The endless thread on Space Colonization

[Earthman]

Welcome fellow Earthmen!

I think we should make efforts to colonize other planets already before it becomes a necessity (like in this documentary):

Spoiler :

Link to video.

Here is a map and data about stars with planets potentially suitable for colonization which have been discovered so far:

Location of the Stars with Potentially Habitable Exoplanets:

http://postimg.org/image/cgyygvbxt/

Spoiler :

Map with the Stars located up to 30 light years from Earth:

http://postimg.org/image/c3xzzawix/

Spoiler :

See also my files (attachments) and feel free to download, edit and update them:

 

[Kyriakos]

I think we should, but i don't think it will happen due to positive reason. It is more likely that it will be forced one way or another.

By itself i am not of the view that moving to another planet has to happen so as to have humanity evolve in a better way. But i am of the view that humanity currently is rather in a tarnished situation by and large, mostly due to politics and related pseudo-cultures and endemic low thinking.
But maybe having 7+ billion people, and an actually massive planet next to human size, can be part of the negative factors.

 

[salty mud]

I still think we should colonise the seas before we colonise the stars.

 

[Winner]

Two things:

1) we'll not (I won't say "ever" here, but that's just my hedging) move a significant portion of human population of Earth. Any notion of "evacuating Earth" or looking for "living space" in... space, is foolish. Those who will colonize other planets will be only a tiny fraction of humans. Incidentally, this is why the sometimes proposed conflict of interests between environmentalism and space enthusiasm doesn't in fact exist; that we go into space doesn't mean we should or could give up on trying to save this planet; one isn't possible without the other.

2) why focus on extrasolar destinations? The technology to unable interstellar travel is centuries away. We should focus on learning how to walk before we try to fly. The Moon and Mars are the next logical steps, attainable in short-to-medium term (from a human's life perspective).

I still think we should colonise the seas before we colonise the stars.

That's akin to sleeping in the bathroom before moving to a new house. And before somebody says that, Antarctica is the freezer.

 

[salty mud]

Two things:
That's akin to sleeping in the bathroom before moving to a new house. And before somebody says that, Antarctica is the freezer.

What.

I think it's more akin to moving into the huge 50 room extension that you have always had but never been in to.

 

[Earthman]

Those who will colonize other planets will be only a tiny fraction of humans.

In case of Mars and Venus colonists can be very numerous because these planets are close.

But in case of extrasolar planets sending a Space Ark with up to 250,000 people to each planet is OK.

I agree with the rest of your post, well nobody is talking about abandoning Earth, why should we?

 

[Earthman]

The technology to unable interstellar travel is centuries away.

We already have such technology. We can build space crafts propelled by nuclear explosions (see Project Orion) or by antimatter. Both these technologies can enable us very fast speed of space travel, significant fractions of the speed of light.

 

[El_Machinae]

I don't see the upside to colonising other planets.

 

[LamaGT]

I still think we should colonise the seas before we colonise the stars.

Not possible. For one, engineering-wise it's MUCH harder than going in space. It's all about pressure differential: in space, at most it's gonna be one atmosphere (potentially even less, humans can survive on half the sea level pressure I think). In the sea, we're talking about tens of atmospheres of difference even just for a few hundreds of meters.
Second, these colonies would have very little energy, as the water would absorb most of the sunlight. It would make for a pretty terrible life, completely dependent on the surface for food and to a large degree electricity. Also, due to the aformentioned pressure differential, glass domes aren't possible.
Third, there's no reason for people to go live in the oceans, there's nothing there that can't be extracted from the surface, and we still got tons of sparsely populated land that could be "terraformed" if needed (at least with deserts like the Sahara where all you need is to give a steady supply of water).

 

[Winner]

What.

I think it's more akin to moving into the huge 50 room extension that you have always had but never been in to.

The point is to move away from Earth, not to settle more dirt (or mud). Ultimately it comes down to what people will find exciting enough to motivate them to spend all their money to achieve it. If enough of them become convinced that building a colony on the bottom of the ocean and watch... pale weird creatures eat each other or something, is a good idea, well, then it will happen.

In my perspective, colonizing space offers humanity something infinitely more exciting because once you learn how to successfully move off Earth and establish a self-sustaining colony somewhere else in space, you basically open the rest of the universe for more human exploration/colonization.

In case of Mars and Venus colonists can be very numerous because these planets are close.

I doubt it. Moving just one warm human body plus the gear to sustain it to, say, Mars, is incredibly energy intensive. This means that the owner of the body either needs to be extraordinarily indispensable (i.e. possessing of skills that make him or her mission critical), or extraordinarily rich to pay for all of it him/herself.

Unless some sort of magic technology is invented that makes space travel several orders of magnitude less energy intensive, space colonization will be an effort physically involving only a tiiiiiiny fraction of humanity - by that I mean thousands, tens of thousands of people at maximum.

