The unmanned spacecraft launched from Cape Canaveral in Florida on a mission to find out how the red planet lost its atmosphere.
Researchers have described the mission as a search for a missing piece of the puzzle as to what happened on Mars, perhaps billions of years ago, to transform Earth's neighbour from a water-bearing planet that might have been favourable for life to a dry, barren desert with hardly any atmosphere.
"Maven is the first spacecraft devoted to exploring and understanding the Martian upper atmosphere," the US space agency said.
"The spacecraft will investigate how the loss of Mars' atmosphere to space determined the history of water on the surface."
The journey to Mars will take 10 months in total, with arrival set for September 2014.
Much of its year-long mission will be spent circling the planet at a distance of 3,800 miles above the surface, but it will execute five deep dips to a height of just 78 miles to get readings of the atmosphere at various levels.
Scientists hope its findings will help pave the way for a future visit by humans to the Red Planet, perhaps as early as the 2030, Nasa has said.