Why does NASA keep going back to Mars?

Ahead of the launch of the Mars 2020 Perseverance rover, NASA's Planetary Science Division Director Lori Glaze explains why the Red Planet is important to explore. [Perseverance rover will use some of the best Martian maps ever made](https://www.space.com/mars-2020-rover-perseverance-best-martian-maps.html) Credit: NASA