Today, NASA is officially saying goodbye to the craft that, for years and years, couldn't be stopped.
But on June 10, 2018, after outlasting Spirit by eight years, Opportunity fell silent under the shroud of a planet-encircling dust storm. John Callas, project manager of the Mars Exploration Rover project, said: "We thought dust falling out of the air would eventually choke it of power after 90 days, but wind unexpectedly came along and blew it off so we could keep going and exploring". But a subsequent "cleaning" event-what NASA calls it when weather conditions clear, exposing the solar panels and allowing the craft to recharge-never happened. That's when the Sojourner craft arrived at Mars, roving for 83 Martian days on what was meant to be a seven-day test mission.
But a giant dust storm past year blocked sunlight from Mars, stopping Opportunity's solar-powered batteries from being able to recharge. Spirit was launched first, leaving Earth in June 2003 and arriving in January 2004.
But even with its sibling gone, Opportunity pressed on.
The rover sent back images of former water reserves, providing signs that ancient life could have once existed on Mars.More news: Rich The Kid & Usher Involved In Studio Armed Robbery
Opportunity and Spirit were built to last 90 days, but Opportunity far exceeded that number, roving for almost 15 years.
When Opportunity's twin, Spirit, became mired in soft soil in 2009 and its five working wheels couldn't free the rover, NASA held a "service" to commemorate the end of the mission in May 2011.
The agency held a news conference to detail the results of recovery efforts since a dust storm encircled Mars a year ago. By consistently actively pinging the rover during both preplanned recovery times and other random intervals, engineers had hoped to catch Opportunity during an awake period.
Nasa's Opportunity on Mars was to search for clues about the history of water.
"Once set, it will take Mars' temperature and tell us how much heat is flowing from inside", it tweeted. After that period, they were planning to go into a "passive listening" mode, where they would stop sending signals and just monitor the rover's signals to see if it was calling home.More news: Michelle Obama shares text from mom on Grammy Awards night
Neither rover was created to endure extreme weather - unlike Nasa's nuclear-powered Curiosity rover, which continues to trawl Mars for information.
"It is because of trailblazing missions such as Opportunity that there will come a day when our courageous astronauts walk on the surface of Mars", NASA Administrator Jim Bridenstine said. It's the accomplished exploration and phenomenal discoveries.
The two rovers' greatest achievement was finding firm proof that water that could have sustained microbial life had once flowed on the Martian surface. Steve Squyres, a professor at Cornell University in the U.S. studying the history of water on the Red Planet, called Mars a "dry, desolate world". After months of trying and winter approaching on Mars, it looks like this is the end.
"Whatever loss we feel now must be tempered with the knowledge that the legacy of Opportunity continues, both on the surface of Mars with the Curiosity rover and InSight lander and in the clean rooms of [NASA's Jet Propulsion Laboratory], where the upcoming Mars 2020 rover is taking shape". May we all be so lucky to have such a rich legacy.More news: George Clooney claims Meghan Markle is being 'pursued and vilified'