Saturn's largest moon may be the only place beyond Earth where humans could live • Hacker News Board

Re: Saturn's largest moon may be the only place beyond Earth where humans could live

#331

Post by magduf » Tue, Mar 10, 2020, 7:45 PM UTC

wmeredith wrote: post #242

rootbear wrote: post #230

Earlier quoted context omitted.

I, too, have concerns about how well humans will thrive in low gravity (the moon, Mars, etc). Over time, we could evolve a branch of humanity, "Homo ares", for Mars, but it won't be easy. Venus is just a tragic waste of a planet. So close to Earth in size, so wrong in every other way.

> Over time, we could evolve a branch of humanity, "Homo ares" These were called Belters (as in asteroid belt) in the excellent book series The Expanse, which is also an excellent sci-fi show available on Amazon.

Sorry to be pedantic, but no, those people were called "Martians". (His term, "homo ares", is referring to Ares, the god also known as Mars.)

The Belters lived in the Asteroid Belt, and were opposed to both the Terrans and the Martians. The Belters were the most different biologically because the gravity is so low, whereas the Martians got to enjoy the relatively high 1/3 g gravity of Mars.

Re: Saturn's largest moon may be the only place beyond Earth where humans could live

#332

Post by FiatLuxDave » Tue, Mar 10, 2020, 7:46 PM UTC

Ajedi32 wrote: post #251

Everyone in the comments here debating the merits of Mars vs the Moon vs Titan seems to have missed the whole point of this article. The author is arguing that anywhere other than Titan is infeasible due to recent research suggesting that Galactic Cosmic Rays cause significant brain damage (not just increased risk of cancer). In fact, the article argues that the danger is so severe that even getting to Titan quickly…

Here (below) is one of the referenced papers from that article, which basically asserts that the worst case long-term scenario (solar minimum) would give about the same amount of dose that the mice had in the study in about two years in space. Of course, a solar event would give a lot more dose quickly, but that is the kind of thing one can have a shelter for.

https://academic.oup.com/rpd/article/115/1-4/44/1600988

The interesting thing to me is that the dose to the mice in the study was so low, and still had measurable neurological effects. 30 cGy is not nothing, but in humans 30 cGy is about what a radiation worker might receive in 6 years at the legal limit, and is about 11 times lower than the lowest estimates for LD50/60 in humans (the amount of radiation which will kill 50% of the exposed population within 60 days). I don't normally work with mice, so I had to look up some info on them. Apparently the LD50/30 for mice varies a bit depending on strain, but it is in the range of 7 to 8 Gy. That is not that incredibly different from humans, because humans can have a similar LD50 if proper care is given.

Sources:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3743168/

https://dental.nyu.edu/content/dam/nyudental/documents/Irrad...

I don't know if the reason for the neurological effects at such low doses are because of the heavy ions used (which would be bad for space travel) or if it is because of the way it was measured in mice (not my field, I can't speak to that). But I note that airline pilots regularly receive career doses a bit lower to what the mice did (30 cGy ~= 300 mSv). And this dose is directly from cosmic rays, the same thing we are worrying about here.

Bringing us back to Sci Am: https://www.scientificamerican.com/article/air-travel-expose...

Re: Saturn's largest moon may be the only place beyond Earth where humans could live

#333

Post by magduf » Tue, Mar 10, 2020, 7:50 PM UTC

btkramer9 wrote: post #239

rootbear wrote: post #230

Earlier quoted context omitted.

I, too, have concerns about how well humans will thrive in low gravity (the moon, Mars, etc). Over time, we could evolve a branch of humanity, "Homo ares", for Mars, but it won't be easy. Venus is just a tragic waste of a planet. So close to Earth in size, so wrong in every other way.

I've always wondered if Venus was as habitable as Mars on the surface which we'd choose. The lower gravity well of Mars makes it much easier to come back from which is practically a requirement to go there. But like you said, the jury is still out on how well we can live in lower gravity. Getting back from Venus after just beginning to colonize it may not be possible with current technology.

