This image from the Mars Orbiter Camera aboard NASA's Mars Global Surveyor spacecraft shows an overview of Mars' "Victoria Crater." The Mars Rover Opportunity has arrived at the rim of the big crater, which scientists never thought it could reach, NASA said Sept. 27, 2006. (Xinhua/Reuters Photo) Photo Gallery >>>

    The rover has traveled for 21 months across the Martian landscape before starting to relay glimpses of the huge impact crater, said NASA's Jet Propulsion Laboratory (JPL) based in Pasadena, California.

    Initial images from the rover's first overlook show rugged walls with layers of exposed rock and a floor blanketed with dunes. The far wall is approximately 800 meters from the rover, the JPL said.

    Reaching the crater provided an insight into Mars' history. Mission scientists said that these images might tell new stories about the past environmental conditions on the red planet, from a long time ago.

    "This is a geologist's dream come true," said Steve Squyres of Cornell University, the principal investigator for NASA's Mars rover program.

    "We especially want to learn whether the wet era that we found recorded in the rocks closer to the landing site extended farther back in time. The way to find that out is to go deeper, and Victoria may let us do that."

    From the rim of Victoria, there are good views of the crater interior. The rover will use its set of cameras to help scientists intensively study the crater, according to Squyres.

    Opportunity has been exploring Mars since January 2004, more than 10 times longer than its original prime mission of three months.

    Most of the journey was to get from "Endurance" crater to "Victoria," across a flat plain pocked with smaller craters and strewn with sand ripples. Frequent stops to examine intriguing rocks interrupted the journey, and one large sand ripple kept the rover trapped for more than five weeks.

    The twin rovers, Opportunity and Spirit, are staying in a northward-tilted position through the southern Mars winter, in order to collect the maximum energy supply for its solar panels, JPL said.

    Spirit is conducting studies that benefit from staying in one place, such as monitoring effects of wind on dust. It will start driving again, when the Martian spring increases the amount of solar power available.

    Operations for both rovers will be minimized for much of October as Mars passes nearly behind the sun from Earth's perspective, making radio communication more difficult than usual. Enditem