The Soviet Union's PrOP-M rover landed in Mars in 1971. It was a walking rover connected to its lander, Mars 3. It was unable to do anything, with the lander losing communication just after 14 seconds of operation. It never was able to deploy. (Discover Magazine)

NASA's Sojourner rover landed in 1997. It was the first rover to be successfully deployed and roam the Martian surface. It had a 7 day mission, but ended up communicating for 83 days. It took photographs and studied chemical and atmospheric aspects of Mars. (NASA)

NASA's Spirit rover landed in 2004. It was launched alongside Opportunity. It made many discoveries, with its most significant discovery of learning that Mars used to have liquid water and learn about Martian wind. It's 90 day mission ended after over 6 years when it got embedded soil with only 5 working wheels. (NASA)

NASA's Opportunity rover landed in 2004.  Discoveries include very solid evidence that an area of Mars maintained liquid water for a long time and could have been sustainable for life. After it surpassed its 90 day mission by 15 years it was caught in a severe sandstorm and NASA lost communication. (NASA) 

Another NASA rover, Curiosity, landed in 2012. It has a mission to determine whether Mars was ever habitable to microbial life and has found significant evidence. It demonstrated the ability to land larger and more equipped rover on the surface of Mars. It's still working on the surface of Mars today. (NASA)

NASA's Perseverance rover landed in 2021. Its mission is to seek for signs of ancient life and collect rock samples to potentially return to Earth. One of its many achievements is converting some of the atmosphere into oxygen. Perseverance is still actively searching for evidence to complete its mission. (NASA)

NASA's Ingenuity is the first Martian helicopter and landed inside of Perseverance. It had no mission other than to test if flight was possible in Mars' thin atmosphere. Once it was successful it now it used to take pictures from above and assist Perseverance by looking for its safest path around the Red Planet. (NASA) 

CNSA's Zhurong rover, China's first, landed in 2021. Its exploring a potential ancient ocean floor. It made a major discovery that Mars' water may have stayed for much longer than scientists originally thought. It was estimated the last trace of water was gone 3 billion years ago, but it could be just 700 million. Zhurong is still active. (NASA)