Is a space ark a workable idea?

[ArguesWithStrangers]

TBH, it wouldn't be a bad thing if the human species did go extinct. We have nothing to offer the rest of the universe. Even if such a thing did exist, it would be a situation where only the very rich or powerful would be given space.

I bet you're a blast at parties.

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More specifically, we DO have the technology required for a generation ship. The cost to build it is just in the hundreds of trillions of dollars. On the low end. You're basically having to create a flying city, with enough hydroponic farmland to supply those people with food and O2, AND find a way to boost it to a significant fraction of light speed, so the journey only takes centuries.

The engine's the hardest part, and between ion engines and solar sails, we're basically there I think.


The REAL problem with the endeavour is that wherever we end up is probably lifeless rocks we'd have to terraform. And if we can manage that, we've got plenty of planets and planetoids right here that we should focus on first. Even if we build the ark and leave it in orbit as an enormous station, that makes more sense than actually sending it anywhere, right now.

I watched a cool video that offered using nuclear blasts to accelerate a ship to the speeds required. I'm no physicist so I don't know the feasibility of it, but it was a rather unique take on the problem. One issue I've never seen convincingly addressed is collisions with unavoidable objects in space. The Kuiper belt is full of fast moving objects that would rip a hull to shreds.

[Zantos]

The only way it would is if we have the resources and time to build it once we do have the technology. For one to be successful, they would need technology to survive for a prolonged period of time until they got to their destination and then the technology to survive there.

[Dhrizzle]

If we can make some sort of space-borne construct that could sustain human life for an extended period why bother sending it to another star? Just build space-borne habitats and have people live in them. Start with a simple O-Neil tube and work our way up to rings with a roughly 3 million km diameter.

[Endus]

I watched a cool video that offered using nuclear blasts to accelerate a ship to the speeds required. I'm no physicist so I don't know the feasibility of it, but it was a rather unique take on the problem. One issue I've never seen convincingly addressed is collisions with unavoidable objects in space. The Kuiper belt is full of fast moving objects that would rip a hull to shreds.

It's feasible in terms of providing thrust, the bigger issue is that explosive thrust is a big delta-V and then nothing, and you need to pack fuel. More fuel is more mass which means you need more delta-V, and that's a problem.

That's why a lot of suggestions for an ark ship (short of a massless drive which is science fiction) looks at long-duration, low-delta-V thrust options, like solar sails or ion drives. You get way less thrust per second, but way more thrust per kilo of fuel (solar sails don't require fuel at all). For normal trips, the low thrust means you'll take forever to get there, but if you're going to take a century or more, being able to boost continuously for decades at that low thrust makes a huge difference in terms of velocity. If we develop a solar laser (basically a giant, aimable magnifying glass set to focus solar radiation to a beam), you basically just set that up, aim it at your destination star, and ride that beam with the sails. When I say "beam", I also don't mean like what we see in science fiction, we're talking a beam as wide as the sails on the ship, so a few dozen kilometers in diameter, at least. The goal isn't to make the beam high-energy, just to provide light pressure that doesn't dissipate over distance.

At that point, the sails can handle the acceleration phase. The only issue is you won't have another beam on the other end to brake. So you either need reaction mass for a conventional drive for a much faster deceleration phase, or have worked out some other solution. Using the sails as a brake MIGHT work, if you can pick up reaction mass with scoops; if the target destination has mass like we do in the Kuiper belt, you could brake as you come in with sails and reaction drives, scoop up more mass as you punch through the system, go out the far side, burning again but putting the sails away. Once you slow enough to start falling back due to gravity (this would take decades, itself; this isn't an elegant finish), you pop out the solar sails, brake more, scoop up more mass, fire the reaction drive, and keep yo-yoing until you slow down enough to settle into an orbit. The nice thing is this gives you a few separate pass-throughs of the system to pick up observational data on planetary bodies and spectra and the like, so by the time you're ready to pick an orbit, you know where you'll want to be. The deceleration phase is basically going to take as long as the acceleration phase, or more, in this kind of setup, but technologically, it's pretty simple. And with a generation ship, if it takes a few more decades or a century longer, so what? You're worried about making it at all, not getting there quickly. The bonus is if anything crops up as a problem from what you see on your first flyby, you've got several lifetimes for crew to work on solving those issues before the solutions need to be implemented.

Solar sails are hugely underrated. They're slow, but they just keep generating "free" thrust as long as there's light pressure.

[Celista]

Whether or not it is a workable idea, it is a bad one, unless very well thought out. Any sort of ark will be filled with rich people/politicians (aka people who can pay for a spot) and there is a disproportionately high number of sociopaths in both politics and especially high-level positions in business. They're also not necessarily the brightest. If good decision-making prevails, we'd choose individuals with traits that show off the best that humanity has to offer. But unfortunately life doesn't tend to happen in conjunction with good planning or decision-making, especially with emotionally-charged issues like mortality.

[munkeyinorbit]

Actually, wealth would be worth nada on a planet that doesn't have/take your currency so the only ones who could board such a ship would be people with useful skills like agriculture, medicine, and the like.

And the slaves needed for the grunt work. Robots? That would be better. But human accomplishment has always relied on breaking the backs of the masses to achieve.

[Kasierith]

More specifically, we DO have the technology required for a generation ship. The cost to build it is just in the hundreds of trillions of dollars. On the low end. You're basically having to create a flying city, with enough hydroponic farmland to supply those people with food and O2, AND find a way to boost it to a significant fraction of light speed, so the journey only takes centuries.

