How a Giant Dust Storm Silenced Opportunity

In January 2004, a golf-cart-sized robotic explorer named Opportunity bounced onto the rust-colored soil of Mars. NASA engineers originally designed the rover to travel across the Martian landscape for just 90 Martian days, or sols. Scientists hoped it would find clues about whether liquid water had once flowed on the Red Planet. Opportunity far surpassed those initial expectations. Year after year, the sturdy six-wheeled vehicle rolled across rocky plains, climbed into deep craters, and sent back thousands of photographs. It discovered minerals that could only form in water, proving that ancient Mars was once much wetter and warmer than it is today.

Opportunity’s secret to longevity lay on its flat upper deck: an array of shiny solar panels. Sunlight is weaker on Mars than on Earth because the planet is farther from the sun, but Opportunity gathered enough light each day to charge its internal batteries. These batteries powered everything from the rover's scientific cameras to the vital internal heaters that kept its computer circuits from freezing during bitter Martian nights, when temperatures can plunge far below minus one hundred degrees Fahrenheit. Occasionally, friendly gusts of Martian wind swept across the panels, clearing away accumulated dust and giving the robot an unexpected power boost. Because of these natural cleanings, the mission stretched from three months into nearly fifteen remarkable years.