The golf-cart-size Spirit rover landed on the Red Planet eight years ago today (Jan. 3). Its twin, Opportunity, touched down three weeks later, on Jan. 25, 2004. The two robots were originally supposed to spend 90 days searching for signs of past water activity on Mars.
They found plenty of such evidence, dramatically reshaping scientists’ understanding of the Red Planet and its history. And the rovers just kept chugging along, continuing to make observations years after their warranties expired. NASA declared Spirit dead just last year, and Opportunity is still going strong.
I propose this set of rovers may be the best-designed thing mankind has ever built.