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[MetalSlimeHunt]

If only we had portal guns, we could just open entrances to the Martian atmosphere inside every car engine and coal furnace.

[Starver]

On the last point however, I quote "the long lunar nights (354 hours long) would means that reliance on solar power would be impeded in any location other than the polar regions"

Barring such special locations, solar everywhere upon a spinning rock is going to be roughly 50% on, 50% off, give or take seasonal skews and advantageous/disadvantageous elevations.

Just factor in more (or better) storage and perhaps more resilient 'dark cycle' rationing/reserve-budgeting as well. It'd beba while before sun-up if things go wrong, but things can go wrong at any time, so it's all part of the design-time planning.

[Max™]

I'll go ahead and say that one of the first megaprojects on another body in the solar system will be setting up solar arrays at the south pole of the Moon. You can set things up to recieve sunlight 100% of the time there, once it is collected you can store and transfer it elsewhere across the surface to supplement local night, you can use it to work on extraction of helium, and given how much of the Moon apparently formed from volatile upper Earth materials there should be a ton of useful gunk inside it, water plus various organic compounds mixed.

If only we had portal guns, we could just open entrances to the Martian atmosphere inside every car engine and coal furnace.

Now you're thinking with your Johnson! Though given the massive pressure differential you could extract useful work just from shunting gas over there, of course setting up an engine using portal ring seals or portal exhausts while having portal technology is fairly absurd anyways.

Well here are my concerns after I've thought about it today.

   The moon orbits us and controls the tidal waves among other things AFAIK. Now, I do however see a potential issue with using that for resources and putting people there as it could in turn disrupt the earth's ecosystem

We would have to spend more money than I think has ever been spent in all of human history to move enough material to alter the orbit enough to matter here.

[DJ]

I think the rate at which mars loses atmosphere is about 3100 tonnes per year.

This sounds catastrophic and scary, but remember that industry puts out something like 7-20 gigatonnes of CO2 per year on earth, and we aren't trying to terraform the planet.

Yeah, but we have a lot of hydrocarbons right here on Earth. Not so much on Mars. And an atmosphere that's mostly CO2 isn't exactly a livable planet. We'll have to bring in asteroids for water, and that's gonna be extremely slow.

[Dorsidwarf]

I never said terraforming was trivial, only that any serious attempt isn't going to have to worry about solar ablation for centuries or millennia

[Reelya]

Probably billions of years. The Martian atmosphere (source: NASA) weighs 2.5 x 10¹⁶ kg. At 3100 tonnes a year, it would last 8 billion years. Sure, if we add more it will lose more, but probably not fast enough to make much of a difference before the Sun dies. Also, crashing some asteroids into Mars (taking care to angle and speed them so that they don't affect the orbit) would bulk up Mars, slowing losses.

[Max™]

It feels like the scales being discussed here aren't being appreciated fully.

Mars has about 2.5x10¹⁶ kg of atmosphere, 96% of it being CO2. Earth has about 5.1x10¹⁸ kg of atmosphere, 0.04% of it being CO2. Mars loses 3100 tonnes per year. We contribute closer to 30 gigatonnes per year here, not the 7~20 value quoted above. Each year plant decay, wildfires, and so forth release ~440 gigatonnes, and new growth soaks up ~450 gigatonnes. Just for fun, Venus has ~4.6x10²⁰ kg of CO2.

~24,000,000,000,000,000 kg Mars CO2
~3,100,000 kg Mars CO2 loss per year to solar wind
~720,000,000,000,000 kg Earth CO2
~30,000,000,000,000 kg Human CO2 per year
~440,000,000,000,000 kg Decay/Wildfire CO2 added per year
~450,000,000,000,000 kg Growth CO2 removed per year
~46,000,000,000,000,000,000 kg Venus CO2

These are big numbers, well out of the ranges we usually deal with on an intuitive level, but there is something we can relate too more easily: if we busted out portal guns and shot all the CO2 in our atmosphere over to Mars, we'd increase the mass around 3% and need to borrow about 30 times as much from Venus to double the mass of the Martian atmosphere, the Veneran atmosphere probably wouldn't even notice. Naturally we'd want some O2 and N2 and such to try and get it closer to something we could survive in, twice the amount of atmosphere on Mars still wouldn't put it anywhere near the survivable-without-a-spacesuit range.

[Reelya]

Let's assume the goal is an Earth-pressure atmosphere, with is 100 times the current one. Looking up CO2 asphyxiation, it looks like 1% atmospheric CO2 would be the operational limit for humans, so going above what's already on Mars makes little sense if we can't breath it. But we could theoretically jet some off Venus to Mars, to process it into the 20% O2 we need. The amount would be 20x the current Martian atmosphere, so 5.0 x 10¹⁷, or 1/1000 of the Venusian amount.

