By SETH BORENSTEIN,
AP Science Writer WASHINGTON—Where to next? It's a simple question that NASA can't answer so easily anymore. The veteran space shuttle fleet is months from being mothballed and the White House has nixed a previous plan to fly to the moon.
For the first time in decades, NASA has no specific space destination for its next stop, although it has lots of places it wants to go. Future space flight, NASA officials say, now depends on new rocket science and where it can take us.
That uncertainty may not sit well with Congress, which will be grilling NASA chief Charles Bolden on Wednesday and Thursday in the first hearings since the George W. Bush moon mission was shelved.
There are only a few places in space where humans can go in the next couple of decades. NASA wants to go to all of them, with the ultimate destination, as always, being Mars.
"The suite of destinations has not changed over time," NASA deputy administrator Lori Garver said in an interview. "The moon, asteroids, Mars - if you're going to go anywhere - is where we are going."
But with any itinerary there is a first stop. So what is that?
Check back in a couple of years. That's when new technology should be developed enough to answer that question, Garver said. President Barack Obama plans to divert billions of dollars from the Bush moon plan toward developing better rocketry.
"The best way to get anywhere ... is really invest in technologies that will reduce the cost, reduce the time, reduce the risk and so forth," Garver said.
Some of those technologies seem like science fiction. The possibilities noted by experts inside and outside of NASA include the equivalent of an in-orbit gas station, electric-hybrid rockets, nuclear thermal rockets, inflatable parts for spaceships, and methods of beaming power between Earth and space.
Former astronaut Franklin Chang-Diaz, who has developed a new type of electric propulsion engine called VASIMR that the NASA leadership mentions specifically, said this new emphasis is especially welcome because six years ago NASA killed its advanced rocket technology program.
"We clearly need the technology leap if we really want to go to Mars," Chang-Diaz said. "We are not going to Mars on chemical rockets."
Chemical rockets are what has always been used to get into space and they require carrying lots of expensive fuel. Electric propulsion would get better mileage, but versions so far don't have nearly enough thrust to get off Earth.
To some critics, however, technology isn't as important as a destination. Sen. Bill Nelson, D-Fla., who will be chairing Wednesday's Senate subcommittee hearing, plans to push for some kind of commitment and specific plan of action.
"The president is the only one that can lead the space program, and he ought to set a goal," Nelson said in an e-mail. "He needs to say where we're going and let NASA design the architecture to do it."
Former NASA associate administrator Alan Stern said he's waiting to hear what NASA officials outline in the Capitol Hill hearings, but he too has concerns about not having a precise destination.
"We need a destination and a timetable and that's really lacking," Stern said. He said that relying on technology to dictate a location "sounds like a program to nowhere."
Because human spaceflight is about inspiration, science and international cooperation, Stern said, "you need a specific destination, a proper noun, something that's capitalized."
The outline for much of NASA's future was sketched out by an independent spaceflight panel the White House appointed last year. Led by retired Lockheed Martin Chairman Norman Augustine, the panel laid out options, including canceling an immediate return to the moon and instead proposing a "flexible path."
Panel member Chris Chyba, a professor of astrophysics and public affairs at Princeton University, said just because the flexible path doesn't point to a specific starting point doesn't mean it's without a goal.
"You begin by saying what your goal is, not what your destination is," Chyba said. "And the goal is the human expansion into the solar system."