Hacker News Reader

> there is nowhere else within reach that is remotely similar to either planet

Now, hear me out here but have you considered Venus?

Cons:

  Runaway greenhouse effect, sulfuric acid clouds, crazy hot, etc
  Very long days (1 year = 1.92 Venus days)

Pros:

  Nearer to sun => better solar energy collection
  Nearly the same gravity as Earth (0.8-ish)
  Lower delta-v to get there from Earth (someone double check my math on that)

You'd need to get material built into a 'solar umbrella' to cool the planet down, reflect light elsewhere. One idea (Kim Stanley Robinson?) was too make mirrors that reflect light from the way-too-bright side and have it instead reach the 'dark for half a year' side.

Once you've got it cooled down, you're a lot of the way there. Bleed off some of that atmosphere (hey, maybe Mars could use it?), get some plants converting CO2 into O2.

It's ludicrous, I know, but I find most conversations about terraforming are. The only real advantage that Mars has is that we could live there while we work on it. Venus, not so much.

Actually, the upper atmosphere of Venus has about the right atmospheric pressure and ambient temperature for Earth. So building effectively cities on blimps means you only need to worry about the sulfuric acid--walking outside only requires a hazmat suit, not a full pressure suit.

It's not clear whether Venus or Mars is an easier target for colonization--that's just a sign of how hard it would be to build a colony on anything that's not Earth.

> It's not clear whether Venus or Mars is an easier target for colonization

Actually, despite my above pro-Venus talk, Mars is still an easier option. I wound up on a wiki-spiral just now reading about options for Venus- turns out plants would not work for converting that CO2. The process for CO2 conversion needs Hydrogen- and Venus has none.

We'd need some kind of trade-triangle between Mars, Venus and Jupiter, dumping CO2 from Venus to Mars, then moving H from Jupiter to Venus. We need to find some product Mars has that Jupiter wants, then we'd have it figured out.

Mars has solid minerals, which I assume could be in short supply on any base near jupiter

Jupizer has lots of moons ...

While true, I was more thinking that there would be shortage of something between those moons. Maybe I'm mistaken

If humanity ends up with the ability to travel to other stars, Mars is but a stepping stone. It would be the testing ground for almost everything else. There's no reason to view that as temporary. It's necessary and the whole terraforming process would include figuring out a way to not lose those resources to space.

We don't really know how long terraforming Mars would take, but it's conceivable that it could take as few as a few centuries, especially given the advance of tech.

https://en.wikipedia.org/wiki/Terraforming_of_Mars#Protectin...

(some scientists say it could be done with current tech)

Mars has useful quantities of ice and an atmosphere that's 96% CO2. We wouldn't need to export any oxygen to Mars and probably wouldn't need to export much or any water either. Really, the biggest doubt is about the quantity of readily-available nitrogen.

On the grandest scale, we could take CO2 from Venus and hydrogen from Saturn or Jupiter. The logistics aren't exactly straightforward, but the quantities available are immense.

I think what he means is any atmosphere on mars would eventually blow away, just like it did the first time.

Over millions and millions of years. A civilization that could colonize another planet could manage to mitigate or outright solve that kind of problem with that kind of time.

https://phys.org/news/2017-03-nasa-magnetic-shield-mars-atmo...

The idea is that shielding Mars from the solar wind would allow out-gassing to rebuild the Martian atmosphere.

>Yet it does seem to go against the basic idea that many of proponents of manned space exploration tout: a second home to ensure our survival.

This is slightly tangential, but I think it's important to point out that Mars is more than a survival shelter.

The point of colonizing Mars is to preserve human civilization, not merely our species. Civilization is a higher level emergent thing that can only exist in large prosperous groups of humans. Almost nothing could actually kill the human species, but tons of stuff could end civilization. A self sustaining Mars guarantees our continued social and technological advance.

An Earth-Mars war could use nuclear weapons without the risk of fallout. So, it may actually lower the odds that civilization survives.

We can't meaningfully speculate about what such a war would look like, technology will advance too much before then.

I don't think it would be nuclear though. Nuclear bombs are delicate devices, the only reason they work on Earth is because they hit too fast to intercept.

Interplanetary war will have at least 1 month long trips between the two planets unless we see some insane tech breakthroughs. A war fleet would be pretty easy to spot and blast out of the sky, as would any missiles launched planet to planet. Hitting something at the insane speeds of ICBMs becomes much easier when you have days to aim.

It's not that hard to fake what is and is not a bomb in space. Consider their is no air resistance so use an inflatable balloon which may or may not have a bomb inside. For 10,000 kg you could probably send up 100,000+ fake bombs which would all have slightly different vectors making hitting them all very hard. Further, if you use something mechanical vs inflation it's not obvious if something was shot down or not.

Worse, the attacker may feel they can use something like that while shooting down any responses.

would it be easier and a better investment to change ourselves? replace mitochondria with something that doesn't need oxygen to produce ATP. If you're planning on you and you descendants spending forever exploring space, would you want to be vacuum native?

Interesting, but is it doable? It is not only breathing that needs refactoring: how do we resist very low pressures? What about radiation?

What else needs a complete overhaul?

I really like the Hyperion Cantos - the Ousters make exactly that decision, to forego terraforming in favor of self-modification. Naturally, the natural humans vilify and hunt them.

http://hyperioncantos.wikia.com/wiki/Ousters