NASA's new ambitious plan to corral a distant asteroid into lunar orbit is touching off another debate over the space agency's future, as members of Congress greet the proposal with skepticism.

Under President Barack Obama's proposed 2014 budget, NASA spending would return to $17.7 billion, a pre-sequester amount that provides a $105 million down payment on plans for a 2021 astronaut visit to the asteroid.

Efforts to establish a long-term price tag for the asteroid mission that merges the human exploration goal handed to NASA by Obama three years ago with a global vulnerability to impacts from Near Earth Objects, awaits definition by the agency's Exploration, Science and Space Technology directorates later this year.

“There will be naysayers all over,” NASA Administrator Charles Bolden acknowledged April 10.

“While [it is creative], a proposed NASA mission to 'lasso' an asteroid and drag it to the Moon's orbit will require serious deliberation,” protested Rep. Lamar Smith (R-Texas), who chairs the House Science, Space and Technology Committee. The panel plans an April 17 hearing on budget requests for NASA and other science agencies.

Also, lawmakers, including Rep. Frank Wolf (R-Va.), chairman of the appropriations panel that funds NASA, are re-introducing legislation that died in the last Congress calling for a human return to the Moon.

Support, suggests Bolden, will likely come from multiple quarters, including those alarmed by the planet's vulnerability to the small undiscovered asteroids such as the one that exploded over Russia in mid-February and a larger cousin that skimmed close to the Earth later the same day. The asteroid mission also has backing from Sen. Bill Nelson (D-Fla.)—a proponent of the Orion Multi-Purpose Crew Vehicle and the heavy-lift Space Launch System (SLS) that would transport the crew. He heads the Senate Commerce, Transportation and Science panel that handles NASA matters.

“This is a very interesting project, and as I already told Charlie Bolden, we are ready to see how ESA can contribute,” said Jean-Jacques Dordain, the European Space Agency's general director, while attending the 29th annual National Space Symposium in Colorado Springs.

The asteroid scenario was developed initially by the California Institute of Technology's Keck Institute for Space Studies in 2011-12 and priced at $2.6 billion, the equivalent of a NASA planetary flagship mission. The Keck estimate includes mission work already well along at NASA, and applicable to the venture.

NASA's top line is sufficient to prepare Orion and SLS for unpiloted test flights in 2014 and 2017, with a crewed flight in 2021—just in time to greet the lunar orbiting asteroid with astronauts, says Bolden.