/sci/ - Science & Math

depends on the lifespan.

I'm sure we wouldn't be so different from our current self. Only thing changing is culture.

Plus there could be advancements in other areas of science by the time we have the capabilities to travel light years from the planet. This could mean that preservation of the body could extend our life much longer than live currently.

>assuming that the human lifespan is a constant
>assuming that human reproduction functions correctly in outer space

>>3068269
most likely is event horizon madness.

Without artificial gravity we'd end up with vestigial or no lower limbs as they're not needed in zero gravity

>But what kind of freaks would we become within these sealed ecosystems?
lolwut?
It's not like there will be significant genetic adaptation going on. Genetic engineering, however...

OP go watch Macross

>>3068313

But there is every possibility that if we have the capabilities to travel light years, we could have the ability to simulate gravity on a ship.

>>3068313
What the hell? That would take hundreds of thousands of generations, at least.

I love that pic OP, any more saturn ones?

>>3068348
Shhhhh I'm hoping he just meant they'd atrophy and be useless when we arrived planetside

A species capable effective interstellar travel wouldn't be constrained by biology.

>>Implying that the humans that go to the stars will have lifespans as short as modern humans

This is a really neat idea.

How many generations would it take, if we were moving at a feasible speed to lets say... a neighboring star?

Im really captivated by this notion that we could stick some people in a vessel where they will live for generations until they reach a new home. Its less about individuals birthing offspring as it is one planet birthing life onto another.

This is assuming that cryogenic hibernation is never perfected.

We'd change ourselves, probably. Become part machine. Machines would likely be necessary for reproduction anyways.

The more interesting question is, if terraforming proves to be unfeasible, how will we adapt to whatever it is we're colonizing?

>>3068410

Certainly we would only hurl our peers at class M planets.

I dont understand why interstellar travel necessitates cryogenics or cyborgs

>>3068410
>how will we adapt to whatever it is we're colonizing?
It's always some mixture of altering yourself and altering the environment. If global environment manipulation is limited, you can either make small habitats, alter individuals by some means, or a mixture of both.

>>3068424
dont be a namefag

>>3068424
It might just work better, that's all.

Anyway, technology is going to change quite a lot before anything like a generation ship is seriously considered, so it's a little worthless to speculate now. You might as well have people from the 18th century talking about how to get to the moon.

>>3068397
The closest star system is Alpha Centauri. The journey of 4.35 light years would take 175 years at 0.025c, or 870 years at 0.005c.

There are numerous methods available for propelling an interstellar spacecraft, but we are not yet capable of constructing one. We lack the necessary infrastructure and, for some methods, the necessary technology.

>>3068424
Well, when you start waving one wand, why stop there?

>>3068350
Google image search for "Silent Running"

x

>>3068429
>Anyway, technology is going to change quite a lot before anything like a generation ship is seriously considered, so it's a little worthless to speculate now. You might as well have people from the 18th century talking about how to get to the moon.
This.

>>3068424
Why would you assume that? A star system without habitable planets still has value, as does one that has planets that may be made habitable. Our own system has one habitable planet and two good candidates for colonization and terraforming. The knowledge, technology, and expertise we acquire in the process of making Venus and Mars livable will aid us greatly when we begin leaving Sol.

>>3068465
Not to mention the possibilities of hollowing out asteroids and NEO-like objects into movable space habitats. So much useful shit, everywhere.

>>3068453
BUT THEY DISCOVERED THE EARTH WAS ROUND. THAT CANT BE ANY MORE DIFFICULAT THAN INTERSTALLAR TRAVEL

>poe's law, I dare you

>>3068495
Very nice.

I'd like to remind any confused viewers that Western civilization has known the Earth is round since the ancient Greeks.

It the interstellar radiation that will do us in... without any means of shielding occupants from cosmic rays, their genetic material will be shot to ribbons.

So... cancer epidemic will wipe out complex organic life once the ship leaves the heliosphere

>>3068504
And that's ignoring the damage the tiny rocks floating around out there would do.

>>3068504
>without any means of shielding

...why would any ship not be shielded?

