NASA's robotic explorer, Maven, atop an Atlas V rocket, lifts off from Cape Canaveral Air Force Station on Monday. (John Raoux/Associated Press)

NASA’s newest robotic explorer, Maven, rocketed toward Mars on Monday on a quest to unravel the ancient mystery of the red planet’s radical climate change.

The Maven spacecraft is scheduled to make it to Mars next fall following a journey of more than 440 million miles.

Scientists want to know why Mars went from being warm and wet during its first billion years to cold and dry today. The early Martian atmosphere was thick enough to hold water and possibly support microbial life. But much of that atmosphere may have been lost to space, eroded by the sun.

Maven set off through a cloudy sky Monday afternoon in its effort to provide answers. An unmanned Atlas V rocket propelled the spacecraft toward Mars, launch controllers applauded and shook hands over the success.

A couple thousand people representing the University of Colorado at Boulder, which is leading the Maven effort, attended the launch.

“We’re just excited right now,” said Bruce Jakosky, principal scientist for Maven, “and hoping for the best.”

To help solve this environmental puzzle at the neighboring planet, Maven will spend an Earth year measuring atmospheric gases once it reaches Mars on Sept. 22, 2014.

This is NASA’s 21st mission to Mars since the 1960s. But it’s the first one devoted to studying the Martian upper atmosphere.

The mission costs $671 million. Maven — short for Mars Atmosphere and Volatile Evolution — bears eight science instruments. The spacecraft, at 5,410 pounds, weighs as much as an SUV.

A question underlying all of NASA’s Mars missions to date is whether life could have started on what now seems to be a barren world.

“We don’t have that answer yet, and that’s all part of our quest for trying to answer, ‘Are we alone in the universe?’ in a much broader sense,” said John Grunsfeld, NASA’s science mission director.

Unlike the Curiosity rover, which was launched in 2011, Maven will conduct its experiments from orbit around Mars.

Maven will dip as low as 78 miles above the Martian surface, sampling the atmosphere. The lopsided orbit will stretch as high as 3,864 miles.