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Is this a realistic way to colonize and explore the universe? No. Apart from problems with generational ships, which you'll find discussed on Worldbuilding SE in other questions, there is a fundamental flaw in the reasoning: they get to work making the planet livable for the people who want to have a sky over their head The people you have described ...


54

Slow being a little less than half the speed of light, thanks to getting a very large boost as they start their journey. Slow down there! literally. At that speed it's not really a generation ship since you can get to many other stars within the original crews lifetime. And there are hazards to going that fast. Lets assume the ship is, say, 10X the ...


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Dredging The first thing to note when you search for dredging is that it's not Wikipedia at the top, it's an advert for a dredging contractor. This isn't something that can be ignored, it's a matter of ongoing maintenance in any managed or artificial waterway. When water enters, whether through the channel or as runoff, it carries suspended particles that ...


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Well, Difficulty considerations aside, if you took a lot of asteroids and merged them together into an earth-mass planet, it would be entirely molten just from the gravitational binding energy. You'd need a few million years minimum just to get a stable crust, then you'd have to deliver water and volatiles.. Then, once all this had settled down, oxygenate ...


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The biggest problem is going to be atmospheric oxygen. The main source of oxygen in Earth atmosphere is photosynthetic plant life. Oxygen is a reactive molecule. It tends to react with minerals (oxidize like rust) and not be present as a gas in the atmosphere. Without plant life, you are going to need a continuously renewing source of oxygen, and I'm not ...


34

Let's make a list, then narrow it down. Here's the criteria to judge scenarios Kill off most people Make big cities uninhabitable Make food and clean water hard to come by Be predictable enough to evacuate world leaders Be plausible enough that it could occur in real life Here are scenarios that won't work, but you could handwave ...


34

Take a look at this description of how DNA sequencing works, both today and 30 years ago. Basically, 30-odd years ago we did sequencing manually with a whole bunch of scientists (and/or interns) chugging through line after line of DNA molecules. It was an incredibly tedious process, which is why we've since passed it off to computers. However, while ...


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What would it take? Answer: Nothing. They're already living in it. If there's a Goldilocks zone, they can park their Space Ark there. That basically sorts out their energy requirements forever, and they can mine asteroids. There's no reason they can't live in their Space Ark indefinitely. But more likely, like any family, they're going to start wanting ...


28

The first reason off the top of my head is the time it would take to find a new world that is already habitable or easier to terraform, versus the time it would take to terraform a world that's close by. Habitable planets are not that easy to find Faster-than-light travel is a not a trivial problem and it may take much longer to solve than terraforming. ...


28

No, you cannot build a world in 1000 years As already mentioned by Andrew Dodds, the time span you have at your hands is orders of magnitude less than what is simply required by a newly formed planet to cool off and get stabilized in its orbit. Of course we are talking about moving asteroids from their orbit and combining/colliding them together to form a ...


27

This is what we do, it's what we've done for thousands of years Plant some of everything to start with, see what survives. You're going to end up with Japanese knotweed, horsetail, Russian vine, bindweed, ryegrass, dandelions. Weeds. The kind of plants where the first google result is "how do I get rid of [...]". Why? because they're hardy, they'll survive ...


26

If the planet is not inhabited by sentient beings but does have flora and/or fauna on it some people might want to protect the biosphere as it. That could cause them to become eco-terrorists who want to stop the terraforming process because it would destroy the original and, most likely unique ecosystem.


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There are reasons to Terraform and there are reasons to not Terraform. Assumptions For my answer, I take the term "Terraforming" as a generic term to create a passive closed-loop environmental system capable of sustaining human life. It's only external requirement is to supply the system with sufficient energy to drive the system. This includes massive ...


25

I would say capturing a bunch of comets and burn them up in the atmosphere, leaving plenty of water vapor. Hydrogen and Oxygen are two of the most common elements in the universe, #1 and #3 respectively. So any 'atmosphere' you have will likely have plenty of both of these elements. As long as there is hydrogen available, you can have microbes or ...


25

This article gives us some useful numbers: The mascons' gravitational anomaly is so great—half a percent—that it actually would be measurable to astronauts on the lunar surface. "If you were standing at the edge of one of the maria, a plumb bob would hang about a third of a degree off vertical, pointing toward the mascon," Konopliv says. So the "water ...


24

Actually, there are multiple reasons it can't be done as you hoped Trying to make a single air-supported structure to cover the entire moon is a rather insane idea. For safety and other reasons, large areas would be necessarily be broken into a (possibly connected) series of pressurized areas. Losing pressure (planned or accidental) would limit the affected ...


