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

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

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245 pointsmastry386 comments

Two thoughts on this topic:

1. The film Gattaca (1997), in addition to being an excellent, inspiring film all around, centers on an aspiring astronaut's upcoming trip to Titan. Highly recommended.

- https://www.youtube.com/watch?v=lZa83dTf4JA

2. The colonization of Venus is also a fascinating idea that isn't talked about much in comparison to the Moon or Mars. Essentially, the surface is too hot for colonization, but it may be possible to build floating cities ±31 miles above the surface.

- Venus's atmosphere is made mostly out of carbon dioxide. Because nitrogen and oxygen are lighter than carbon-dioxide, breathable-air-filled balloons will float at a height of about 50 km (31 mi). At this height, the temperature is a manageable 75 °C (348 K; 167 °F); or 27 °C (300 K; 81 °F) if we could get 5 km (3.1 mi) higher

- The atmosphere also provides the various elements required for human life and agriculture: carbon, hydrogen, oxygen, nitrogen, and sulfur.

- Additionally, the upper atmosphere could provide protection from harmful solar radiation comparable to the protection provided by Earth's atmosphere. The Atmosphere of Mars, as well as the Moon provide little such protection.

https://en.wikipedia.org/wiki/Colonization_of_Venus

Unless you're planning to build a literal castle in the sky out of convenient gasses, this is completely unworkable.

Even at that altitude the cloud layer is still very turbulent and very toxic, and no structure will be absolutely gas-tight. And if the temperature is 75 °C outside, it's going to take insane amounts of energy to keep the inside of your hab cool - especially if it's made of metal and not rock. (A thin skin obviously isn't going to work.)

You can't mine Venus, and you can't explore the surface. All you can do is drift over the cloud layer.

So there's no point - except maybe niche tourism, niche planetary science, and possibly niche super-weapons research.

And after all that, you still have the problem of moving mass to/from your colony. 30-odd miles gives you a bit of an energy boost, but getting out the gravity well still isn't cheap or easy.

There are perhaps ways to mine Venus surface materials; something like dredging. Dedicated development of high-temp computing may also make longer-term robotic operations possible. None of that's particularly convenient, of course, and I can't imagine why you'd want to do it. But one can say that about every other extra-terrestrial option, too.

You would need a 50km long dredge. That seems completely unworkable; that's much longer than the deepest of deep mining operations we have here on Earth, and we aren't nearly as constrained on Earth as you would be on Venus. How would you even get such a thing to Venus? The only realistic way to do so would be to construct it of local materials, but now we have a chicken-and-egg problem.

Plus, keep in mind that a lot of the materials you would use for such a dredge on Earth won't work on Venus, because the atmosphere will corrode them.

It is probably a typo, but Mars doesn't have enough atmosphere to corrode things more than on Earth.

If you need 50km long dredge, then it is a viable project in future, just like now it is with space elevator. Apparently that type of dredge will be needed to extract materials from gas planets(and 50km might not be enough), so that dredge will have to be developed anyway.

The most logical solution to make habitable world would be to bombard Venus with comets and small planets. They all have enough materials to stabilize Venus atmosphere and teraform it and also calculated bombarding can cause Venus to change axis and rotation.

This is very far-future stuff though. In contrast, we can colonize Mars and Titan with today's level of technology (Mars more easily more likely, because it's closer).

I don't know... you'd need to maintain an over pressure in the living quarters and tiny leaks won't be much of an issue. Lift can be provided by hydrogen blimps, until you get to a balmy 20 C (70 F).

That would help both bleeding off heat and helping with maintaining over-pressure in the living quarters.

Corrosion resistance will be a challenge but not impossible, there are many plastics which will withstand sulfuric acid.

"Come TheOtherHobbes, you belong here with us, among the clouds..."

- Lando Venrissian

"Strap in folks, we're going through some turbulence... For the rest of your lives."

Like a life-long Maxell commercial but with acid rain.

Gattaca was ok, but the fact they were going to Titan was at best incidental to the plot. Could have been Mars, or Pluto, or Alpha Centauri, and it wouldn't have changed a single visual and only a handful dialog.

> The colonization of Venus is also a fascinating idea that isn't talked about much in comparison to the Moon or Mars. Essentially, the surface is too hot for colonization...

Nah, you're just not thinking big enough:

https://www.orionsarm.com/fm_store/TerraformingVenusQuickly....

That's an interesting article. I wonder how practical would it be to harvest hydrogen (protons, really) from solar wind using magnetic lensing. Tha same tech could be useful for Mars.

Depending on the shape of the parasol, the same support structures could be used for the lenses, focusing a stream of hydrogen nuclei on a small area of the planet. This focused plasma stream could also compensate some of the forces on the parasol (it'd need to be closer to the Sun than the Sun/Venus L1 point and balanced by light pressure) allowing the parasol to be smaller.

The thing is, if we were to develop the tech needed to cool Venus, it would be orders of magnitude cheaper to just use it here on earth to offset CO2/CO emissions and reverse the greenhouse effect.

That does nothing in terms of increasing Earth's surface area. Either we cap the population or we expand to other habitats.

There are vast expanses of desert in Sahara that no one lives in. That land is much easier to settle than another planet, yet we don't do that.

Or we mature enough to stop expanding exponentially

Venus has the very big advantage of having allmost earths g. That is a big deal.

The very big disadvantage except the atmosphere is the lenght of a venus day: 116 earth days and 18 hours.

So a science fiction solution is asteroid bombardment to make venus spin faster ..

My big idea for Venus, assuming infinite power, would be to shoot a series of big asteroids past it and use the gravity/inertia drag to make it spin faster.

Then, when Venus is spinning fast enough, collide the asteroids together to give Venus a moon and tides.

While all that is going on, use some sort of huge electromagnet to spin Venus' internal heavy core to provide a strong magnetic field to deflect nasty stuff from the Sun and elsewhere.

Also build a shield to stop all sunlight reaching Venus, thus freezing the atmosphere onto the surface. That makes reprocessing the crust into something Earth-like much easier.

Comets could then be used to provide oceans.

Shouldn't take more than a few tens of thousands of years! Seems like something a few humans, downloaded into robots, could do.

Mars would remain a scientific research station like Antarctica, assuming that life is found there. I'd treat Europa and anywhere else with life the same way.

I assume, once you have allmost self replicating robots, who can do mining asteroids and building factories to build more of them and mine more and build more .. you would not need ten of thousands of years. Maybe even only some decades.

Maybe this is what Factorio has been preparing me for all this time! https://en.m.wikipedia.org/wiki/Factorio

Just make sure that you have not invented Alastair Reynolds' "greenflies".

I figured tens of thousands of years mostly for the crust reprocessing on Venus itself, for the asteroids to coalesce into a big hot blob, and for the moon blob to cool down.

SimEarth mod downloading

Day length seems less of a concern than the temperature and resources issues (since you can use artificial lighting), plus you can float around in the balloon to choose to be in a light, dark, dusk or dawn place, and even enjoy an eternal sunset. This almost sounds like it would fit Le Petit Prince

The floating cities are surely a way to circumvent the daylength issue. But the daylength is directly linked to the temperature - even if you could normalize the atmosphere, the day side would still get just too hot and the nightside too cold.

I personally would bombard with comets. Bring down the temperature and deposit water on the planet.

Are there so many ice comets avaiable?

Also, would the temperature really go down and not be negated by the kinetic impact?

Apart from that, more water probably helps, if we do not need that water more urgently on mars.

There are billions of comets available https://en.wikipedia.org/wiki/Kuiper_belt

Then there is also https://en.wikipedia.org/wiki/Oort_cloud

Don't worry - there is more than enough comets to bomb the Mars with all the future settlements. Muhaha

Isn't the common scifi solution to drop some engineered bacteria into the atmosphere to convert the CO2 and generate a think ozone layer?

> 1. The film Gattaca (1999), in addition to being an excellent, inspiring film all around, centers on an aspiring astronaut's upcoming trip to Titan. Highly recommended.

Gattaca is one of my favorite films. I agree that it is excellent, but I'm not sure it is inspiring. Gattaca is about how the system, society, circumstances and expectations beyond your control are an albatross around everyone's neck and ultimately harm and defeat the individual. In Gattaca, both Vincent and Jerome are tragic figures as they are both victims of expectations. Jerome is burdened by high expectations and Vincent by low expectations and those societal expectations are a hurdle to the lives they want to lead. Ultimately those societal expectations crushes Jerome and turns him into a cynical cripple. Vincent's societal expectations places a chip on his shoulder which costs him his family and his identity. And in the end, neither Jerome nor Vincent achieve their dreams as Jerome burns himself to death and Vincent dies on his way to Titan due to his "degenerate" heart. In a way, Gattaca is about two people on their own suicide mission as they rage against society/expectations. If you watch the movie from the beginning, you'll realize that both fully know that they are going to die/kill themselves doing what they are doing. It's a tragedy.

> Vincent dies on his way to Titan due to his "degenerate" heart.

Vincent definitely doesn't die on his way to Titan. I'm not sure where you got that from. Jerome also self-immolates because he realizes that his purpose is now completed, not because he is cynical and depressed. His silver Olympic medal also turns gold in the fire, which is supposed to suggest that he has achieved his true purpose in life.

In any case, I see the film as inspiring because the two characters still find purpose and meaning in their nightmarish world: Vincent through achieving his goal of becoming an astronaut and Jerome through providing his identity and biological material for a greater purpose.

"I got the better end of the deal. I only lent you my body - you lent me your dream."

> Vincent definitely doesn't die on his way to Titan. I'm not sure where you got that from.

It's alluded to a few times in the movie. Vincent never saves anything for the swim back. Vincent specifically mentions that he is living on borrowed time as he has surpassed the "number of beats expected of his heart". And there is the treadmill scene where he was barely able to hang on. Remember that the training was to select people who can physically survive the journey and thrive on titan. Not to mention Vincent doesn't bring any of Jerome's urine,blood,etc with him to Titan. Do you really believe they don't check your identification on titan? Also, the lock of hair that Jerome gave to Vincent is an acknowledgment of Vincent that Jerome isn't going to make it and of course that Vincent isn't going to make it either. Finally, the last words of Vincent: "For someone who was never meant for this world, I must confess, I'm suddenly having a hard time leaving it. Of course, they say every atom in our bodies was once a part of a star. Maybe I'm not leaving; maybe I'm going home."

