A spacecraft blasted off Friday into a golden early morning sky, beginning a mission to Mars (search) to gather more data on the Red Planet than all combined previous missions.

The Mars Reconnaissance Orbiter (search) lifted off on an Atlas V rocket on a seven-month journey to Mars. The booster rocket shut down and dropped off into the Atlantic Ocean minutes into the launch. Seconds later, the second-stage rocket engine ignited.

"Surveying for the deepest insights into the mysterious evolution of Mars!" NASA commentator George Diller said after liftoff. The launch came just three days after space shuttle Discovery (search) completed its mission.

Circling the planet for at least four years, the orbiter is to provide unparalleled information on Mars' weather, climate and geology, which could aid possible future human exploration of the Red Planet.

The $720 million mission is divided into two parts.

During its first two years, the orbiter will help build on NASA's knowledge of the history of ice on the planet. The planet is cold and dry with large caps of frozen water at its poles. But scientists think it was a wetter and possibly warmer place eons ago — conditions that might have been conducive to life. Scientists are also trying to determine if it could support future human outposts.

Equipped with the largest telescopic camera ever sent to another planet, the orbiter also will collect data that will help NASA plan where to land two robotic explorers later this decade. The Phoenix Mars Scout, in search of organic chemicals, will be launched in 2007, and the Mars Science Laboratory will follow two years later.

During the second phase of its mission, the orbiter will serve as a communications messenger between the robotic explorers on Mars and Earth. The reconnaissance orbiter has a powerful antenna that can transmit 10 times more data per minute than the current trio of satellites positioned around the planet — NASA's Global Surveyor and Mars Odyssey (search) and the European Space Agency's Mars Express (search).

Two NASA rovers launched in 2003, Spirit and Opportunity, continue to roam the planet and may be the first to relay information back to Earth via the reconnaissance orbiter.

The orbiter is loaded with two cameras that will provide high-resolution images and global maps of Martian weather, a spectrometer that will identify water-related minerals and a radiometer to measure atmospheric dust. The Italian Space Agency has provided ground-penetrating radar that will peer beneath the surface of layers of rocks or ice.