Interstellar space travel: which designs have the best chances of getting...

[matt-browne-sfw]

... implemented by the end of this century?

Here’s the Wikipedia definition from Interstellar travel - Wikipedia, the free encyclopedia

Interstellar space travel is unmanned or manned travel between stars. It is tremendously more difficult than interplanetary travel due to the vastly larger distances involved. Given sufficient travel time and engineering work, both unmanned and generational interstellar travel seem possible, though representing a very considerable technological and economic challenge unlikely to be met for some time, particularly for crewed probes. NASA has been engaging in research into these topics for several years, and has accumulated a number of theoretical approaches.

Wikipedia lists several designs (including a human crew):

A: Slow interstellar space travel based on generation starships (normal lifespans)
B: Extented human lifespan to reduce number of generations on the starship
C: Sleeper ships with hibernating human passengers (using cryopreservation)
D: Embryo space colonization approach (using artificial wombs and androids)
E: Fast sub-light-speed travel using light sails (slow but long acceleration process)
F: Fast sub-light-speed travel using fusion engines (e.g. based on Bussard ramjet)
G: Fast sub-light-speed travel using antimatter engines
H: Locating and using a wormhole (as a “shortcut” to get to a distant star)
I: Creating and using an artificial wormhole
J: Faster than light travel based on “warped” spacetime or other currently unknown concept

A – E: are all “slow” approaches with trips that can take thousands of years
F + G: are all “fast” approaches with trips that can take many dozens of years
H – J: are all “extremely fast” with trips that can take months or years

Can you name your TOP 3 designs which have the best chances of getting implemented by the end of this century?

Here are mine:

TOP 1 - D: Embryo space colonization approach (using artificial wombs and androids)
TOP 2 - B: Extented human lifespan to reduce number of generations on the starship
TOP 3 - C: Sleeper ships with hibernating human passengers

[Dave]

I would think that only option A is currently available, the others being science fiction. Even that option would be very expensive, technologically challenging and would take such a long time that I doubt they would even try. At the present time there is no great need to do this; overpopulation and resource depletion have not driven us to that stage yet. Even if they did try a generational ship, chances are that one of the other faster options might become possible within that time-frame, leapfrogging them to the destination more quickly. That sounds like an idea for a story actually!

[chrispenycate]

How about steady expansion away from the sun, until the space stations deep in the Oort cloud are essentially star ships, getting reaction mass from so far outside the sun's gravity well (well, not outside it, obviously, as it essentially never stops, but so shallowly in it that escape energy is negligible) - slow obviously.
Vacuum energy; obbviously, since conservation of momentum holds, this involves harrying reaction mass (a bit like the antimatter drive) mid speed
Some new physical principle: perhaps gravity control, which would allow the transfer of momentum to other celestial bodies, in particular the sun( no way of predicting the probability of this, as it's original research, so the results are, by definition, unknown. Speed? Equally dependant on whatever system comes out of the research.
The light-sail system only works if you have a laser launching system - solar energy drops off too fast (even then, it'sonly good for short trips; feedback gets dodgy when the light system takes a couple of years do do a return trip, and slowing is much more difficult than accellerating, but it's a really nice theory, needing no reaction mass, and the power plant can stay at home with the service engineers (getting home, of course involves building a similar power plant at the destination star. And the sail for a payload involving a life support system for a centuryor so is enormous - bigger than a planet (thouggh weighing relatively little)
Hibernation sounds good. However hibernation is metabolic slowdown (maybe a hundred times or so) but no total stoppage. Still, cryonic research will be going ahead for other reasons (well, so will research on artificial placentas for your embrionic transport)
We're a long way from any of the systems required; but we're a long way from requiring them, too. But don't think that any of these are going to help Earth's population problems; even the space elevator running continuously could only increase the population in space, not reduce it on Earth; you'll have to use more traditional methods for that.

[pyan]

Generation ships may sound like a reasonable idea - but they don't have a very good record in SF....

[matt-browne-sfw]

Originally Posted by Dave

I would think that only option A is currently available, the others being science fiction. Even that option would be very expensive, technologically challenging and would take such a long time that I doubt they would even try. At the present time there is no great need to do this; overpopulation and resource depletion have not driven us to that stage yet. Even if they did try a generational ship, chances are that one of the other faster options might become possible within that time-frame, leapfrogging them to the destination more quickly. That sounds like an idea for a story actually!

Thanks all for your input so far. Dave, why do you think A is more realistic than D? Generation starships would have to deal with hundreds of generations all living on the very same ship. My personal opinion is that the embryo space colonization concept will be easier to implement.

