Hi Guys

I have to wonder what the balance between loss and gain was on Mars. McKay and colleagues have an Icarus paper which discusses the outcome of certain assumptions about the volatile inventory of early Mars, and it seems the most probable is a low inventory rather than a rich one. Thus Mars probably doesn't have immense amounts of CO2 locked away in the regolith through adsorption - which would've made terraforming a lot easier, but it just may not be there.

Venus is a different matter again. Venus Express's measurements of the H/D ratio with vertical height will tell us a lot more about the original quantity of water.

Adam