NASA's bold plan to drag an asteroid into orbit around the moon may sound like science fiction, but it's achievable with current technology, experts say.

President Barack Obama's 2014 federal budget request, which will be unveiled today (April 10), likely includes about $100 million for NASA to jump-start an asteroid-capture mission, U.S. Senator Bill Nelson (D-FL) said last week.

The plan aims to place a roughly 23-foot-wide (7 meters) space rock into a stable lunar orbit, where astronauts could begin visiting it as soon as 2021 using NASA's Space Launch System rocket and Orion capsule, Nelson said.

While challenging, the mission is definitely doable, said Chris Lewicki, president and chief engineer of billionaire-backed asteroid-mining firm Planetary Resources. [NASA's Asteroid-Capture Plan (Video)]

"Return of a near-Earth asteroid of this size would require todays largest launch vehicles and todays most efficient propulsion systems in order to achieve the mission," Lewicki, who served as flight director for NASA's Spirit and Opportunity Mars rovers and surface mission manager for the agency's Phoenix Mars lander, wrote in a blog post Sunday (April 7).

"Even so, capturing and transporting a small asteroid should be a fairly straightforward affair," Lewicki added. "Mission cost and complexity are likely on par with missions like the [$2.5 billion] Curiosity Mars rover."

Spurring solar system exploration

NASA's idea is similar to one proposed last year by scientists based at Caltech's Keck Institute for Space Studies in Pasadena.

The Keck study estimated that a robotic spacecraft could drag a 23-foot near-Earth asteroid (NEA) which would likely weigh about 500 tons into a high lunar orbit for $2.6 billion. The returns on this initial investment are potentially huge, the researchers said.

"Experience gained via human expeditions to the small returned NEA would transfer directly to follow-on international expeditions beyond the Earth-moon system: to other near-Earth asteroids, [the Mars moons] Phobos and Deimos, Mars and potentially someday to the main asteroid belt," the Keck team wrote in a feasibility study of their plan.

See more here:

Capturing an Asteroid: How NASA Could Do It