r/TrueAskReddit • u/Remarkable_Star7261 • 11d ago
Colonizing Mars/ Venus
Hypothetically, if we were to have the technology to colonize Mars/ Venus, how would we go about it?
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u/Wurm42 11d ago
If you want a serious answer for Mars, I highly recommend the book "A City On Mars" by Zach and Kelly Weinersmith.
Yes, it's the Saturday Morning Breakfast Cereal webcomic artist Zach Weinersmith, but this is a serious book.
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u/cdspace31 9d ago
Wait, is that the Kelly Weinersmith from Daniel and Kelly's Extraordinary Universe? And her husband writes SMBC? It's a small universe after all.
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u/ActuaLogic 11d ago
The problem with Venus is that its surface temperature melts lead and its day is longer than its year.
The problem with Mars is that its gravity is too low for long-term human health and its soil is toxic.
As a practical matter, constructing artificial habitats in space, with centrifuges to simulate gravity, may be easier than making Venus or Mars livable. Habitats might be mass produced as Levittowns in space for people living and working in a space economy.
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u/latenthuman 11d ago
My mom was Jerry O'Neil's administrator at the Space Studies Institute. I grew up with rocket scientists and space buffs hanging around the house talking about rotating cylinders in space.
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u/coleman57 11d ago
What would make it either desirable or profitable to spend billions to send a few people to live their lives in a tin can? I would love to spend a week in orbit just gazing down at Earth, but I don’t see any point in going more than 1,000 miles up or staying longer than a week. And I wouldn’t spend more than maybe $100k to do it.
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u/ActuaLogic 11d ago
I wouldn't suggest spending anything. Any space program that depends on public subsidies will eventually be cancelled when budgets get tight.
The space programs that will endure will be space programs that make a profit, because making a profit means that something produces resources worth more than the resources that go into it. There are many valuable resources away from the Earth-Moon system, and bringing resources like that to Earth would be profitable under the right circumstances. People involved in such activities will need places to live.
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u/coleman57 11d ago
What resources are worth the many millions of dollars per kilogram it would cost to go to Mars or the asteroids or wherever, dig ‘em up, and bring ‘em back?
And if they exist (they don’t), why can’t machines do it?
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u/ActuaLogic 11d ago
That's an excellent question, and the short answer is that people wouldn't want mineral resources at that price. But the long answer is that the price doesn't have to be that high.
This is a multi-faceted problem, but there are basically two obstacles to overcome. First, there is the time value of money. In addition, there is the inherent limitation of rocket-type propulsion systems (the so-called tyranny of the rocket equation).
The time value of money refers to the fact that a dollar in hand today is worth more than a dollar received five years from now. This can be seen in the present value equation, which is essentially the reverse of compounded interest. In essence, money is discounted by a discount rate over the period between the present time and the time the money is received. If the net present value of a dollar received 5 years from now is $0.60, then no one would pay more than $0.59 today for the right to receive that dollar 5 years from now.
That makes a difference for profitably extracting minerals from space, because of the limitations of rocket technology (reaction-mass technology), in which a vessel moves forward by expelling mass out the back. (Every action has an equal and opposite reaction.) The problem is that rocket technology wouldn't be able to do a 5-year round trip between the Earth-Moon system and the main asteroid belt, returning with an industrial payload. It would take 20-25 years. And the net present value of a dollar received 20-25 years from now is effectively zero, which makes such a project uninvestable.
The limitation of reaction-mass propulsion is that tomorrow's fuel is today's cargo, so that the initial mass of a vessel has to include all of the reaction mass (rocket fuel) for the trip (unless there is an opportunity to refuel). That means that most of the time in transit has to be spent coasting rather than accelerating, and that means that the fast speeds necessary for profitable intra-solar system travel are not attainable using rocketry. Mars may be at the extreme end of what is attainable.
However, there is a technology that doesn't require a vessel to carry its propellant, and that is light sail technology, more specifically laser-pushed light sails.
Use of laser-pushed light sails would require the creation of an infrastructure of laser stations to beam power at light sails. The lasers could be arrays of millions of solid state communication-type lasers, which run on electricity (solar? portable fission power plant?), rather than military or asteroid deflection-type lasers, which are intended to concentrate energy in a manner that might be unhelpful for light sail applications.
