The Most Scientific Plausible Method of Interstellar Movemen

[General Mung Beans]

What is the most scientifically likely method that we may be able to use in going from here to some other star system?

[Serafina]

What is the most scientifically likely method that we may be able to use in going from here to some other star system?

Right now?

Build a ship that can accelerate for a pretty long time. Make it big enough so that it can carry multiple generations.
Start the drive, accelerate half the way to your target as fast as you can do comfortably and then reverse after you made half the way to your goal.
If you are lucky, relativistic effects will spare the ship itself some time.

Cryogenics (freezing people) would be an improvement, but i think it is not scientifically possible right now.
And we do not know of anything practical that could shorten the way or make the ship go faster than light or ease the stress of high acceleration. So yeah, we are pretty damn limited - and if we are not lucky, our universe doesn't allow any of the above.

[Simon_Jester]

If we had to design a starship right now it would probably have to use an Orion drive. There are conceivable interstellar rocket designs that would be much more efficient, but we don't have all the pieces we'd need to build them yet, while we do have the pieces to build an Orion (more or less)

[Samuel]

If we had to design a starship right now it would probably have to use an Orion drive. There are conceivable interstellar rocket designs that would be much more efficient, but we don't have all the pieces we'd need to build them yet, while we do have the pieces to build an Orion (more or less)

Orion drives are to lift off from the planet- a nuclear powered ship is more effecient than an Orion drive for moving in space. Plus, it is hard to get the blast to hit the pusher plate once you are out of the atmosphere.

[Simon_Jester]

True. Scratch what I just said.

And designing a nuclear rocket would probably be easier than designing an Orion drive anyway.

[Ilya Muromets]

If you're talking about plausible given current capabilities then part of that plausibility is the consideration that the crew also arrives alive and in good health. As far as I know, there's just no way given current capabilities to design anything to keep the crew alive that long, or a practical way to design a self-sustained generation ship which'll have the riders' descendants reach the place in good health. Not for the mind-numbingly long travel times involved. And that's assuming everything will remain in working order without anything breaking down.

[Akkleptos]

I'll say go nuclear. Use an Orion for the lift off, but, hey, since this would have to be a generational starship, it's bound to be quite big, thus orbital building would become almost imperative. That makes the benefits of an Orion-type drive negligible for the far trip, albeit it coud be useful for lifting all of the parts to the orbital shipyard. Consider that anything shipped via Orion could be subjected to huge G increments, so a really big structure such as a generational ship would have to be able to withstand an incredible ammount of structural stress.

Solar sails come to mind, but how much usable energy could they gather until the Sun is too far away to be a reliable source of push? How much of an advantage would that be over nuclear propulsion?

Antimatter and darkmatter... How much of these could one find along the way and collect (even at fantastic interstellar speeds) so as to make them a reliable source of fuel for propulsion? Maybe hydrogen clouds, as Asimov once proposed in -at least- one of his tales? How could that be any better than nuclear fision?

Maybe nuclear fusion? We've got to figure that one out first.


Also, if we decided to go nuclear for the propulsion (I'm sorry if I sound ignorant here, please indulge me this time), how would the nuclear drive work, exactly? It's not as if we could just boil water in boilers to make steam to move propellers like we do now with nuclear submarines, right? There would have to be some kind of particle beam or something being shot backwards, so the ship could move forwards, right?

[PaperJack]

I think the best method of propulsion is anti-matter based, and the second best utilizes nuclear fusion as energy source.

[Jeremy]

I know we are a in a vacuous volume right now, would a ramjet work in a normal area of space or are they still too sparse?

[Serafina]

I think the best method of propulsion is anti-matter based, and the second best utilizes nuclear fusion as energy source.

Problem is, for all we know antimatter is not feasible to mass produce. Compared to that, fusion and fission are dirt-cheap, and can be produced in quantities that are orders of magnitudes bigger.

[Samuel]

Antimatter and darkmatter... How much of these could one find along the way and collect (even at fantastic interstellar speeds) so as to make them a reliable source of fuel for propulsion? Maybe hydrogen clouds, as Asimov once proposed in -at least- one of his tales? How could that be any better than nuclear fision?

