The rovers landed in January 2004, on opposite sides of the planet in locales that scientists suspected had been affected by liquid water in the past. Their main scientific objective was to search for a range of rocks and soil types and then look for clues for past water activity on Mars—and what they found rewrote textbooks.
In addition to proving that water once existed on Mars, the rovers also far exceeded their initial planned lifetimes. Spirit operated for 6 years, 2 months, and 19 days, more than 25 times its original intended lifetime, and Opportunity operated for almost 15 years, setting several records.
Image Credit: NASA/JPL-Caltech
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