I was thinking of Martian soil nitrates as a possible Nitrogen source. Wind-blown sediments across the surface of Mars seem to be 0.1 - 1.0 composed of nitrates. The question is how much total is there?

BTW, you messed up the CO2 numbers for the three planets there. On Mars, It makes up ~95% of the 2.5 x 10¹⁶. You only had 15 zeros. For Earth, CO2 makes up 0.04% of 5.15x10¹⁸ which is 2.0x10¹⁵, not 7.2x10¹³ and would make up 10% of the Mars atmosphere, not 3%, and you missed a zero on Venus, too.

[DJ]

Yeah, local nitrates are a very nice thing, but processing them all would take a long ass time. My point is that any terraforming attempt on Mars would take thousands of years, possibly tens of thousands. By that time we should have developed interstellar travel which would give us access to planets a lot better for terraforming than Mars. That, and it's too slow of a process to include in any short and medium term plans, so just waving off colonization problems with "we'll terraform it" isn't very productive. We need plans for development of large enclosed cities there with full life support and local food production. And AFAIK we don't have the technology for that stuff just yet, so proper colonization is a no go.

[Reelya]

Well sure, if you're willing to travel for 16 years to reach the nearest star.

Half light speed is the limit according to research (due to impacting hydrogen atoms are extreme speeds), probably 1/4 light speed taking into account accel and decel, giving 16 years for a trip to Proxima Centauri. That also assumes there will be places within reach which are cheaper to terraform than Mars is, taking into account the additional logistics of interstellar flight.

[DJ]

We're talking about tens of thousand of years, though, that's been enough to get from stone spears to interplanetary travel. I'm wagering it'll be enough to go from interplanetary to interstellar, probably by circumventing speed of light rather than breaking it (AFAIK there's already some proposed "warp" drives that aren't theoretically impossible).

[Max™]

Let's assume the goal is an Earth-pressure atmosphere, with is 100 times the current one. Looking up CO2 asphyxiation, it looks like 1% atmospheric CO2 would be the operational limit for humans, so going above what's already on Mars makes little sense if we can't breath it. But we could theoretically jet some off Venus to Mars, to process it into the 20% O2 we need. The amount would be 20x the current Martian atmosphere, so 5.0 x 10¹⁷, or 1/1000 of the Venusian amount.

I was thinking of Martian soil nitrates as a possible Nitrogen source. Wind-blown sediments across the surface of Mars seem to be 0.1 - 1.0 composed of nitrates. The question is how much total is there?

BTW, you messed up the CO2 numbers for the three planets there. On Mars, It makes up ~95% of the 2.5 x 10¹⁶. You only had 15 zeros. For Earth, CO2 makes up 0.04% of 5.15x10¹⁸ which is 2.0x10¹⁵, not 7.2x10¹³ and would make up 10% of the Mars atmosphere, not 3%, and you missed a zero on Venus, too.

Whoops, was converting a couple of the values from tonnes and others were volume based rather than mass based values so I had to track down the mass from various locations and apparently didn't follow the link trails far enough, as one of them was actually in grams, and I think it should have been 7.2x10¹⁴ kg as it was converting from 720x10¹⁵ g, but I had a terminal I was using as a scratchpad to keep track of the values so I probably swapped a couple of the zero sections around at some point when swapping them into the calculator and such.

Still huge damn numbers, but yeah, converting CO2 to O2 in-situ and extracting N2 was indeed the idea.

We could probably get by with less than 1 bar, adapting to mountainous terrain is a thing we can do pretty well, but we're still talking about needing a huge amount of gases added to the wispy atmosphere present before we would reach a point that the mixture would be more dangerous than the pressure or lack thereof.

[x2yzh9]

So, quick, honest question here then: Wouldn't Olympus Mons(sounds cheesy, I know) or a similarly high mountain on mars be the first acceptable spot for a colony?

[DJ]

The higher you go the thinner the atmosphere, so I think you'd actually want to aim for the lowest surface point that's reasonably close to polar ice.

[JoshuaFH]

Terraforming a completely uninhabitable planet is probably the least useful expenditure of Humanity's resources. It'd be much more efficient to borrow from scifi and instead just build very large, orbiting colonies. Think about it, what's a better use of effort: trying to convert a huge, polluted garbage heap into a livable space, or just building a new home where we can dictate the conditions as precisely as we need to?

And granted our robotics advances sufficiently, those barren planets can still be useful in being huge, unmanned mining operations, providing cheaper materials for our colonies since transferring materials off of a smaller planet (or moon) needs significantly less power due to the smaller gravity well.

And granted our architecture advances sufficiently, transferring materials off of smaller planets won't even need much fuel, we'd just build a space elevator to accommodate each mining operation as it dismantles each planet for materials.

So the matter of interstellar travel isn't one of trying to flip every big rock into a two-bit bastard Earth, but rather making the best use of existing resources to build a long string of hobo houses  that gradually stretch into deep space. That's how I see the colonization of outer space being economical.