While all the focus has recently been on the Mars Curiosity Rover, another of NASA's creations just completed nine years of data gathering on the red planet.
On January 3, 2004 the Opportunity rover touched down on Mars and was joined three weeks later by Spirit.
The two were on a 90-day mission to search for signs of historical water activity on the Red Planet but would end up surpassing scientists wildest expectations.
Opportunity and Spirit found strong evidence of water on Mars, discovering that the "dry" looking planet actually was much warmer and moist billions of years ago.
Spirit stopped communicating with NASA in 2010 but will long be remembered for its discovery of ancient hydro-thermal activity.
The robot found an old system where heat and liquid water may have existed, creating conditions capable of supporting life.
Spirit was declared dead a year after it stopped working.
The Opportunity rover continues operation to this day and is currently exploring the Endeavour Crater, which only two years ago was considered a far off dream.
"The ripples look like waves on the ocean [the rim of the Endeavour Crater], like we're out in the middle of the ocean with land on the horizon, our destination," said Steve Squyres of Cornell University in a release from 2010. Squyres is the principal investigator for Opportunity and Spirit. "Even though we know we might never get there, Endeavour is the goal that drives our exploration."
So far the robot has covered over 35-kilometres on the ground while Spirit covered closer to eight.
Opportunity has not shown signs of decline and continues to send important information back home.
The rover recently studied winds on the Martian surface — described by scientists as "the most active process on Mars today."
Opportunity has also been able to collect substantial amounts of astronomical observations and atmospheric data.
NASA does not know how long the rover will continue to function but is more than happy to collect its data as long as it can.