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 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 Wednesday and Thursday in the first hearings since the George W. Bush moon mission was shelved earlier this month.
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.
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," he said. "We are not going to Mars on chemical rockets."