On Friday, August 3, 2018 at 6:11:56 AM UTC-4, Alain Fournier wrote:
Le Aug/2/2018 Ã* 11:41 PM, Scott M. Kozel a écritÂ*:
On Thursday, August 2, 2018 at 7:34:27 AM UTC-4, Jeff Findley wrote:
In article ,
says...

Terraforming Mars is one of those religious arguments, anyhow.

True. But my guess is that Mars will prove lifeless. If that's the
case, who's going to object to terraforming a lifeless planet?

Nothing fundamental in physics to stop humans from doing it. It will
surely take centuries or more to do it, but there should be more than
enough material in the solar system to do it. Mostly Mars needs
volatiles to recreate a thicker atmosphere. Once you get it up to 5
psi, you can walk around in breathing masks and (relatively) normal
clothing.

I forget how many octillion tons of oxygen it would take, but the
problem is getting it there in the needed quantities and then keeping
it there.

Not many octillions, less than a trillionth of an octillion tons. An
octillion is a somewhat large number (that's using the short scale, the
long scale would be even worse). But yes, it is true that many trillion
tons of O2 is a lot of O2.

Keeping it there isn't really the problem. It will be blown away by
solar wind as Mars' original atmosphere was. But that happens on a time
scale of millions of years. If you can't replenish it on that time
scale, it basically means that you couldn't put it there in the first
place. No one is going to start adding O2 to Mars with the plan of
having completed the job in a million years.

A trillionth of an octillion tons would be in the quintillions.
Nobody knows what did or would take place in millions of years,
as nobody has any such observational span.