A self-portrait of the Mars rover Curiosity.
Amazing Pictures From 20 Years Of Nonstop Robots On Mars
NASA has had rovers studying the Red Planet since July 4, 1997.
July 4 marks the twentieth year that NASA has had a robot working on the surface of Mars.
In 1997, the Mars Pathfinder landed on the planet and explored the surface for three months, analyzing the Martian atmosphere and climate and assessing the composition of its rocks and soil. (Learn about efforts to send humans to Mars in “Mars: Inside the High-Risk, High-Stakes Race to the Red Planet.”)
Since Pathfinder, eight other NASA robots have explored Mars.
Both the Spirit and Opportunity rovers touched ground in 2004 with the mission of finding evidence of water. Together, they took thousands of pictures of the rocky Martian terrain and collected data that led researchers to believe Mars was indeed once a wet planet.