The engine's the hardest part, and between ion engines and solar sails, we're basically there I think.


The REAL problem with the endeavour is that wherever we end up is probably lifeless rocks we'd have to terraform. And if we can manage that, we've got plenty of planets and planetoids right here that we should focus on first. Even if we build the ark and leave it in orbit as an enormous station, that makes more sense than actually sending it anywhere, right now.

From a medical perspective, we aren't there yet. We know that there are significant concerns with muscle and joint development, radiation exposure, and the effects of long term isolation and confinement. We also don't know how zero gravity is going to impact certain health conditions since a basic requirement is peak physical health; one of the benefits of gravity with edema from congestive heart failure is that the feet swell and while that's not good at least it's away from central organs, for example. And then there's medicine. The way modern pharmacology functions is that you don't start from scratch to make a drug; you piggy back from more natural processes. A key blood thinner is derived from plants only found in southeast asia, for example. There are numerous rare minerals used in making drugs. And anyone who has taken organic chemistry knows that there is a lot of waste made from creating even basic drugs.

It's not as sexy as ion engines, but ultimately modern medicine is built on rare and nonrenewable resources and being able to account for a good amount of chemical byproducts. And we aren't anywhere near the level of recycling technology to incorporate waste and chemical byproducts back into usable material.

[For_The_Horde]

I swear I've seen this movie before... oh right.

[Endus]

From a medical perspective, we aren't there yet. We know that there are significant concerns with muscle and joint development, radiation exposure, and the effects of long term isolation and confinement. We also don't know how zero gravity is going to impact certain health conditions since a basic requirement is peak physical health; one of the benefits of gravity with edema from congestive heart failure is that the feet swell and while that's not good at least it's away from central organs, for example. And then there's medicine. The way modern pharmacology functions is that you don't start from scratch to make a drug; you piggy back from more natural processes. A key blood thinner is derived from plants only found in southeast asia, for example. There are numerous rare minerals used in making drugs. And anyone who has taken organic chemistry knows that there is a lot of waste made from creating even basic drugs.

It's not as sexy as ion engines, but ultimately modern medicine is built on rare and nonrenewable resources and being able to account for a good amount of chemical byproducts. And we aren't anywhere near the level of recycling technology to incorporate waste and chemical byproducts back into usable material.

Some of that can be pushed aside, the zero-G and radiation in particular. We can do radiation shielding, especially when we'd need water stores and water is a pretty effective radiation shield. Gravity we can't replace, but we can fake it with centripetal force. If we hollow out a large asteroid (and by "large", I mean like 30 kilometers across), you can give it an axial rotation and build everything into a cylinder. Long-term storage and engines and such can go along the axis; you access it as needed so low-gravity is, if anything, a benefit, reducing stress and making manipulation easier. Living quarters go closer to the outer edge of the cylinder, where centripetal force gives you a decent equivalent of gravity. Below that, you have the water storage tanks, and then whatever additional shielding you deem necessary, and then, outside that, a lot of rock. Which provides even further shielding; you design the cylinder so it should serve by itself, and the rock both acts as scaffolding for construction, and as additional shielding and, if need be, emergency material resources, since most asteroids are rich in things like iron.

As far as pharmacology goes, this is a long-term trip. If we can't create it from what we bring, we'd have to do without it. We're not going to be transporting the planet's entire ecosystem. Does this mean going without some drugs? Sure. We can potentially mitigate this somewhat by finding less-effective but easier-to-produce alternatives, or limiting crew membership if there's any genetic heritage of certain conditions to obviate any need for the drugs that treat it. Will they be as well-off as people remaining on a healthy Earth? No. But that's been true of explorers and colonizers for basically all of human history. As long as we're not talking about something that could lead to the death of the crew as a whole, it's not absolutely necessary.

[endersblade]

Everyone is always full of "great" ideas, but no way to pay for them.

And that is the crux of the problem. Money. Nobody wants to save Humans, or this planet, because it costs too much money and there is no money to be gained in the end. Except existentially, of course; humans living longer = more spending. But no immediate gains.

So thusly the human species is doomed, all because of greed.

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I swear I've seen this movie before... oh right.

I loved that movie, thanks for the reminder! Gonna go dig out the DVD and watch it :-)

[smityx]

I think that by time if such a thing were to happen by time that first generation ship reaches it destination after 100's if not 1000 years they will arrive to find out we already arrived centruies earlier on another ship that used faster engine tech. We'll always be advancing during those years during the trip.

[yetgdhfgh]

I expect so but it would be a shitty life imo but its prolly our best shot to outlive the universe.

We know how to recycle water, we can use artificial sun rays to help plants grow and stop us from getting rickets, we could control the population inside it etc

A space ark is the only way our species will survive cause we cant planet hop forever! Once this planet is kapput our next stop is mars and once that becomes unihabitable our next stop would be one of the moons of Jupiter or even Saturn and once that is a no no then we better learn how to travel faster than light or how to create stasis so we can survive till we get to the next planet.

Eventually we will run out of planets and our only hope is just to survive onboard a spaceship forever and ever amen!

[Deleted]

TBH, it wouldn't be a bad thing if the human species did go extinct. We have nothing to offer the rest of the universe. Even if such a thing did exist, it would be a situation where only the very rich or powerful would be given space.

With humans gone, what will stop asteroids from hitting precious animals like elephants, pandas, bunnies, bumblebees etc. ??