>>3068504
atleast our feces will make it there safe.

>>3068526
budget constraints

>>3068504
Giant superconducting magnets, batman. If a magnetic field can do a reasonable job of shielding the Earth, why shouldn't it work on a space ship?

>>3068526
Large ships are near-future feasible
Ion-based propulsion is near-future feasible
Radiation shields are magic future unicorn bollocks

By the time we have interstellar ships, we will be transhuman. We may even upload ourselves into a ship and actually BE the Enterprise

interstellar is possible you dense asshole
You need to warp time and space
It will be done eventually in the 22nd century

>>3068535
I think making sure the vessel's payload survives is worth the cost.

Since, you know, that's the whole purpose of the mission.

>>3068543
Wrong. All a radiation shield needs to be is dense. You can make one out of ice if you have enough of it.

>>3068269
>What kind of freaks would we become in these sealed ecosystems?

AHEM.

Just use water as a radiation shield you fucking clods, you need it anyway.

>>3068557
This. If radiation shielding isn't feasible cost-wise, neither is the entire mission.

Wasn't DARPA touting it's whole "100-year starship" idea just a little while ago?

>>3068543
>magic bullshit
If you mean some kind of energy fields, then yes.
But a staggered defense of light nuclei, heavy nuclei and electromagnets.

Googled it and it seems satellites use something called Graded-Z shielding, with progressively heavier nuclei materials are layered to produce a 60% improvement over solid single-material shielding.

>>3068465

Im just assuming we should aim for easy targets first before we start colonizing crazy uninhabitable planets.

>>3068535

Also the life support system will be some air fresheners.

>Implying proper cryogenic technologies are not the most reasonable prerequisite technologies for interstellar travel

USE WATEEEEERRRRR FFFFFFFFFFFFUCK.

>>3068439

So assuming we can accelerate instantly to 0.005c, and assuming a new generation of crew are born every 30 years... there would be 29 generations by the time the star was reached which is a genetically stable timeframe.

How long would it take to accelerate to 0.005c?

>>3068622
The easiest targets are the closest. In any case, there is no need to make hard choices as far as targets go. When we actually start constructing interstellar vessels, we should have the capability to build and launch several, or many, at a time.

why would someone want to spend his whole life on a fucking ship?

We could just embrace the freakness and engieneer ourselves into better space travelers.
Pic is the new hands I want. two more where my feet were.
Other adaptations to keep my bones from getting weak in zero G, stuff like that.
We could also just spin a cylinder for "artificial gravtity" live mostly normalish lives on the inside of it (trees, dogs, the whole deal) and since we can still raido back and forth to earth (slowly of course) our culture would not even diverge that much.
Also, our nearest star is 4.3 ly away but we are unlucky like that. there are hundreds within 50 ly.
I also think we will convert most of the matter available in this system into living space before we take an interstellar leap. Something like Mars could be taken apart and converted into habitats like I described above. We would get a lot more living space that way than by just using the surface.

>>3068269
you know, every generation has to rebel against it's parents so, when the next generation takes control you know they're just going to turn it around and head back home just to be edgy

>>3068269
>generational spacecraft

I like the idea of generational spacecraft, but you have to keep in mind that they are not going to be ships with missions, and that precludes any particular organisation, agency or country funding and operating it. Unless you think that 20 generations later the inhabitants of the ship will care about taking readings of some star a dozen light-years away. Instead these ships will become permanent homes to carry humans into the void, and we should think of them as just that - permanent artificial colonies.

>>3068649

I dont know the answer, but .005c is 5,400,000km a hour. Which is a lot faster than I thought. But if my crappy astronomy skills arent crappy, I think thats about the speed of the space shuttle. amirite?

>>3068649
At a constant acceleration of 1g, it would take 4.84 years to accelerate to 0.005c. The maximum sustainable acceleration is higher, depending on which method is used for propulsion, but a ship might accelerate more slowly than 1g in certain circumstances. Adaptation is possible, of course, but a conscious crew might not find, say, two years at 2.5g very pleasant.

