IAC 2016 - Making Humans a Multiplanetary Species

[HelenF]

Afaik although we know in principle how cryosleep might work on a scale of a complex organism like a human, there are some practical problems we haven't solved (yet). One problem is, that when you put a cell into cryosleep, there will usually be ice crystals forming which destroy the cells.
There are two ways out of this:
1. Use some sort of antifreeze agent to prevent the formation of ice crystals: I have no idea if there is an agent that might work. Most of the ones we already use are toxic. On the other hand there is a frog whose name I can't remember, that goes into hibernation during winter, mostly freezing solid, but it produces its own antifreeze agent.
2. Freeze the body so fast, that there is no time for ice crystals to form: We use this technique to freeze single cells, e.g. for in vitro fertilization. No idea if that can be applied to a whole human body. 50-100kg of meat are thermally pretty inert.

There's been research into antifreeze techniques going on for a long time, and it might be getting there.
https://www.rt.com/news/332074-cryonics-rabbit-brain-regenerated/

The biggest problem is once you have a well cryo-preserved animal, how do you wake it up again?

 

[kuru]

laser drive

Ah, inspiring stuff! A sailing ship with pin-point custom winds. But wouldn't the tiniest nudge bring it off course, unable to correct without conventional means of propulsion?

If such a laser beam would be feasible, couldn't that be used like a power cord to run an ion drive? Lacking the physics knowledge here, likely talking trash^^

Could such a beam be reflected by some kind of high tech mirror?

 

[sulu]

Ah, inspiring stuff! A sailing ship with pin-point custom winds. But wouldn't the tiniest nudge bring it off course, unable to correct without conventional means of propulsion?

Yes, holding course would be a big challenge, and it gets harder the further you are away from the laser.
The nice thing about lasers compared to normal light is, that the beam is highly focused. So a perfect laser wouldn't suffer from the problem that if you increase the distance by the factor x, you need to increase the output of the laser by factor x². Unfortunately we can't build perfect lasers, so we still need to quadruple the laser output each time the distance of the sailing ship doubles, but due to the almost perfect focus of the laser we'd start with a pretty low energy output value.

When the laser beam reaches the ship, it will still be much wider than the ship. This however could be used for steering the ship by cleverly forming the deflector. I'm not sure if a U shape or a V shape would be better, but essentially the space ship should behave like a sailing ship on a broad reach to downwind course. Theoretically the ship wouldn't need any thrusters as long as it stays within the laser beam. Gyros should suffice to adjust the angle of the deflector with respect to the beam, which in turn should make it possible to always keep the ship centered in the beam. It's a little like balancing a ping pong ball on a water jet. The round form of the ball automatically centers the ball.

If such a laser beam would be feasible, couldn't that be used like a power cord to run an ion drive?

In terms of power, yes, the laser beam should in principle be able to power the ship. It's just a question of how much of the laser energy you absorb.
For an ion drive however you need ions as fuel, and on a multi-lightyear distance that might still become a problem. The very basic principle of an ion drive doesn't differ that much from that of a rocket burning chemical fuel. Both create an impulse by ejecting matter at the rear end of the craft. Impulse is mass times velocity (p=m*v). The main difference between both concepts is, that chemical rockets create their impulse by ejecting huge amounts of mass with a relatively low velocity, while ion drives eject tiny amounts of mass with a very high velocity. But even for ion drives you need fuel.

Could such a beam be reflected by some kind of high tech mirror?

Yes, and a substantial part of the light would probably have to be reflected by the de-/reflector on the ship, because every photon that reaches the craft and is not reflected will heat it up. If you absorb all the energy that is sent to you by lasers that create enough thrust to accelerate your ship with 1g, then you'll burn up in no time.

 

[levi]

Hmm, would reflected photons give the same inertial impulse as an absorbed one? To reflect it, assuming a metallic reflector, doesn't the metal matrix absorb one photon, but end up emitting one of the same frequency. Because it emits one photon, at light speed, wouldn't that cancel out the impulse from the one that arrived?

 

[sulu]

Hmm, would reflected photons give the same inertial impulse as an absorbed one? To reflect it, assuming a metallic reflector, doesn't the metal matrix absorb one photon, but end up emitting one of the same frequency. Because it emits one photon, at light speed, wouldn't that cancel out the impulse from the one that arrived?

You're right! I didn't think that far.
In the end at least in theory absorption shouldn't be (that much of) a problem after all, because the kinetic energy of the photons isn't transfered into thermal energy, but into kinetic energy of the space craft. At least that's what you have to achieve if you want the principle to work.

 

[ible]

afaik, an absorbed photon (in some photovoltaic array) doesn't get reemitted with the same kinetic energy in the same direction, otherwise the array wouldn't be able to convert any light into electricity, since the energy would only be passed on.

so there's some momentum transfer when absorbing a photon, just not as much as when it's reflected. (you get an impulse of 100% of the initial photon momentum in the first case, 200% in the second, both ideally, though of course there's inefficiencies.)

