NASA declared its Opportunity Mars rover dead. Opportunity roamed the Martian surface for nearly a decade and a half, covering more than a marathon’s worth of ground and finding conclusive evidence that the Red Planet hosted large bodies of liquid water in the ancient past. The golf-cart-size rover and its twin, Spirit, also helped bring Mars down to Earth, in the minds of scientists and laypeople alike.

Spirit and Opportunity launched separately in the summer of 2003, kicking off the Mars Exploration Rover (MER) mission, and landed a few weeks apart in January 2004. Spirit came down first, settling in at a crater called Gusev situated about 14 degrees south of the Martian equator. Opportunity landed on the equatorial plain Meridiani Planum, on the other side of the planet from Gusev.

Both rovers then embarked on surface missions designed to last for about 90 Earth days, during which they hunted for signs of past water activity. Such evidence had previously been spotted from above — by NASA’s Viking 1 and Viking 2 orbiters.

Spirit finally got bogged down in a sand trap in early 2010. As a result, the rover couldn’t reorient itself to catch the sun during the approaching Martian winter and essentially froze to death.

Opportunity avoided such pitfalls for eight additional years, studying rocks on the rims of four different craters, as well as the Meridiani Planum flats. The rover put 28.06 miles (45.16 km) on its odometer during these travels — more than any other vehicle, robotic or crewed, has traveled on the surface of another world.