Today on Mars the robotic rover Opportunity (that’s right, Opportunity--remember when we all used to care about Opportunity?) is hitting a major milestone. The rover touched down on the surface of Mars Jan. 24, 2004, just three weeks after its sister rover Spirit landed elsewhere on the planet. That makes today the beginning of Opportunity’s tenth year of Mars exploration--not bad for a machine that was designed for a three-month mission.

Spirit and Opportunity were sent to the Red Planet in search of signs of its hydrological history (and, therefore, potential past life).