Water flowed on Mars' surface. Thus, the Earthly neighbor might have been or might still be able to support microbial life. That's what the longest-working and furthest-roaming lander in space exploration discovered during its tenure on Mars.
The last attempts at contact came this week before NASA leaders pulled the plug. They had sent more than 1,000 messages to the machine since it went unresponsive in June 2018.
Opportunity, as NASA's space rover was named, ironically, met its final defeat in Perseverance Valley when a fierce dust storm disrupted all contact for good.
Opportunity landed on Mars in 2004. Initially, the mission was expected to last 90 days. Opportunity roamed Mars for 15 years! It also set a distance record, roaming 28 miles.
NASA has two rovers still studying on Mars, Curiosity and InSight. Three more, one each from the U.S., China and Europe, are set to launch in 2020. NASA says it hopes these missions will eventually lead to sending astronauts to the red planet.