Whatever the science may be, surely this is ethically unfeasible - the children of the crew will become the crew, essentially being born into slavery. Unles you have a leisure class and a crew class, then your ship will self destruct in the class war of 2276

>>3068656
Hows that different from earth?

>>3068656

I think the question is flawed.

First of all, if you are born on a ship, you dont have an option. Second of all, like all choices, and endeavors in live it comes at a cost of comfort. There are lots of people who would choose to live in a space ship if it meant serving such a purpose.

>>3068696
How is that different from being born into servitude of a particular government? Really this brings up the point that a generational spacecraft is not a ship with a mission, but a permanent settlement in space.

>>3068682
Actually, it's 5.39 billion kilometers per hour, not million. The space shuttle generally only travels about 30,000 kilometers per hour in orbit.

>>3068696
If the entire culture of the ship were introduced as "everyone must do their part or everyone will die, and eventually, through your hard work, we will discover a new paradise with a blue sky that never ends", from birth, I seriously doubt kids on board will have any reason to miss a lifestyle they may as well never know exists.

>>3068692
You have to use inertial dampeners

>>3068656

a lot of people have lived a lot shittier existences

>>3068696
They must work to survive. How is that different from Earth?

Also, if your generational ship is big enough, like, say, a hollowed out asteroid or an o-neil Cylinder, you could conceivably live just as comfortably as someone on earth.

>>3068716

Anonymous made a good point.

Its not that there is a big brother ordering you to live a certain life. Its that you are born into a community that is heavily dependent on one another. And there isnt any tolerance for failure, not because some authoritarian figure wants you to obey, but because everyone will die if they dont cooperate with each other.

You could say its unfair that on earth you could be born into variable circumstances, by different parents. Thats just the reality that some people will be born in demanding environments and other people wont be.

I just realized.

If you had a generational ship that was isolated for lets say 30 generations, they would speak a different language when they arrived.

>>3068994
Presumably the inhabitants would inherit a large volume of instructions on maintaining and operating the ship, and this kind of pressure would keep the language fairly static. But people who separate into their own roles would rewrite the instructions as they make alterations to procedures and teach the next generation. I suppose its conceivable that eventually the inhabitants would never be aware of the original state of the ship (unless they kept meticulous records or a central computer logged it), and thus the original technical documentation would eventually be lost due to being outdated. From there they would have no pressure for linguistic purity.

Unless they were French of course.

>mfw resident economist was right about something

>>3068398

It needn't even be cryo. Bears, tardigrades, many animals can go into a natural stasis. If we could replicate it-slowing down cellular metabolism to a crawl, body temperature lowered to room temp-we could survive for decades in space. Induce stasis, then add cryo (with magnetic fields to prevent ice crystals forming), and we're practically ageless...if we can find a way to evenly thaw out.

>Interstellar travel is impossible within human lifespans - generational spacecraft are the only feasible means of traveling to other star systems.

OP are you seriously going to come here and tell us interstellar travel within human lifespans is impossible, quite clearly showing that you don't know shit about relativistic rockets, and then ask us a question about evolution on generational ships?

>>3068994

You're assuming they (or their ship's AI) wouldn't be in constant contact with the people on earth. Yes, communications would be slow beyond one light year from earth, and impossible if you get to more than a lifetime between responses, but they'd still get massively time-delayed communications with earth.

Also, that's assuming we don't find a way to use quantum entanglement as a sort of FTL communication.

>>3069044

Thats pretty cool. I would suppose, even if there is central linguistic purity, that wouldnt imply there would be static conventional language. Their accent could change no matter what.

Now that I think about it. They would probably be able to maintain contact with earth. For a large chunk of their voyage they could be within a few months of radio contact with Earth. So in emergencies they could be like "Yo how do we fix this?"

Interstellar travel is pretty fucking expensive.

I would expect medical technology to provide lifespans of over a thousand years before our industrial development reaches the point where we could launch a generational spacecraft.

>>3069102
>Also, that's assuming we don't find a way to use quantum entanglement as a sort of FTL communication.

This thread is about shit that is feasible is real technology, not "what-if" magic.