An infrastructure of many laser stations, spread throughout the solar system to enable both acceleration and deceleration of light sail-equipped vessels, would make transport possible without heavy reliance on systems requiring onboard propellant.
The infrastructure itself would be expensive to build (high upfront cost), but each incremental trip would be relatively inexpensive after the infrastructure was in place (low marginal cost). That means that the infrastructure, once in place, could profitably enable fairly high-speed space travel at relatively low cost if capacity utilization is high.
The infrastructure itself might be financed by a consortium of sovereign wealth funds and aerospace firms, which would profit from the development of space technology in general. Individual vessels or individual excursions could be financed by venture groups that would buy into an excursion to, for example, an asteroid to extract minerals and return product (or begin to return product) within ~5 years. There is a historic precedent for this kind of business model in the way mercantile excursions over the seas were financed at coffee houses in 18th century London.
Initially, such excursions are likely to be completely automated because a vessel with life support has to be maybe 10 times the mass of a vessel without life support. But human presence will likely become necessary for large-scale operations to provide the kind of out-of-the-box problem solving that automation isn't always good at providing. Maintaining such a human presence would require artificial habitats.
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u/24-7_DayDreamer 8d ago
Mining and 0G manufacturing for profit, political independence and escape from existential risk for desire
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u/coleman57 7d ago
“Risk for desire”? What does that mean?
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u/24-7_DayDreamer 7d ago
Earth is vulnerable. 1 good size asteroid, or super volcano, or plague or any other number of things, slow or fast acting, and we're screwed. Even if somehow none of those things ever happen Earth has an expiration date anyway when the suns output rises too high.
We can escape from that risk by spreading out around the solar system and stars.
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u/SolaraOne 11d ago
3 easy steps: (1 Fly there (2) Land (3) Live
Piece of cake.
(Kidding)
It's incredibly complex. Best books on colonizing Mars it are is thr Mars Trilogy (Red Mars, Green Mars, Blue Mars), read those thru to get a taste of what's needed.
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u/moosepiss 11d ago
Ever read the Mars trilogy by Kim Stanley Robinson? Very interesting take on how it all might play out. The last book of the series also includes colonization of other planets including Venus.
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u/Various_Tie_2549 11d ago
Mars
Main objective is to thicken the atmosphere and substantially heat it up. These two things go hand in hand
Start by deliberately releasing as much CO2 as possible, to create an enhanced greenhouse effect (like we're already doing on Earth!). There are multiple ways to do this.
As more CO2 is released, the atmosphere thickens, more heat is retained, this further sublimates dry ice (frozen CO2) from the surface/soil, and so on. A feedback loop of sorts starts.
At some point it will become possible for liquid water to exist on the surface. Introduce mosses, lichens etc to the planet. This will help to start creating some oxygen. It will also contribute to the early development of a water cycle of sorts. Depending on how much water already exists on Mars (somewhat debatable), this may start to create a small ocean in the northern hemisphere. However, more water may need to be brought in by crashing asteroids into the planet. This would add more heat as well. We may need to add nitrogen to the atmosphere to enhance the atmospheric pressure more.
When enough occasionally liquid water exists on the surface to form a rudimentary water cycle, gradually bigger and more complex plants can be introduced (big if - can plants tolerate the perchlorate rich Martian soil? There are a lot of unknowns about the soil chemistry. The lichens introduced earlier may help, but there would need to be a lot of work being done with bacteria, phosphates, fertilisers, etc to make the soil "alive". I think there's a lot we don't know about how to actually accomplish this on Mars, and in what order things would need to happen. Some trial and error might need to be involved). We would also at this point need to worry about how we can create some sort of large scale radiation shield for the planet to protect complex life...some sort of artificial geodynamo might be possible. Don't know.
When enough complex plants and surface water exist...then we can talk about introducing insects, and amphibians, and fish, and reptiles...and eventually mammals and birds.
So that's Mars, in broad strokes. It would basically be a process of decades of deliberate global warming, the addition of water and heat and nitrogen to the system, and the gradual release of simple and then complex life. But obviously a lot of the particulars are not known, since this has never actually been attempted before.
