A new breed of explorer is on board the two Mars Exploration Rover spacecraft — Astrobots Biff Starling and Sandy Moondust are part of The Planetary Society Astrobot Corps. Biff and Sandy are LEGO minifigure representations suited up for space. They appear on each of the DVDs on the MER spacecraft. Their job: tell their stories to the world through a series of entertaining, fun, online communications.