By studying the chemical elements on Mars today—including carbon and oxygen—scientists can work backwards to piece together the history of a planet that once had the conditions necessary to support life.
![](https://scx1.b-cdn.net/csz/news/tmb/2020/1-nasascuriosi.jpg)
Source:
https://phys.org/news/2020-05-curiosity-rover-clues-chilly-ancient.html