Artist's concept of the Mars Reconnaissance Orbiter and its SHARAD (Shallow Subsurface Radar) instrument.(Photo: NASA)

    BEIJING, Feb. 27 (Xinhuanet) -- A NASA spacecraft, the Mars Reconnaissance Orbiter (MRO)  will soon reach the Red Planet, nearing the end of a 498-million-kilometre journey from Earth that began last August 12.

    The most advanced spacecraft ever sent to Mars will end its seven-month dash from Earth with a critical firing of its main engines on March 10 to slow the craft enough for the gravity of Mars to pull it into orbit.

    If something goes wrong with the 27-minute engine firing, the craft will zoom past the planet and go on into a useless orbit around the sun.

    If it succeeds, it will circle less than 200 miles from pole to pole above the Martian surface, joining the most intensive exploration of the planet ever undertaken -- photographing the surface and scouting for future landing sites in the next two years.

    "We're getting into the dangerous portion of the mission," James Graf, the project manager at NASA's Jet Propulsion Laboratory in California, told reporters.

    Within the last 15 years, NASA has lost two spacecrafts during the orbit-insertion phase around Mars.

    In 1993, scientists lost contact with the Mars Observer just before it was to enter orbit. NASA was dealt another blow in 1999 when the Mars Climate Orbiter failed on arrival.

    Engineers hope the two-ton Reconnaissance Orbiter will not suffer the same fate.

    "The $720-million mission will greatly expand our scientific understanding of Mars, pave the way for our next robotic missions and help us prepare for sending humans to Mars," said Douglas McQuistion, director of NASA's Mars exploration program.

    "MRO's instrument capabilities are unprecedented," added Michael Meyer, the lead scientist for NASA's Mars missions.

    The arrival of the new orbiter will focus a major force investigating the planet's atmosphere and its surface. 

    One of the MRO's major tasks will be to scout out safe sites for two Mars landing missions due in coming years, said McQuistion. 

    Two Mars rovers, Spirit and Opportunity, have already far exceed their life expectancy of only three months and are still probing Martian rocks more than two years after they landed. Enditem

(Agencies)