Getting back from Venus is as easy as launching from Earth: i.e., completely doable with present-day technology. The only issue is getting it there to begin with, but that's not really hard, though we'd probably need to launch several rockets here on Earth, and assemble stuff in space, to get all the mass needed for a single launch on Venus. Landing stuff on this hypothetical Venus would be much easier than on Mars, since this Venus has an atmosphere, and Mars only has an "atmosphere" (one that's 1/200 the pressure of Earth's, not really much of one), so we'd be able to use aerobraking, parachutes, etc. In fact, landing stuff on today's Venus is pretty easy, and the Soviets were doing this ages ago; the only problem is that landers didn't last long because of the heat and corrosive atmosphere.

Re: Saturn's largest moon may be the only place beyond Earth where humans could live

#334

Post by magduf » Tue, Mar 10, 2020, 7:51 PM UTC

btkramer9 wrote: post #258

kjs3 wrote: post #252

Earlier quoted context omitted.

The only thing going for the moon is its proximity to Earth. Oh...that's all . So let's ignore for just a second the logistical advantages of figuring out how to actually mount a manned mission to build something non-trivial on another body when you're 3 days away, not 6 months away. Pretend that isn't important. The moon has water, raw materials, enough gravity things don't just float away, abundant solar and we've…

I've mostly addressed this in the siblings comments. Mars has all the same resources and more. The way humans went from the moon's orbit to surface is so far off from how it would be done today I would hardly call it and MVP. Both are too far for any meaningful emergency response. I believe the ongoing work with starship debunks your claim of an "un-funded wank-fantasy". The moon also has a disturbingly high failure…

You think 3 days is "too far for any meaningful emergency response"? I mean, yeah, if someone needs to be in an ICU within an hour, that's too long, but if they develop a new coronavirus on the Moon, 3 days to get people back to Earth is not bad.

By your logic, it seems like we should just give up on building any bases in this solar system altogether, and just start building a ship to go to Alpha Centauri.

Re: Saturn's largest moon may be the only place beyond Earth where humans could live

#335

Post by westmeal » Tue, Mar 10, 2020, 7:52 PM UTC

lukifer wrote: post #316

WalterBright wrote: post #277

Earlier quoted context omitted.

I expect colonizing the solar system will not be completely practical without genetic modification of the colonists to partially adapt to local environments.

One reason I'm bullish on humans being a stepping-stone to electronic/software life forms, is that we are ill-equipped in every way to meaningfully travel the universe: from short life spans, to radiation vulnerability, to the complexity of converting electrical energy into bio-available energy, to psychological effects of long journeys in cramped quarters. Software-life, on the other hand, can tailor its physical fo…

It's just difficult to implement something like this because we have no idea what consciousness actually is. I don't even know if we will ever find out.

Re: Saturn's largest moon may be the only place beyond Earth where humans could live

#336

Post by philwelch » Tue, Mar 10, 2020, 8:02 PM UTC

athenot wrote: post #206

philwelch wrote: post #182

Earlier quoted context omitted.

0 degrees is "really fucking cold outside" and 100 degrees is "really fucking hot outside". Celsius resorts to negative numbers even for a normal snowy day while wasting about half of the positive two-digit numbers for temperatures that have never been recorded on Earth. It's a terrible scale for weather.

Having negative numbers for when water is in a different state is quite a convenient representation, especially for weather. To follow your scale, -50ºC is really cold (polar weather) and +50 is really hot (desert weather). Yes there are places hotter and colder but it's a continuum with convenient points that stick out less than a phase change of the liquid which is so integral to life, be it human, fauna or flora.

Even -40°C is very far outside the range of where virtually anybody lives, though. It's equivalent to -40°F. Most places never reach that temperature. The problem with a 100-degree scale centered around the freezing point of water is that the freezing point of water actually is approximately 1/3 of the way along the scale between "exceptionally cold" and "exceptionally hot"--it isn't a midpoint--and so by the time you reach -50°C you're solidly in the realm of "potentially record-setting low temperature for most places on Earth". The more analogous range is -20°C to 40°C, and that's with 2-3 degrees of rounding on both sides.

