On Wednesday, August 8, 2018 at 7:34:07 AM UTC-4, Jeff Findley wrote:
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. Apparently nearly all of its atmosphere (even assuming it was
Earthlike at one time) has long since departed due to the effects of
gravity and solar radiation.

Keeping it there isn't much of a problem. In the short term (hundreds
of thousands of years) it won't lose enough to matter. A few more
Kuiper belt objects would make up for the loss.

So the idea is that they spend a decade or so "pumping it up" to Earthlike
atmosphere, and then that will last for millions of years before it leaks
away?

In the long term, you put a giant electromagnet between Mars and the sun
in order to produce an artificial magnetic field to mimic the protection
earth's magnetic field gives it. Note from above this gives you
hundreds of thousands of years to perfect that tech and scale it up to
sufficient size.

The arguments against terraforming Mars sound a lot like the myriad of
arguments against heavier than air travel before the Wright Brothers
successfully demonstrated that it was possible. Yet a few weeks ago, I
flew to Shanghai and back for a week long business trip which is a 12
hour time zone difference from where I live, so roughly half way around
the planet. And that was only a bit over one hundred years later.
Terraforming is on a much bigger timescale, so we have a much longer
time frame to perfect the tech necessary to complete the task.

Really. Heavier than air travel was a matter of engineering developments
that provided a powerful enough engine and an airframe that could handle
the 100+ mph speeds that would keep it airborne. A 600-pound machine.
The theory was known for hundreds of years if not thousands.

The arguments against terraforming Mars are like trying to explain to
someone how the Sun can be a hydrogen bomb but there is so much mass there
that gravity alone is sufficient to create the temperatures needed for
hydrogen fusion, and this hydrogen fusion process will last for at least 5 billion more years before it runs out of fuel.