WASHINGTON — Launching the future of U.S. human spaceflight on an uncertain trajectory, President Barack Obama surprised lawmakers and industry with a budget proposal that scraps NASA’s Moon-bound Constellation program in its entirety and bets a chunk of the savings on the ability of commercial firms to ferry crews to and from the international space station.

Obama’s proposed NASA budget of $19 billion for 2011 — a 1.5 percent increase over 2010 — commits to retiring the space shuttle after five more flights, halts development of the Orion Crew Exploration Vehicle and Ares 1 rocket, and solidifies U.S. intentions to keep using the nearly completed space station for another decade. The centerpiece of Obama’s proposal is a promised $6 billion investment in the crew taxis and billions more for assorted “game-changing technologies” intended to put the United States on a sustainable exploration footing once the nation is ready to venture beyond low Earth orbit for the first time since the last Apollo Moon landing in 1972.

NASA Administrator Charles Bolden told the agency’s 18,000 employees Feb. 3 that Obama’s decision to cancel the Constellation program after five years and $9 billion worth of effort was final and unlikely to be overturned by Congress. The program also included the Ares 5 heavy-lift rocket and Altair lunar lander.

“You can hope forever that the president’s going to change his mind,” Bolden said during the all-hands address broadcast to the agency’s 10 field centers. “You can hope that I will go to the Hill and get beat up, and … will say, ‘OK, Congress, you’re right, my recommendations to the president were all wrong. I was dumb. And we need to go back and spend $30 billion … on the Constellation program.’ Ain’t going to happen.”

Bolden said the longer the agency resists the loss of Constellation, the longer it will take to devise a new plan.

“The sooner we all get through this period of denial and grief … the sooner we’re going to go to the Moon and to Mars and to other places,” he said. “If it takes a year to get through this, we’re a year behind. If it takes us two years to get through it, we’re two years behind.”

Bolden’s words of appreciation for NASA’s Constellation team throughout the week stood in contrast to the rough treatment the program received during the agency’s budget rollout, a hastily arranged media teleconference handled largely by his deputy, chief financial officer and a White House science adviser. Bolden read an opening statement and left the call without taking questions.

Jim Kohlenberger, chief of staff of the White House Office of Science and Technology Policy, told reporters that Constellation was undone by a raft of bad choices and that sunk costs were no reason to stick with a flawed program.

“The fact that we poured $9 billion into an unexecutable program really isn’t an excuse to pour another $50 billion into it and still not have an executable program,” Kohlenberger said.

In place of building Orion and the Ares family of rockets, NASA is now being told to embrace a new approach to human

spaceflight that emphasizes broad investment in enabling technologies combined with a focused effort to spur development of commercially operated vehicles built to ferry astronauts to orbit and back.

By killing Constellation and its Moon-or-bust near-term focus, the Obama administration hopes to free NASA to work in closer collaboration with a wider range of international partners to devise a more sustainable space exploration plan encompassing a wider range of potential destinations.

“This isn’t a step backwards,” Kohlenberger said. “I think the step backwards was trying to recreate the Moon landings of 40 years ago really largely using some of yesterday’s technology instead of game-changing technologies that take us further, faster and more affordably into space.”

Commercial space advocates hailed the change as long overdue. “The reforms … fix some of the worst errors of the Bush Vision for Space Exploration,” said Space Frontier Foundation Chairman Bob Werb. “More than that, they make NASA exciting and relevant again. Canceling the expensive, ill-fated Ares 1 rocket opens the door for private enterprise to create a safe, reliable and low-cost commercial spaceflight industry, with government as a customer and partner instead of a competitor.”

U.S. lawmakers from states with a heavy stake in the Constellation program — including Alabama, Florida, Louisiana, Texas and Utah — have been largely unrelenting in their criticism of NASA’s new direction since details began to leak the week before Obama’s budget went to Capitol Hill. Sen. Richard Shelby (R-Ala.), whose state is home to the NASA field center in charge of Ares, said the president’s budget “begins the death march for the future of U.S. human spaceflight.”

