CAPE CANAVERAL, Fla. (AP) — With just a day to go, NASA's InSight spacecraft aimed for a bull's-eye touchdown on Mars, zooming in like an arrow with no turning back. InSight's journey of six months and 300 million miles (482 million kilometers) comes to a precarious grand finale Monday afternoon. The robotic geologist — designed to explore Mars' insides, surface to core — must go from 12,300 mph (19,800 kph) to zero in six minutes flat as it pierces the Martian atmosphere, pops out a parachute, fires its descent engines and, hopefully, lands on three legs. It is NASA's first attempt to land on Mars in six years, and all those involved are understandably anxious. NASA's top science mission official, Thomas Zurbuchen, confided Sunday that his stomach is already churning.