Comment by frank-weindel | Hacker News Reader

Comment by frank-weindel | Hacker News Reader

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Looks like someone has lost all hope for humanity and at that we should just accept our "inevitable" self-destruction.

Even if the dream of colonizing mars is farfetched beyond fixing all of the problems we currently have on earth, it doesn't mean its not worth striving for. Goals like this drive people to do their best work and come up with creative solutions to problems that would otherwise never have been thought of. This is the exact kind of drive we need if we are to even have the chance at becoming interplanetary. Maybe we end up just getting to Mars and setting up an "antarctic" like lab that is occupied by teams for months at a time? That's fine. The innovation that got us even there would have been amazing. Maybe the goal then shifts to self-sustaining interplanetary spacecraft. Humanity isn't done yet, and not shooting for the far reaches of the galaxy is a waste of time that we cannot spare.

Musk Co. isn't just focused on that interplanetary goal. There's a lot that is also being done to make this planet better and prolong its life. These are honorable and not nearly as farfetched goals. Musk's drive to solve these problems is a real inspiration to many and may be our only chance in hell to pass through the Great Filters.

!Mars != !Space.

Mars is a dusty, barren deathtrap of a rock that's at the bottom of a very deep hole. The only thing to do on Mars is to _be_ on Mars. It's not (plausibly) terraformable, sustaining life there will obvious continuous and hugely expensive technical input, there are no resources there worth going there for, and once you've gone there, to get back you have to climb out of a hugely deep hole.

Meanwhile the solar system is full of places that are easier to get to, more hospitable, more profitable, and which you can get away from. Asteroids. Comets. Ceres. The moon, even. Further afield, the rings of Jupiter and Saturn --- the radiation's a bit rough, but if you can survive there, you've got it made. Hell, if you're into planets, Venus is a better option. Did you know that there are parts of Venus which are a shirt-sleeve (and breathing mask) environment?

Mars is fascinating, and there should absolutely be a science station there eventually, but it's not colonisation material. I certainly don't think it should be a priority right at this moment. With our current state of the art, I believe the Moon to be a much better choice.

> Did you know that there are parts of Venus which are a shirt-sleeve (and breathing mask) environment?

Nope, that's news to me. According to:

http://earthguide.ucsd.edu/eoc/special_topics/teach/sp_clima...

the minimum temperature on Venus is 870F, well above the melting point of lead. Do you know something that UCSD doesn't?

They aren't on the ground.

http://www.iflscience.com/space/nasa-wants-establish-floatin...

We're talking about colonization here, not exploration. That's not even a practical plan to make more living space here on earth, let alone on Venus.

It's actually not all that impractical. Venus' atmosphere is much more dense than Earth's; floating in it should be quite a bit easier.

> Venus' atmosphere is much more dense than Earth's

Won't help:

"The ships would float 50 kilometers (31 miles) above the planet’s surface. Here, there would be only one atmosphere of pressure, and the temperature would be a reasonable 75"C."

75 C is 160 F. Granted that's cool enough to keep water from boiling, but unless you're a tubeworm you're probably not going to be happy living there without air conditioning.

Considering the temperature fluctuations faced routinely even in Earth's own orbit, 75 degrees Celsius is actually very reasonable. It's certainly no less comfortable than Mars' rather frigid climate. If anything, the greater hazard would be the toxic and corrosive clouds of sulfuric acid that blanket the Venusian surface.

The density, however, more has to do with whether or not it's feasible to build a permanent settlement in Venus' atmosphere. It turns out that it's very feasible; Venus' carbon-dioxide-based atmosphere would be thick enough even at those altitudes to keep a "balloon" filled with an Earth-like atmosphere (nitrogen, oxygen, trace CO2) afloat with little effort. This means that such a ship or city wouldn't need separate balloon and living spaces; the living space itself would be buoyant.

You can handle extreme temperature fluctuations in Earth orbit because you can dump excess heat into space with radiators. That won't work inside a hot, dense CO2 atmosphere. Maybe there's some other solution to the cooling problem that I have overlooked, but I don't see any way to keep from turning into a sous-vide.

One such approach would be to use Sterling coolers, which (IIRC) is one of the suggested approaches for surface activities on Venus. Standard refrigeration techniques should also work reasonably well.

