The Mars Atmosphere and Volatile Evolution -- or MAVEN -- will take critical measurements of the Martian upper atmosphere to help scientists understand how the climate changed from wet and warm to cold and dry over the planet's history, NASA said.
In a running-commentary blog about the launch, NASA said the 5,410-pound spacecraft had separated successfully from its Centaur engine and was flying on its own.
NASA said it expects the craft to reach Mars and begin orbiting the planet in September 2014.
The solar-powered craft will slip into an elliptical orbit ranging from a low of 93 miles above the surface -- whose features are reminiscent of the impact craters of the moon and the volcanoes, valleys, deserts and polar ice caps of Earth -- to a high of 3,728 miles, NASA said.
The craft also will take five "deep dips" during the course of the mission, flying as low as 77 miles in altitude and providing a cross-section of the top of the atmosphere.
"MAVEN will begin to look at those processes that tell us what happened to Mars' atmosphere, and why Mars perhaps underwent a major climate change in its past," NASA Director of Planetary Science Jim Green told reporters in a pre-launch briefing.
"We expect to learn how the modern Mars works, really in detail," NASA investigator James Garvin told CNN. "To see its climate state, to understand how the atmosphere is lost to space -- how Mars may have lost a magnetic field -- to take that information and map it back in time."
The $671 million mission follows the Curiosity rover mission, which is exploring a martian crater after landing on the planet in August 2012.
By the time MAVEN reaches Mars, Curiosity will have made surface measurements that will help guide the interpretation of MAVEN's upper-atmosphere measurements, NASA says.