Even if we managed to somehow move a million people to Mars (completely unrealistic with present or near-term technology), these million people would represent only 1/7000th of the overall human population.

But in case of extrasolar planets sending a Space Ark with up to 250,000 people to each planet is OK.

Again, completely unrealistic. I spoke about the insane energy intensiveness of space travel inside the Solar System. Now magnify that by about 100,000 and you get how impossibly difficult it is to move something to another star system in something that's not measured in geologic time.

For this reason, sending an interstellar expedition will probably involve just a few people (and lots of frozen embryos). In fact, some people believe it would be better to send just robots and the frozen embryos...

We already have such technology. We can build space crafts propelled by nuclear explosions (see Project Orion)

There is a world of difference between knowing something is possible on paper and actually being able to do it. Building an interstellar ship using nuclear explosions for propulsion is of course possible; whether it is a good and practical idea remains to be demonstrated.

or by antimatter.

You mean the substance we've so far managed to manufacture a few picograms of? I'll quote Wiki to save myself the time of explaining why this is a bit of a problem:

The biggest limiting factor in the large-scale production of antimatter is the availability of antiprotons. Recent data released by CERN states that, when fully operational, their facilities are capable of producing ten million antiprotons per minute.[38] Assuming a 100% conversion of antiprotons to antihydrogen, it would take 100 billion years to produce 1 gram or 1 mole of antihydrogen.

(...) in 1999, NASA gave a figure of $62.5 trillion per gram of antihydrogen

And of course we have no feasible way of storing that antihydrogen - magnetic traps only work with ionized antihydrogen and then you can store only microscopic amounts, and neutral antihydrogen doesn't respond to magnetic containment.

Both these technologies can enable us very fast speed of space travel, significant fractions of the speed of light.

Sure, once you overcome the OVERWHELMINGLY daunting technological challenges of bringing them from paper (or Michio Kaku's 'documentary' on Discovery channel) to reality.

This is why you don't build space arks housing hundreds of thousands of people and propel them to relevant fractions of the speed of light. The amount of anti-matter fuel, even assuming you can somehow store it and efficiently use in propulsion, needed for that would be measured in thousands of tonnes. There is no currently known way of making that possible.

So, I suggest aiming little lower... you know, somewhere where we can actually reach within one human lifespan without needing to invent magic first.

 

[Bootstoots]

We already have such technology. We can build space crafts propelled by nuclear explosions (see Project Orion) or by antimatter. Both these technologies can enable us very fast speed of space travel, significant fractions of the speed of light.

Project Orion proposes an interesting way to dispose of our excess nuclear bombs, but I doubt that would be looked on favorably by the international community. Especially if the ship carrying the bombs exploded after launch while still in the atmosphere or LEO.

Not that I'd really have a problem with taking the risk for an unmanned craft traveling to the Alpha Centauri system - that would be so interesting that, if I were Grand Poobah of the World, I'd be willing to subject my fellow Earthlings to some risk and make them spend large portions of their military budgets on getting that craft to work instead of killing each other. Sadly I don't think I stand a chance to become Grand Poobah.

More speculatively, it could be done with small fusion reactions as in Project Daedalus, but that technology really isn't there yet. Antimatter is completely out of the question: we can only produce it in nanogram quantities at the present and (AFAIK) there's no serious proposal to ramp up production enough for it to be useful in propulsion. Also, most of the energy in matter-antimatter annihilation is converted to gamma rays, which would be hard to use for spacecraft propulsion.

 

[Tee Kay]

I fully support colonisation and terraformming of other planets, asteroid mining, interstellar travel, and wholesale human imperialism among the stars. Eventually. When it is, you know, practical.

That's the dream, for the far-off future, but in the meantime we take small steps to get us there: more funding for R&D, missions and stations to/on the Moon and Mars, and perhaps most important looking after our original and currently only planet so that we can survive at an industrial or more advanced level as a civilisation well into the future.

 

[classical_hero]

We were made for this planet and no other planet will be able to support life like this one does. All this is pure Science Fiction and ill never be a reality.

 

[Tarquelne]

Sure, once you overcome the OVERWHELMINGLY daunting technological challenges of bringing them from paper ...

... you can go visit the colonies already established via the "embryo" method. Though it might require something even more compact/transportable than embryos.

Though developing those "daunting" technologies might usher in another era of colonization.


"Upside":

For interplanetary colonization to be economically beneficial you need a technology for cheap ground-to-orbit transportation. Might not be too far in the future.

Extra-terrestrial life could make a colony beneficial without that tech, and might even make going interstellar worthwhile. Though a scientific outpost would likely do just as well. (If it's one-way, I suppose you've got a colony.)

Assuming there's stuff worth $$ in the asteroids or on moons, we could make do technology not too far off from what we've got now. But the economic demand would have to be pretty high. (Think "shale oil.")

 

[El_Machinae]

What is the 'embryo' method?