Even Rep. Bart Gordon (D-Tenn.), the House Science and Technology Committee chairman who has no real parochial interest in Constellation, branded NASA’s budget request “a radical departure” from the Bush-era plan twice endorsed by Congress.

Obama administration officials defended the changes as necessary to put U.S. human spaceflight on a steady foundation for the future.

“Keep in mind we found out during the Augustine review that we weren’t going to the Moon in 2020,” NASA Deputy Administrator Lori Garver said Feb. 1, referring to the review of U.S. human spaceflight plans called for last year by the White House and led by former Lockheed Martin chief Norm Augustine. “The Augustine report made it clear that we wouldn’t have gotten beyond low Earth orbit until 2028 and even then would not have the funding to build the lander. So we had lost the Moon, and what this program does is give us back the solar system.”

For now, however, NASA is not ready to say when the United States will send astronauts beyond low Earth orbit, or begin building the heavy-lift rockets necessary for such missions.

Those omissions troubled staunch NASA champions, such as Sen. Bill Nelson (D-Fla.), chairman of the Senate Commerce science and space subcommittee. Nelson has scheduled a Feb. 24 hearing to delve into the NASA budget and examine the feasibility of continuing testing of the Ares 1 rocket as a lead-in to development of some variant of the now-canceled Ares 5.

Nelson also took White House budget director Peter Orszag to task for committing to NASA billions of dollars less than what the Augustine committee said would be necessary for a stable and worthwhile human spaceflight program.

The Augustine committee called for swiftly ramping up annual human spaceflight spending to $3 billion above current levels, a growth path that would equate to $55 billion in total from 2011 through 2015. Obama’s budget includes $45.5 billion for that period, roughly half of which is earmarked for the international space station and the commercial crew initiative.

Total NASA spending is set to rise $6 billion between 2011 and 2015 relative to Obama’s previous budget, but only by $3.85 billion compared with the path set for NASA in President George W. Bush’s final budget.

“You can’t do it on the cheap,” Nelson said Feb. 2 during a Senate Budget Committee hearing. “The problem is that you have put all the eggs in the basket of assuming that those commercial rockets are going to work and that NASA is not going to have to spend a lot more on making sure those commercial rockets are safe for humans.

“There’s no fail-safe position. If those commercial rockets don’t work, then for the foreseeable future we’re going to be relying on the Russians just to get to our space station.”

Bolden, in his address to employees Feb. 3, sought to turn the tables on Nelson’s argument. “That’s what we were doing with Constellation. Stop and think about it. How many Constellation programs were we working on?” he asked. “We have the opportunity to work with multiple partners in the commercial sector and try to come up with some alternative ways to get to low Earth orbit.”

Although Orion and Ares comprised NASA’s baseline solution for its post-shuttle transportation needs, the agency in 2006 began subsidizing alternatives for delivering cargo to the space station under the Commercial Orbital Transportation Services (COTS) program. One of the COTS winners, Hawthorne, Calif.-based Space Exploration Technologies Corp. (SpaceX), now considers itself NASA’s best near-term hope for fielding a commercial crew solution.

“COTS was one of the first things I put on the agenda,” said former NASA Administrator Mike Griffin, who several years before rejoining NASA in 2005 urged SpaceX founder Elon Musk to build a low-cost launcher.

In an interview, Griffin said he was disappointed to see the Constellation program he hatched scrapped and disparaged as ill-managed. He said he still believes government should provide incentives for commercial space development and guarantee markets for new capabilities once they exist.

“However, if the development is to be commercial, the lion’s share of the financial burden must lie with the private developer and not the government,” Griffin said. “This gets to the central point of this new budget. For 50 years presidents and congresses have funded NASA to be a mission-focused organization. This president assumes to want NASA to be a technology organization and mission development is to be passed through to private interests. I fail to see how that is in the national good.”