WASHINGTON — The resurrected debate about the direction of the U.S. human spaceflight program moved to Capitol Hill April 3 where members of the House subcommittee that authorizes NASA spending levels seemed sharply divided on the issue themselves.

The debate over how NASA is carrying out U.S. President George W. Bush’s Vision for Space Exploration reached Congress two months after a panel of 50 scientists, astronauts, engineers, policy analysts and industry executives met for two days at Stanford University in Palo Alto, Calif., to discuss their concern over NASA’s budget priorities.

The group agreed with the vision Bush introduced in 2004 to return to the Moon and eventually explore Mars, said former U.S. astronaut Kathryn Thornton, an organizer of the Stanford meeting and co-chair of the group. The group also reached consensus that NASA should focus on human spaceflight to Mars, and beyond, over the next 30 years, but members of the group disagreed on the intermediate steps for getting there, she said.

How much money NASA should be spending on Mars now is a sensitive issue with members of Congress. Future human exploration on Mars should not dictate NASA’s spending, despite a growing drumbeat to tailor lunar missions to the specific challenges of reaching Mars, said U.S. Rep. Dana Rohrabacher (R-Calif.). Rohrabacher’s comments at the April 3 hearing before the House Science space and aeronautics subcommittee followed suggestions by space consultant Noel Hinners and two subcommittee members that Congress should remove language in the 2008 budget prohibiting NASA from spending money on research, development and studies related exclusively to human exploration on Mars.

“I would not want [people] to think there is any type of consensus that we should be making Mars the driving force for prioritizing or spending,” Rohrabacher said. “That would be giving up what we can accomplish today for something that is a majestic dream as we march to the future. That’s not the way to have a realistic, responsible policy for America’s space exploration.”

Hinners, who also attended the Stanford meeting in February, acknowledged longstanding tension between the human spaceflight and space science arenas, but pointed to the Apollo, Skylab, space station and space shuttle programs as evidence that the two camps can work together. In determining where to make budget cuts, NASA and Congress should maintain those missions that directly benefit future missions to Mars, he said.

“In my mind I would start with the requirement for Mars and feed that back into a lunar architecture, rather than the other way around,” Hinners said. “A lot of the things you do on the Moon have little applicability to eventual Mars exploration.”

Hinners said Congress could help by eliminating that language in the 2008 NASA appropriations bill that prohibits the U.S. space agency from spending money that is related directly to sending humans to Mars.

Rep. Nick Lampson (D-Texas), and Rep. Tom Feeney (R-Fla.), said they would join Hinners in trying to sway members of Congress firmly opposed to lifting the prohibition.

But Rohrabacher said more immediate problems deserve NASA’s attention, such as repairing the Hubble telescope, identifying asteroids or comets that might collide with the Earth and developing a system to counteract those threats, and using space to put greater effort into conserving Earth’s resources.

“I am 100 percent in favor of that limitation that we should not be spending money on things that are exclusively, or for accomplishing, a future manned Mars mission,” Rohrabacher said. “It would be a horrible disservice to the people of the world and especially the taxpayers of the United States if we were to start prioritizing our spending based on the idea of humans stepping foot on Mars 30 years or 40 years down the road.”

The prohibition poses challenges at NASA, said Richard Gilbrech, associate administrator of NASA’s Exploration Systems Mission Directorate.

“It has a somewhat chilling effect down at the lower levels because engineers see that and they think we are not even thinking of Mars, as opposed to the letter of the language that says we will not spend 2008 dollars on anything specific to human landing on Mars,” he said. “We are, of course, following the law; we would like to see that [law] change in future years.”

NASA is developing lunar exploration plans that while not exclusively related to Mars exploration should pay off eventually for a Mars mission, Gilbrech said.

NASA unveiled in September 2005 its blueprint for sending humans back to the Moon and later to Mars. NASA has awarded more than $7 billion in contracts, and is expected to spend $230 billion more on the initiative during the next two decades, said Cristina Chaplain, director of acquisition and sourcing management for the U.S. Government Accountability Office.

NASA has set March 2015 as the deadline for fielding the Orion Crew Exploration Vehicle and its Ares 1 launcher to carry astronauts to the Moon. Within the agency, program officials are working toward a more aggressive goal of late 2013 that Gilbrech said — in response to a question during the hearing — the agency would have a better chance of meeting if $2 billion were added to NASA’s budget.

Gilbrech defended plans for lunar exploration, which he said will build the infrastructure needed for human exploration on Mars. He also said he believes NASA should continue on its path to the Moon.

“There is lots of science left to be discovered on the Moon,” Gilbrech said. “The Apollo program put 12 people on three-day stints at a time. With a surface area the size of Africa, to say we’ve exhausted all scientific discovery there doesn’t compute to me.”

Thornton, with four missions to space as a NASA astronaut, cautioned against allowing the Moon to become a permanent outpost anchoring human space exploration in low Earth orbit.

“It is time for humans to go beyond low Earth orbit,” Thornton said. “Orbiting our Earth, as thrilling as it is, it is not exploring space.”

NASA’s budget challenges could intensify due to uncertainty during this presidential election year.

The election in November could delay passage of the 2009 budget that begins Oct. 1, which would force federal agencies to operate under a continuing resolution with the same amount of money appropriated in 2008.

With a $357.4 million difference between NASA’s proposed 2009 exploration budget and its 2008 budget, a yearlong continuing resolution like a similar one in 2007 would set back the 2015 Ares 1 and Orion completion target by four months, Gilbrech said.

“The biggest risk, to me, is not really technical,” Gilbrech said. “It is the ability for us to stay the course and go through the changes in the administration and congressional cycles and be able to stay on a longer-term path.”