GENERATIONAL SHIP

This is a fully self-sustaining ship in which, you guessed it, generations of people live and die on the journey to another star. The original crew would not reach the destination, but maybe a great-great descendant would (if all goes to plan).

Without a discovery of artificial gravity, these ships would have to rotate to provide it by using centrifugal force. This leads the designs of such a vessel into O’Neill cylinders – a ship with two counter-rotating cylinders to cancel out gyroscopic effects. Common sizes are that each cylinder would be 5 miles in diameter and 20 miles long.

The other way is to hollow out an asteroid and build the environment inside it. This has the added benefit of having a shell of armor to better withstand possible impacts as the shell can be anywhere from 10’s of meters to kilometers thick. It would also more easily shield the occupants from cosmic radiation. Also during the voyage the colonists could mine additional resources as needed.

Either way, the ship would be large as all food would have to be grown and all water recycled. The air would have to be purified as well. With enough vegetation it could be possible to do this naturally, especially if you add in the possibility of genetically engineering them specifically for the tasks.

The amount of power required to light this artificial world and power all the needs of the ship and colonists would be massive and need to last the long journey. The most obvious power would be nuclear.

The means of self-sustainment must be able to operate for the entire length of the journey, which could be thousands of years. You wouldn’t want any system to stop working and have no way to fix it – there would be no resupply or rescue ever. This leads to having a complete natural ecosystem on board, such as was attempted in biosphere 2.

The number of colonists needed to keep the population genetically healthy has been estimated from 160 (if they mix their genes with 10 other people) to 40,000 – with 10,000 being a satisfactory amount.

So if all those challenges are met, this type of ship has the problem of the human factor. While you can screen and pick the personalities of those initial members, their children and children’s children personalities you cannot. Locked together forever and having to live with people they do not get along with.

What would those generations that are to live and die completely inside the ship to do? Sure they would maintain the ship, but many people suspect that a lack of technical skills would develop as the generations passed. The systems were designed to survive, so repairs should be few and far between.

There is also the mention of culture. Some have suggested having vastly different ideological groups on the ship to increase the chances for survivability when they reach the planet. It has even been suggested that each group be isolated from each other to maintain different cultures so that at least one can adapt to a completely new world. But what happens if they do break isolation? A war on the ship between cultures?

They also say there would be boredom as the whole world was just a few miles squared. Could the latest TV shows, movies and books being transmitted from Earth offset this? What about computer games and VR tech? In the past most humans lived and died in a small 20-40 mile radius of where they were born, so would the answer be to keep humans employed by not using technology as often as possible. Keep the need for farming as manually intensive as necessary? Would this not also have the benefit of helping the future world colonization efforts? Let me know your thoughts, how would the passing generations react?

SLEEPER SHIP

In this design the crew undergoes suspended animation until the destination star is reached. I recently wrote an article on the current progress of human cryptobiosis or suspended animation, click here to read it.

This one sounds great, you volunteer to colonize that new planet, and sleep the whole way there. Eventually decades or hundreds of years later the ship arrives, it wakes you up and you feel as if it was just yesterday that you left Earth.

But what if aging is just slowed down, but not completely stopped during suspended animation? You could go to sleep at age 20 and have aged to 60 when you awoke. Of course there is always the cryonics version where you are frozen and are officially ‘dead’ but the technology is there to be able to revive you exactly as you were. So let’s just say it all works out and you wake up just like when you went to sleep.

Suspended animation ship from the movie Avatar

The ship would still need to be maintained, a failure in a pod would mean death for a passenger. Could computer systems and robots do the entire job or would some humans be needed to oversee it. If so, could the sleepers take shifts to watch over the ship and passengers? Could small groups of 2-5 people wake up for a year shift, and turnover to the next? If you have seen the movie Pandorum you know that whoever is awake is in control. In that movie each crew is awake for 2 years of the journey, but one person goes insane and kills the rest of his crew and then stops future crews from awakening, so some system of negating absolute control would have to be implemented.

This strategy would require large amounts of energy to keep the passengers cold enough, but could be offset by not needing as much elsewhere. Suspended animation also means that some metabolism is active, at a deep sleep it requires 4% of the normal need. That means 4% of the need for sustenance and oxygen. Enough for the journey would have to be stored or created/recycled onboard.