>>3069044
And then there'd be a war between the 'Original Shipists' and the 'MetaShipists'

They'd argue for decades, trying to determine what the original generation really wanted.

>>3069132
This is disturbingly probable.

>>3068994
>If you had a generational ship that was isolated for lets say 30 generations, they would speak a different language when they arrived.
Actually, we have no idea whether this sort of thing even happens after you get cheap and reliable audiovisual recording technology.

>>3069132
"The Ship Maintenance Manual is a living document!"

sure is troll in here

>why should we colonize other worlds
the sun will grill earth in 800 million years
>lol so long...
... yeah so long, so better start now
>but radiation and food and shit!
who said we have to go as humans, some 100.000 human minds uploaded into a database sent to a distant planet around a new star to recreate biological humans there would work fine
>but thats magic, fucking miracles!
it's magic until someone does it, science marches on

>>3069123

Everything is "what if" magic until you can do it. And then it becomes so ordinary that no one notices it until it breaks down. Flying, landing on the moon, nuclear weapons, computers, etc. T

>>3069228
But the "minds uploaded into a database" IS magic. Minds are not storable data.

You're thinking of a description of a mind, and we hardly need those in a seed of humanity. They would be unreasonably large, hard to use for anything, and completely unnecessary. Whether it's even possible to make a description of a mind good enough to simulate it or build a brain that recreates it is an open question.

Far simpler to send a description of a human fertilized egg and genome, and of devices for caring for and educating children.

>>3069132
>>3069139

Maybe I just have a very optimistic idea of such a community. I figure they wouldnt be like Americans today arguing about what the founding fathers. Maybe the original shipists would become irrelevant.

It wouldnt be "My grand pappy wanted us to land and colonize"

They would think instead "Well, we are heading towards this planet, and when we land, I guess we should colonize"

>>3069144

Waiwhuh

Im assuming face to face communication still exists on this ship.

>>3069147
+10 internets to you, anon. Brilliant.

"Shipwide life support failure is a hoax! The founding crew never intended for maximum population limits, merely the RIGHT to birth control."

>>3069288
I think what you're struggling with is the 'flight of fancy fallacy'

It regards that as soon as the number of fancy rational expectations outpaces the number of voices in a discussion, the discussion tends towards a flight of fancy.

>indistinguishable from magic

If this were a Sci-fi novel, I would determine that you, rather than adhering to a understood framework, even if magical, you are now relying magic to drive your plot, not rational or logical outcomes.

>>3069379
>>3069147

I swear I once read a short story about this.

About, a generational ship that broke into two factions that lived in different parts of the ship, and both lost any knowledge of how the ship functioned and just assumed the ship itself was the entire universe.

Looks like I'll have to educate everybody here.

INITIATING PELLEGRINO DUMP

>>3069359
The difference is between people who only have face-to-face communication and people who have face-to-face communication PLUS a rich, static, consistent reference of what their language is.

Of course slang and jargon would come and go, but with a huge, readily-available library of historical media, the core vocabulary and grammar might stay consistent for thousands of generations.

Noted polymath Charles Pellegrino and Brookhaven physicist Jim Powell have an innovative antimatter powered starship design called a Valkyrie. They say that current designs are guilty of "putting the cart before the horse", which create ships that are much more massive than they need be. Their "spaceship-on-a-string" starship is capable of accelerating up to ninety-two percent the speed of light and decelerating back down to stationary. At this velocity, relativity mandates that time on board the ship will travel at one-third the rate of the stay at home people on Terra (actually it's closer to 1/2.55). They figure this will be adequate for visiting stars up to about twelve light-years from Terra, without using up excessive amounts of the crew's lifespan.

Dr. Pellegrino served as a scientific consultant on James Cameron's Avatar movie. The interstellar vehicles seen in the film are based on the designs of Pellegrino and Powell's Valkyrie rockets, fused with Robert L. Forward's designs. I figured this out when I noticed that the Avatar starship had the engine in the front, which is a unique feature of the Valkyrie.

