WASHINGTON and SAN FRANCISCO — During two days of contentious congressional hearings that included allegations that NASA Administrator Charles Bolden is not in charge of his own agency, the former astronaut and retired U.S. Marine Corps general took the blame for a White House proposal to cancel the Constellation program and count on commercial space firms for transportation to low Earth orbit.

Opening a Feb. 24 hearing before the Senate Commerce science and space subcommittee, Sen. David Vitter of Louisiana — the panel’s ranking Republican — made abundantly clear that he blames NASA Deputy Administrator Lori Garver, not Bolden, for the human spaceflight overhaul proposed in President Barack Obama’s budget request for 2011.

“I’m just sorry, quite frankly, in terms of this hearing that we are not going to hear from who I suspect are the true lead architects of this very radical budget proposal, including Deputy Administrator Garver,” Vitter said.

Bolden said many individuals were involved in the budget process and declined to cite any specific architect, adding that if the panel wanted to blame someone, it could blame him. That response did little to appease Vitter, who said he had heard speculation that Garver might one day be nominated to fill the post of NASA administrator. “Based on this budget, I would be a strong, fierce, active opponent of that,” he said.

Sen. Bill Nelson (D-Fla.), the subcommittee’s chairman, suggested that the White House Office of Management and Budget (OMB) was the real culprit. “I think OMB is running the space program because it designs the budget,” Nelson said. “The president has to take control. The president has to offer leadership.”

Both Nelson and Vitter complained that NASA’s plan to cancel Constellation and invest billions in enabling technologies leaves the United States without a clear goal for human spaceflight.

Bolden said NASA’s ultimate destination is Mars, adding that his “superiors” shared this view — an assertion that prompted Nelson to declare that Bolden had “made some news.”

Meanwhile, one of Bolden’s superiors, White House science adviser John Holdren, was telling House appropriators much the same thing. “We’re not ready to put a date on that yet, but yes, Mars is the ultimate destination,” Holdren said during a House Appropriations commerce, justice, science subcommittee hearing held at the same time Bolden was being grilled in the Senate.

To prepare to send astronauts to Mars, Bolden said, NASA needs to make significant investments in research to better understand the impact of long-duration spaceflight on the human body. In addition, NASA should develop spacecraft capable of reaching the red planet quickly, he said.

Nelson endorsed Mars as the right destination and praised NASA’s proposed technology investment, but said more needs to be done to shield the nation’s spaceflight work force from irreparable harm. “A significant upheaval in this work force related to shuttle retirement is going to occur,” Nelson said. “That massive loss of jobs is now exacerbated by the perception of the cancellation of Constellation and all the programs under it.”

To save some of those jobs, Nelson said, NASA should continue testing the Constellation program’s Ares 1 rocket, pursue a robust heavy-lift launch vehicle development effort, and continue working on a spacecraft for manned missions beyond low Earth orbit.

Both Nelson and Vitter also questioned NASA’s plan to rely on private space companies to develop the capabilities needed to offer transportation of astronauts and cargo to low Earth orbit. Nelson cited safety concerns, while Vitter chided the administra

tor for offering a budget that would “cancel all major existing human spaceflight programs … with little more than a hope and prayer that commercial providers will eventually pick up the slack.”

Bolden said he was confident that the private companies would succeed. “It’s my hope that by 2015, 2016, we will have enabled American industry to provide us with routine, reliable access to low Earth orbit,” he said.

Nelson said he expected Congress to call for changes in the NASA budget, adding that his concerns were shared by his colleagues on the congressional committees responsible for appropriating NASA funding.

“I can tell you I have never seen the appropriators and authorizers unified as we are,” Nelson said.

Bolden encountered a similar mix of skepticism, anger and concern the next day when he testified before the House Science and Technology Committee, where he faced more questions about his involvement in the decision-making process that led to the abandonment of Constellation.

“It seemed to be made by a very small cabal, for lack of a better term, of people here in Washington, D.C.,” Rep. Pete Olson (R-Texas) said during the Feb. 25 hearing.“I particularly want to make sure that you were involved in that decision.”

Bolden declined to discuss internal deliberations, but said he was among “those that advised the president” on the budget. “And once that decision was made, it became my budget,” he said.

Rep. Bill Posey (R-Fla.) said lawmakers were frustrated by the lack of visibility into the administration’s deliberative process and wanted to know who made the decision to cancel Constellation.

“I am deeply disappointed in the alleged ‘most transparent’ administration in the history of this country not to be able to get a direct answer on that,” Posey said.

Rep. Gabrielle Giffords (D-Ariz.), who chairs the space and aeronautics subcommittee, was not as confrontational, but she also made clear she was frustrated with NASA and the White House for not doing a better job preparing Congress for what she termed a “radical” decision.

”What you’re proposing in a four-page draft memo — it’s just too great of a shift to really not have those details presented to us in Congress,” she said.

Rep. David Wu (D-Ore.) called NASA’s plan to rely on commercial crew taxis to get to the space station risky and premature. NASA’s budget includes $6 billion over the next five years to foster development of multiple commercial crew systems. ”I don’t think there’s a workable business plan for lifting humans up in to low Earth orbit,” Wu said.

Rep. Marcia Fudge (D-Ohio) welcomed NASA’s plan to invest in new technologies, but questioned whether NASA’s technology money would be raided the first time NASA’s commercial crew program runs into trouble.

“Technology development projects are always vulnerable when not tied to a specific flight program,” she said. “How can we be sure these technology programs won’t meet the same fate, especially with no independent assessment of the cost of supporting commercial crew transport development?”

House Science and Technology Committee Chairman Bart Gordon (D-Tenn.)said he was concerned NASA eventually would have to come to the rescue of the commercial firms and questioned the administration’s reliance on market data from some of the very firms that stand to profit from NASA’s $6 billion commercial crew initiative.

“I don’t want to say that they’re bad folks, but this is a little bit like the fox looking after the hen house,” Gordon said.