I've been trying to use this large chunk of jellied tissue between my ears and the idea of liquid water on Mars isn't adding up.

 

"They" say that in the distant past Mars had a more Earth like environment and liquid water but "they" also say the sun was dimmer way back when as well.

 

That only compounds the problem of liquid water...

 

Just how dense an atmosphere would Mars have had to have under a dimmer Sun to support liquid water and oceans and rivers?

 

I have an alternative opinion... I think Mars was once covered by ice, under the ice water flowed and created the land forms we see today that look reminiscent of river alluvial fans and such but these things never happened on a Mars under the open sky!

 

The ice sublimed and was lost to space over time leaving the marks of flowing water we see today!

 

We do see these things in arctic regions on the Earth today!

 

http://rspa.royalsocietypublishing.org/content/471/2176/20140907

 

What say you?

A spot of googling tells me that bits of Mars reach 20C- that's clearly in the range for liquid water.

Near 0 C the vapour pressure of water is about 4.6 mmHg so,as long as the pressure was more than that you could have liquid water without it boiling.

Add a bit of salt to the water and you are on to a winner with the current martian conditions (just).

A spot of googling tells me that bits of Mars reach 20C- that's clearly in the range for liquid water.

Near 0 C the vapour pressure of water is about 4.6 mmHg so,as long as the pressure was more than that you could have liquid water without it boiling.

Add a bit of salt to the water and you are on to a winner with the current martian conditions (just).

 

This true but with the Sun significantly cooler back then... Something like 30% less when the Sun first lit up!