When America's space shuttle program ends in September, the U.S. will be completely dependent on Russian rockets for launching men and women into space -- and bringing them back. But what will happen to America's astronauts if relations between the U.S. and Russia sour?
Until American companies come to market with commercial rockets and launch vehicles to replace the shuttle, the only nation ever to put a man on the Moon won't even be able to put a man into orbit. And that, experts tell FoxNews.com, has the potential to be a "tragic mistake," one that could hold America's astronauts in orbit hostage to the whims of the Kremlin.
"The U.S. has surrendered its advantage in space, conceding the high ground to others who are probably our enemies," said Jane Orient, a science policy expert and professor at the University of Arizona. "We are apparently leaving seven astronauts in space as hostages. Their loss would be a tragedy, but only a small part of the total disaster. It would symbolize the lack of respect that America has for its pioneers."
Former rocket scientist Shannah B. Godfrey is equally outspoken in her criticism and concerns, noting the need for constant training and condition to remain prepared for a crisis in space.
"Remember a few years ago when china 'accidentally' hit a satellite in space?" she asked, adding that "they were subtly sending us a message that they could cripple us instantly by taking out our satellites."
" Think of the intelligence data that would be lost: GPS capabilities, cell phones, many other communications, etc. We may need to send people up in a hurry to replace, repair, and man satellites and other stations, too. I can’t fathom why we would put ourselves in such a vulnerable position."
NASA scoffs at concerns that Russia could strand American astronauts in space.
"There are always Soyuz spacecraft docked to the station, providing enough crew seats for a return to Earth," said NASA spokesman John Yembrick.
And some scientists agree that these fears are misplaced. Dr. Howard C. Hayden, an emeritus professor of physics at the University of Connecticut, believes there will be "no problem" in serving the International Space Station. "I can't imagine that the Russians would avoid a rescue mission simply because relations had soured," Hayden told FoxNews.com. "That would bring very loud international condemnation. They'd go out of their way to establish their moral high ground."
But others are less confident; they worry about problems that may result from relying too much upon others.
"The looming, multi-year gap in U.S. human spaceflight capability is a major embarrassment that represents a failure of U.S. leadership," John Lindner, a professor of physics and astronomy at The College of Wooster in Ohio, told FoxNews.com.
The Obama administration's decision to end the space shuttle program is causing great concern among politicians on both side of the aisle as well. Sen. Richard Shelby, R-Ala., has said that reliance on the Russians could last even longer than NASA anticipates, since replacements for the aging spacecraft are far from ready. It's a situation he finds "unacceptable."
"The administration's ill-conceived proposal to rely on commercial rockets that are unproven and untested for human transport to space ensures that our astronauts will likely be hitching a ride with the Russians for the indefinite future," Shelby said. "That outcome is unacceptable when we already have a sound plan in progress with Constellation."
"The President made a mistake" in canceling the shuttle program, Nelson said recently.
In his 2011 budget request, President Obama announced that NASA would cancel its Constellation shuttle replacement program and encourage private companies -- including SpaceX, Orbital Sciences Corp., and others -- to develop spacecraft to carry astronauts to low-Earth orbit.
That would free NASA to focus on other missions, such as monitoring climate change.
"The re-tasking of NASA as a climate monitoring agency in the stimulus bill, with a vast increase in its budget but a diminution in its role in the exploration of space, is a strategic error of heroic proportions," Lord Christopher Monckton, a former special adviser for science to British Prime Minister Margaret Thatcher, told FoxNews.com. Monckton is well known as an skeptic of global warming.
Realizing the shift in space power, Russia's space agency this week convinced NASA to sign a fresh contract for taxi service to space: $55.8 million per astronaut to fly into space on Soyuz capsules in 2013 and 2014. NASA currently pays less than half as much -- $26.3 million per astronaut -- when it hitches a ride aboard Russian spacecraft.
"The contract modification covers crew return and rescue capabilities aboard the Soyuz spacecraft," Yembrick said.
Since no American firm currently has a vehicle capable of regular access to space, NASA does not really know when it will be master of its destiny again -- and that doesn't sit well with some members of Congress, who have made it illegal to end the Constellation program without congressional approval.
Sen. Kay Bailey Hutchison, R-Texas, and others have proposed extending the shuttle's life beyond the last three flights scheduled this year. Hutchison wants the shuttle extended two years while NASA develops a new heavy-lift rocket replacement.
Other experts worry that the administration's plan will not actually encourage U.S. commercial space development, as a transition period is required for it to succeed.
"The problem with the new administration's plan comes into focus with this very issue," says Michael Carroll, author of the book, "The Seventh Landing: Going Back to the Moon, This Time to Stay."
"Without shuttles, we have absolutely no access to the ISS without Russia. It is fine to encourage private sector involvement in space transportation, and I believe that is the way to go in the future. But there must be a transition."
Lord Monckton believes the Obama plan will be harmful to U.S. defense interests as well, since the U.S. launch capability is now quite limited. "The administration's change of policy in space was calculated to do maximal damage to the defense interests of the U.S., and without even yielding a financial saving," Monckton told FoxNews.com.