NASA chief Charles Bolden found himself defending the U.S. space agency's practice of investing in commercial companies to ferry cargo - and one day crew - to the International Space Station. The grilling came less than a week after Orbital Science's successful rocket test flight and after several successful SpaceX cargo flights to the International Space Station.

Senators on the appropriations subcommittee for Commerce, Justice and Science questioned NASA's priorities as they scrutinized the president's request for $17.7 billion to fund the U.S. space agency in fiscal year 2014. Specifically, they questioned NASA's ability to see through its plans to develop a heavy-lift rocket, known as the Space Launch System or SLS, while balancing investments in commercial enterprises to transport cargo and crew to the space station.

Priorities
The subcommittee's two top lawmakers, chairwoman Barbara Mikulski of Maryland and vice-chairman Richard Shelby of Alabama, have NASA facilities in their states. Senator Shelby said he was concerned that the proposed budget is an example of "chasing the next great idea while sacrificing current investments."

"This budget focuses, I believe, too heavily on maintaining the fiction of privately funded commercial launch vehicles, which diverts, I think, critical resources from NASA's goal of developing human spaceflight capabilities with the SLS," said Shelby.

NASA Administrator Bolden said NASA's priorities remain the world's most powerful rocket - the SLS, as well as the James Webb Space Telescope - the Hubble's successor - and the International Space Station, shored up by commercial crew and cargo transportation. He called 2013 "a year of decision."

"If we do not get $822 million in the 2014 budget as requested by the president, it will be my unfortunate duty to advise the Congress and the president that we probably will not make 2017 for the availability of an American capability to get our astronauts to space," said Bolden. "And I will have to tell you that I'm going to have to come back and ask for authorization to once again pay the Russians to take our crews to space."

Reliance on Russia
The NASA administrator noted that a funding request in 2011 was not met, so the United States was unable to launch astronauts from its soil in 2015, as had been hoped. The U.S. has not had a vehicle to take astronauts to the space station since it retired the shuttle fleet two years ago.

NASA is relying on commercial firms to handle transport to the space station so it can focus its attention on developing the next-generation of rockets and capsules that can go beyond low-Earth orbit - to an asteroid or Mars.

Russian transport to the space station is costly. The U.S. signed a contract in 2011 to pay $753 million to Russia in exchange for transport and related services for 12 astronauts from 2014 through mid-2016.

Sequestration
NASA's Bolden, himself a former astronaut, also emphasized the negative effects of looming, mandatory across-the-board spending cuts known as sequestration. He said, if implemented, the cuts will potentially impact the James Webb Space Telescope, certainly impact the SLS heavy lift rocket and Orion capsule and, in his words, "devastate commercial crew and cargo."

"You know, right now we're flying 20 commercial cargo missions to the International Space Station over the next five years for three-point-some-odd billion dollars - an incredible value to the nation," he said. "I can't carry that out under sequester."

The U.S. space agency chief also countered suggestions that some agreements with commercial companies lack transparency and are too lenient on deadlines. Bolden disagreed, saying such agreements give American industry leeway to produce spacecraft that fulfill NASA's requirements. He added that the agreements have worked very well, as demonstrated by the successes of both Orbital and SpaceX vehicles.