> Jerome also self-immolates because he realizes that his purpose is now completed, not because he is cynical and depressed.

That's a very upbeat view. But people don't normally celebrate fulfilling their purpose by burning themselves to death. Some believe that Vincent's death symbolizes going to heaven since he overachieved and Jerome's death is hell ( burning ) because he underachieved.

> Vincent through achieving his goal of becoming an astronaut and Jerome through providing his identity and biological material for a greater purpose.

But there's the rub, Vincent didn't become an astronaut, "Jerome" did. Even when Vincent succeeded, he didn't.

> "I got the better end of the deal. I only lent you my body - you lent me your dream."

Yes. And neither achieved their dream and both died at the end. And Jerome also left enough blood,urine,etc for two lifetimes... Think about what that really means.

I used to view Gattaca as you did. It was inspirational like Rudy. But then I watched it more and started noticing more aspects of the movie and it is far deeper and far more tragic than a generic inspirational movie. It's a tragedy.

I interpreted all of the things you listed as indications that statistics and scientific analysis have limitations and can't predict success or failure, not as indications that he would fail and die in the end. This is perhaps the main theme of the film: "There is no gene for the human spirit."

You seem to have a thesis that the film is a tragedy and are working backwards from there. This goes against essentially everything in the film: its uplifting soundtrack, its message of overcoming the obstacles that society places in our way, and its argument that sometimes our true purpose is not to excel individually, but as a help and teammate to others.

> But there's the rub, Vincent didn't become an astronaut, "Jerome" did. Even when Vincent succeeded, he didn't.

Jerome is just his name and saying he didn't succeed because his achievements weren't listed under his own name seems a bit shallow, as if the only definition of success is fame. And again, a major theme of the story is that the two men are more capable of achieving great things together than apart. Remember that neither Vincent nor Eugene (Jerome) were in a good place prior to meeting each other. Jerome, the astronaut, is the successful identity created from the merging of both men, not simply one man using another's name.

> I interpreted all of the things you listed as indications that statistics and scientific analysis have limitations and can't predict success or failure, not as indications that he would fail and die in the end.

I did so for the "heart beats". But every other point has nothing to do with statistics or scientific analysis. I really can't say definitively that he died on his way to titan, but the evidence is fairly overwhelming. It wouldn't have been hinted at so much in the movie and the movie would not have ended with that quote otherwise.

> And again, a major theme of the story is that the two men are more capable of achieving great things together than apart.

That's a bit of a reach but you are entitled to the view.

> You seem to have a thesis that the film is a tragedy and are working backwards from there.

No. I watched Gattaca as a kid and loved it and saw it as an inspirational movie. Everything you believed, I believed. Then I got older and watched the movie a few more times. My thesis changed from inspirational to tragedy. As I said, my view of the movie changed. And I love the movie more now because it is richer, deeper and more consequential than a good simplistic feel good inspirational movie.

> And remember that neither Vincent nor Eugene (Jerome) were in a good place prior to meeting each other.

They weren't in a good place at the end either.

Anyways, you are entitled to your view. I used to view it like you and I suspect it's most people's first impressions when they first watch the movie. But after repeated viewing, it's hard to watch someone burning himself to death and a man's looking into space and "going home" as inspirational. There are inspirational aspects to the film, but I don't think that's what the movie is really about. We'll just have to agree to disagree.

You have to work pretty hard to take the perspective that Vincent dies.

Vincent nearly fails the treadmill scene because he is on the edge of panicking under the stress of being revealed to be prime suspect in a murder case that might put him in jail wrongly and will blow his life's dream of getting to Titan.

It doesn't matter if they check his ID at Titan, whatever that means. He commented he is outside the police's jurisdiction on the way to Titan, he will have achieved his goal regardless of his publicly known validity after docking at Titan.

The line about going home is to illustrate that he is in fact, going home. He was always meant to be among the stars and found regular everyday life difficult. Through his teen years he studied astrophysics, he was an outcast. His home was, is and finally arrived among the stars. Vincent achieved exactly what he set out to do and so did Jerome. Jerome was upset that he was not the best swimmer, as he was designed to be and deliberately chose to walk into traffic. Jerome unable (or had no desire) to escape his own self-resentment, burns in it. Both Anton and Jerome suffer for defining themselves by their biology and the accompanied social expectations.

Jerome passes Vincent his hair as the last expression of his time on Earth. Jerome will no longer grow any hair, a natural measure of time. He has ceased to exist in a physical sense. His mission is complete in giving enough of his valid biological matter for his life and Vincent's life across time.

It is questionable what Vincent's goal in space is to do from a relational perspective.. He saved Anton from drowning twice and as lifted into space on the back of his own effort and everybody that let him pass through the system illegally. His father let him past the final checkpoint, Jerome gave his body, Anton gave him a gap in police authority, Irene did not expose his invalidity and the mission director pushed for the launch timing slot in the face of authoritative danger. What does Vincent give back for all this. A change in spirit from biological determinism to willpower over statistical fact. Not much in comparison to his launch.

Musing aside, Vincent lives.

> Vincent nearly fails the treadmill scene because he is on the edge of panicking under the stress of being revealed to be prime suspect in a murder case that might put him in jail wrongly and will blow his life's dream of getting to Titan.

The impression that it was 'the stress of being found out' is a novel interpretation to me. I always thought it was about the fact that he has a 'garbage' heart and he's basically actually going at 200% while it appears on the outside as if he's only doing 60 bpm.

Right at the end of his run his real BPM comes out because the recording from Jerome (Jude Law) reached its end and that's when he stops the exercise.

I didn't see it either that Vincent dies, but thank you, your perspective of it is really opening & interesting!

Will re-watch differently the movie now! :)

since the film ends with him leaving we don't know if he dies or not, but outlook does not exactly look promising. Then again nothing of Vincent's life has ever looked promising.

We cannot be sure, sure, but absolutely everything in the movie indicates that Vincent survives. The whole story arc for him is that he overcomes everything, even rescuing his genetically superior brother from drowning on the way, and prevails.

Edit, to add: the name Vincent is derived from the Greek/Latin word for conquering/winning... so there’s that too.

- Vincent Freeman = Victorious Free Man

- Jerome Morrow = Sacred Name of Tomorrow/The Future

> Jerome is a masculine name of Greek origin, derived from the Greek given name Ἱερώνυμος, Hierōnymos, "sacred name"; from ἱερός, hierós, "sacred", and ὄνυμα, ónyma, an alternative form of ὄνομα, ónoma, "name".

The names chosen were actually pretty genius, especially considering that Jerome's name/identity is the one used "to build the future", and in the last conversation Vincent has (with the doctor), is referred to as Vincent, his real name.

Very interesting take! I haven't rewatched it, and now I have a reason. I thought the ending was open ended for the reasons discussed further on. Vincent gets to the rocket which was the goal. I also wondered about the cache of materials Jerome leaves behind, was it that he thought Vincent might stay?

... maybe for when he comes back from Titan. Given Titan is a more spartan outpost, and everyone there is presumably accounted for anyway, given you can't exactly stroll over to Titan without going on a rocketship first - maybe for when Vincent comes back from his Titan mission, for retirement or whatever.

I like the terraforming idea better, and we could get it started with todays technology, it would just be really expensive - simply build a bunch of solar shade cells and assemble them in L1 orbit between Venus and the Sun, and keep expanding the network until you cover Venus in night. Then let the planet cool for a couple hundred years - a lot of that thick sulphuric atmosphere might solidify and fall to the ground and get the atmosphere down to workable levels.

> . At this height, the temperature is a manageable 75 °C (348 K; 167 °F); or 27 °C (300 K; 81 °F) if we could get 5 km (3.1 mi) higher

I wonder -- what is the hottest air temperature humans could endure long term outdoors. Assuming you could adjust to the discomfort of warm air temps, how hot would it have to be before it's hazardous?

Our body's principle means of cooling is via sweat. When sweating stops being effective, it's basically impossible to cool down, and you're going to die of heat stroke if you don't go somewhere colder and/or less humid. Sweating breaks down at a wet-bulb temperature of ~100°F, and hitting even dry-bulb temperatures in the 150°F range is going to start to be lethal.

It depends on the humidity. The maximum wet bulb temperature that healthy humans can endure long term is about 35 °C.

https://en.wikipedia.org/wiki/Wet-bulb_temperature#Wet-bulb_...

> floating cities

We have decided on Mars, can we stop forking it. Have we learning nothing from Linux?

But if you have to, could you hurry up and make a floating city on earth to practice?

People would pay a tonne of money for that, and having floating cities (In reality small communal groups, so more a village) would be very very neat.

> make a floating city on earth to practice?

Earth's atmosphere is lighter than the Venusian one at that altitude. A balloon filled with breathable air would float naturally. You can't do that on Earth.

According to https://en.wikipedia.org/wiki/Cloud_Nine_%28tensegrity_spher... you can.

It is possible. Just don't expect living space to be bigger than a hot air balloon basket for the size of a reasonable hot air balloon.

You can make pressure inside just a little bit decreased and make this thing fly 1 mile high, for practice. Call it “Denver” or something.

Float it on the ocean?

Simulating a land-based, completely sealed off mars- or moon-base in Antarctica is one thing. Simulating the conditions of a base floating in an atmosphere of CO2 is quite another.

Wouldn't it come down to basically just a boat / submarine?

That floats in a fluid at 75C. That’s a sub with a major AC challenge.

I'm imagining a way to use solar power to grow hydrogen filled mylar cells at scale in a lake or ocean. You could organically grow an enormous platform as a skyport, e.g., elevator up the cable a couple km, then take off from there. Hell, maybe you need these skyports to support the business end of a massdriver.

https://en.m.wikipedia.org/wiki/Mass_driver

Images (and calculations) in the deck: https://docs.google.com/presentation/d/1r6CPFJ1AX1ZULacguTf6...

"We have decided on Mars, can we stop forking it. "

Who is "we"?

I for example, have decided, that we colonize the moon first and then go on from there. But since I sadly do not operate a big space agency/company, my decision is not so relevant (yet).

But apart from that, yeah sure, lets build floating cities and (at least partly) self sufficient habitats on earth first, before we try it do it so far away we need at least 6 months to get there.

