Could we build a generation ship today?

[Kilmeister]

I came up with this idea while about to respond to another thread (What should we do if an alien race needs our help) and I didn't want to derail it.

So the question is, Using today's technology,would it even be possible to even construct a huge generation ship to carry 250,000 people to another star system, other technological shortcomings aside. My thoughts is no, we couldn't and here's my reasoning.

I just did some quick calculations to get a rough guestimate of what the construction would entail. Using a large modern day cruise liner as a starting point: Royal Caribbean's Oasis of the Seas. I'm using a cruise liner because it's the best analog I could think of. Although our generation ship probably won't have pools or a grand dining hall, It will require a lot of other infrastructure.

It carries 6000 Passengers with a displacement of about 100,000 tones

Ton Per Person=16.66 Ton/Person

Lets just go ahead and assume lighter weight material all around and shave off 35% arriving at 10.8 Tons per person

So for the lucky 250,000 Humans we will be sending off in the cosmos we need to build a ship weighing in at 2,708,333 Tons.

The Falcon 9 Heavy can lift a payload of 53 Tons/Launch.

At that rate It'd require a Minimum of 51,101 launches just on materials alone. Not to mention other launches to carry construction workers.

At 1 Launch Per Day: 140 years

I don't know what the current max production rate of launch vehicles is, but I'm sure we don't have the infrastructure to maintain such a schedule. Even if all the major nations of the world mobilized their economies to support such an effort. So until we move on past traditional rocket launches. A generation ship is out

Anyways, I just thought I'd share my little though experiment.

[NASAFanboy]

Firstly.....

Show me the money.

The main difficulty would be for finding investors and funders. This would require one the greatest acts of generosity in history.

The society that built the ship will have little to no payback at all.

They'll never see it again.

[Deadpangod3]

Firstly.....

Show me the money.

The main difficulty would be for finding investors and funders. This would require one the greatest acts of generosity in history.

The society that built the ship will have little to no payback at all.

They'll never see it again.

Except when that asteroid wipes out all life from earth and the generation ship is our only lifeboat

[SargeRho]

Only if you include "Develop a life support system that can last for centuries" in "Build".

[NASAFanboy]

Except when that asteroid wipes out all life from earth and the generation ship is our only lifeboat

Except that.

Asteroids are natures way of saying "How's that Space Program coming along?"

[LordOfTheOrbits]

Assuming that we don't care about political or financial issues, I think it would be possible.

The largest spacecraft design analyzed in Project Orion was 8,000,000 tons heavy and 400m wide and would be able to host a city with more than 100,000 people living in it. If we either made an even bigger version of it or launched three of them into space, we certainly could take 250,000 people to another solar system.

Assuming we include political and financial concerns, it's probably impossible because this would take thousands of billions to build and other countries (and the people who live near the launch site) may not like it when you build a spacecraft that uses 3,000 ton nuclear bombs for propulsion.

Assuming that earth would somehow get destroyed in ~100 years we might be able to build it if all states worked together and there would be lots of workers willing to work on this even though they will stay on earth and die.

[Idobox]

There is absolutely no good reason to put 250 000 living people in a generation. Put a few hundred skilled workers and a few million frozen embryos.

If you have the resources to make a single 250 000 people ship, you have the resources to build a bunch of smaller ships, which largely improves your chances, and might even allow you to save more people (building stuff in series is something we're really good at).

Building a generation ship with current rocket technology is out of reach. Luckily, we have an other option: Build it on the ground, strap an Orion Drive, and nuke the launch pad. Who cares if you render the Earth inhabitable if you are facing extinction anyway?

[SargeRho]

And you'd not build just one, you'd build an entire fleet of them. Perhaps in the asteroid belt or in orbit around the moon, so that the Orion drive doesn't damage Earth's ecosystem. But sleeper or seed ships might be a better way to do it, and you might find more willing victims, err...volunteers

[Deadpangod3]

There is absolutely no good reason to put 250 000 living people in a generation. Put a few hundred skilled workers and a few million frozen embryos.

If you have the resources to make a single 250 000 people ship, you have the resources to build a bunch of smaller ships, which largely improves your chances, and might even allow you to save more people (building stuff in series is something we're really good at).

Building a generation ship with current rocket technology is out of reach. Luckily, we have an other option: Build it on the ground, strap an Orion Drive, and nuke the launch pad. Who cares if you render the Earth inhabitable if you are facing extinction anyway?

Have fun then when the earth would've been habitable again but instead you felt the need to polite the entire planet with radiation, now you'll have to wait another million years.

[Anton P. Nym]

Only if you include "Develop a life support system that can last for centuries" in "Build".

Yup. People like to gloss over this one, but it's a HUGE unsolved problem. (So far, at least.)

-- Steve

[Idobox]

Have fun then when the earth would've been habitable again but instead you felt the need to polite the entire planet with radiation, now you'll have to wait another million years.

Why?

Orion Drives are dirty, for sure, but you wouldn't sterilize the planet for millions of year.

First of all, you would launch all your ships form only a few sites. These sites would get very polluted, but that would reduce the pollution elsewhere.

Second, nuclear weapons are essentially hot neutron reactors burning weapon grade fuel, and thus generate little transuranids (compared to a power plant). Thermonuclear weapons generate most of their energy through fusion, and release a bunch of hot neutrons. As a result, you will release a lot of nasty short-term waste, but little long-term one. Also, only light elements will travel far, and those are always short-lived.

So yeah, it will have disastrous effects on the environment, but the radioactivity would go back to normal in a few decades only, maybe centuries.

[falofonos]

The world's richest 85 people control about $US1.7 trillion in wealth.

If there were a clear and present reason to evacuate the planet and enough time, they could probably afford to fund a moon bunker for themselves, their families and whichever valued servants they needed to peel their grapes and keep the life support running.

Generation ships are a whole different level of investment and technical challenge.

[LordOfTheOrbits]

Actually a long lasting life support system wouldn't be that hard to make, as you could grow a forest and even carry animals that provide food and oxygen and you have always enough people to maintenance everything.

One of the bigger challenges would be turning that monstrosity, especially at the launch. I think that you would need rockets bigger than anything used for propulsion today just to turn that thing.

[peadar1987]

Absolutely. If it was a "generation ship", and not a "multi generation ship". We can put an essentially unlimited mass in orbit with multiple launches. Then it's just a matter of having lots of spare parts, huge amounts of supplies, recycling for water, etc. Supplies would eventually run out, but I reckon we could put something self-sufficient in space that would keep at least some of the people inside it alive for 50-100 years.

[3_bit]

I know we could do it today... What would be more efficient is a 15 or so man crew, with the rest of them not born yet, being frozen single-celled human zygotes. This would allow for exponentially less equipment to be on board, needing only a large nuclear reactor and rod storage, solar arrays when you can use them, batteries, a greenhouse, and an array of artificial wombs. We don't have such things developed yet, but I'm confident making one wouldn't be too hard.

[Idobox]

I know we could do it today... What would be more efficient is a 15 or so man crew, with the rest of them not born yet, being frozen single-celled human zygotes. This would allow for exponentially less equipment to be on board, needing only a large nuclear reactor and rod storage, solar arrays when you can use them, batteries, a greenhouse, and an array of artificial wombs. We don't have such things developed yet, but I'm confident making one wouldn't be too hard.

We don't really need a greenhouse. An algae bioreactor provides the same service for a much lower eight. Of course feeding only on spirulina for the next 500 years might cause problems.

Nuclear reactors in space are troublesome because you need to dump heat somewhere. It's still the best solution, but would probably be very challenging.

And finally, why would you use artificial wombs when it's so much easier to have an all female crew?