WASHINGTON — Apollo 17 astronaut Gene Cernan, the last man to walk on the Moon, told U.S. lawmakers May 12 that NASA Administrator Charles Bolden recently confided that the federal government may need to fund a “bailout” of entrepreneurial space firms if a commercial market fails to materialize for the crew taxis they are developing under the agency’s new plan.

Cernan said Bolden made the bailout remarks during a conference call NASA convened the prior week to brief Cernan and Apollo 11 commander Neil Armstrong on NASA’s plans ahead of the Senate Commerce Committee’s human spaceflight hearing.

”Charlie expressed some concern over the potential of the commercial sector to be successful in any reasonable length of time,” Cernan said during the three-hour hearing.

“He indicated we might have to subsidize them until they are successful, and I can say with authority because I wrote this down, and I put the word ‘wow’ right next to it, because Charlie did say it may be a bailout like GM and Chrysler. As a matter of fact, it may be the largest bailout in history,” Cernan said.

Bolden, who testified earlier in the hearing on a panel that included White House science adviser John Holdren, told lawmakers he did not recall using the word “bailout” during the conference call with Cernan and Armstrong.

“I’m not sure I said that, sir,” Bolden said under questioning by Sen. David Vitter (R-La.). “I’m not sure who was in the room, but as I have always said, I will do everything in my power to facilitate the success of the commercial entities in access to low Earth orbit.”

As part of President Barack Obama’s 2011 spending plan now before Congress, NASA plans to stop work on the Ares 1 rocket and an Orion Crew Exploration Vehicle capable of ferrying astronauts to the international space station and begin a new commercial crew initiative modeled after the Commercial Orbital Transportation Services program under which NASA is subsidizing competing efforts by Space Exploration Technologies and Orbital Sciences Corp. to field new cargo-carrying capsules and rockets.

Bolden said the success of the proposed commercial crew initiative is critical to  NASA’s plans for leaving low Earth orbit a decade from now. But he admitted that the chosen companies could need sustained technical and financial assistance.

“I have to look at the possibility that the commercial sector may have difficulty, and we will do everything in my power to facilitate their success. So that’s what I meant when I said anything about it,” Bolden said, referring to the conference call.

Later in the hearing, Armstrong said lowering the cost of access to space through increased reliance on the private sector is a good goal, but questioned the decision to walk away from the nation’s roughly $10 billion investment in Constellation.

“I support the encouragement of the newcomers toward their goal of lower-cost access to space,” Armstrong said in his opening remarks. “But having cut my teeth in rockets more than 50 years ago, I am not confident.”

So far, lawmakers critical of Obama’s NASA plan appear to outnumber those championing it. During the hearing, however, a small handful of lawmakers, including the committee’s chairman, expressed cautious support for the president’s proposed new direction.

Sen. John D. Rockefeller (D-W.Va.), the committee’s chairman, said congressional opponents of Obama’s plan are justifying their views solely on the potential for job losses among the nation’s aerospace work force.

“I don’t think we can afford to do that,” Rockefeller said. “I think we have to strike a balance between economic development, which means jobs, and modernizing our space program so we can remain competitive for years to come.”

Sen. Sam Brownback (R-Kan.) praised the commercial thrust of Obama’s plan. “Opening up commercial space ensures a strong future for the U.S. and the competitive aerospace industry,” he said.

Sen. Mark Warner (D-Va.) said commercializing space transportation “holds some great possibilities and opportunities,” including for NASA’s Wallops Flight Facility, the Virginia launch site that Dulles, Va.-based Orbital Sciences plans to use for the Taurus 2 rocket and Cygnus space tugs it is building to haul cargo to the space station.

But other members, including Sen. Kay Bailey Hutchison (R-Texas), said serious flaws in the Obama plan remain. She characterized reliance on commercial space taxi providers as “risky,” and said “fledgling companies” could leave the United States with as much as a 10-year gap between shuttle retirement and the fielding of a domestic human spaceflight capability.

Hutchison, who introduced legislation in March to extend the shuttle program several years, said the administration should at a minimum commit to adding one more flight to the shuttle manifest, a proposal that Bolden said is under consideration.

Sen. Bill Nelson (D-Fla.) praised Obama’s willingness to refine the NASA proposal, but said more must be done to ensure timely development of a heavy-lift rocket needed for human missions beyond low Earth orbit.

“As the authorizing and appropriating committees continue to review the president’s proposal, we here in the legislative branch are going to try to work with the administration to refine his plan, and change some parts of it,” Nelson said.

Specifically, Nelson said he wants NASA to select a heavy-lift design sooner than the 2015 deadline Obama set in his April 15 speech at Kennedy Space Center in Florida.

“We’d like to speed that up,” he said.