In article ,
says...
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.


Actually you can estimate the rate of loss over time based on how much
of an atmosphere is there today. You can also estimate it based on
other factors like how big Mars is, how strong the solar wind is at that
distance, and etc. It's not like we're completely clueless here.

Jeff
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