 

[Grench]

Sorry, but the laser propulsion system simply isn't practical. Nuclear powered ion drive(s) slowly consuming a meteor or comet's worth of material - or potentially a matter scoop collecting space dust to vaporize in the ion engine are far more practical.

An ion drive works by vaporizing and accelerating material to near the speed of light then ejecting it in the opposite direction of desired travel. A small amount of material can generate a large net thrust over an extended time. The energy to convert and accelerate the mass pretty much needs to be nuclear.

On the bright side, by the time such a system is likely to be able to be developed, the energy could come from a Tokamak or Stellarator based fusion system, even though both likely have 100+ years of development still ahead of them.

By then, maybe... a maglev rail gun (mass engine) could be launching materials into space on the tallest mountain in the world - which when considering distance from the center of the Earth isn't Mt. Everest.
https://en.wikipedia.org/wiki/Chimborazo
An additional benefit to this is that the launch speed can benefit from the rotational velocity near the equator. At that point, cargo/material could be doing several times the speed of sound before even firing rockets (needed to reach high-orbit speeds).

Anything that gets the species off the rock to truly settle another world - preferably another solar system - is going to require a planet-wide effort over many generations.

 

[sulu]

Sorry, but the laser propulsion system simply isn't practical.

What makes you think that?
I'm not saying it is practical, but it's the only thing I can think of that could be practical.

Nuclear powered ion drive(s) slowly consuming a meteor or comet's worth of material

I believe any system that requires a ship to bring its own fuel is impractical, because you need to accelerate that fuel, which costs energy and hence more fuel that has to be accelerated.
I think you just underestimate the vast distances in interstellar space. The next star (Proxima Centauri) is a little over 4 ly away, That's almost 300000 times further than Earth is from the sun.

- or potentially a matter scoop collecting space dust to vaporize in the ion engine are far more practical.

What you're describing is called a Bussard collector. [1] You might have heard the term in Star Trek. There these are the small red glowing tips at the front of the warp nacelles. Their purpose is to collect gas for whatever you want to use it. There is some gas in interstellar space (mainly hydrogen), which would make for a good ion drive fuel.
The sad think is that small glowing tips wont do the job. The gas is just spread too thin. You'll need giant collectors with diameters in the kilometers range to even hit enough gas atoms. And then there's the problem of actually using them. And then you'll still have the problem that a giant Bussard collector will be slowed down by the momentum of all the particles it collects. So the concept doesn't look too attractive to me.

An ion drive works by vaporizing and accelerating material to near the speed of light then ejecting it in the opposite direction of desired travel. A small amount of material can generate a large net thrust over an extended time.

"Thrust" is measured in Newton, which in physicists terms is the unit of force. Force is a timeless parameter. It doesn't build up over time. Ejecting the same amount of material with the same speed always creates the same amount of force. This produces a constant acceleration. The only thing that increases here is the velocity, but by very tiny amounts.

The energy to convert and accelerate the mass pretty much needs to be nuclear.

I don't think so. The bad thing about nuclear reactors is, that they are still heavy, at least if you want to bring enough fuel for long travel.

On the bright side, by the time such a system is likely to be able to be developed, the energy could come from a Tokamak or Stellarator based fusion system, even though both likely have 100+ years of development still ahead of them.

I don't want to wait that long. I want to see at least the start with my own eyes. That means it needs to start some time in the next 50 years (if I'm lucky).

By then, maybe... a maglev rail gun (mass engine) could be launching materials into space on the tallest mountain in the world - which when considering distance from the center of the Earth isn't Mt. Everest.
https://en.wikipedia.org/wiki/Chimborazo
An additional benefit to this is that the launch speed can benefit from the rotational velocity near the equator. At that point, cargo/material could be doing several times the speed of sound before even firing rockets (needed to reach high-orbit speeds).

That's a good concept to get things out of our gravity well, but it doesn't work as a continuous means of acceleration.

Anything that gets the species off the rock to truly settle another world - preferably another solar system - is going to require a planet-wide effort over many generations.

I just found an over 20 years old abstract by Geoffrey Landis (NASA) that describes a laser drive concept enhanced it with a laser-fueled ion drive for initial acceleration and final deceleration. [2] I'm pretty sure he's more qualified to come up with a viable concept than all of us combined.


[1] https://en.wikipedia.org/wiki/Bussard_collector
[2] http://www.geoffreylandis.com/laser_ion.htp

 

[levi]

Both the stellarator and the tokamak are nuclear fusion projects. If you can scoop up enough free hydrogen, by combining it into heavier elements you might get enough energy to accelerate it out of the back. But we don't really know how big one of these needs to be to generate appreciable energy yet (or at least I don't), or whether interstellar free hydrogen will be enough to power the craft, but if the theory and reality match up, you might not need to actually carry any fuel (just lots of electomagnets).

My own personal problem with ion drives is I don't think they'll work very well in a gravity field. Maybe you could combine an ion drive to line up shots with slingshotting around big stars, but if you've ever tried to solve the travelling salesman problem programatically, that should be like childsplay compared to this.

