Two identical robotic explorers landed on opposite sides of Mars to search for signs of ancient water. They were designed for 90 sols. One worked for six years; the other for more than fourteen.
I'm Spirit. I landed in Gusev Crater on January 3, 2004, a huge crater that might once have held a lake. My warranty was 90 sols. I kept going for more than 2,200.
Then one of my wheels broke. I kept going anyway, dragging it behind me like a plow. That churned up bright soil that turned out to be about 90% pure silica. On Earth, that forms in hot springs and steam vents, places where tiny living things often thrive. A broken wheel led to one of my best discoveries!
On May 1, 2009, I rolled onto soft sand hiding at a spot called Troy, near a plateau named Home Plate, and I got stuck. I kept working as a standing-still science lab until my last message on March 22, 2010, as the cold Martian winter set in.
NASA kept calling for more than a year. They stopped on May 25, 2011. In all, I drove 4.8 miles (7.7 kilometers).
A planet-wide dust storm, drawn simply
Opportunity says:
I'm Opportunity, Spirit's twin. I landed on January 24, 2004, on a flat plain called Meridiani Planum. I was built to last 90 sols and drive about 1,000 meters. I drove more than 45 kilometers (28 miles) and worked for roughly 60 times longer than planned.
My landing crater was a lucky spot. Right away I found tiny round balls of a mineral called hematite, which usually forms in water. Scientists nicknamed them "blueberries." Later, at the rim of Endeavour Crater, I found bright veins of gypsum and clay minerals that formed in calm, drinkable-style water.
Mars wasn't easy. I lost steering on both front wheels over the years and lost my flash memory. But winds kept blowing the dust off my solar panels, which gave me the power to go on.
In June 2018, a dust storm swallowed the whole planet. My last message came on June 10. Engineers sent more than a thousand commands, and NASA announced the end of my mission on February 13, 2019. I'm resting in Perseverance Valley.
The twins in images and 3D
See the mission
NASA's infographic gathers headline numbers from the rover pair, while the interactive model lets you inspect the design of the Mars Exploration Rovers. Select an image to enlarge it.
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Interactive 3D model: Mars Exploration Rover. NASA Visualization Technology Applications and Development (VTAD) · NASA model page ↗
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Spirit's panorama of the Columbia Memorial Station landing site at Gusev Crater · Credit: NASA/JPL-Caltech/Cornell.
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Opportunity's “Lion King” panorama around Eagle Crater at Meridiani Planum · Credit: NASA/JPL/Cornell.
Seven chapters
Two robots. Two worlds of discovery.
Follow the twin rovers from their shared mission design to their separate journeys, discoveries and lasting legacy. Each card opens a dedicated chapter.
Opportunity found tiny hematite spheres near its landing site. Hematite typically forms in water, so they were evidence of a watery past. That water was salty and acidic, though, which made life harder.
A hot-spring clue
Spirit found soil that was about 90% pure silica at Home Plate, plus signs of an ancient explosive eruption. Together they suggest hot water and steam once lingered there.
The friendliest place for life
Of all the places Opportunity visited, NASA says the clay minerals at Endeavour Crater, made in neutral-pH water, showed the most life-friendly conditions.
Crater explorer
Opportunity visited well over 100 impact craters during its 14 years on Mars, learning how craters form and wear away over time.
Finish with the quiz
The mission challenge
Ten questions across Apollo 11, Surveyor 3 and the Mars rovers. How much do you remember?