NEW YORK — NASA has joined the federal probe into the cause of unintended acceleration of Toyota-built cars, with nine expert NASA engineers looking into the problem as part of a new study, the U.S. Department of Transportation (DOT) announced March 30.

U.S. Transportation Secretary Ray LaHood said the new study is one of two new investigations into reports of sudden acceleration in Toyota vehicles. The study is expected to last through at least late summer and include NASA experts on computer-controlled electronic systems, electromagnetic interference and software integrity.

“We are determined to get to the bottom of unintended acceleration,” LaHood said in a statement. “For the safety of the American driving public, we must do everything possible to understand what is happening. And that is why we are tapping the best minds around.”

The NASA engineers are based at the space agency’s Langley Research Center in Hampton, Va.

“A small group of engineers out of NASA’s Engineering and Safety Center (NESC) is going to be supporting DOT in their study of Toyota unintended acceleration,” Langley spokesman Keith Henry said. “The agreement was just signed [March 26] but the details are still being worked out.”

Some scientists have suggested that cosmic-ray interference or other electromagnetic sources may be a contributor to the acceleration problems reported in Toyota vehicles. Space radiation, they say, could potentially interfere with the proper performance of tiny computer chips in the vehicle controls.

NASA scientists will investigate the Toyota problems as part of a review of the vehicles’ electronic throttle control systems overseen by the National Highway Traffic Safety Administration (NHTSA) — the auto safety branch of the Department of Transportation.

“We normally do aerospace, obviously, but in this area of looking at electrical systems, we have guys who do that for aircraft or spacecraft,” Henry said. “They do an assortment of technical assessments all the way from shuttle issues to space station to Hubble to planetary stuff to aeronautics … everything and anything within NASA where a technical assessment is needed. I think the reputation of the NESC is what got them the invitation to participate.”

The second investigation announced by the Transportation Department March 30 is a 15-month study by the National Research Council to make a broader review of unintended acceleration and electronic vehicle controls across the entire auto industry.

That study is not limited to just Toyota vehicles, and will ultimately lead to recommendations to the NHTSA on how the agency’s research, rules and defect-investigation activities can better ensure the safety of electronic control systems in motor vehicles, transportation officials said.

“We are bringing the best minds and talents to resolve this issue,” said NHTSA Administrator David Strickland. “We will not rest until we have identified and addressed any potential vehicle-related causes of unintended acceleration.”

Together, both studies are expected to cost about $3 million, Transportation Department officials said.