NASA Opportunity rover celebrates its 5,000th Martian day

Back in the summer of 2003, NASA launched a pair of Mars rovers named Opportunity and Spirit. Both landed on the Martian surface in January 2004, each designed for a mission that would last 90 Martian days (which are called sols). Both rovers managed to drastically outlive that 90-sol mission. Though Spirit became stuck in 2009, eventually losing communication with …