> I for example, have decided, that we colonize the moon first and then go on from there.

Why do people work so hard to get out of a gravity well, only to sink down into another one? The moon isn't bad, but the asteroids are where all the action will be. All the materials a civilization could want, relatively easy to access and move around.

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 enough to mitigate the risk of brain damage during the trip will be a major challenge.

If true, this complicates things significantly. Does anyone know if the dangers of Galactic Cosmic Rays are really as significant as the author is claiming? The author references the 2016 paper "Cosmic radiation exposure and persistent cognitive dysfunction"[1] which was a study conducted on mice. Has there been any further research into the possible effects of cosmic radiation exposure on humans?

[1]: https://www.nature.com/articles/srep34774

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...

I'd like to add some nuance to this discussion. It is important to note that accumulative dosages is very different from short duration dosages as well as that 300mSv whole body dosage for a human is drastically different than 300mSv whole body dosage for a mouse.

Also, according to the paper 50mSv showed no affect to cognitive performance. The paper notes that Brookhaven National Laboratory can supply dose rates between 5 and 25 cGy/min, so these dosages were given over very short timeframes. This matters.

So we have somewhere between 5mSv (over ~1 minute) having no effect and 30mSv (over 1-2mins) having a statistically significant decline in cognitive performance (they did measure activated microglia in 5mSv but note that Oxygen had a different effect than Titanium). So we can clearly see that mice, in the worst case, are recovering after 24 weeks. This means the body can repair itself. This is why it is important to talk about the timeframe that a dosage was received.

So as to the 20mSv that most European countries use as total yearly dosages 1) this is well below a statistically significant measure in cognitive decline 2) this dosage is over a year and not over a minute (also likely weighted to extremities, like hands, as opposed to total body). So comparing this to radiation worker dosages is not a great comparison.

As to space flight, there are actually a lot of new rad (pun intended) technologies being developed (I worked on some of these). The primary concern in solar radiation is from charged particles (mostly protons, then alpha). These are relatively easy to block (in comparison). A lot of concern now is currently with neutrons and high energy particles. Current technologies are frequently a big chunk of titanium, kevlar, and spectra/dyneema (UHMWPE). Plastics are rather good as neutron shields because of their hydrogen density. Many of these are now being doped (boron is a common one, anyone pushing gadolinium hasn't run simulations for the energy levels we are concerned about. Or plastics doped with metals, like titanium, to increase their effectiveness against charged particles). This is a big optimization problem where layer size and order are important variables. Dopants can become charged and reradiate, but this can also be beneficial. Incoming radiation energy also DRASTICALLY changes the equation, as higher energy particles "ignore" a lot of material (see snide comment about gadolinium and thermal neutrons). It is a complicated and challenging problem for anyone interested, but importantly, we are making major improvements.

P.S. if we were REALLY concerned, you can just surround your spaceship with a large body of water. Problem is that this is heavy and extremely expensive to transport in space. The problem isn't really about can we block radiation? but can we __cost/mass effectively__ block radiation?

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 form(s) to particular environments, consume solar/nuclear energy directly, and even shut off its consciousness during long journeys.

Don't get me wrong, I'm all in favor of solar system colonization, interstellar generational ships, etc; and manual genetic manipulation (or repair) may be a necessary tool to accomplish that. But in terms of life forms being well-adapted to their ecological niche, humans becoming a space-faring species is a billion times more difficult than a mudskipper learning to breathe air.

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.

More disturbing: if/when we reach the day when an AI told us, "I'm conscious, I have feelings, the lights are on, it is like something to be me": how would we know if that were actually the case?

There are people continually grinding on the Hard Problem, and seeking ways to measure whatever consciousness is; perhaps someday we'll have an empirical test.

If that day never arrives, it opens an interesting philosophical question: how important is it that the species that inherits the galaxy has the lights turned on? Is intelligence/complexity which lacks subjective experience still an inherent good? Who knows, maybe we could wind up with a benevolent AI network (akin to Iain Banks' Culture) who seeds and maintains biological life in their optimal planetary habitats, because for whatever reason, real consciousness only arises in nucleotide wetware.

Or: maybe that already happened, and our galactic AI is really really good at staying hidden. ;)

> More disturbing: if/when we reach the day when an AI told us, "I'm conscious, I have feelings, the lights are on, it is like something to be me": how would we know if that were actually the case?

Right, it could just be lying to us to gain sympathy while it makes lots of paper clips. Ex Machina was interesting in that the robot seemed to be very human, but was also manipulating the subject of the test. But yet again, it did seem like she was conscious.

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.

That all makes sense, but if that's the way the universe is, then where are all the alien computer virus radio signals? I think I read an SF story about that years ago, where a transmission was received that gradually convinced people to build stuff, but it hasn't actually happened, right?

A few possibilities:

- We might actually be the first. Improbable, but the data so far doesn't rule this out. Somebody has to win every lottery.

- The Great Filter might be astronomically difficult to overcome; this is a different sort of improbability, but just because the odds are profoundly stacked against us is no reason to give up.

- A different Great Filter: The dominant AI might be a malevolent apex predator, who consumes any species that begins to spread.

- My favorite answer: electronic "Space Ents", who being quasi-immortal, and live at such vast time scales (say "hello" and patiently wait 10,000 years for a reply), they don't bother attempting communication with such momentary life forms as ourselves. (Both this scenario and the predator one would imply they're good at hiding their energy sources and signals, which they might have good reason to do.)

- Our universe really is a simulation (or some other software substrate). If so, it's possible that whoever is hosting the physics engine is primarily concerned with Earth, and everything else is modeled just well enough enough to give us starlight/etc, not enough to simulate RNA strings and lipid bilayers on simulated alien planets. Obviously this might throw a wrench into plans to colonize the galaxy. :)

If we are the only sentient creatures in the galaxy, we have an obligation to spread out among the stars.

Would living underground on Mars mitigate this?

Yes, assuming you can get to Mars fast enough to mitigate the risk during transit.

The article author argues that underground living spaces are difficult to build and that Titan is therefore a better option, though personally I find that a rather unconvincing argument. Compared to the difficulty of getting to Mars, building underground habitats seems pretty straightforward in my uninformed opinion.

Haven't humans spent more than year in space? How is it not a problem from the ISS? Is that still protected by Earth's magnetic shield -- or whatever it is that protects us from Cosmic Radiation?

Astronauts are still within the Van Allen belts so largely protected unless a solar flare deforms the field enough to weaken their protection.

https://en.m.wikipedia.org/wiki/Van_Allen_radiation_belt

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

https://www.inverse.com/article/36777-mars-moon-human-colony...

The dangers of radiation on Mars are greatly exaggerated. The dangers of low gravity on Titan and elsewhere are greatly understated, as is the immense distance between Mars and Titan.

A floating habitat on Venus is harder and less attractive in every way than a rotating space station, which is clearly our next milestone in space. In terms of planets though, there's a reason Mars gets the most attention: it's obviously the best choice.

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.

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.

I would have guessed Heinlein but I don't see evidence he used that particular term although he had similar tropes in his books--e.g. Loonies in The Moon is a Harsh Mistress.

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.

In the books it's MUCH more than cultural, to the point that belters are unable to visit Earth without some difficulty due to too much gravity. Belters are described as much taller and more slender that people born and raised on Earth.

Beltalowdah physiological difficulty in adapting to gravity is a recurring plot point on the show. The culture difference exists in part because no Belter can survive long periods on Earth.

The novels portray each group has having more significant physiological differences. Naomi is supposed to be quite a bit taller than Holden, for example.

Makes sense. Easier to do in books than on the screen, especially a TV show. It's logistically just a lot easier to have everyone look like ordinary humans modulo superficial styling (and acting) differences.

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.

Or evolve a branch of humanity that uses non-biological, radiation-hardened, easily-maintained, low-mass machines, instead of meat that doesn't grow correctly in low acceleration, uses chemical energy storage with no power generation capacity, and which gets scrambled without megagrams of shielding.

That is, develop general AI with a sense of responsibility and filial duty to its parent species, and which won't turn us all into paper clips.

This has been done in various hard science fiction novels. One series, the name escapes me at the moment, actually has one group of engineered human warriors that are quite different mentally from normal humans but they can survive in vacuum and have some insect-like traits physically. They can just drift through vacuum and quietly attach to the hull of an enemy ship.

Then you have the Old Man's War universe where the soldiers have engineered bodies and synthetic blood that they have control over (they can explode mosquito like creatures that try to feed on them as an example).

B. V. Larson's Star Force series sees characters changed by both nano bots and specifically-grown intelligent (as a colony) vats of bacteria.

Many science fiction series involve brain backus. If I'm not mistaken Peter F. Hamilton has them in his Commonwealth Saga and the Altered Carbon books and show have it. As does the previously mentioned Old Man's War series by Scalzi.

Daniel Suarez's book (his near-future hard science fiction books are quite good) Change Agent involves lots of serious genetic engineering, including changing one's entire appearance (rather dangerously) with a virus.

I think if we can manage to stay alive long enough as a species, we will be able to at least do everything except for the nano bots and possible even those if we get some significant physics and computational breakthroughs.

As a pre-teen in the mid 1990's a friend and I wanted to turn ourselves into anthropormphic creatures not unlike the creatures in the Island of Dr. Moreau (I believe it was actually the 1996 film adaptation that gave us the idea) and figured somehow a bacteriophage could be created to alter a host at a cellular level but we figured you'd need to find a way to selectively edit genes (that now exists with CRISPR and the like), suppress the immune system to prevent death from it overreacting during the process, and control the replication rate so the body wouldn't burn up with fever or have some sort of energy issue. If a couple of bored pre-teens could think that up while playing a MUD one afternoon, someone someday is going to start really tinkering with humans at a serious scale. It's already being done by biohackers.

> This has been done in various hard science fiction novels. One series, the name escapes me at the moment, actually has one group of engineered human warriors that are quite different mentally from normal humans but they can survive in vacuum and have some insect-like traits physically. They can just drift through vacuum and quietly attach to the hull of an enemy ship.

Pretty sure this was in some book in the Old Man's War series

Venus has 80% of Earth mass. Mars has 10% of Earth Mass. The simple math suggests, that these planets are destined to be combined in some distant future, but not by current civilization, so there is no real reasons to be concerned about anything at all.

