The air will slowly leak away to space due to Mars' low gravity, so we'll need to continually make it up by adding more. We can do that by bringing small water-rich asteroids to burn up in Mars' atmosphere. Moving them is slow, but easily fast enough to maintain Mars.
2/ You could also simply bring icy asteroids into Mars, not just to maintain the atmosphere, but to make its atmosphere thick in the first place. My co-author argues that this is not ideal since it would take too long to make Mars live-able.
3/ So he argues the we should use the Martian soil to get the initial dose of oxygen, making Mars live-able very quickly. Then we could bring ice from space just to maintain the Martian atmosphere over the long term, because we only need a slow process to do that maintenance.
4/ Eventually you might run out of small icy asteroids or small comets, of course. You can't maintain Mas forever. But by then the sun burns up the inner solar system, anyway. Hopefully by then, humanity will no longer even need planets. It is all about timescales.
5/ So my co-author's insight was that we can use self-reproducing factories on Mars to RAPIDLY thicken the atmosphere using the oxygen that is already locked in the minerals of the soil. (So even if there is inadequate CO2 on Mars all by itself, we can still solve this problem.)
6/ His (Tony's) insight is that we already have technologies to get oxygen from the soil on the Moon, so let's build lots of those pieces of hardware all over Mars and rapidly it will become a life-supporting planet. We just need to build those devices quickly. Very quickly!
7/ Back in 2013, I wrote a paper with Tony's contribution about bootstrapping self-reproducing factories on the Moon. We showed that very little hardware is needed to initiate that process, and in just a few decades that industry can dwarf the productivity of the entire Earth.
8/ So Tony argues that we can do that on Mars to rapidly get a giant industry to build these oxygen extraction machines. But to get enough oxygen you'd need to extract it from about half the surface of the planet to a depth of 5 meters! A vast, planet-scale operation.
9/ But with a self-reproducing factory system you can do that in just a few decades, completely remaking the Mars environment, just like bacteria did to Earth's environment billions of years ago. The factories will be "artificial bacteria", and much faster than bacteria.
10/ After the factories are done making Mars a liveable world, they recycle themselves, create forests, rivers and cities with transportation and a closed-loop economy. The remaining factories go underground, powered by clean, beamed energy from space. Leave the surface for life!
11/ One question I have is what would it be like having the top 5 meters of Mars consisting of metal silicate grains rather than oxidized minerals? Will it affect plant uptake of nutrients? Can soil bacteria live in it? Maybe we shouldn't use the uppermost soil for oxygen!
12/12 This, too, is easily solvable. We make all the self-reproducing factories work underground. Either use soil just a few meters below the surface then replace the original soil on top, or go even deeper by mining into rock underground. Either way, Mars is terraformed & alive.
