NASA's next marquee mission might be described as the great asteroid boulder pluck.

At a news conference Wednesday, agency officials saidthey had revised their original plan to capture an asteroid and drag it into deep lunar orbit.

The new plan calls for a spacecraft with two robotic arms to remove a boulder of up to 12 feet in length from the surface of an asteroid and bring that into orbit around the moon instead.

The agency still plans to send two astronauts to collect a sample of the boulder once it is in a stable orbit around the moon.

The new plan may seem less dramatic than the original conceptfor the Asteroid Redirect Mission (ARM) first announced in 2013, but NASA associate administrator Robert Lightfoot said the boulder-plucking plan ultimatelyutilizes more of the technologies needed for humans to eventually get to Mars.

"ARM is an important part of the overall mission of us taking humans further into space," he said. "The systems we are going to bring into play are the kinds of things we know we are going to need when we go to another planetary body."

He added that the new plan also allows for more flexibility within the mission itself.

"There will be a sensor suite on the spacecraft that will let us look at the boulders and make an educated choice about which one we pull up," he said. "We'll also have three to five opportunities to pull up the boulders, lowering the mission risk."

The timeline of the mission, for now, is to launch the spacecraft in 2020 and have it arrive at the asteroid about two years later.

After capturing the boulder, the spacecraft is also to test a new technique, called a gravity tractor, that could be used to alter the orbits of asteroids headed for a collision with Earth. Once the spacecraft has procured the boulder, it will fly in a halo orbit around the asteroid. Lightfoot said that the mass of the boulder combined with the mass of the spacecraft should be able to exert enough gravitational pull to tug the asteroid into a new orbit.

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NASA aims to pluck boulder from asteroid, bring it to the moon