From Flying To Valhalla by Charles Pellegrino (1993):

...For propulsion purposes, microfusion bursts triggered by antihydrogen-hydrogen annihilation (possibly with a component of lithium added) will prove efficient up to ship-cruising speeds approaching twelve percent the speed of light, owing to jets of relatively slow, massive particles. Above twelve percent lightspeed, propulsion shifts from antimatter-triggered fusion jets to straightforward matter-antimatter annihilation, which produces a lower mass thrust than fusion, but provides particles with the high-exhaust velocities necessary to push the ship to a high fraction of lightspeed.

How much antimatter might be needed for a trip to Alpha Centauri - assuming that Asimov Arrays or something very much like them will eventually provide humanity with the excess energy required for its large-scale production? We have estimated that the fuel stores (both antimatter and matter combined) might be equal to roughly half the mass of the rest of the spacecraft, or about one hundred tons (to assure "burning" of all available antimatter, an as-yet-undetermined excess of matter will be required).

Others have been more pessimistic, including an earlier study by space scientists Donald Goldsmith and Tobias Owen which yielded an estimate that a journey to Alpha Centauri would require four hundred million tons of matter-antimatter fuel. Such estimates arise from assumptions that the spacecraft will be huge, with powerful engines mounted in the rear. Everything forwards of the engines becomes, in essence, a massive, rocketlike tower, requiring enormous amounts of shielding from the rocket's gamma ray shine, supplemented by complex (and massive) cooling systems to shed intercepted engine heat (and a traditional rocket configuration must absorb most of the head-depositing gamma rays, even if they do, like X rays, have a tendency to pass through things). The addition of each layer of shielding and cooling equipment placed on top of the engine becomes increasingly prohibitive as ship mass increases, requiring higher burn rates, which in turn requires more cooling and shielding, which increases ship mass and burn rates, and so on.

With our elongated, two-crew-member ship on a string, gamma shine and heat are spilled directly into the unfillable sink of outer space. A pulling rather than a pushing engine eliminates most of the structural girders that would not only, by their mere existence, add unwarranted mass, but would multiply that mass many times over by their need for shields and coolers. Valkyrie, in effect, is a fuel-efficient, twenty-first-century version of today's "ultralight" aircraft...

...Since antimatter and matter annihilate each other on contact, releasing enormous bursts of energy from literally microscopic amounts of propellant, you cannot simply fill a shuttle tank with liquid antihydrogen and let it slosh around inside.

The only storage method that has a hope of working is solid antihydrogen, supercooled within one degree of absolute zero (within one Kelvin of -273 degrees C). At this temperature, antihydrogen condenses into "white flake," with an extremely low evaporation rate.

Particles of solid antihydrogen will be suspended and held away from the "pod" walls, probably by electrostatic forces and/or magnetism. According to our latest models, near 0.0005° K, antihydrogen should be sufficiently stable as to allow, in the form of matter-antimatter micropellets or wafers (we are presently working to determine which design, layered pellets or wafers, will provide optimal thrust). With one-fifty thousandth of a degree Kelvin, matter-antimatter storage becomes thinkable because wave functions do not overlap enough to produce an appreciable reaction, at least in principle.

>(And in practice?)

We do not know. It has not been practiced yet, and can only be verified by experimentation. Personally, carrying matter-antimatter pellets already assembled, even at 0.0005° K, gives me nightmares. I keep seeing a cosmic ray particle stopping at the matter-antimatter interface, giving off its heat, and triggering a horrible chain reaction... Jim says we can prevent that, but I am still opting for storing our antihydrogen in complete isolation from matter until virtually the moment it is needed. I am reminded of that scene from the movie version of 2010, in which Roy Scheider describes the aerobraking maneuver his ship is about to make through Jupiter's atmosphere. "It's dynamite on paper," he says. "Of course, the people who came up with the numbers on paper aren't here."...

...Upon warming, electrons and positrons self-annihilate to produce small bursts of gamma rays which, in terms of thrust, can be totally ignored. The positrons are there simply for stability's sake. The proton-antiproton pair, however, produce three varieties of elementary particles called pi-mesons...

