As of today, NASA’s rover, Opportunity, has finally stopped working after 15 years on Mars.
NASA’s Opportunity was only meant to work for 3 months... but managed to hold on for 15 years. Opportunity helped us discover the red planet's history, collect and analyze rock samples, discover evidence of water that used to exist and more. NASA tried numerous times to make contact with Opportunity after being hit with a dust storm. The team that controlled Opportunity had a really hard day in Pasadena, California after failing to make contact.
Opportunity's twin, Spirit, that was on the other side of the red planet, died 8 years ago. The two rovers both landed on Mars back in 2004.
The project cost NASA about $500,000 USD a month. Operations to try to revive the rover is no longer on the table.
Currently, there are still 2 rovers left on Mars, Curiosity, who has been there since 2012, and InSight who landed fairly recently. Scientists hope to be able to send humans to the red planet sometime in 2030.