The Spirit Mars Rover, which landed on Mars in 2004 but went defunct in 2011, has collected data that showed the red planet had an oxygen-rich atmosphere of at least 1.5 billion years before Earth did.
NASA is analyzing the data that Spirit sent back to Earth. The Spirit has found ancient rocks with some dated 3.7 billion years old, which held evidence of the presence of oxygen and plenty of it. That means the neighboring planet might have the necessary elements for life way before Earth did.
Professor Bernard Wood of Oxford University told The Guardian, “As oxidation is what gives Mars its distinctive colour, it is likely that the 'red planet' was wet, warm and rusty billions of years before Earth's atmosphere became oxygen-rich."
Spirit far outlasted her planned 90-day mission. Among her myriad discovering, the rover found evidence that Mars was once much wetter than it is today and helped scientists better understand the Martian wind.
In May 2009, the rover became embedded in a soft soil at a site called “Troy” with only five working wheels to aid in the rescue effort. After months of testing and carefully planned maneuvers, NASA ended efforts to free the rover and eventually ended the mission on May 25, 2011.