Posted: Wed, Mar 25, 2015, 8:51 PM ET (0051 GMT)
NASA announced Wednesday that it selected an option for its Asteroid Redirect Mission (ARM) that involves grabbing a boulder off the surface of a larger asteroid. Under this approach, known as Option B, a robotic spacecraft would grab a boulder up to four meters across from the surface of a large near Earth asteroid and return it to lunar orbit to be visited by astronauts. NASA selected it over Option A, which would have involved redirecting an entire asteroid, up to ten meters across, into lunar orbit. The tentative target for the mission is the asteroid 2008 EV5, although NASA said they can wait until one year before the planned December 2020 launch to select a destination. The spacecraft would return the boulder to lunar orbit in the mid-2020s. The selected mission option, while $100 million more than Option A, still fits into a cost cap of no more than $1.25 billion, agency officials said.