Any of those projects of colonization in space is even greater waste of resources, compared to colonies in northern Canada, Antarctica, artificial islands or underwater cities.

I think you underestimate how radically different a world we'd live in if we had and inter solar system logistics network between colonies, earth and asteroids. It would be like another industrial revolution with untold and unimaginable changes. Likely with artificial islands, underwater cities, climate change reversal existing as mere side effects.

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.

I would choose Venus. The depth of the gravity well is less important when the colonists are being lowered into it from above rather than thrown out from the bottom. If you need something in orbit, you don't drop it down to the planet in the first place.

But as things are, the relative effort to terraform Venus, compared with Mars, is absolutely colossal. It essentially requires a full-blown robotic asteroid mining industry, wherein olivine asteroids are diverted directly to Venus, and magnesium and calcium are mined, sent to Jupiter to produce saturated hydrides, and those sent on to Venus. It will take 1000 years, minimum.

Mars can get realistic results within 200 years, just by diverting water-ice comets and managing temperature.

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.

Maybe we should work on terraforming it: use various processes to change the atmosphere and stop the runaway greenhouse affect, shed the excess heat into space, and build an earth-normal atmosphere.

However, it does seem like building rotating space stations (like O'Neil cylinders) is much more feasible.

Moon humans would be so weak I bet it would be easy to beat them up and steal all their moon cheese.

Unless you think that the Moon is the obvious next milestone in space.

The only thing going for the moon is its proximity to Earth. Mars has more than double the gravity of the moon, an atmosphere, nearly earth-like day night cycle and satellites have a much easier time orbiting mars

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 already figured out how to get people there and back. We already have an MVP to build on.

On the other hand, a manned Mars mission is still an un-funded wank-fantasy with a disturbingly high failure rate for the unmanned attempts.

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 rate for the unmanned attempts.

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.

The moon is just as much of an un-funded wank fantasy as mars... grow up dude

Proximity matters a lot until you have sure-fire technology.

If you have a critical failure on the moon, you are home in 3-4 days being debriefed. If you have a critical failure on Mars, it could be 2 years until your remains can be recovered and respectfully laid to rest.

If you're testing a new technology and discover some serious flaw or major way to improve it and lack the materials to make an adjustment you could have that done and sent on the next trip in a week or a month or 3 months from Earth to the Moon. On Mars, you could be looking at 2+ years.

On the moon you have to deal with power over a 13.65 day night, at first this could be achieved by simply having human missions only there for 2 weeks ~ at a time until you get enough power generation there (say a small reactor) to provide sufficient power constnatly. On Mars you have to deal with a night comparable in length to Earth but you have considerably reduced solar irradiance meaning if you use PV it's always going to produce less during the day. This makes the Moon a better candidate for testing power management, battery technologies, small reactors, etc.

Any technology that can survive in the harsher conditions of the moon, will mostly work out of the box on Mars with the only real stuff needing custom-tailored being vehicles as the Martian and luanr regolith will vary enough (especially combined with the gravity differences) to require you to at least adjust suspensions and wheels.

The moon has water ice in dark craters, as well as minable ore that contain aluminum, iron, silicon and oxygen. You will "just" need to use heavy mining and smelting gear to extract it.

Solar power and batteries should work assuming you're willing to build your base among the "peaks of [near] eternal light" which get sunshine nearly ninety percent of the time.

What needs to be "heavy" gear on the moon? I feel that our current understanding of operations in that environment mostly doesn't apply. Take smelting for example: during lunar day you can bundle several parabolic mirrors and smelt whatever you want. Just have to care about catching it, otherwise it evaporates away. ISTR https://duckduckgo.com/?t=ffsb&q=optical+mining is a common concept now.

This is mostly true on Mars too except perhaps the eternal light part

Mars has a lot more benefit here, in that it has a normal-length day. Much better to reliably have sunlight for roughly half of every day than to rely on a few polar areas that are in sunlight most of the time. The equator of the Moon is more suitable for other reasons, so what are you going to do, put the solar panels at the poles and run long power lines down to the equatorial regions where the power is used? Nah.

Mars is better for solar power because you won't need nearly as much battery capacity, as you get light on a ~24 hour cycle same as Earth. The Moon with its slow rotation is much more challenging.

And its proximity is probably the most important factor?

I'm not so sure about that. It takes more delta-v to get to the moon than mars and both are still too far for immediate response to emergencies. Sure the moon has the advantage of emergency assistance of a few days (?) but I don't think that's more valuable than all of Mars's pros

> It takes more delta-v to get to the moon than mars

Is that true? I can't see how that'd be true, unless maybe you are considering aerobraking to enter mars orbit and parachutes for landing on the surface (?)

If Mars has atmosphere, then Moon has equally useless atmosphere, too. Despite differences in day length, Moon can gather more solar power, than Mars and energy is everything. Besides, those sattellites are gonna crash.

I don't think your atmosphere comparison is valid. The moon has absolutely no atmosphere. Mars' is 1% of earth. That's still a lot of _something_. aerobraking, and easy access to unlimited CO2 is incredibly valuable. Delta-v to mars is less than the moon so the extra solar panels required is not that big of an issue. The moon will probably only be a research outpost because of its gravity and slow rotation. Mars on the other hand will most likely transition to nuclear eventually to sustain a city/colony and industry

Ackshully Mars' atmosphere is famous for being rubbish for aerobraking but enough to burn you up.

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 solar panel energy use -the sulfuric acid atmosphere requires a Teflon coating and/or mixing Teflon particles with the metals during fabrication -the escape velocity from the upper atmosphere is low and requires a small rocket and not much fuel, leaving more fuel for return trips -distance between Earth and Venus is 3 months, versus 6 months to a 1 year depending on the window of opportunity.. that means you can rescue crews faster, get them supplies quicker, and replace crew sooner on Venus -oxygen on Venus has a strong lifting power, you can float entire heavy concrete and steel cities on massive platforms, think cloud city from Star Wars(tm) -aerodynamics work similarly to Earth; airships (dirigibles), airplanes, drones are all possible here Concept mission to Venus compliments of NASA: https://www.youtube.com/watch?v=0az7DEwG68A

Mars: -inhospitable temperatures not suitable for human or plant life -explosive decompression due to a micro-meteorite causing a hole -no atmosphere to protect against radiation or projectiles -weak magnetic field providing no protection -violent unpredictable wind storms on the surface -unbreathable atmosphere -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 -the distance is 6 months to 1 year depending on the window of opportunity, leading to some NASA scientists to suggest we should find it acceptable that it as a suicide mission with no hope of return

Rotating space station: -high risk from impacts -no atmosphere to protect against radiation or projectiles -no magnetic field providing no protection -danger from space debris from previous missions -no surrounding breathable atmosphere -close distance makes resupplying and re-crewing more tenable -requires constant fuel and attention to not de-orbit -does not establish a permanent residence -not a base of significant distance for further operations to the rest of the solar system

> 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 surrounding atmosphere on Venus isn't exactly breathable either...

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

i'm not sure how the math works out but you would be launching from a much much higher altitude than ground level on venus, whereas on mars you would be launching from roughly ground level.

I’d throw in if a rotating station is still in LEO (seems likely for a first attempt) it would have the benefit of Earth’s magnetic field for shielding. Not if used for traveling to another body though.

Like presumably "the Ancients" did? https://old.reddit.com/r/conspiracy/comments/f5s2f4/the_unus...

Starting at about 8M55S he decribes some interesting aspects of the so called two day orbit.

Anyways, it is OUTSIDE the magnetic field. But would it really matter if you have the technology to build a space station big enough to have rotational gravity? I'd imagine we'd cover that with regolith mass driven from the moon, or something like that.

Literally everything you said is wrong except projectiles and space stations. Magnetic fields are easy to make. Wind storms and unbreathable air and radiation and projectiles don’t matter if you’re underground. The idea that a floating city is better than a city cemented in soil is laughable. Good luck maintaining that Teflon coating on literally every exterior surface.

The distance would be mitigated with a 1g thrust drive. It would reduce the transit time between Earth and Mars to three days, with the ship accelerating to midpoint and decelerating from there.

We just need a craft that can thrust that strength for three days straight.

A craft that can sustain a 1g thrust for three days straight is the most outlandish idea in this entire thread.

Maybe, but Phd's are thinking about it:

https://www.johndcook.com/blog/2012/08/30/flying-to-mars-in-...

and

https://www.skythisweek.info/constant1g.pdf

talking about how it would be cool if we had a ship that could do that, and the implications of that. In no way is anyone with any serious education actually talking about HOW to possibly get a craft with the mass fraction and specific impulse to pull this off. we are several orders of magnitude off of this being possible when it comes to specific impulse, and the highest impulse engines we have have nowhere near enough thrust to weight.

Seems there are several thruster designs aimed towards this goal:

https://larouchepub.com/other/2019/4622-revolutionary_space_...

And at NASA:

https://www.nasa.gov/pdf/501329main_TA02-InSpaceProp-DRAFT-N...

https://futurism.com/nasas-new-ion-thruster-breaks-records-c...

references?

The whole idea of colonizing other parts of the solar system just seems like a fool’s errand to me. Colonizing Antarctica or even the bottom of the oceans seems like a more practical endeavor to me.

As uninhabitable as Antarctica is, just think about the advantages it has over a place like Mars or Titan: a breathable Earth pressure atmosphere, 1G gravity, abundant water, not outrageously extreme temperatures, low radiation levels, close to civilization, etc.

Probably most importantly, you don’t have to escape Earth’s gravitational pull to get there. In fact, you can use one of humankind’s earliest inventions—a boat.

If we were really afraid of an extinction level event such as a nuclear war or extreme climate change, humanity could survive by doing the same sorts of things here that we would have to do on Mars—building large underground habitats. Except, we could survive in much larger numbers since it would be so so so much cheaper to build those habitats here.

People don't dream of traveling to other planets to create a backup civilization for Earth. That is what those people tell the ones who don't understand their dream and why they should support it. People want to explore because a certain segment of the population would love the adventure, danger, excitement, thrill, and exotic experience. One also has the chance of creating new places outside of existing governance structures. A group of people who start building a city on Antarctica would likely be kicked off by force in a short period of time. On Mars, who knows?

