It has been driving on and off for more than seven years, but now it has reached its new destination. Opportunity, a small exploratory rover that landed on Mars in 2004, has trundled to a crater called Endeavour.

And the first rock it looked at has already opened a new chapter in the study of Mars, NASA scientists said Thursday. On a telephone news conference, mission scientists giddily described that rock: full of zinc and bromine, elements that, at least for rocks on Earth, would be suggestive of geology formed with heat and water.

“This rock doesn’t look like anything else we’ve seen before” on Mars, said Steven W. Squyres, a professor of astronomy at Cornell and principal investigator of the rover mission.

The rim of Endeavour — a 14-mile-wide depression that was carved out by an impact long ago — consists of rocks from an earlier geological era that the impact lifted up from below. If the aging rover holds up, it could spend years examining the new terrain, giving NASA scientists ample grist for discovery.