Close-up of the Asteroid Redirect Vehicle departing the asteroid after capturing a boulder from its surface. Credit: NASA artist’s concept. Under Option B, a robotic spacecraft will travel to an asteroid several hundred meters in diameter and grab a boulder up to four meters across from its surface. The robotic spacecraft would then return the asteroid into a distant retrograde lunar orbit. An Orion spacecraft, with two astronauts on board, would then fly to the asteroid to collect samples for return to Earth.