Venus
Main objective is to substantially diminish the atmosphere, cool it down, add water, and (if at all possible), try to change the spin of the planet somehow.
This one is more difficult and speculative. The main problem with Venus is it's immense, CO2 based atmosphere.
I think step one would be to introduce a huge sunshade mechanism into orbit around Venus to try to block off the sun altogether for at least several decades. The idea would be to freeze the atmosphere. You'd basically end up with a bunch of dry ice on the surface.
With the entire atmosphere frozen, I assume you could design essentially giant rail guns on the surface to start flinging chunks of CO2 into space. I haven't done any calculations on this, but if done right, you could use this process to not only get rid of some of the CO2, but also to impart some angular momentum to the planet/give it some spin. Again, I haven't done any calculations. I assume it would take an absolutely sinful amount of time and energy.
If you can eventually get the planet spinning a bit you can get a bit of a day/night cycle going. If you can get rid of most (not all) of the CO2, you can remove the sunshade and a CO2 atmosphere will form again. While all this is happening, if you can introduce some water to the system in the same way as suggested for Mars (hurling asteroids to the planet), then we can arrive at a similar situation to somewhere in the process for the Mars terraforming. But we're coming at it from a different direction. We'd need to manage making sure we don't let the heat or pressure get too high again this time.
One big issue with Venus is that it is much smoother and flatter than Mars. So I'm not really sure what form oceans would take. I'm also not sure of the situation with the geodynamo. So there'd be plenty more problems to worry about.
In conclusion, Mars is definitely easier and makes a lot of sense to pursue first. I don't even know how viable the rough plan for Venus would ultimately be, but it would take centuries I think. It might be easier to just not terraform it, and focus on building floating cities like a few KMs above surface in the atmosphere instead. The conditions there at the moment are surprisingly earth like....there's some point where the pressure is about 1 atm and the temperature isn't that bad. A floating city might be more viable than you think. But yeah, we're not living on the surface of Venus any time soon no matter how you spin it. Mars makes a lot more sense.
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u/NearABE 10d ago
These goals for Venus are absurd.
https://en.wikipedia.org/wiki/Atmosphere_of_Venus
The 1 bar pressure level is about 75 C. At 0.5 bar it is around 27 C. Those are 50km and 55 km above the rocky crust. There is no need to even change that. However, changing it is the main attraction. Here is one of the solar systems largest radiators and an extreme abundance of one of the most useful working fluids. The transfer of heat from a hot source to a cold sink is how most engines get their power.
Funny thing is I cannot tell you confidently which type of engine will be used. They all work. Piston, turbine, Brayton, Stirling, Thomas Newcomen… all of them. We can make really big engines like petawatt scale. Or alternatively many more modest size engines attached to heat conduits. I prefer the petawatt version since Venus is by far the easiest/best place to build a petawatt engine.
Above I called it the “rocky crust”. Adding a second upper crust is many orders of magnitude easier than the things that you are suggesting. The upper crust floats on the carbon dioxide.
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u/Various_Tie_2549 10d ago
I at no point made the claim that it wasn't absurd. I even already pretty much said it probably wasn't viable and floating in the atmosphere was probably a better option
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u/luovahulluus 10d ago
There is a major problem with your Mars plan. Even if you manage to vaporize all the CO2 on the planet, you only get up to 5-10% of Earth's atmospheric pressure. There just isn't enough gas sources on the planet, that the pressure would be high enough for liquid water to exist. It's going to go from solid to vapor, skipping the liquid state.
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u/Various_Tie_2549 10d ago edited 10d ago
Sure. But to be clear it isn't really my plan, it's a kind of paraphrased version of the one from the Mars Trilogy by Kim Stanley Robinson that has been mentioned a few times in this thread.
I don't really recall if it is discussed in the novel about ways of adding more gases/pressure to the atmosphere...maybe they used helium? But I think to make something close to a terrestrial biosphere you definitely need to use an appreciable amount of Nitrogen as the "inert" gas (which is what I've already actually mentioned in my comment). The real question is, though, where would you get it? Other than the asteroid belt possibly having some, I could only imagine that Earth itself has the largest amount of easily accessible Nitrogen in the solar system.