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I saw several answers here close to what I wanted to say, but none of them quite do. So: Plastic Wrap Not Needed If you supply the Moon with an atmosphere, that atmosphere will not be instantly lost to space. On human time scales the Moon holds most atmospheric gases quite well. However, it will slowly bleed water away to space. So the important ...


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As I know very little about your world and your terraforming and travel methods here are some general ideas. 1) Terraforming is expensive — Terraforming in the solar system costs more than travelling to already habitable planets. Maybe interstellar travel costs next-to-nothing or terraforming requires a rare/expensive element. 2) Terraforming takes time — ...


20

Build a fusion candle. You have a large gas giant? Perfect, you have a world mover with its own reaction mass/power supply. I assume this gas giant has a few largish moons? If not, move it around the system to capture some other suitable planet. Forget the asteroids, they contribute nothing of value, at least concerning raw mass. (Wikipedia: "The total ...


20

Is this a realistic way to colonize and explore the universe? Sure it is, this is the same process used by Polynesians to colonise the Pacific Islands. They had boats with everything they would need and would find a place, build. Then a few generations later when population pressure mounts they would split and some would go looking for another Island group....


19

Setting aside what "terrorism" actually means in our modern context, I'll answer assuming that you are asking for reasons why any group would violently oppose terraforming (the process of making other planets habitable for humans). In a twist from dot_Sp0T's answer, what if it were an extremist arm of environmentalists who see terraforming as "giving up" on ...


19

Three possible solutions spring to mind off the top of my head: One The advanced civilization bio-engineered silt slugs to eat the silt, crawl out of the canal and deposit the silt on the banks of the canal, all done in an environmentally friendly way, of course, and nicely integrated into the ecosystem(s) surrounding the canals. Two Automated dredgers ...


19

If you want an Earthlike planet, and Mars is out, Venus is the only option. No other rocky body has gravity high enough to hold an atmosphere, especially close to the Sun where the solar wind is strong. (Titan is far enough away to not make this an issue, but it is VERY cold). It won't be easy, though. It would require removing most of the atmosphere, which ...


18

Protect the Rocks! As far as I remember the books, in Kim Stanley Robinson's Mars-Trilogy there actually is a group that wants to at least minimize terraforming, to protect the natural shape of Mars. There may not be an eco-sphere, but there ARE rocks and mountains and craters formed by planetary evolution nonetheless. And terraforming WILL destroy those! Do ...


17

A lot of the good ideas for these apocalypse scenarios have already been done, although unfortunately they are often done badly (most asteroid impact scenarios for example have horrific scientific flaws). There is one idea I can suggest though that should achieve most of what you need and that I don't think I've seen done before. A small rogue planet (...


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Mass of the moon: $7.4*10^{24}kg$ Average amount of poop produced an an average human in an average day, on average: $0.5kg$. Amount of time required for a trillion people to produce that much poop: $4.05 * 10^9 \textrm{ years}$. I'm not sure your plan is very viable. To answer your question in a slightly different way, related to Kepotx's comment, why ...


15

Movement of Gases That's the most obvious thing to happen, which you've accurately identified. Assuming the portals are both on the surface, the air at the portal will have the respective air pressures (with forces acting on that area of the portal given in parentheses): Venus: ~92 bar (28,902,652.4 newtons) Mars: ~0.00636 bar (1,998.05293 newtons) ...


15

Volcanic planets are actually in the process of cooling themselves down already (see bolded answer further down.) In addition, the heat is not from the volcanoes but rather the greenhouse effect. "Venus is hotter due to the greenhouse effect: Venus has an atmosphere about ninety times thicker than that of Earth, and made almost entirely of carbon dioxide, ...


15

Having any kind of atmosphere, in the natural sense, is pretty much not going to happen. With only 3% of Earth's gravity and no magnetosphere, Ceres has virtually no ability to retain atmosphere against the solar wind. Even Mars has difficulty holding a useful atmosphere, and it's substantially bigger and outgassier. If you try melting a subsurface ocean, ...


15

Terrain While generally similar to Earth, Schmell's biosphere is mainly swampy. Its murky water is packed with organisms similar to phytoplankton, which humans harvest to fill dietary niches previously occupied by grains. There is also an abundance of zooplankton and many other larger species that dine on the phytoplankton. Aquatic organisms are in such ...


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