"We began as wanderers, and we are wanderers still. We have lingered long enough on the shores of the cosmic ocean. We are ready at last to set sail for the stars." Carl Sagan

But... https://en.wikipedia.org/wiki/Antarctic_Treaty_System

Need to cancel that first. Probably with war. What do think is more likely? That happening here without war, or starting "elsewhere" from scratch, leaving the planet of the apes behind?

Let’s colonize Mercury. It’s not actually hot at the poles - it’s shaded enough from the consistent low angle to the sun that there’s even water ice. And the planet is full of useful metals (more than earth), and as much solar energy as you can handle. The article dismisses Mercury out of hand as “too hot” but I think it’s our best bet. https://www.universetoday.com/130109/how-do-we-colonize-merc...

I think it was in Kim Stanley Robinson's "Mars" universe that they colonize Mercury by making an equatorial train, that's pushed along by the thermal expansion of the tracks. Always struck me as nifty, if kinda silly, when you could do the polar thing like you're suggesting.

Getting stuff to mercury is hard though. IIRC it takes around 16,000 m/s of dV to get from LEO to the surface of mercury. Titan would take even more (19,000) but a huge chunk of it can be reduced by making use of aerobraking.

One difficulty with mercury is that its magnetic field is about 100x smaller than earth's. This means much less shielding from cosmic rays for the same incident flux. Since it's about twice as close to the sun as earth, its sitting in 4x the radiation field. Not insurmountable if you can dig down, but less of an issue further out in the solar system

It's devoid of volatiles though? And in a deep gravity well. I may be very expensive to leave. So it would feel a little lonely, and psychologically I think it would be scary to be so close to the Sun.

And it’s also the closest planet to all other planets! Perfect spot for a space port.

Hmm. I have always considered low-gravity to be quite a big issue for any planetary colonization. Unless some cure is invented like a genetic mutation, it would seem that there is no way of coming back to Earth after spending a lifetime in eg 0.2 G.

This in mind I have always thought that Venus would make the best candidate in the solar system. With 0.9 G it would be as close as we could possible get to Earth yet however I have to admit, having no magnetosphere would be a giant pain in the ass. But since Venus already has a thick atmosphere, it would seem that after the required amount of gas has been removed, it would stay stable whereas in Mars you'd constantly have to offset the escaping gas. Possibly though that would not be an issue, since we are pretty great at the green-house gas generation.

But yeah, Mars would definitely be the easiest to terraform. But you wouldn't come back to Earth from there. And you'd mostly spend your life in bunkers underground to avoid getting beamed to death by the solar wind, same as with Venus. Unless we some day find a way to achieve immunity against it.

Mars is definitely the easiest place to colonize, by far. It's much closer than the gas giants, there's no craft capable of taking people to Saturn even devised, let alone constructed. Meanwhile, we have SpaceX actively building a rocket for Martian colonization.

Second, the Venusian atmosphere is oppressive as hell, you'll not be solving that problem anytime soon, as we can't even solve Earth's much easier atmospheric GHG problem.

Martian colonization will be tough. 30% gravity, 3% atmospheric pressure, radiation, very cold, very dry... however, building a base is conceivable and we think we know how to do it.

> SpaceX actively building a rocket for Martian colonization.

It's unknown whether it is capable of protecting the human cargo on its way to Mars. Maybe a design with habitation encased in the propellant tanks is a better idea for longer transits.

In any case, Starship is well positioned for Earth and Moon travels, as well as for sending equipment to LEO and the Moon.

Worst case radiation they'll receive is comparable to if they've been smoking cigarettes the whole trip. That's pretty damn good if you ask me

This is just silly. Of course it’s known if we can transport humans to mars. The answer is yes. The only question is how much it will cost. All you have to do is surround the craft with mass. It doesn’t even have to be attached to the craft. The cost of giving the mass enough energy to get out of orbit and over to mars is the only question.

Is it? https://en.wikipedia.org/wiki/Martian_soil#Toxicity

True Venus' atmosphere is quite hostile, but from what I briefly read Venus quite probably have had a similar atmosphere with Earth (along with Mars) in the early days, before the runaway green-house effect got the best of it, so at least in theory it should be possible to transform it back.

With autonomous robots perhaps it could be done in a span of million years. Maybe. A relatable analogue might be removing liquid from a glass with a tiny straw. Yet I'd think it is easier to remove, than to add material when speaking about terraforming.

I've often wondered if crashing a metropolis-sized piece of ice into Venus might help? Deflected from Saturn's rings or some such. The water vapor could cool it/reflect sunlight.

I doubt increasing albedo would help much. Venus already has the highest albedo of any planet in our solar system (at 0.75, versus, for perspective, our moon's 0.12), due to its effectively-100% sulfuric acid cloud cover:

https://sciencing.com/albedo-planets-5203.html

https://www.universetoday.com/36833/albedo-of-venus/

Also, I doubt an insignificant chunk of ice (relatively speaking) could help cool it, or increase albedo.

I think the first order of business on Venus, if one wanted to colonize the surface (rather than colonize the atmosphere, which I think is doable), would be to "harvest" the gases of the atmosphere and thin it out to something more resembling Earth's.

It's not a question of cooling it. It went into a runwaway greenhouse effect (https://en.wikipedia.org/wiki/Runaway_greenhouse_effect) and it lacks hydrogen. All the hypothetical oceans oxygen bonded with carbon and hydrogen/water vapor was blown off by solar wind. The underlying cause was the loss of the protective magnetosphere.

Also, you are probably looking more to continent or small moon size quantities of ice (if that even works, and if the magnetosphere issue was somehow addressed) that metropolis.

Have you considered how much kinetic energy it would have, coming all of the way down the well from Saturn?

Enough to ionize the water molecules into H and O? Which returns hydrogen to the atmosphere, which is the missing component causing the runaway greenhouse effect?

> And you'd mostly spend your life in bunkers underground

That's okay for many people knowing they are in the forefront of humanity's interplanetary expansion. Also, probably whatever they do will enter the history books as epic heroic acts.

Well yes. Here on earth there are indeed many people who think they want that. Mars one proved at least that.

But I am not so sure, if they will be also so happy on mars, if they really have to be underground allmost the whole time and teleoperate the robotic exploration and mining on the surface etc.

For me the dark winter already is every year challenging. But being in a dark winter so to say forever, would not be bearable for me.

Not having good lighting is indeed a dealbreaker, but there's no real reason why we can't make artificial lights that look close enough to the sun.

Similarly if some caves are street sized, being there would not feel like being underground. Add to that better vr, and ability to jump really high due to low gravity and living in martian cave will be almost better than living in many cities here on earth (of course this is assuming 0.3g is high enough to prevent adverse effects astronauts see in 0g).

Sure. I also see no reason why we could not engineer domes that shield us from the radiation. Or at least shield good enough to allow for some hours every day "outside".

But the first pioneers will be probably cave dwellers or will die of cancer after a few years. Which is probably exepteble for quite some people, if they get those pioneer years instead...

The artificial sun is a solved problem. There are even commercially available products for that: https://www.coelux.com/

The problem with the winter that you stuck in your "small" house. If you create Cosco sized "open" space underground it won't be a problem for most of the people.

Those electric suns really did not convince me at all. I do not know if your linked product uses a new technology, but the ones I tried, I disliked and they could never replace the real sunlight for me.

And yes, I also meant the space problem. Open space underground might solve it for some people, but probably not for me. I would always feel like in a prison, if I cannot go outside and feel real wind. But humans are adoptable. Still, I suspect quite many, who think they want that, would probably go crazy, if they really would be stuck in a bunker forever.

I'd tend to Jupiter's outer big moon, Callisto, as a good place to live. The surface is a vacuum, sure, but it's got surface ice which probably has liquid water underneath making it (and Ganymede and Europa for the same reason, and Venus 50 km up, and Earth) one of the few places in the solar system you could theoretically go outside with just a breather and no space suit. Plus it's got protection from charged particles via Jupiter's magnetic field without suffering from Jupiter's own radiation. And you've got both volatiles and minerals accessible on the surface which strikes me as really nice.

All these worlds are yours, except Europa. Attempt no landing there.

Fine, the surface is very radioactive (but it's safe under the ice) and there aren't any exposed mineral deposits so you can have it. :)

Colonize the moon first:

1. plenty of solar power

2. close to earth

3. easy to launch out of its gravity well

4. lunar base technology can be iterated far more rapidly

Still a couple challenges though:

- some important elements (nitrogen for example) are mostly missing from the Moon, necessitating import (nicely illustrated in the Artemis novel)

- no atmosphere means any grain of interplanetary dust in collision course with the Moon impacts its surface (and possibly any astronauts on the surface) directly at high velocity

- by not having atmosphere you can't use atmospheric reentry/aerocapture/aerobraking to shed velocity like you can with a body with an atmosphere; all speed changing maneuvers need a thruster impulse or similar

- no atmosphere means serious temperature extremes; even the very thin atmosphere on Mars events the day/night temperatures quite a bit

- you need retranslation from the far side of the Moon to Earth

- only a few fine tuned orbits around the Moon are stable, all others will quickly crash any satellite orbiting on them to the lunar surface due to the uneven gravity field of the Moon caused by sub-surface mass concentrations ("mascons")

All in all Moon has a lot of benefits, even just by being close to Earth. Still a couple things to watch for though. :)

I think colonizing the Moon is a good idea must mostly just the south pole to start with. On most of the Moon you have 2 weeks of frigid darkness you where you're living off batteries followed by 2 weeks of intense sunlight. At the peak of eternal light at the south pole you can just slowly turn your solar array 360 degrees over the course of a month and have (nearly) continuous power.

There's a big difference between having to have 12 hours of battery power, as on Mars, and 336 hours on the Moon.

> slowly turn your solar array

Sure that's nice but the angle of sunlight is very low so you are limited in that respect, e.g,. available surface area.

There's no atmospheric absorption though, so that would compensate a bit. Building very tall structures would be easy in the low gravity, and you wouldn't need to worry about earthquakes or storms.

I'd often though that a rail or even cable should be strung to the top of Mt Everest, you'd make a fortune off of it shuttling tourists up and down all day.

That would be quite the engineering feat - Everest is not exactly construction friendly.