Darkmatter is not a fuel source. And you won't find any antimatter between the stars (none you can collect anyways). What you mean by hydrogen clouds is a Bussard ramjet which uses interstellar hydrogen for fuel so that it doesn't have to waste mass on carrying fuel with it. The problem is it ony works at high fractions of c and brings its own problems. It isn't something I would want to use as your first interstellar craft as testing it would be difficult.

[Sarevok]

The biggest problem with a starship is the crew. They are the weakest link. If we wanted to build a spacecraft capable of going to Alpha Centauri we could do it within the century. Therefore the logical solution would be the increase the crews lifespan. Genetically engineering humans to be biologically immortal or surviving crygoneic stasis should simple. When compared to the gargantuan task of developing relativistic propulsion systems that is.

[PaperJack]

Genetically engineering humans to be biologically immortal or surviving crygoneic stasis should simple. When compared to the gargantuan task of developing relativistic propulsion systems that is.

Actually, nope. The human DNA has a total of 32,185 genes, which summed up have 3,079,843,747 bases; and we have absolutely no idea what 90% or more of all that genetic code means.
Figuring out everything our DNA means and then IMPROVING it is itself a literally garguantic task.
The process of aging is not a simple matter of DNA, either. There are many more things that factor age.

Besides, let's not mention the inherent ethical and moral issues about creating humans superior to ourselves, too.

In fact, while biochemists have been working on decoding the human dna for a very long time now and still pretty much haven't got a clue about it, other scientific programs aimed at harnessing space-travel feasible energy sources such as atomic fusion have been progressing a lot lately, with NIF and others theorically able to achieve ignition.

[K. A. Pital]

Besides, let's not mention the inherent ethical and moral issues about creating humans superior to ourselves, too.

Because there aren't any ethical issues with this, except irrational fear and the desire to have humans be mortal meatbags all the time? On the other hand, even the theory of physics struggles with developing a workable theory of moving at supralight speeds (much less doing this in practice on any useful scale).

I think the biologicial solutions may come before any useful interstellar flight technologies even see completion in bare theory. Fusion doesn't help interstellar travel that much. The crews are mortal and short-lived, orbital construction is pathetically undeveloped (with 100-200 ton-to-LEO rockets few and far between, many superheavy lift projects ditched), and moving faster than c, so far, is a theoretical dead-end for modern physics.

[RedImperator]

Physical crews are a waste of mass and make every single thing you're trying to do more difficult. It's almost certainly easier to reliably code a robot probe that works for 100 years than it is to design a life-support system that will work for the same length of time, even taking into account the fact the crew can repair the spaceship (ironically, cryo-storage gives you the worst of both worlds--the mass of people and the life support systems they'll eventually need to survive, minus the ability to put on a spacesuit and fix the broken space widget in an emergency).

[Sea Skimmer]

True. Scratch what I just said.

And designing a nuclear rocket would probably be easier than designing an Orion drive anyway.

Just as importantly, a nuclear rocket is less sensitive to fuel quality. Mainly once you enrich uranium to reactor grades, but you don't put it in a reactor, it will last a very long time before impurities build up from natural decay and make it crappy fuel. Nuclear bomb material is more sensitive, and some components like tritium have quite limited lives. Stuart has suggested that even some modern nukes only last 6-8 years, this is not very good. Since even an Orion drive ship will take decades to reach the closest stars, and you need a lot of engine thrust to break into an orbit, you'd basically have to haul along a nuclear weapons factory and perhaps a fuel reprocessing plant with you. This would rather heavily undermine the advantage of the high ISP of orion. Around 2000 seconds IIRC, on par with a bad turbojet. Also you would have huge moving parts in the shock absorbers that could break, and that would require heavy industrial equipment to repair. Such equipment might be brought along anyway, to build the colony, but its one thing to bring equipment, quite another to be able to use it while you fly through interseller space at 10% of the speed of flight.

A nuclear rocket should be able to get away with just having spare fuel rods stored in tubes, though storage of the propellent gas may be troublesome. But at least you can dream of finding more propellent in space by collecting interseller hydrogen or something or harnessing a comet. You aren't going to find an astroid made of working atomic bombs unless you slip through a crack in reality and enter HAB space. Redundancy would be easy enough, since you can have more then one reactor and engine setup, and if one breaks, you just burn the others for longer.