[Dave]

Originally Posted by matt-browne-sfw

Dave, why do you think A is more realistic than D? Generation star ships would have to deal with hundreds of generations all living on the very same ship. My personal opinion is that the embryo space colonization concept will be easier to implement.

With the current leaps forward in infertility research you are probably right. But who would care for these embryos and keep them secure? Would a machine be reliable enough to do so on such a long timescale?

And "Hundreds of generations" - at 20 years per generation that is 20,000 years +

Surely, our very first steps would not be quite so far?

Frankly, I can't see them doing this until we develop a much faster drive, or there is some cataclysmic reason for leaving Earth.

[Parson]

Originally Posted by Dave

Frankly, I can't see them doing this until we develop a much faster drive, or there is some cataclysmic reason for leaving Earth.

Agreed. Until we have some drive that can push a payload up to and back from some significant fraction of the speed of light (10% perhaps), 20,000 years is about what it would take to reach the next star at present acceleration/fuel possibilities. The only present technology that holds any real promise would be the ion engine but with the current paranoia about anything "atomic" it is unlikely to get the kind of research and development necessary in the foreseeable future.

[matt-browne-sfw]

Originally Posted by Dave

With the current leaps forward in infertility research you are probably right. But who would care for these embryos and keep them secure? Would a machine be reliable enough to do so on such a long timescale?

And "Hundreds of generations" - at 20 years per generation that is 20,000 years +

Surely, our very first steps would not be quite so far?

Frankly, I can't see them doing this until we develop a much faster drive, or there is some cataclysmic reason for leaving Earth.

Well, with all the talk about a "technological singularity"... don't you think it's a bit simpler to build androids capable of raising children (belonging to the species of friendly AI).

In my book I tried to show that the embryo space colonization concept could work...

[Mr Baatard]

I think this century will see AI using option E, maybe F. We'll send robots into space until we figure out how to get there in reasonable timeframes.

Humans won't take the plunge into space unless 1.) we're evacuating, or 2.) we get a handle on gravity wells. I guess the latter would be option J, with the former being whatever we could get off the ground in a hurry.

[Dave]

Originally Posted by matt-browne-sfw

...don't you think it's a bit simpler to build androids capable of raising children (belonging to the species of friendly AI)...

I'd never thought about it before. Obviously, we don't have AIs that would be capable of rearing children right now, but maybe in the future??

The only thing I would say is that they would need to be extremely human-like androids. Children and Babies learn everything in their development from imitating adults, right from first smiles and facial expressions, to walking, talking, eating, toilet training, to schooling and studying.

I think that the things that would make such androids capable of space-travel, when humans were not, might make them just too different, too odd, for that task of child development. Even the longevity/immortality issue alone would cause a problem.

[iansales]

George Mann's The Human Abstract takes this as its starting point - it's set on a colony world whose founders were raised by AIs.

And for what it's worth, I don't think we'll see any interstellar space travel this century. The distances are too vast, the environment is too dangerous, and the cost is too high. We have plenty to explore and exploit in our own planetary system, and it's going to be several centuries before that becomes routine.

[matt-browne-sfw]

Originally Posted by Dave

I'd never thought about it before. Obviously, we don't have AIs that would be capable of rearing children right now, but maybe in the future??

The only thing I would say is that they would need to be extremely human-like androids. Children and Babies learn everything in their development from imitating adults, right from first smiles and facial expressions, to walking, talking, eating, toilet training, to schooling and studying.

I think that the things that would make such androids capable of space-travel, when humans were not, might make them just too different, too odd, for that task of child development. Even the longevity/immortality issue alone would cause a problem.

No, indeed we don't have AIs that would be capable of rearing children right now. But given the accelerating scientific progress, don't you think it's likely to appear around the year 2045 or later?

[iansales]

We don't even know if AI is possible. It may never happen. If, on the other hand, we use an extremely sophisticated computer... I'm not convinced even that level of sophistication is possible. There are physical limits, after all - and we've already reached those for magnetic media.

The other problem you have is ensuring the viability of the embryos you've sent out to colonise other worlds. Outer space is a harsh environment, and humanity is coddled on Earth.

[Parson]

I would be equally concerned about the time when the children become teenagers with little sense, but sophistication enough to circumnavigate the AI. Raising children is an art and not a science. I really doubt AI's raise to the level of art.

[speedingslug]

Creating and using an artificial wormhole, 'stargate' would be the best solution but it will be many years if ever that anyone travels through hyperspace. Even faster than light travel is still too slow.
A planet has been found 41 light years away that is in the right orbit to support life, it's a gas giant but has some promising moons. Space is just too big for us to understand how insignificant we really are.