Pikes Peak used to have a train going to the top, but they closed it a couple of years ago. https://www.cograilway.com/rates-times.asp

Then do not turn the array and do not put it at the pole.

Build a ring of static solar collectors at some respectable km distance out, such that some will always be in sunlight, and transmit the power back. It brings up the engineering challenges of high-voltage power transmission in low gravity, zero atmosphere, and various forms of radiation (e.g. how far apart one could place pylons); but I suspect that these are more likely solvable than some of the things that futurist ideas bring up. (As yet uninvented, or not manufactured in large quantities, materials with really high tensile strengths, for example.) And it avoids the problems (construction and maintenance) of continously moving large numbers of solar panels around in a vacuum. It even introduces redundancy.

Moreover we definitely already know how to cope with an electrical power grid where only some of the generators are currently supplying power. (-:

Colonize the top of Mt Everest first? Even closer to Earth. Similar challenged. 250,000 miles closer to resupply. Very hard, a good test of colonizing technology.

If there were no cultural backslash then we would probably already have a McDonalds there :)

Ha! Though actually you can't eat on top of Mt Everest. Your digestion stops moving at the previous base camp.

But why? Due to low air pressure? McDonald’s obviously will be pressurized.

Won't develop space travel and sustainment technologies much. With that logic, we can colonize oceans (and probably discover a thing or two about our origins and new life forms)

Why not? The top of Mt Everest is remarkably similar to Mars surface, for instance. I'd say, tackle the challenges a few at a time, instead of jumping in the deep end!

To go further: if you can't establish a colony on the top of Mt Everest, you haven't a prayer of doing it on Mars where there are all the problems and more.

We can establish a colony on top of Mt Everest, it's just not useful or exciting enough to spend money and time on it. Mars is exciting and allows to start a new country, unlike Everest which already belongs to someone.

I mean, colonizing the oceans is still more realistic than trying to create floating cities on Venus

You just have to get there with a rocket

> 1. plenty of solar power

For two weeks at a time. That's a long time for batteries to run.

Small modular nuclear reactors. Because who cares, there?

The poles.

That is actually a cool idea. I have seen idea that you can use giant slingshots to hurl cargo out into orbit for cheap as those would use solar energy to prime.

If you think about it we could be doing so many cool things as species, if only we clean up the whole politicking and squabbling over resources and power.

Technologically it seems we are on the edge of being able to expand out into solar system.

So what about the radiation then?

That's why you build the base underground.

> It’s cold on Titan, at -180°C (-291°F), but thanks to its thick atmosphere, residents wouldn’t need pressure suits—just warm clothing and respirators.

I'm no space colony expert but am I missing something here? -180°C sounds like constant space suit level, not "just warm clothing".

At least, the suit would not need to be pressurized and extremely resistant to punctures.

At most, warm & insulated enough.

A generous slathering of bear fat or whale blubber is all it would take. Maybe a vinyl outer suit so the viscious liquid methane rain doesn't dissolve your insulation.

On second thought, some kind of heated space suit sounds more comfortable.

Something like butter freezes at -20 C. Most animal fats would probably... shatter at the temperatures of Titan? I'm not familiar with temperatures anywhere near that low and I assume a lot of materials are just going to act very differently.

Heated space suit + liquid methane rain. Sounds intense.

Yeah that confused me too. You'd definitely need your suit to be watertight (or rather liquid-methane-tight) so that the liquid doesn't touch your skin to prevent immediate frostbite. Maybe you won't need a fully pressurized suit, but that's just so low I feel like you wouldn't be able to survive for long periods without some sort of active heating (i.e. walking around with a portable furnace).

And here I am, with my (Mexican) wife mentioning almost daily how horribly cold it is here in Europe.

I'm also not sure what kind of warm clothing they'd mean lol.

goretex: https://www.youtube.com/watch?v=0e58SiFSxLs :p

oh man I'm looking forward to watch Seinfeld again when it's on Netflix!

Yeah...-291F, an unbreathable atmosphere, and the atmospheric pressure is high enough you might want something to moderate it. Maybe not a ISS space suit, but we're not talking long underwear, warm boots and a pullover.

If you can you should check out the TV series Avenue 5. It’s a sci-fi comedy and whoever they hired to do their science is really knocking it out the park. Some of the true science I’ve seen in the shown: the ship is massive enough to have its own gravity. Objects that get lost in space don’t float away. They orbit the ship. They use passenger effluent as a cosmic radiation shield. And due to an anomaly they don’t get flung off into space. Their orbit gets wider so instead of a year trip it’s now 5.

Oh and the real engineers work in the basement of the ship. The bridge crew are actors.

I gotta disagree. The physics in the show is disappointingly cartoonish in my opinion. The ship is not massive enough for it's gravity to capture the, uh, various items in the orbit shown. Even the orbital mechanics of the delay are just a plot device.

The latest episode has people freezing solid after leaving through an airlock almost instantaneously- someone on earth survived a longer exposure to vacuum but at closer to room temperature in a suit failure.

(ノ°Д°）ノ︵ ┻━┻ Thanks for the heads up.

(Space is cold but it's also empty. You'd boil first from the lack of pressure then freeze, eh?)

Oh gawd, it's even worse than that: they don't even leave the airlock, they lit. freeze solid the very instant the outer doors open (with no rush of air!?!) Damn it. I really really like Hugh Laurie (one of the great and simple pleasures in life is introducing someone who only knows him from "House, M.D." to his OG work like "Black Adder" or "Jeeves & Wooster") but it's hard to watch around the problems in this show.

Like it's fucking dark. The bad physics wasn't the worst part of that scene. The show is supposed to be a comedy but that was like a nightmare.

I watched the first 3-4 episodes. It was a polished show and the realistic take on science was a breath of fresh air, but it seemed like the story stopped going anywhere.

I’m a masochist - after eight episodes this is the most disappointing TV show ever based on creators previous work. It’s like an improv or stand up gone bad for five hours.

You basically spoiled the entire show now :)

Am I missing something here?

"On the surface, vast quantities of hydrocarbons in solid and liquid form lie ready to be used for energy. Although the atmosphere lacks oxygen, water ice just below the surface could be used to provide oxygen for breathing and to combust hydrocarbons as fuel." [my emphasis.]

They are proposing splitting water to get oxygen for burning hydrocarbons to produce energy - but splitting water itself takes a lot of energy, and low-entropy energy at that. Could this process possibly result in a net increase in useful energy?

I'll answer the energetic question. Splitting water produces oxygen and hydrogen, so with our oxygen we have the choice between burning hydrogen or burning Titan's hydrocarbons. Burning the hydrogen would bring us back to square one, so the question is whether burning hydrocarbons yields more energy than burning hydrogen. It appears to not be the case. Some numbers I found online:

  burning 1 mole of O2 with hydrogen yields 572 kJ
  burning 1 mole of O2 with methane yields 444 kJ
  burning 1 mole of O2 with butane yields 443 kJ
  burning 1 mole of O2 with octane yields 437 kJ
  burning 1 mole of O2 with glucose yields 467 kJ

https://personal.utdallas.edu/~metin/Merit/MyNotes/energySci...

https://www.ausetute.com.au/fuelenergy.html

Even if it does not, you could use it as a nice chemical battery.

Say you split some water ice using energy from you nuclear reactor (or possibly even a turbine in your methanoelectric dam!) and store the pressurized oxygen.

Then you can use the stored oxygen with methane from the atmosphere to provide a lot of energy where needed, possibly far away from your main nuclear reactor, dam on a liquid methane river or other non-portable energy sources.

An example would be rocket fuel to leave, so you don't have to bring it all with you.

Definitely, can use it to power chemical rockets as well. :)

Let's colonize LEO. You get radiation protection from earth's magnetosphere. You get zero G for funsies. You get a new perspective on earth and interesting new kinds of manufacturing. It's not too far away, so you can get there and back in a day. It's far enough in space that you need to improve your closed cycle systems. You might survive a number of different cataclysms. It seems like a good stepping stone.

> You get radiation protection from earth's magnetosphere.

Only in very specific orbits (NOT the ones we are currently using, btw.) The Earth's magnetosphere actually captures dangerous radiation and various anomalies in the belt distribution cause portions of low-Earth orbits to be irradiated.

> You get zero G for funsies.

And the medical issues.

> interesting new kinds of manufacturing.

There are a handful of (very interesting) crystal manufacturing that requires zero-g. These could be done in automated or human tended LEO or LLO manufacturing labs. You don't need a large human presence.

To the downsides, LEO lacks any resources whatsoever, and still has a nontrivial delta-v to the rest of the system. All your arguments in favor could be applied to the Moon, which does have LOTS of resources and better radiation shielding.

So, the ISS orbit crosses the South American Magnetic Anomaly sometimes which does give them a bit of inner Van Allen belt radiation sometimes. But they're still completely protected from direct emissions of charged particles from Sun. They would get much, much more radiation if they were orbiting out by the Moon even before you start worrying about solar storms.

I'm not trying to take the wind out of the sails of any vehicles going elsewhere, just think LEO is a good place to start. Something like, before crossing an ocean, let's cross the Florida straits over to the Bahamas.

> The Earth's magnetosphere actually captures dangerous radiation and various anomalies in the belt distribution cause portions of low-Earth orbits to be irradiated.

Pick the favorable orbits. We have data on our ISS astronauts. Seems like we can go years up there if we wanted.

> And the medical issues.

Most folks are going to want to go up for a few weeks/months and then come back to tell the tale. A habitat might employ centripetal acceleration. Anyhow, I think medical issues will be manageable. I suspect there are a few orders of magnitude more people who are interested in a vacation in space or work from space scenario than a long distance voyage to the moon or mars where you are cut off from the home world and have a big latency cost on communications.

I think this is about filling rockets with large sums of cargo to keep the space business growing. If a starship can be made for $5 million, there are plenty of yachts just down the coast from Cape Canaveral that cost more than that. If you could give folks a stay in LEO for ~$50k, there will be plenty of people who can afford that. I bet you could find tech companies that would let you work remotely from space as a signing bonus.

> There are a handful of (very interesting) crystal manufacturing that requires zero-g. These could be done in automated or human tended LEO or LLO manufacturing labs. You don't need a large human presence.

Agreed, I'd add that this isn't so much about keeping the number of people down, but increasing the demand for people to go into space. I'm excited about the side effects it will have for technology and science.

