As CBS News Correspondent John Blackstone reports, the entire shuttle program will be open hard questions about its future, and an aging fleet now down to three shuttles.
"It is an enormously complicated machine and the safety regime to make sure everything is right is enormously taxing on any system," says Alex Roland a former NASA historian from the 1970s and 80s.
Getting the shuttle ready for each flight requires more than a million individual safety checks.
After Challenger exploded in 1986, NASA was urged to develop the next generation of space vehicle with new and simpler technology.
The unmanned X43 is the latest in a long string of test vehicles that NASA hopes will lead to a new manned spacecraft. But the X43, like so many others before, is behind schedule and over budget.
"We have the X33, X38, all kinds of vehicles. Billions of dollars are spent, promises are made and nothing happens," says Rick Tumlinson, founder of Space Frontier Foundation.
NASA has kept the aging shuttle flying, insisting that safety has never been compromised. Others, however, worry that cuts in the shuttle budget, some 40 percent since 1990, have gone too far.
"The panel's concern was that the work force was being potentially reduced ... where you could maintain the level of safety," says Norris Krone, a former member of the safety advisory panel.
Sam Beddingfield was among the first employees in the Shuttle program. He says the heat absorbing tiles were long viewed as vulnerable, but an alternative metal system proved too expensive.
By one measure, the nation no longer seems so committed to space. Since the 1960's NASA got only 5 percent of the federal budget. Today, that is now down to less than 1 percent.