After spending a year scooting around inside a big hole in the ground, the Opportunity rover is heading for an even bigger one. It's not in a rush, though -- it could take two years to get there.
When Opportunity landed on Mars five years ago, scientists had to get things done in a hurry -- the mission was supposed to last just three months. But Opportunity and its twin, Spirit, lasted far longer than anyone expected. That's given scientists the confidence to think in terms of years instead of days or weeks.
Opportunity landed in the smooth Martian plains. It drove to a small crater, where it spent a few months, and then to a larger one, named Victoria, where it spent more than a year.
Craters are of particular interest because their deep walls expose layers of rock far below the surface. These layers were deposited over millions or billions of years, so they reveal a great deal about the planet's history.
Opportunity has found, for example, that some of the layers were laid down at the bottom of a lake or sea, indicating that Mars was once warmer and wetter than it is today.
The new crater is about 20 times bigger than Victoria. It's seven miles away -- as far as Opportunity has traveled in its entire time on Mars.
And there's no guarantee that it'll survive the trip. Its wheels could fail, or it could get bogged down in the sand. But the potential discoveries are worth the effort -- the ultimate road trip for a Mars explorer.
Script by Damond Benningfield, Copyright 2008
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