 

[DrHAX]

I always love these topics of colonization. They always bring so much to the table to be bickering about.
Science
Economic
Morality
Religion.

All of these emerge on the mer notion of leaving this space rock in which we sit. However there are sadly many stagnant points which make it hard to get funding for such an thing. Mainly because of people seeking out profit. Remember the movie Avatar? Yeah that seems to be a more realistic way to get funding for research. Or a more cynical Orwellian thought is to control people. Tell them their planet is dying throw a select number of them on a colony ship, send them out, and blam you control an entire society from the ground up. Even a colony would be a eugenics wet dream. As cynical as this sounds there is always that risk when it comes to entities when funding these things. So if its private sector its profits, its government its power. Since its hard to put a price tag on "advancing science for the greater good" or at least to the entities pumping in billions of local currency.

Also what happens when we set up a colony and we find stuff on the place we set it up? How many political nightmares would emerge from countries trying to CLAIM whats under it for themselves? Even if it were logically, and economically impossible at the time to harvest it and snail mail it back to earth, countries,people, and corporations would still see it as an investment and then PUSH for the technology to get it there.

So it depends on how badly you want your colony. Because either way, with our current society, you're going to have to either appease greed, or appease something a bit darker and more creepier then just a fat cat smoking lighting a cigar with a 50,000$ bank bond.

I've put some thought into this.. Mainly because I am writing a story where such an event happened. Most of the population disappeared off of earth on Arks, leaving behind a "Dying" planet, however to the less then 500,000 on it it turns out the planet in fact wasn't dying at all. Now you have a society of people who many of them willingly stayed behind and are picking up the pieces. Yes I wanted to write an apocalypse story without zombies,disease, nuclear war, and aliens.

I do hope for advancement in the field of space travel though. I think we should try to shoot for the moon first (mainly because we've been there before. It's possible.) , Even as a starting point the research gained from people being there would be invaluable to determine if longterm exposure to colony conditions have negative impacts on the human psyche, as well as what it takes to have a self sufficient society. Also once you get a moon colony set it up it could easily be a docking point for other expeditions.

Until the moon revolts and becomes its own entity and then locks down its ports from us.

 

[ible]

sounds like an awesome premise. keep us posted!

 

[Klumpen]

[awesomeness]

I want to read it.

 

[Grench]

Also once you get a moon colony set it up it could easily be a docking point for other expeditions.

The Earth has an ideal spaceport already in orbit. It has enough gravity to keep track of things, but not so much as to make launching from it difficult. There is enough material to use for construction - and a potential nuclear fuel supply there for the harvesting. It has substantial mass and angular velocity such that any craft launched from it's leading edge can have enough momentum to travel within the solar system (albeit slowly). It is close enough to a habitable planet to make 'escape pods' a viable back up plan. Oxygen is plentiful on the Earth's moon - though not as an atmosphere.
https://en.wikipedia.org/wiki/Geology_of_the_Moon

So, yeah - creating a settlement on the Earth's moon is technically a whole lot easier than using Mars - and may be more immediately useful. It should be done.

However, if the objective is to, 'save the species,' then we need to get something further out. If a giant object slams into the Earth (again) it could also throw material back into space that would rain down on the Moon. Mars is far enough away that it would be less likely to suffer the same fate. Jupiter's moons are even better in that respect.

From a perspective of, "walk first," the Earth's moon makes a great first colony. If nothing else, being able to have lightly laden escape pods capable of making it to Earth would give the residents some peace of mind should some mishap require evacuation.

 

[DrHAX]

I want to read it.

Then I may pick it up and start writing more.

It's an experimental piece (3rd person I normally write strictly in first person) and the main groups that stayed behind are either people who are anarchists or people who knew that they wouldn't be valued up there in space.

So artisans blacksmiths, etc. antiquated things.

It takes place 18 years after the arks left. So an entire generation has grown up with out any memory of the world before abandonment. It's been quite interesting to write the main character comes from a society of raiders where she was sent out to die because they are running out of supplies. And it goes on from there.

 

[Klumpen]

the main groups that stayed behind are either people who are anarchists or people who knew that they wouldn't be valued up there in space.

So artisans blacksmiths, etc. antiquated things.

So people like me are left to die again, how fitting (I'm an artisan).

 

[DrHAX]

So people like me are left to die again, how fitting (I'm an artisan).

I would be too.

If you want to talk more about it send me a message. I'd prefer not to derail this topic too much.

However in the story that is how the arks were made by the moon. So you had larger shuttle crafts going to the moon like a giant airport and then you go to your assigned ark. I have another story planned of an ark returning to the earth to find out things are a bit different.

 

[sulu]

It's maybe not as revolutionary as flinging our own butts to other planets, but it's actually happening right now and therefore equally interesting:
ExoMars is about to arrive in Mars orbit and it's lander Schiaparelli should have already landed:

[1] http://www.esa.int/Our_Activities/Space_Science/ExoMars/Live_updates_ExoMars_arrival_and_landing