The freezing point of water is an important temperature, but it's not a temperature that should be treated as being "off the scale" or even at the edge of the scale, which is what the number 0 implies. Being able to represent most survivable air temperatures with unsigned 2-digit numbers is more convenient than not having to remember the freezing point of water, as is the heuristic of any exception to that rule representing an exceptional weather condition.

Re: Saturn's largest moon may be the only place beyond Earth where humans could live

#337

Post by palisade » Tue, Mar 10, 2020, 8:08 PM UTC

AnimalMuppet wrote: post #317

palisade wrote: post #296

Earlier quoted context omitted.

A floating habitat on Venus is actually more attractive. Venus (upper atmosphere): -human livable temperatures with modest temperature control -Earth-like pressure (Himalayans) leads to slow leaks that can be patched, and pressure can be increased inside to stop the leaks inward -protected by thick atmosphere from radiation, meteors, asteroids -strong magnetic field against radiation -atmosphere still thin enough for…

> the escape velocity from Mars requires a massive rocket equivalent to the one we use to leave Earth and therefore more fuel leaving less payload for delivering other resources or supplies Wait, what? Isn't escape velocity from Mars lower than that from Venus? The surface gravity is far lower on Mars. I also note that you list "no surrounding breathable atmosphere" as a negative for a rotating space station, but the…

https://space.stackexchange.com/questions/13865/how-to-produ...

Re: Saturn's largest moon may be the only place beyond Earth where humans could live

#338

Post by X6S1x6Okd1st » Tue, Mar 10, 2020, 8:15 PM UTC

westmeal wrote: post #335

lukifer wrote: post #316

Earlier quoted context omitted.

One reason I'm bullish on humans being a stepping-stone to electronic/software life forms, is that we are ill-equipped in every way to meaningfully travel the universe: from short life spans, to radiation vulnerability, to the complexity of converting electrical energy into bio-available energy, to psychological effects of long journeys in cramped quarters. Software-life, on the other hand, can tailor its physical fo…

It's just difficult to implement something like this because we have no idea what consciousness actually is. I don't even know if we will ever find out.

The question is is it harder to make true AI or the human mind on a chip than it is to colonize the solar system?

Furthermore past that if we ever get to move beyond our solar system and FTL is impossible then amount of Gs you can take and total mass will be extremely important to who gets out and when.

If silicon life exists by the time we are sending extrasolar missions it will likely be able to travel much more quickly and cheaply than current day humans.

Humans as we know then today won't be living outside of a few select and hard to find environments. Ships that carry current day humans will need to be huge and have shielding, meaning Delta V will be a problem.

Re: Saturn's largest moon may be the only place beyond Earth where humans could live

#339

Post by X6S1x6Okd1st » Tue, Mar 10, 2020, 8:17 PM UTC

dumbfoundded wrote: post #259

Ajedi32 wrote: post #251

Everyone in the comments here debating the merits of Mars vs the Moon vs Titan seems to have missed the whole point of this article. The author is arguing that anywhere other than Titan is infeasible due to recent research suggesting that Galactic Cosmic Rays cause significant brain damage (not just increased risk of cancer). In fact, the article argues that the danger is so severe that even getting to Titan quickly…

There's danger everywhere outside of Earth. All of the problems seem fixable except for gravity. We don't know if humans can even be born and raised in low gravity environments. Venus would seem to be the right choice for a long time scale. Maybe we could use the practice too at learning how to reverse a runaway greenhouse effect.

An intervention free birth would be extremely hard, but C-sections have a very high success rate. If we have a large enough base we could easily make areas that have constant acceleration

Re: Saturn's largest moon may be the only place beyond Earth where humans could live

#340

Post by rootbear » Tue, Mar 10, 2020, 8:21 PM UTC

JdeBP wrote: post #274

ghaff wrote: post #253

Earlier quoted context omitted.

The Expanse is quite good. But the earth/Mars/Belt differences are mostly cultural at least in the TV series. The "Belters" meme in SF has been around for a long time though. See Larry Niven for example. (And I'm sure it's older than that.)

Jeff Prucher's Brave new words gives its earliest attestation for the word as Niven's Warriors in 1966.

Oh, that looks like an interesting book! I read a lot of Niven back in college and I wondered if he invented the word "Belter", for Asteroid Belt dwellers.