Course the limited lifespan of nuclear bombs might be solved by pure fusion designs, but that's a pie in the sky technology right now.

[eion]

Nuclear Salt-Water Rocket is buildable with current tech and could theoretically get you up to 3.6% of C if you use the 90% enrichment design.

It's simple, powerful, fairly easy to refuel, and quite reliable, just remember it is essentially a continually detonating Orion Drive, so no take-offs on planets you care about.

Of course, even more important than how you get there is how you stop. Wasting half your propellant slowing down could be avoided if we can perfect magnetic sail technology, which will allow the ship to decelerate against the solar wind of the destination star.

Eventually you'll have to send some manner of crew if you want to ensure the survival of the human species past a solar-spanning disaster. Either bring em or grow when you get there, unless we've moved beyond physical bodies by then.

[Werrf]

Physical crews are a waste of mass and make every single thing you're trying to do more difficult.

Not if what you're trying to do is set up an extrasolar colony to provide for the survival of the species in the event of a world- or solar-system ending catastrophe.

[CSJM]

Spoiler

I'm not sure how serious a discussion this is, but... let's throw a firebrand in there. From the various things I gathered on general and special relativity, I still fail to understand why travelling at FTL speeds is a physical impossibility. Not moving faster than light, just travelling at faster-than-light speeds. From what I understood of GR and SR, you cannot be moving faster than light relative to any observer or, ergo, any object you can observe. This implies an interesting point, however, that only the observed, measured velocity cannot exceed the observed velocity of light. When I think "FTL", I think simply of traversing a given distance with an average speed greater than the observed lightspeed. With time dilation and length contraction seemingly working to lessen the observed velocity, I kinda fail to see whether or not there's a "lightspeed barrier" at all.

On the topic itself though, I think we'll first need to work on reactionless drives. Something like the Alcubierre drive thing. When we're not constrained by the velocity of the reactive medium (even the photon drive, the giant laser, only has a theoretical maximum speed of 1C, since you won't be pushed faster than light itself travels), we'll be actually able to get to other stars reliably.

[Ghost Rider]

Physical crews are a waste of mass and make every single thing you're trying to do more difficult.

Not if what you're trying to do is set up an extrasolar colony to provide for the survival of the species in the event of a world- or solar-system ending catastrophe.

Good thing Red isn't answering that scenario, huh? Also where the fuck did you come up with the sentiment that this topic has anything to do with survival of the species?

I mean the OP is asking:

What is the most scientifically likely method that we may be able to use in going from here to some other star system?

Which is as obvious as one gets. No frills, no hidden message, nothing except asking how what is the most likely method of getting from point A to point B in space.

With Red's entire answer being:

Physical crews are a waste of mass and make every single thing you're trying to do more difficult. It's almost certainly easier to reliably code a robot probe that works for 100 years than it is to design a life-support system that will work for the same length of time, even taking into account the fact the crew can repair the spaceship (ironically, cryo-storage gives you the worst of both worlds--the mass of people and the life support systems they'll eventually need to survive, minus the ability to put on a spacesuit and fix the broken space widget in an emergency).

So unless somewhere in that starting statement is the code word for survival of species, you're blithering. Sure, Red was answering it towards Sarevok's point of crews and doubly so of why cryogenic crews are more hinderance then not. But nowhere does he hint as anything towards your asinine assertion of what he should be answering.

Even weirder, none of the statements have even come to what your point tried to say because this is about what could be done rather then "End of Human race Race, how do you save us all?".

[CSJM]

As far as the travellers are concerned, there really isn't one. They could cross the visible universe in a human lifetime, if they could keep up the acceleration.

I'm glad I'm not quite so stupid when think how much sense it makes.

That'll probably never happen, so it most certainly isn't the "most scientific plausible method".

Well, I did say "we'll need to work on them first", so yeah. If we were to think of a way now, do-or-die mode, we'd probably settle for launching everything we can with chemical rockets and Orion drives, and then putting it together and making better sense of it once we're there.

Is this is why chemical rockets can never get faster than 4.5 km / s?

I'm not sure if that's the actual limit of chemical rockets. (wouldn't it mean they can't reach escape velocity then? I'm probably forgetting something here. )

[RedImperator]

Physical crews are a waste of mass and make every single thing you're trying to do more difficult.

