How did Mars turn into an uninhabitable desert? Curiosity rover rock samples may have answers 

 NASA's Curiosity rover has new insights into how Mars might have changed from a potentially habitable, water-rich planet to an absolutely uninhabitable desert. 

https://cdn.mos.cms.futurecdn.net/XXyKaycG5ybnUytNLFoBoX.jpg

https://www.space.com/curiosity-rock-samples-uninhabitable-mars