Why NASA calls landing the Mars rover '7 minutes of terror' 01:26 (CNN)In 22 days, NASA's Mars 2020 Perseverance rover will land on Mars in Jezero Crater to search for signs of ancient life that may have been on the red planet in the past. The rover, which is the largest and most advanced rover NASA has ever built, will act as a robotic geologist, collecting samples of dirt and rocks that will eventually be returned to Earth by the 2030s. For that reason, Perseverance is also the cleanest machine ever sent to Mars, designed so it doesn't contaminate the Martian samples with any microbes from Earth, providing a false reading.