Opportunity, the longest-lived roving robot ever sent to another planet, explored the red plains of Mars for more than 14 years, snapping photos and revealing astonishing glimpses into its distant past. But on Wednesday, NASA announced that the rover is dead.

“It is therefore that I am standing here with a sense of deep appreciation and gratitude that I declare the Opportunity mission as complete,” Thomas Zurbuchen, NASA’s associate administrator for science, said at a news conference.

[See pictures from the Opportunity rover’s journey across Mars.]

The golf cart-size rover was designed to last only three months, but proved itself to be an unexpected endurance athlete. It traveled more than the distance of a marathon when less than half a mile would have counted as success.

As it moved across the surface, Opportunity provided an up-close view of Mars that scientists had never seen: fine layers of rock that preserved ripples of flowing water, a prerequisite for life, from several billion years ago.