NASA's new Mars-atmosophere probe launches today from Cape Canaveral, and viewers can follow the launch live via NASA TV. MAVEN, the Mars Atmosphere and Volatile Evolution spacecraft, is set to study how Mars' atmosphere developed and changed over time. "We really do believe that at one time Mars was a planet that was not much unlike Earth is today," NASA chief Charles Bolden said. "We want to know what happened. What happened to its atmosphere?"