 

[uppi]

And of course we have no feasible way of storing that antihydrogen - magnetic traps only work with ionized antihydrogen and then you can store only microscopic amounts, and neutral antihydrogen doesn't respond to magnetic containment.

That's quite wrong. Neutral antihydrogen does respond to magnetic confinement and storage times in excess of 10 minutes have been achieved with neutral antihydrogen:
http://home.web.cern.ch/about/engineering/storing-antimatter

By the way, it doesn't make sense to talk about ionized antihydrogen. If antihydrogen loses its positron what remains is not an antiatom anymore but just an antiproton.

So far only microscopic amounts have been produced, so it remains to be seen whether it is possible to store a macroscopic amount.

 

[Tarquelne]

What is the 'embryo' method?

I was referring to what Winner mentioned up above: You don't send a full colony's population as walkin', talkin' people. You send a few - maybe even no - people, and make up the difference with a lot of embryos or some other low-maintenance, low-weight form of potential-organisms.

Compared to a few hundred people and all their life support people, you'd get a massive reduction in mass.

OTOH, compared to what we'd currently need for a reasonably speedy interstellar ship (10% C? 20%?), I'm not sure it'd make a significant difference.

If you had reliable suspended animation you could make a slowboat work with very few people, but that's yet another tech that we don't seem about to get any time soon.

 

[Winner]

What is the 'embryo' method?

Hypothetical method of 'seeding' the stars - instead of sending a complicated starship that needs to keep a human crew alive and well for decades, you send a simpler, AI/robotic ship that contains frozen human embryos. Upon arrival, the machines build a basic colony, defreeze the embryos and grow babies in artificial wombs. Upon "birth", the AI raises and educates the kids until they are capable of taking care of themselves and go on populating their new planet.

(in an extreme version, even smaller ship is sent; it replicates everything in situ and uses DNA synthetizers to produce humans from digitally stored genetic information).

That's quite wrong. Neutral antihydrogen does respond to magnetic confinement and storage times in excess of 10 minutes have been achieved with neutral antihydrogen:
http://home.web.cern.ch/about/engineering/storing-antimatter

By the way, it doesn't make sense to talk about ionized antihydrogen. If antihydrogen loses its positron what remains is not an antiatom anymore but just an antiproton.

So far only microscopic amounts have been produced, so it remains to be seen whether it is possible to store a macroscopic amount.

From what I understand about how this works, it doesn't really scale up well, both time-wise and mass-wise. Don't forget that in a starship you need to store kilos/tonnes/hundreds of tonnes of this stuff under acceleration - and system mass is critical; if the containment system weighs many times more than the amount of antimatter stored, you can forget about going anywhere.

As for ionized (anti)hydrogen - I know that technically it's just a lone proton, but chemically it behaves like ionized hydrogen gas. The repulsive force is very strong, therefore you cannot really store ionized gasses in a electromagnetic 'bottle' (unless you produce crushingly powerful fields, thus running into the aforementioned problem of the containment system weighing more than the antimatter it contains).

 

[gangleri2001]

Project Orion anyone? Atomic bombs can be a good think. At least it's better to try to give them some use instead of having them covered in dust.

 

[uppi]

From what I understand about how this works, it doesn't really scale up well, both time-wise and mass-wise. Don't forget that in a starship you need to store kilos/tonnes/hundreds of tonnes of this stuff under acceleration - and system mass is critical; if the containment system weighs many times more than the amount of antimatter stored, you can forget about going anywhere.

Yes, this kind of trap will probably be killed by three-body losses when you scale up the density of the antimatter. Time-wise the limit is how good you can get your vacuum. This could actually work better with antimatter than with regular matter once have a macroscopic amount, because the antimatter would act as an extra vacuum pump.

As for ionized (anti)hydrogen - I know that technically it's just a lone proton, but chemically it behaves like ionized hydrogen gas. The repulsive force is very strong, therefore you cannot really store ionized gasses in a electromagnetic 'bottle' (unless you produce crushingly powerful fields, thus running into the aforementioned problem of the containment system weighing more than the antimatter it contains).

Yes, storing antiprotons is not going to work beyond a few particles. I just wanted to point out that the term ionized antihydrogen is not going to be useful for anything, because if you go to the trouble of making antihydrogen (which is much harder than going for antiprotons), it would be quite stupid to ionize it again.

The most promising approach might be storing antimatter as a plasma as tried in magnetic confinement fusion research. That way you could make use of strong magnetic forces without the problems that come with a net charge of the system. Whether a trap for antimatter can be weight effective is unclear and you are right to be skeptical about that. But there is no fundamental physical reason why this cannot work and the problems are mostly technical.

Efficient production of antimatter is the much bigger problem in my opinion. The physical mechanism we use to produce antimatter is extremely inefficient so if we want to produce a macroscopic amount of antimatter we would need to find another mechanism. And we have no idea whether there is such a mechanism (well, theoretically I could propose one, but that can probably never be realized).