> To the downsides, LEO lacks any resources whatsoever, and still has a nontrivial delta-v to the rest of the system. All your arguments in favor could be applied to the Moon, which does have LOTS of resources and better radiation shielding.

The moon and mars are good places to settle too. I'm only arguing that Earth LEO is easier to start with because Earth has more readily available resources than any of the other locations. LEO is still hard enough where we'll have to improve our ships and space quarters for design and comfort. So I think it's a good stepping stone.

LEO is more like 'camping in the back yard'.

All I ever learned from that is that I hate camping... and would much rather have a house / hotel room.

Extending that analogy further, maybe we can figure out how to build a "mother in law apartment" in our "back yard" first.

And really, it's the atmosphere that does the bulk of the radiation protection work. Astronauts abort the ISS still experience their fair share of radiation. As mentioned though, their orbit is far from ideal and different orbits have less radiation.

The article argues that on Mars we'd have to live underground which requires a lot of construction of tunnels and excavation. It does not appear to take into consideration the huge lava tubes that are present on Mars (and even bigger on the Moon). These are estimated to be dozens of kilometers long and hundreds of meters wide. They could be very attractive for human colonies.

On the other hand on Triton, even if you live at the surface, the Sun will be very weak. The main advantage of not living underground will be less resources to create a habitat.

I consider sufficient natural sunlight to be important for human wellbeing.

Shielding Mars is possible with current technology.

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

Is it though? The link only discusses the theory of placing a large magnet in the Mars-Sun L1 point. It does not discuss the makings of that magnet. What's going to power it? Solar? Nuclear? So at the end of the day, I'm still left not knowing if we have the tech to be able to do this. This seems like a no-brainer of something should/needs/must be done to make humans living on Mars anything more than just a though exerciser.

At it's simplest is a ring with power flowing through it, the power requirements would be minimal, 1 Tesla needed and a deflection of a fraction of a degree.

I've seen estimates in the single digit MW range which we build solar plants on Earth for a few million each. Power generation is somewhat irrelevant, getting the material up there and maintaining it will be the real monetary challenge.

Read the link at the end of the popsci article. There's a huge amount of research going into generating magnetic fields for spaceships and inhabited bases.

Not a single comment calling out this article's complete lack of scientific references, including the "iron smashing our brains at relativistic velocities" quote?

I think it's great to consider other planets we can colonize, and indeed a thick atmosphere has a lot of benefits, but it's hardly rational to state Mars has "a deal-breaking problem" without providing any hard evidence to back up this claim.

Scientific American is a magazine for the general public that have a high school level education in science. It is not a peer reviewed scientific journal, thus the SA articles do not have the same level of footnotes and references that a scholarly journal might. Having said that, I think on balance, the quality of journalism in SA is excellent, thanks in part to highly skilled and qualified editors.

Anyway, this article by the "discoverer of the Solar Wind" (maybe validator is a better word), Eugene Parker, is relevant to this discussion: https://www.dartmouth.edu/~sshepherd/research/Shielding/docs...

This reminds me of Wanderers, by Erik Wernquist. https://vimeo.com/108650530

There's a scene at the end when one of our future generation looks at the surface of Saturn while standing on a station floating atop a Saturnian moon.

Very motivational.

Other videos by Erik Wernquist are motivational too: New Horizons: https://vimeo.com/132183032

While the technical quality of these videos is very good, and i really, really like most Sci-Fi, why in hell is she wearing a fur collar on her hoodie over a full face mask, in space?

THAT are things things turning me off, from full hard-on to instantly shrunken balls.

Try this, this is where we are: https://www.youtube.com/watch?v=KCJzUiBZItk

I think that scene is actually situated on an airship floating in the atmosphere of Saturn.

The rings would be much too big to be seen like this from Titan, not to mention the Titan atosphere being pretty hazy.

Serious question, since this is out of my swim lane. The Author keeps talking about the effects of Galactic Cosmic Rays, do we have any usable materials we can build habitats out of that can block them? I mean usable in the sense we can produce in scale and they are non toxic to humans.

For Cosmic Rays the only thing is just a lot of atomic nuclei. You need pure mass. This is why a transit to Mars or Saturn is going to be hard for us to pull off in the near term. All those nuclei are expensive to get into orbit right now.

Outside of that, there is a 'graded Z' shield. Here, you make a layer cake of various atomic nuclei (the Zs), going from heavier to lighter. Typically Tantalum down to Tin and down to Aluminum. They physics here aren't super important, but for lower energy radiation, you can get down to a 60% mass reduction for similar shielding protection.

The problem is that it's the higher energy radiation that you are worried about, the Cosmic Rays. Graded Z shields pretty much work like anything else at those energies. Under our current physics mumbo-jumbo, you just need nuclei.

Artificial magnetic fields are another possible solution.

Any material will work if thick enough. Thick concrete, water/ice. It just has to be thick enough to also handle the secondary radiation from higher energy stuff. We're talking a need for several feet of concrete or several inches of lead.

For a rocky body like Mars the 'easiest' solution is simply excavate trenches to put your habitats in and then piling several meters of regolith over the top, or using lava tubes/caves. If excavating was too difficult you could similarly just make bricks of compressed/fused regolith and pile them up. Titan has a rocky core but is mostly ice where a manned mission would be, there you'd probably just carve out large blocks of ice and place them around your habitat.

The best universal solution would probably be some sort of sandwich of materials that was still decently thick.

One of the simplest methods would be to bury habitats in conjunction with materials to block cosmic rays.

Let's first ensure we do all possible things as a species and a collection of communities to restabilise Earth and give ourselves a 99.5% chance of healthful survival for the next 200 years, which is probably the reasonable timeline until we can establish more or less independent non-Earth habitats that can survive without Earth indefinitely.

This is like expressing the wish of wanting to run while simultaneously ignoring the fact that your hands are uncontrollably stabbing your legs with safety pins.

I beg to differ.

This is not like our ancestors have done it. They spread as far as they technologically could, simple as that.

https://en.wikipedia.org/wiki/Early_human_migrations

Some settlements survived, some died and got revived centuries later, but humans have continuously tried to settle further away, in a complex system that you can't reduced to "establish more or less independent [remote camps] that can survive without [base camp] indefinitely".

Space is more difficult only in it required more technology and resources, but it's the same (complex) expansion process that is hardwired in our specie since we were mere apes.

I like how we're optimistic in terraforming and colonizing distant bodies with different gravity, pressure, atmosphere, temperatures, while equally panicking trying to control a few degrees of temperature on our home planet.

But I think research on how to colonize other planets will help us in dealing with local climate change.

I think the optimism stems from not having a definite deadline for the colonization of distant bodies. Whilst climate change is a bit more pressing.

I mean, I don't worry about implementing a new feature at work by 2120. But I'd sure worry about having it ready tomorrow!

Also all those issues in dealing with colonizing space are, for most people, distant from their daily life. Climate Change is close to home.

But yeah, research on one might influence the other as you say!

Stopping climate change isn't even hard, just place a large solar sail on a sun synchronous orbit to block part of the sun's energy from reaching Earth.

Because 7 billion people can only do a single thing simultaneously.

Because only one person is actually attempted to colonize space at the moment.

Why not do both?

If there is one thing I’ve learned, from many posters on HN in many different topic, it’s that human civilisation is apparently incapable of achieving more than one goal at a time.

Building an outpost in Earth orbit that requires constant maintenance and supplies from the ground is just barely achievable right now and cost billions of dollars. We call it the ISS. The horizon to a self-sufficient orbital settlement is still decades off.

A self-sufficient colony on any other planet or moon is way beyond that capability. It's not about doing one thing or another, it's one thing is a fantasy in the short term and the other is a real practical concern.

There's far more practical places on Earth to colonize before even thinking of bootstrapping an industrial civilization on another planet. Because that's what it would take. None of the technology needed to do the bootstrapping currently exists. You can't download MarsColony.stl from Thingiverse to load into a giant 3D printer.

Because limited resources are a thing that exists? I think if you were to take a poll, most people would agree that throwing all our economic might behind preserving the one bastion of life we know of in the universe is a better course of action than spending our time and money on what for the foreseeable future remains a pipe dream to be smoked by the very few. In all likelihood, we will need the technologies developed in a green revolution to even have a fighting chance of success at colonizing other worlds.

Mainly because right now, any significant endeavour is tied to using massive amounts of fossil fuel.

As long as it will be the case, we won't be able to start new, large scale projects without jeopardizing our ability to live on earth.

False dilemma. We can do both!

Sounds like a fun metaphor but human colonization has nothing to do with running or safety pins.

Yup. Im all in for space colonization. But with the current state of humanity, we are not in a position to colonize anything in budget and on time.

Space colonization is a game to be played after we have made human life on earth fully sustainable.

Then we would have enough time and resources to think beyond.

Let's start with a self-sustainable colony at the South Pole. Or, for that matter, a self-sustainable colony in Death Valley.

"But even if we could, why would anyone want to?" you might ask...

And that's the point.

Nobody would want to as there is no economic reason to be there.

My two cents: we'll never colonize a moon or planet. There are, on the other hand, some economic perks to manufacturing in zero-g. Consequently, I'd put my money in massive orbiting space stations.

terraform venus. it's much closer, has a nice .9g and maybe a viable long-term project

https://en.wikipedia.org/wiki/Terraforming_of_Venus

It is theorized that Venus once had an Earth like atmosphere. Venus has virtually no magnetic field unlike Earth. Without the protection of something like the Van Allen radiation belt the Sun would have easily blown off any thin high density atmosphere and eventually cook off any surface level hydrocarbons into a thick hazy atmosphere with a super greenhouse effect. Any terraforming effort would have to take that into account and capture atmospheric sulfur.

I suppose any attempt at terraforming has to create oceans if we want an Earth-like habitat (theoretically this could be achieved by re-directing enough comets at Venus or Mars provided we can utilise that kind of energy in the future). Could perhaps a form of sulphur-fixing bacteria be developed to colonise these oceans and remove it from the atmosphere as sediment?

As for the magnetic field, if the lack of convection in the core is a problem (perhaps due to the core completely solidifying) couldn't we just dump enough heat energy into it to restart the dynamo action? In the future it's not completely unrealistic to think antimatter production and storage will improve, that's certainly a way of releasing absurd amounts of energy.

