Water on Mars?

We've seen a hint that Mars may have water: Questions:

1. Where is it now?


2. How could it ever have existed?

Look at an atmospheric phase diagram for H2O and CO2:

Conditions aren't right for liquid water!
What does this mean?

3. Long-lived bodies of water or transient flows? How could you tell?

2004/5: Mars rovers find nodules of jarosite and hematite in Mars rocks -- minerals that form over time in the presence of water.


Jarosite nodules (greenish-blue)

Hematite nodules