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Artificial womb

EMBRYONIC/EGG SHIP

Why bring a large grown human when you can grow your own there? With this ship we load up an interstellar ship with frozen embryos to be grown near or upon arrival. The ability to freeze embryos is a technology we already possess, and artificial womb would need to be developed.

Since less supplies and human body storage space would be needed the ship could be smaller. The challenge of this method lies with raising a baby without any human adults.

Firstly, an AI would have to be created that can perform as a parent. Babies learn so much from parental interactions that this would all have to be programmed into the AI. This would most likely mean a robot that looks and acts completely human, which is not too far off – at least in the looks department.

Radiation is a problem since just one cell in the embryo having DNA damage could cause a major problem and result in the loss of the entire cargo. Shielding around the storage would have to be the best there is.

In addition we need to provide the babies with the proper gut bacteria for digestion, which is passed from mother to child in the womb.

But the largest questions are in how they would be raised and taught. Would they be raised to be a collective society or independent people? What language and culture would they receive? What would they learn of Earth, or would that be kept hidden? If told of Earth would they be told that it was perfect, or would the horrible histories as well as the good?

So saying that the human looking robots do not malfunction and kill the human cargo, do you think this is a good option? What other ethical type questions for how the babies would be raised did you think of? Let me know in a comment.

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One of millions of possible probe designs

SELF-REPLICATING MACHINES

One way of colonizing the galaxy would be to send out probes that could arrive at another system and use the materials there to replicate and send probes off once again. A theory states these probes traveling at 10% the speed of light would completely colonize the galaxy in 500,000 years.

This fact is also one possible solution to the Fermi Paradox, if it ‘only’ takes 500,000 years why hasn’t another intelligent species done it already? I wrote about one possible answer to that, if you want to read it click here.

Ok, so they could arrive at a system and start building what they are programmed to. Would it build just more probes to continue the process? Would they create infrastructure for a following human colony ship? Would they terraform the worlds? Would they seed worlds with Earth animals and plants, even so much as to be a form of human embryonic ship? If DNA is completely mapped and understood, could life be built from scratch by these machines using molecular nanotechnology?

The more advanced the process, the more need for an advanced or sentient AI. Would such a creation continue its mission, or would it do its own thing? What would limit their spread so they do not become a ‘grey goo’ menace and consume everything? A fail-safe limiting factor would need to be built in.

One method is that human minds are uploaded into these probes and downloaded into a grown human body. We make the journey between stars without our body and all the problems that entails. The minds that are uploaded being copied again and again in each new system – hopefully without errors.

Of course we could just remain machines, but I think the most important question is can we really say we colonized that system if there are no humans present?

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Colonists on a planet around a different star

CONCLUSION

Of course all these ships will need to carry, in addition to the passengers and supplies necessary for the voyage, the tools, machines and materials needed to start the colony in the first place. The ideas can be mixed and matched as well. For instance, an embryonic ship could be sent inside a hollowed out asteroid with the interior as a practice area for the young humans to learn and gain experience before being dropped onto the new planet.

If FTL propulsion is never possible, the galaxy will remain always out of easy reach. The best we can hope for is an extremely powerful sub-light means of propulsion. The faster the spaceship can accelerate, the less time the crew will experience on the journey. Time will still go on as normal for those not onboard, so to be an interstellar traveler would mean giving up everyone else in your life.

While these are fun to watch in a movie or read in a book, in our lifetime we will not have the ability to even start building a ship capable of carrying humans to another star. This is just a fun way to think about it. The technology necessary to complete a trip will slowly build up piece by piece as the years pass, maybe it will be possible in as soon as 200 years.

First things first though, we need to start doing more stuff in space and then other planets and moons. Elon Musk says he will build the first human colony not on Earth, but we shall see if it comes to pass. If anything, the experience and practice from his efforts will be worth it.

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Sources:

• GENERATION SHIPS
• Generation Ships
• Sleeper Starship
• Controlling the Galaxy with Von Neumann Probes
• Starship “Egg”: Sending unborn, frozen embryos across interstellar space
• Associated Wikipedia pages

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