WASHINGTON, Jan. 3 (Xinhuanet) -- As the first of US twin Mars rover, dubbed Spirit, is hours way from a critical landing on the red planet, scientists at the US space agency NASA are upbeat, saying the robotic explorer appeared on course to hit the targetedMars area.

    "Today is a great day to land on Mars," Mark Adler, deputy mission manager, said at a pre-landing press conference at NASA's Jet Propulsion Laboratory in Pasadena, California.

    Spirit, launched on June 10, 2003, is scheduled to touch down on the Mars surface Saturday at 11:35 p.m. EST (0435 GMT Sunday) after a space odyssey of 487 million km.

    In only six minutes, the spacecraft carrying the Mars rover will perform a series of acrobatic maneuvers, slowing down from 19,000 km per hour to zero km per hour, before bouncing and rolling to a safe stop on Gusev Crater, which is thought to be an ancient lakebed.

    The rover will spend a week or more unfolding itself before stepping out of the lander and roaming on Mars.

    At a height of about 1.5 meters, Spirit carries five scientificinstruments and can work as a robot field geologist for about 90 days, self-driving across the Martian surface, navigating itself around obstacles and examining rocks and soil for clues about water and life.

    Its identical twin, a rover named Opportunity, is due to land on Mars on Jan. 24. Enditem