Mars Opportunity And Spirit Rovers Could Have Lived Practically Forever With One Tiny Change

Forbes Technology 

The identical robotic explorers, Spirit and Opportunity, were able to trek up to 109 yards each Martian day. They found evidence for liquid water among many other things, with Opportunity traveling farther than any autonomous vehicle on any world: over 45 km (28 miles) over more than 5000 days. In 2004, NASA launched two exploration vehicles to the red planet: the Spirit and Opportunity rovers. These two Mars Exploration Rovers were originally designed for 90-day missions to image, explore, and investigate the Martian surface. Yet these twin solar-powered rovers far exceeded their design lifetimes.