By Li Hongmei

NASA on Monday launched its unmanned MAVEN spacecraft toward Mars to study the Red Planet's atmosphere for clues as to why Earth's neighbor lost its warmth and water over time.

The white Atlas V 401 rocket carrying the Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiter blasted off on schedule at 1:28 pm (1828 GMT).

"Everything is looking good," said NASA mission control.

The flawless liftoff of the $671 million spacecraft began its 10-month journey to the Red Planet.

Arrival at Mars is scheduled for September 2014, with the science mission of the solar-wing paneled orbiter set to begin two months later.

The probe is different from past NASA missions because it focuses not on the dry surface but on the mysteries of the never-before-studied upper atmosphere.

Much of MAVEN's year-long mission will be spent circling the planet at a height of 6,000 kilometers (3,800 miles) above the surface.

However, it will execute five deep dips to a distance of just 125 kilometers (78 miles) above the Martian landscape to get readings of the atmosphere at various levels.

Researchers have described the mission as a search for a missing piece to the puzzle of what happened to Mars' atmosphere, perhaps billions of years ago, to transform Earth's neighbor from a water-bearing planet that might have been favorable for life to a dry, barren desert.