WASHINGTON (AP) -- To fix a potentially fatal shaking problem on its snazzy new moon rocket, NASA is considering something that works for mud-stained pickups: heavy-duty shock absorbers.

For nearly half a year, NASA's No. 1 technical problem in designing its Ares I rocket, which will eventually propel astronauts back to the moon, has been a sound wave vibration problem from its solid rocket motors.

If the vibrations hit the right frequency, they could shake the astronauts to death -- or at the least make it impossible for them to work. The astronauts would be in the Orion crew capsule launched on top of the Ares.

The leading solution is to put weight on springs in parts of the bottom end of the rocket and underneath astronauts' seats to dampen the vibrations. Think MacPherson struts, said Garry Lyles, who heads a NASA team working on the problem.

"These are actually absorbers that are used in vehicles today, especially 1-ton and 1½-ton pickup trucks," Lyles said Thursday.

He said it's possible that further analysis and tests will reveal that the shaking problem that's turned up in computer models of the still unbuilt Ares may be a non-issue. But engineers are seeking solutions just in case.

NASA is not ready to proclaim the case closed and still considers it the highest level of potential problem, Lyles said.

Ares project manager Steve Cook called it "a very manageable issue."

There are many such challenges that face NASA's return-to-the moon program, according to a report issued Thursday by outside federal auditors.

The Government Accountability Office highlighted other potential problems, including too much weight in both the rocket and Orion capsule, design issues with a new engine for a booster, insufficient facilities for certain types of testing, and private industry's inability to make the Orion capsule's 1960s-style peel-away heat shield.

None of the technical problems is "a fatal flaw," the report's author, Christine Chaplain, told a House Science subcommittee Thursday.

Former astronaut Kathryn Thornton, associate dean of engineering at the University of Virginia, said experts believe that one of the biggest problems is that the space agency is set on a schedule of returning people to the moon by 2020 without enough money.

Getting to the moon by that date is "exceedingly unlikely," she told the subcommittee.