NASA’s next Red Planet explorer has arrived at Vandenberg Air Force Base in California — a big step forward in the countdown to T-zero. The spacecraft is called InSight — short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport — and it’s being tested, fueled and encapsulated for launch aboard the powerful United Launch Alliance Atlas V rocket. The upcoming liftoff will mark the first time an interplanetary mission has launched from the West Coast.