NASA has announced that it has selected “Option B” for its Asteroid Redirect Mission (more commonly referred to as ARM), meaning that rather than towing an entire asteroid into lunar orbit, it will instead retrieve a boulder from an asteroid and bring it into a distant retrograde lunar orbit. Using Solar Electric Propulsion (SEP), an uncrewed spacecraft will retrieve a boulder from a yet-to-be-determined asteroid and tow it into lunar orbit, where it will be visited by astronauts on a future Orion / SLS mission. NASA Associate Administrator Robert Lightfoot said that Option B offers more choices for what object...