LOS ANGELES, Aug. 12 (Xinhuanet) -- A new spacecraft designed to search water on Mars was launched Friday by an Atlas rocket from the Kennedy Space Center, Florida, the US space agency NASA said.

    The two-ton spacecraft, named Mars Reconnaissance Orbiter, is scheduled to arrive at Mars in March 2006 for a mission to understand the planet's water riddles and advance the exploration of the mysterious red planet, said the NASA Jet Propulsion Laboratory (JPL) in Pasadena, California.

    "We have a big spacecraft loaded with advanced instruments for inspecting Mars in greater detail than any previous orbiter, and we have the first Atlas V launch vehicle to carry out an interplanetary mission. A very potent and exciting combination," NASA's Mars Exploration Program Director Doug McCuistion said.

    For trips from the earth to Mars, the planets move into good position for only a short period every 26 months. The best launch position is when the earth is about to overtake Mars in their concentric racing lanes around the sun.

    When the orbiter arrives in March, it will turn into a Martian satellite after a half-year "aerobraking" process, during which the spacecraft will gradually adjust the shape of its orbit by using friction from carefully calculated dips into the top of the Martian atmosphere.

    The mission's primary science phase is scheduled for November 2006. The spacecraft will photograph dusty Martian canyons and towering mountains, testing the atmosphere and using radar to peekbeneath its rocky ground.

    "Mars Reconnaissance Orbiter will give us several times more data about Mars than all previous missions combined," said James Graf, project manager for the mission at the JPL.

    Researchers will use the data to study the history and distribution of Martian water. Learning more about what has happened to the water will focus searches for possible past or present Martian life.

    Michael Meyer, chief scientist of NASA's Mars exploration program, said some of these investigations could help scientists discover "whether or not life ever started on that planet (and) ifnot, why not."

    The data also could help scientists map out potential water deposits that could be used by astronauts on a future human mission to Mars.

    Observations by the orbiter will also support future Mars missions by examining potential landing sites and providing a communications relay between the Martian surface and the earth.     

    The craft can transmit about 10 times as much data per minute as any previous Mars spacecraft. This will serve both to convey detailed observations of the Martian surface, subsurface and atmosphere by the instruments on the orbiter and enable data relayfrom other landers on the Martian surface to the earth.

    NASA plans to launch a new Mars rover, the Phoenix Mars Scout, in 2007 to land on the far northern Martian surface. An advanced rover, the Mars Science Laboratory, has also been set to launch in 2009. Enditem