NASA's emerging exploration plan will call for safely sending humans to Mars, possibly by the 2030s, and de-emphasize exploration of the moon, the agency's leader said Tuesday.

“That is my personal vision,” NASA Administrator Charles Bolden said. “I am confident that, when I say humans on Mars is a goal for the nation, not just NASA, I'm saying that because I believe the president will back me up.”

Bolden cited appearances set before congressional committees on Feb. 24 and 25 as a deadline for creating the “beginnings of a plan” for human exploration.

At those hearings, Bolden said, he will be able only to give a range of dates for a Mars trip because scientific questions, such as mitigating radiation exposure and bone loss, remain unanswered.

But he confidently said the 2030s, even the early 2030s, were viable if given a reasonable and sustained budget.

Bolden was in Houston this week making his first visit to Johnson Space Center since the release of President Barack Obama's budget on Feb. 1. Obama has been on the defense as the budget, while adding $6 billion in new money over five years, calls for the cancellation of the Constellation program that the Houston space center manages.

Bolden's expansiveness on the attractiveness of Mars as a clear goal for NASA may blunt some of the criticism Obama has received for not addressing space policy since taking office, nor clearly outlining what will replace Constellation.

Under Constellation, NASA was to build two new rockets to fly astronauts to the International Space Station and, by the early 2020s, back to the moon where a lunar base would be built. Researching and living on the moon would be a steppingstone to exploring outward to destinations like Mars, perhaps by 2040.

‘Fight, fight, fight' vowed

Congressional critics have said NASA should not be asked to change plans when $9 billion has already been spent on Constellation and that by canceling the space agency's next-generation exploration program, Obama is turning his back on human spaceflight.

“The president's plan is not what our country needs at this time,” said Rep. Pete Olson, R-Sugar Land. “We have been the world's leader for 50 years, and I can't accept that we're going to fall behind. We are going to fight, fight, fight to ensure that the next person who steps on the moon is an American.”

Olson said the right thing to do is add $3 billion to NASA's budget annually for the next five years to ensure Constellation is fully funded.

But Bolden's comments Tuesday, made at a Houston Chronicle editorial board meeting, indicate the president hopes to reach Mars before the timeline envisioned by the Constellation program.

Bolden said this could be accomplished by sending robotic or possibly human missions to the lunar surface, but to skip the costly and timely step of building a permanent lunar base.

“I don't see us colonizing the moon as some people do,” he said. “That's not NASA's job. Our job is to explore.”

And if someone beats NASA back to the moon while it is conducting research on rockets that can blast humans to Mars?

“When the Chinese or the Japanese or the Russians, or anybody else that people are worried about, get back to the moon before we do, I'm not worried about that,” said Bolden, a former astronaut. “Because when they land they're going to be walking in the footsteps of 12 Americans who have already been there.”

Planetary Society likes it

Some pro-space exploration organizations have embraced Obama's plan because it has the potential to get humans beyond the moon more quickly than Constellation.

“The proof will be in what they do with this new plan, but I have great hopes for it,” said Louis Friedman, executive director of The Planetary Society.

Friedman noted Constellation budget's is largely focused at present on developing the Ares I rocket, to carry astronauts to Earth orbit, and the Orion crew capsule that would house them both in orbit and on longer journeys.

The president's proposed budget spends more, about $3.1 billion over the next five years, on the design of a heavy-lift rocket that can carry the fuel and supplies needed to propel and sustain astronauts on long journeys, Friedman said.

Hard sell ahead?

Bolden said he would like to use some of the money previously earmarked for Constellation's Ares I rocket to fund newer technologies that might get humans to Mars more quickly.

“I think the path that (Obama) has asked us to go down now gives us a better chance of getting to some destinations, if not as fast, maybe even faster in some cases because there are technologies that we overlooked, or just pushed aside, because we couldn't afford them for the last several years we've been developing the Constellation program,” Bolden said.

His task during the next two weeks will be to flesh out more details for the Mars vision, and then sell the plan to a skeptical Congress that ultimately will have to approve funding.

eric.berger@chron.com