科技英语新闻:NASA's Mars rover arrives at new site on Martian surface

WASHINGTON, Aug. 10 (Xinhua) -- After a journey of almost three years, NASA's Mars rover Opportunity has reached the Red Planet's Endeavour crater to study rocks never seen before, the U.S. National Aeronautics and Space Administration (NASA) announced on Wednesday.

Scientists hope it will find rocks and terrain much older than any other that the itinerant robot has examined during its seven years on the red planet.

The U.S. space agency said that Opportunity arrived at the rim of Endeavour on Tuesday. The golf cart-size rover is expected to remain at the 22-kilometer-wide crater for the next few years.

"NASA is continuing to write remarkable chapters in our nation' s story of exploration with discoveries on Mars and trips to an array of challenging new destinations," NASA Administrator Charles Bolden said in a statement. "Opportunity's findings and data ... will play a key role in making possible future human missions to Mars and other places where humans have not yet been."

NASA's Mars Reconnaissance Orbiter, which has been circling the planet since late 2005, detected clay minerals that form in wet conditions in the crater. Scientists want to find out if the minerals date back to Mars' distant past, when the planet is believed to have been wetter and warmer than the dry frozen desert it is today.

"We're soon going to get the opportunity to sample a rock type the rovers haven't seen yet," said Matthew Golombek, Mars Exploration Rover science team member, at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Clay minerals form in wet conditions so we may learn about a potentially habitable environment that appears to have been very different from those responsible for the rocks comprising the plains."

NASA is searching for signs that Mars had a habitable environment billions of years ago. Knowledge of the Martian climate will be important to future manned missions there, and can shed light on the forces that shaped Earth's climate.

NASA launched the Mars rovers Opportunity and Spirit in 2003 for what were planned to be three-month missions. But both continued operating well beyond that. Spirit stopped communicating in March 2010.