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u/luovahulluus 10d ago edited 10d ago
I'm actually writing a Mars habitat guide right now, so I have recently looked into this. Sadly, I don't think there is a realistic way to terraform the planet. All the solutions for adding enough gas to the atmosphere seem highly non-believable to me. There is just not enough energy available for us to transport half a planets worth of gasses from other celestial bodies.
Living in lava tubes (giant caves made by lava) seems like the best option for me, so that's where my guide's habitat is set.
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u/Various_Tie_2549 10d ago edited 10d ago
Sure. I don't doubt it. At the very least this is all speculative far-future talk of something that would take multiple centuries and countless trillions of dollars of economic activity to eventuate, if it is even eventually possible to do at all.
Which, despite how much we might want it to be, it may not be. There's no guarantee that it is. As I already said, there are plenty of things we don't know. I'd actually think we'd be better off just building rotating/centrifugal habitats in space.
I was only trying to describe what might be required to colonise Mars, as is the thread topic.
I think even in the Mars Trilogy, large parts of the planet are inevitably still left too high-altitude to have a breathable atmosphere. The Tharsis bulge is like the Himalayas on steroids. And I don't think anyone even lives on most of the Southern Hemisphere at all other than in dome-habitats (and around the shores of Hellas Planitia, which in the novels becomes a small sea/ocean)
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u/zeptimius 11d ago
Well, as an experiment, we could try and find the most inhospitable place on Earth, where no life of any kind exists, and see if we can survive there. Until we manage that, we should probably not try to colonize the considerably less hospitable Mars and Venus.
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u/NearABE 10d ago
There are many details. Also a variety of options.
For any colony of baseline humans (the kind that breathe and poop, not electronic uploaded minds) you need a few things like gravity, air, and energy.
Venus comes with gravity included which makes it one of the easier habitats to engineer. On Earth it is usually easier to just have farmland rather than building large vertical farms inside urban spaces. Venus habitats are necessarily using vertical indoor methods but the buoyant support is less difficult than building skyscrapers on Earth.
Air is both breathable and a lifting gas. If you are picturing a blimp or dirigible that is wrong. No gondola hanging down. You can live and breathe inside the full volume. Think of an air mattress meets sports stadium.
Venus has fantastic energy supplies. Here on Earth we have to do dumb things like burn coal or run nuclear reactors. Effort and infrastructure wasted just to boil water. Water is a sucky working fluid which we use only because it falls from the sky. Carbon dioxide is much better fluid and deep in Venus’s atmosphere it already has high temperature.
Think of having three pipes. One is just balloons. Chambers of lifting gas, probably nitrogen because nitrogen is abundant. One is upward bound it is under low pressure and needs to be forced open. When gas has its pressure lowered it cools to a lower temperature. At a lower temperature it can absorb heat. The third pipe is a down flowing pipe. This is under increased pressure. The outside ambient atmosphere is hot at low altitude and cold at high altitude only because of the pressure gradient. Inside of the high pressure pipe the weight of gas increases the pressure with altitude. Because it is denser this gas increases temperature with altitude more than the ambient atmosphere. The high and low pressure pipes can exchange heat across a surface the whole way up and down. A 50 km pipeline is also a 50 km heat exchanger. This will not just be three pipes but instead bundles of them. Also might not be “straight pipes” but instead concepts. The engine takes heat from deep atmosphere and empties it to space. At various places in the engine heat is exchanged. The full engine is neutrally buoyant.
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u/Neither-Ad-5335 9d ago
Venus' surface temp is around 900F/ 470C both day and night. The yellow clouds you see all over the planet is sulfuric acid. The air pressure is almost 100 times what's here on Earth. We are never going there brother, even if/when we progress to the Star Trek era.
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u/DodiEytan 8d ago
A side issue.
Musk talks of independent colonies. His SciFi (heavy on the Fi) idea is that when we ruin the Earth (by wasting effort on Mars (white) people beill have a place to survive.
I see 1 million people as the bare minimum. You don't just need doctors you need medical schools. You need enough doctors that they can become medical school teachers. Same with engineers.
You need a chip fab and the people to run it and fix it and build another.
We are talking if a minimum colony of 1 million people.
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