Viewing a single comment thread. View all comments

Pluto_and_Charon OP t1_it2wty0 wrote

Excellent question! This is one of the biggest debates in Mars science - we really don't know to be honest! All we know is that the atmosphere must have been far thicker than today and must have contained a lot of greenhouse gases to explain how a planet much further than the sun was able to sustain liquid water on its surface without it freezing.

Candidates include: CO2 NH3 CH4 SO2 H2O

2