CAPE CANAVERAL, Fla. -- NASA's newest robotic explorer, Maven, rocketed Monday toward Mars on a quest to unravel the ancient mystery of the red planet's radical climate change.
The Maven spacecraft is due at Mars next fall, following a journey of more than 440 million miles.
Maven's principal scientist, Bruce Jakosky of the University of Colorado at Boulder, and others 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 afternoon sky in its bid to provide answers. An unmanned Atlas V rocket put the spacecraft on the proper course for Mars.
An estimated 10,000 NASA guests gathered for the liftoff -- the most exciting one of the year from Cape Canaveral -- including a couple thousand representing the University of Colorado.
Surviving liftoff was the first big hurdle, Mr. Jakosky said. The next huge milestone will be Maven's insertion into orbit around Mars on Sept. 22, 2014.
To help solve Mars' environmental puzzle, Maven will spend an entire Earth year measuring atmospheric gases.
This is NASA's 21st mission to Mars since the 1960s, but the first devoted to studying the Martian upper atmosphere. The mission costs $671 million.
Maven -- short for Mars Atmosphere and Volatile Evolution, with a capital "N" in EvolutioN -- bears eight science instruments. The spacecraft, at 5,410 pounds, weighs as much as an SUV. From solar wingtip to wingtip, it stretches 37.5 feet, about the length of a school bus.
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 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.