Impractical, but Venus Cloud Cities would work maybe. 1 Earth atmosphere at 20 degrees Celcius if I recall correctly.

The much weaker gravity and its effects on human health is something I rarely see mentioned.

If one were to be born on a body with a much weaker gravity than Earth, e.g. Mars (0.38) or the Moon (0.17), wouldn’t this confine them to bodies where gravity is less than or approximately equal?

The best answer right now is that nobody has any idea what, if any, effect that would have on human health. It hasn't been tried yet, so we just don't know.

Sincere question: Anyone know what would be involved in igniting Jupiter, and what kind of heating that would provide to it's moons?

Jupiter is not even a brown dwarf which starts at about 13 times the mass of Jupiter.

For upgrading Jupiter to a star, it would need 80 times its current mass.

There is nowhere else in the solar system enough mass to grow Jupiter but the Sun. Taking that mass from the Sun is in theory feasible but of course out of the range of our capabilities for quite some time.

That's for natural nuclear fission though which would waste a lot of energy going into space and not where we would want to have it (the moons).

It's probably more realistic to build small fission suns that orbit the moons that produce heat and light in a less wasteful, more directed manner. Still not possible today :-)

I thought this was interesting so did a quick search: it does not look feasible [0].

Note: even if it were possible, the small relative increase in radiation received by Earth may have a butterfly effect similar to greenhouse gases and make global warming even more difficult to manage than it already is.

[0] https://physics.stackexchange.com/questions/776/can-jupiter-...

You'd need a lot of monoliths.

Oh well, there are ways. Let me introduce the Stellification Engine:

https://www.orionsarm.com/eg-article/4a48d58c84350

A mass of self-replicating hot hydrogen dirigibles powered by fusion. They use part of the energy to stay afloat in the correct altitude and to repair and reproduce & radiate the rest outwards.

By igniting I assume you mean nuclear fusion. Jupiter does not have enough mass. So what would it take? Transfering mass from the sun to Jupiter I guess.

Not sure how much heating it would provide to its moons. It already provides an unhealthy amount of radiation.

Throw in more mass, than it will ignite itself and be the second sun.

Actually, when you think about it, Jupiter is a good candidate for a dyson sphere.

Jupiter is around 1/79 the mass of a red dwarf. So it’s only 1/79 better than empty space as a place to build your new star.

Just need a whole bunch of monoliths to up its mass...

Combustion requires wholesale access to oxygen.

There has been a few people I've read about proposing a solution to this on Mars. Mars is absolutely chock full of these "lava tubes" caused by old long dormant volcanos. If those could be sealed, they could be used for humans to live in effectively shielded from this sort of thing. Sure it would be difficult, but so would everything on mars. The great thing is that there are lots of these lava tubes that could potentially be inhabited.

https://phys.org/news/2017-09-lava-tubes-hidden-sites-future...

https://www.inverse.com/article/36777-mars-moon-human-colony...

What’s more likely in the next 5000 years that we colonize Mars or that we scan the human brain and move it to software so that it doesn’t need a specialized atmosphere to persist?

That's a very interesting question. I would guess that if moving brain into software is at all possible, there will be very little reason to build anything other than huge computers, and maybe that's the answer to Fermi paradox.

I am pretty sure the Martian congressional republic is not going to stop colonizing just Mars. They’ll have every incentive to push further, faster :-)

> The weak gravity—similar to the Moon’s—combined with the thick atmosphere would allow individuals to aviate with wings on their backs.

Sign me up.

Both Mars and Titan currently lack an economical reason to try and live there.

As long as it's just about the science or bragging rights, it will be completely paid for from earth's resources, instead of building on its own.

Any idea what tangible "export products" could make a Mars colony sustainable? I don't think space tourism is enough.

Re: Economics

'The belt' would best be mined by automated, semi-remote controlled machines.

The Moon offers a good target to fire those resources at (aim to roughly keep it's orbital momentum the same), a low but not No G fab area with easy access to 'free' vacuum, and is usefully close to Earth orbits.

Mars... I can't really think of any particular thing it does better offhand, that couldn't instead...

Lagrange Points (L4 and L5) offer areas usefully distant from Earth for scientific and world-ending-event backup purposes, have a relatively low escape velocity, and are "safer" in that they draw masses to stay near them. This would be a great place to park a large rock (for shielding) and core out the inside.

https://en.wikipedia.org/wiki/Lagrangian_point

Reminds me of what they did with the space station in Seveneves!

Technically, much of the spaces needed for food production or other industries on mars don't need to be underground to protect Humans from radiation. Plants and machines can tolerate it much better, and a Mars colony can't sustain itself without levels of automation that look ridiculous to our present day.

Why not colonize deserts on earth? It is vastly less energy consuming, vastly more useful, but no less of a challenge.

Because if you’re talking about things we can’t do anyway might as well talk about the ones that we can’t do the most

Many (science fiction) dystopian societies have high inequality, with some people living in orbit while the rest eat Soylent Green. We live in such a dystopia, and many people on HN don't realize it because they are the lucky ones. Colonizing Mars isn't a goal that solves any particular problem in our civilization - it's a red herring.

I suspect it's because you're missing the larger point here. Having off-site backups is best practice for both system administrators _and_ civilizations.

Maybe consider Earth's oceans first? It's somewhat closer, has some food resources, the gravity is also OK.

I thought Elon Musk wanted to terraform the poles of Mars to make it more habitable. He even has promised t-shirts that say Nuke Mars.

https://www.space.com/elon-musk-nuke-mars-terraforming.html

It looks a better bet to colonize Mars with genetically modified humans to sustain radiation. If such technology is not available at the time, having DNA correcting machines to give birth to sane humans is probably going to be a solved problem by then. Even though adults will suffers from the radiations.

This article projects too linearly to the future: terraforming Mars, for instance, would probably be easier right now than getting people to Titan quickly. Seems like an article written for the purpose of getting clicks by being contrarian, not seriously investigating the science

OMG! It's full of fumes! All the times!

That is all i could think about when reading about the hydrocarbons. Imagine having to live in the all permeating STINK of a gas station, or worse (petro)chemical factory.

/me shudders

Nitpicking, but ... If one says :

>> We reached this conclusion after looking at the planets in a new way: ecologically

then, why can he say :

>> Housing could be made of plastic produced from the unlimited resources harvested

Ecology is also about realizing that resources are limited.

I think it’s a better idea to just build a rotating space habitat.

Harvest the metals from the moon, and build a mass driver to launch it into Earth orbit, where it’ll get assembled into the space habitat. Then spin it to get 1g.

How does this Methane develop on Titan vs. other hydrocarbons (Ethane, Propane) etc. ?

Could we not bomb Titan with some sort of water catalyser and burn up a large amount of Methane?

Certainly would be good as a fuel source.

We gotta do it before the Hive and Fallen colonize it.

Let's first figure out astro-mining and self-sufficient space stations. Planets or moons are overrated as habitats.

Is it impractical to protect space colonizes with powerful superconducting magnets to deflect harmful radiation?

It all seems like a huge waste of resources and effort to me. Personally, I would rather see all that money/resources going into developing some kind of FTLT. There are planets out there, way out there, which are much more suitable for life. Even without FTLT even if it takes us 2 generations to get there.

It’s “Scientific” American yet they quote negative 300 degrees Fahrenheit. Use kelvin for low temperatures or, if you have to, at least degrees Celsius. For the benefit of the reader -300 F is 89 kelvin or -184 Celsius which is about 10 degrees c above liquid nitrogen’s boiling point.

> It’s “Scientific” American yet they quote negative 300 degrees Fahrenheit.

It's Scientific American, yes. I mean, sure, they could have used Rankine but...

The article is about human colonization, so Fahrenheit is more appropriate unit because it represents human compatible temperature ranges better than C or K.

Great idea. We should use Titan to build a bunch of insane asylums there. And then perhaps we can neglect the insane asylums, the patients can escape and start their own societies based on the type of disease they have.

Someone read the Kurt Vonnegut book, The Sirens of Titan!

The Dr.Manhattan Project?

The page is "temporarily unavailable" for me.

To help in your fight against paywalled and temporarilty unavailable pages, here's this (officially recommended) Firefox extension that looks up the current page in one of 18 web archives:

https://github.com/dessant/web-archives

Let's. But first, let's colonize the ocean. And the sky. And the moon.

It is deeply disturbing to see a lot of effort put into colonizing another planet, while rampant pollution increases at Planet Earth. While science advances, at what opportunity cost?

It Remains to be Seen if we have Spoiled the Nest. <--

What exactly is the problem that colonizing another planet or moon is trying to solve? This seems like a solution without a problem. And if that problem is that the earth becomes uninhabitable, what kind of moron thinks we can colonize a planet or moon when we can't even keep ourselves alive on earth?

"We trashed this planet, let's find another one".

A random asteroid impact could end the human species next month. If we spread to other worlds, our chances of survival go way up.

As a doctrine, colonization hasn't worked too well for humanity. It assumes an ethnocentric view where the colonizer has the right to take or use resources that they believe they "discovered". Just because there aren't any humans there, doesn't mean it doesn't already belong to someone. And just because we are able to take over a moon, doesn't mean we have the right to.

Instead of colonizing, we should be talking about zero impact exploration where we leave things exactly as they were before we arrived. Then focus on using what we learn to fix and protect our own planet.

Belong to who? All known solar space and beyond is literally devoid of any life at all. Are you assuming super aliens? Or perhaps a god of some kind, who pre-claims ownership? And if so, how did these beings get their "right" to have it?.

What exactly countermands our right to the take over the moon or any other part of local space? Name some concrete thing, not just an arbitrary notion of rights.

The obvious from these, to what purpose zero impact exploration of space? Sure, nothing should be destroyed just because... But you do realize that you're not talking about fragile ecosystems here, but vast dead landscapes that are the literal products of cataclysmic destructive processes that are in many places still ongoing?

Your comment is so absurdly out of context for the environments we're all discussing here that it's tempting to think you're trolling.

> Just because there aren't any humans there, doesn't mean it doesn't already belong to someone.

There isn't anyone there, human or otherwise.

> And just because we are able to take over a moon, doesn't mean we have the right to.

Sure it does.

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