Not if what you're trying to do is set up an extrasolar colony to provide for the survival of the species in the event of a world- or solar-system ending catastrophe.

Running to another star system to escape a world-ending catastrophe is like flying to Hong Kong to escape a house fire in New York.

As for solar-system ending catastrophes, other than a collision between the sun and another star (exceedingly unlikely), we won't have to worry about one of those for five billion years. Even when the Sun goes into its red giant phase, there will be plenty of time for an orderly retreat into the outer solar system, assuming by that point we haven't figured out how to perform large-scale stellar engineering. I think it's fairly safe to assume that by the time we actually have to worry about the death of the sun, we'll have better technology available for interstellar travel than fission rockets.

Anyway, given the enormous cost and difficulty of transporting actual human bodies across interstellar distances, you're still probably better off trying to figure out how to upload human minds onto machines and sending them out into space on some kind of self-replicating robot.

But at any rate, the OP wasn't asking about interstellar colonization. It was asking the most scientifically viable method of traveling to another solar system, and I answered that: some kind of low-thrust, high specific impulse nuclear rocket carrying a space probe. Bluntly, I'm extremely pessimistic about the prospect of humans colonizing another solar system at all.

[CSJM]

I'll admit I haven't done much research into rockets. I've long dismissed them as utterly unsuitable for any sort of serious travel. I mean seriously, I wouldn't trust even my vacuum cleaner (a particularly hated device lately) to what is essentially a glorified firecracker. Unwieldy, unsafe, fuel-guzzling things. Something that runs off electricity alone, and preferably with more efficiency than ion drives, would fit my tastes better. Of course, that's "a little" beyond current technology.

And I hate writing things off as "impossible". If it's believed to be impossible, isn't that a reason to try and do it anyway? (within sane safety limits, of course ) It's partly the reason why I made that avatar of mine - "Go beyond the impossible and kick reason to the curb" is a catchy motto. Reactionless propulsion is an oxymoron, true, but this isn't about "pushing off of nothing", it's about "changing position without pushing off of something". This is why I like the Alcubierre drive, in principle. If it works, you get all the speed of any imaginable FTL drive, but get to enjoy sights along the way because there's no relativistic crap affecting you.

(I'm probably mixing up my fictional 'verse with the real 'verse too much, but I still believe this stuff is possible - you just have to look in the right places.)

[Werrf]

Physical crews are a waste of mass and make every single thing you're trying to do more difficult.

Not if what you're trying to do is set up an extrasolar colony to provide for the survival of the species in the event of a world- or solar-system ending catastrophe.

Good thing Red isn't answering that scenario, huh? Also where the fuck did you come up with the sentiment that this topic has anything to do with survival of the species?

<Snip>

So unless somewhere in that starting statement is the code word for survival of species, you're blithering. Sure, Red was answering it towards Sarevok's point of crews and doubly so of why cryogenic crews are more hinderance then not. But nowhere does he hint as anything towards your asinine assertion of what he should be answering.

Can we calm down a little, please? I was simply disagreeing with the assertion that physical crews make "every single thing you're trying to do more difficult". My point was only that if you're attempting colonisation, for any reason, physical crews are required. That's all. It was a slight inaccuracy that I saw and felt the urge to disagree with. Very specific statement - very specific disagreement. That's all.

[Ghost Rider]

Good thing Red isn't answering that scenario, huh? Also where the fuck did you come up with the sentiment that this topic has anything to do with survival of the species?

<Snip>

So unless somewhere in that starting statement is the code word for survival of species, you're blithering. Sure, Red was answering it towards Sarevok's point of crews and doubly so of why cryogenic crews are more hinderance then not. But nowhere does he hint as anything towards your asinine assertion of what he should be answering.

Can we calm down a little, please? I was simply disagreeing with the assertion that physical crews make "every single thing you're trying to do more difficult". My point was only that if you're attempting colonisation, for any reason, physical crews are required. That's all. It was a slight inaccuracy that I saw and felt the urge to disagree with. Very specific statement - very specific disagreement. That's all.

And he's right. Crews require a variety of thing extraneous that take up more space that can be used for other things.

And his statement had nothing to do with colonisation. That was an assertion you made, along with your secondary assertion of world/solar catastrophe. So you attacked him on his statement when his statement had nothing to do with what you were saying.