space writer and historian living in Colorado Springs, Colorado. He is co-author with Erika Lishock of The First Space Race (Texas A&M University Press, 2004).
Bille said that, given any plan to use space shuttle hardware to produce a Moon-Mars heavy lifter makes it imperative to perfect the external tank, or a modified ET, for future missions.
Additionally, the push for a hard Shuttle retirement date is unwise, Bille said. "That can lead to pressure to cram in missions before the deadline, and to unwise risks. NASA should establish the absolute minimum number of shuttle missions needed to finish the ISS -- plus, perhaps, one for Hubble -- and then base the schedule on the time needed to safely complete those missions," he told SPACE.com.
As for the entry-into-service date for the Crew Exploration Vehicle, such a calendar date "must be a goal, not a hard requirement," Bille advised. "Space flight will never be risk-free, but it must be pursued as safely as technology allows. A fatal accident with either Shuttle or CEV will likely mean the end of human spaceflight for a generation."
Innovative human transportation systems
The whirlpool of worry regarding the space shuttle program is spawning creative momentum in entrepreneurial space circles.
Alternative ways to transport space crews into Earth orbit is a key driver behind the work of Transformational Space Corporation (t/Space) of Reston, Virginia. David Gump, President of t/Space said that task was set before the non-traditional companies last month by NASA chief, Mike Griffin.
Gump said that it has become clear to NASA that it could not afford to operate the International Space Station with "business as usual" methods - meaning use of the space shuttle and Crew Exploration Vehicle, he said.
"So it's highly probable that NASA will ensure that the ISS crew program will birth one or more innovative human transportation systems. In time, these systems could provide an alternative base upon which to build lunar exploration initiatives," Gump said.
Robust access to orbit
The shuttle track record since its maiden flight in 1981 underscores the major issue with its use, said Peter Diamandis, Chairman and Chief Executive Officer of the X Prize Foundation in Santa Monica, California.
"The difficulty remains the frequency of flight," Diamandis said. "The fact that we're still running into difficulties isn't unexpected."
Following some 25 years of shuttle takeoffs and nearly 115 flights of the system under NASA's belt, "we're still 'shaking out' the vehicle and learning what needs to be fixed," Diamandis noted. "There's only so much modeling that can be done by humans and computers. To build a robust vehicle you need to fly it...a lot," he said, identical to what is seen with any complex system from aircraft, to computers and software.
"NASA's best hope for a robust access to orbit is tied to the development of low-cost vehicles created to serve the personal spaceflight market where hundreds of flights per year is the norm," Diamandis concluded.
Hitting the reset button
Could NASA's shuttle follow-on, the Crew Exploration Vehicle, become yet another aborted space agency launch vehicle development project?
That prospect is a concern, observed space historian, Roger Launius, of the Smithsonian's Air and Space Museum. The CEV has similar ambitions akin to those of previous projects - to build a new system, one that lacks both sufficient funding and public enthusiasm.
"That is not a prescription for success if history is any guide, and I believe it is," Launius said. "I am concerned that we will begin the CEV research and development effort and find it is non-sustainable for any number of reasons, and like X-33 [a canceled NASA reusable project] and the National AeroSpace Plane decide to hit the reset button."
Launius told SPACE.com that he is increasingly viewing "as a horror story" the half-hearted quest for human space access since the space shuttle. "And the events of the last couple of days do not make me sanguine for the future," he said.
Unsure trajectory
A central question to deal with: Is the nation on a trajectory toward ending the human spaceflight program?
"With sufficient diligence and resources, of course, virtually anything we can imagine in spaceflight may be achieved. What concerns me is that neither sufficient diligence nor resources will be available for the continuation of human spaceflight beyond the end of the shuttle program," Launius stated.
That all being said, Launius concluded he is far from sure how shuttle and future human spaceflight discussions will turn out.
"I do believe it is time to give the shuttle an honorable retirement," Launius said. "It has been a venerable machine and it is time to move on to a new human spaceflight vehicle."
If the shuttle is retired now or in 2010, Launius said, "it and those associated with the program -- from the designers to the maintainers to the engineers to the astronauts - have earned an important place in history and deserve our recognition.
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