Also, why wouldn't standard heat-dumping work well in a CO2 atmosphere? If anything, it should work better; the vacuum of space is the best insulator known to man, so literally anything else would be better for heat dissipation.

> Sterling coolers

Doesn't matter what technology you use, you are still bound by the second law of thermodynamics. The excess heat has to go somewhere, and so unless you have a cold sink, you have to add energy. And if you're going to colonize rather than just explore then you have to add energy all the time forever. If the power fails, you die, she dies, everybody dies.

> why wouldn't standard heat-dumping work well in a CO2 atmosphere

That depends on what you mean by "standard heat dumping". In space, you can radiate heat into the cosmic background radiation, which is the ultimate cold sink. It's about 3K, which is almost always colder than you want to be [1], so in space you get cooling for free.

If you're inside a dense atmosphere, radiative cooling doesn't work. (There's a reason they're called "greenhouse gasses"). You have to dump the heat into the environment, which is hotter than the temperature you want to maintain, so you're fighting the second law, so you have to add energy. At the altitudes we're talking about here, you're maintaining a gradient of 30-40C. That's huge. It's not impossible (the artificial ski slope in Dubai maintains a similar gradient) but it takes a tremendous amount of energy. Where are you going to get it?

---

[1] There are some cases where you need active cooling in space, for example, if you're running an infrared sensor on a telescope. Those have to be actively cooled, usually with a supply of liquid helium that is launched with the spacecraft. But see:

http://jwst.nasa.gov/sunshield.html

for an example of what has to be done to keep an infrared telescope cool for a long mission.

"Did you know that there are parts of Venus which are a shirt-sleeve (and breathing mask) environment?"

Please expand on this.

Venus has a very thick atmosphere. At the height of a few miles above surface, there are layers with room temperature and human-acceptable pressure. Of course, the atmosphere is still CO₂ with some nasties, so a gas mask is required. But a Star-Wars-esque floating city would be quite manageable there. You can use hydrogen for floating because there's not oxygen around, so no risk of a blast.

NASA is already working on it: http://www.cnet.com/news/nasa-wants-to-build-a-floating-city...

50km up, actually. (Venus' atmosphere is scary thick.)

And it's better than you think: the atmosphere there is largely carbon dioxide, which is denser than air; so you don't need hydrogen for bouyancy. You can use breathable air and live inside the balloons. The inside's at a slight overpressure, so any leakage will be outwards rather than inwards, and the pressure differential's pretty small so it's likely to be pretty unexciting.

You're above the clouds, so there's plenty of sunlight. Luckily there's this really big surface to spread solar panels on; your balloon. Then you can electrically break down the carbon dioxide into oxygen. Or just use plants. What is it they like again? Oh, yeah, carbon dioxide...

What you don't get is much in the way of heavy elements; light organics (CHON, mostly) can be extracted from the atmosphere, but that does solve your immediate life support issues. Metals you'll need to go to the surface for, which may be a little exciting, but is perfectly doable (by machine, preferably). You're probably better off building out of organically produced carbon fibre, i.e. wood.

Venus really is one of the most hospitable planets in the solar system, after Earth. If you like planets, of course.

Found some info myself.

https://en.wikipedia.org/?title=Colonization_of_Venus

> sustaining life there will obvious continuous and hugely expensive technical input

Not if we send first our 3D printers and deep learning based robots that we are going to build soon. We just need to build a replicator and send it there to terraform for us.

Living on Venus won't save you from a future red-giant-phase Sol. Mars may not either, but it's a better bet.

Perhaps not, but it gets humans used to the idea of traveling to and living in/on/etc. worlds that aren't exactly hospitable. Additionally, the sulfuric acid clouds in Venus' atmosphere might be useful for various industrial processes.

> Great Filters

Quick link for those who haven't read Fermi paradox et al. https://en.wikipedia.org/wiki/Great_Filter

Inline summary for the lazy: If we don't see intelligent life, and the universe is as old as it is, then it must be unlikely for life to persist to a stage where we could detect it. This unlikeliness can come in two forms: either it's unlikely to ever be created (hurray, we won!) or there's some future stage that's it's unlikely to pass (uh oh us).

To elaborate on the future stage, Carl Sagan suggested that technological civilizations tend to self-destruct (e.g. perhaps nuclear war.)

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