...The charged pions and muons are the particles we want and when not being used below twelve percent lightspeed to immediately trigger fusion explosions (a matter of simply modifying the type of pellet or flake used), we want to simply bounce the pions off the outermost fringes of the engine's magnetic field, and thus steal whatever thrust they have to contribute, before a significant fraction of them have traveled twenty-one meters and shed part of their energy as useless neutrinos. The engine we have designed ejects pions and muons (and, at lower velocities, pion- and muon-triggered fusion products) along a diverging magnetic field nozzle to produce thrust, in much the same fashion as hot, expanding gases in a conventional rocket impact against the solid wall or pusher plate at the back of the ship, propelling the entire assembly forwards. Since the pions and muons are acting only against a magnetic field, they can propel the Valkyrie without ablating or wearing down the engine walls (as does space shuttle propellant, with the result that the engines must be rebuilt after every flight, and eventually thrown away). However, gamma rays emitted by the decay of neutral pions will knock atoms out of position in structures near the antimatter reaction zones, making the material stronger, yet brittle. One solution is to add structures called shadow shields wherever practical.

(Shadow shields are nifty little devices already being used in certain very advanced nuclear reactors. They are a major component of Valkyrie, so stay with me and I will get around to describing them in just a few moments.) Another, supplemental solution is to weave most structures residing within four kilometers of the reaction zone from hundreds of filaments, and to send electric currents through the filaments, heating them, one at a time, to several hundred degrees below their melting point. Gamma ray displacements in the wires are thus rearranged, and the atoms can reestablish their normal positions. (ed. note: this is called "In-Site Annealing")
There appears to be nothing we can do to prevent the occasional transmutation of atoms into other elements. Fly far enough with your engines burning at full throttle, and your ship will turn slowly into gold, plus lithium arsenic, chlorine, and a lot of other elements that were not aboard when you left.

These new substances will be concentrated around the antimatter reaction zone, and it is important to note that advanced composite materials already coming into existence dictate that our Valkyrie, even at this early design stage, will be built mostly from organic and ceramic materials, rather than from metals. It is conceivable that expanding knowledge of composites can be taken into account by the time relativistic flight becomes a reality, so that the ship actually incorporates the transmuted elements into its filaments in a manner that ultimately results in structural improvements for a ship designed to essentially rebuild itself as it flies. Exploiting what at first glance seems to be a disadvantage (transmutation) is simply a matter of anticipating the "disadvantage" before you begin to build. It's the disadvantages unforeseen or unaddressed that will get you in the end.
The gamma ray flare from the engine dictates other major features of ship design. In particular, it has caused us to turn rocketry literally inside out.

Riding an antimatter rocket is like riding a giant death-ray bomb. An unshielded man standing a hundred kilometers away from the engine will receive a lethal dose of gamma radiation within microseconds. In designing spacecraft, even when considering propellant as efficient as antimatter, RULE NUMBER ONE is to keep the mass of the ship as low as possible. Even an added gram means extra fuel.
Here's how we can shave off many tons of shielding.
Put the engine up front and carry the crew compartment ten kilometers behind the engine, on the end of a tether. Let the engine pull the ship along, much like a motorboat pulling a water skier, and let the distance between the gamma ray source and the crew compartment, as the rays stream out in every direction, provide part of the gamma ray protection - with almost no weight penalty at all. (ed. note: this should remind you of "Helios") We can easily direct the pion/muon thrust around the tether and its supporting structures, and we can strap a tiny block of (let's say) tungsten to the tether, about one hundred meters behind the engine.

Gamma rays are attenuated by a factor of ten for every two centimeters of tungsten they pass through. Therefore, a block of tungsten twenty centimeters deep will reduce the gamma dose to anything behind it by a factor of ten to the tenth power (1010). An important shielding advantage provided by a ten-kilometer-long tether is that, by locating the tungsten shield one hundred times closer to the engine than the crew, the diameter of the shield need be only one-hundredth the diameter of the gamma ray shadow you want to cast over and around the crew compartment. The weight of the shielding system then becomes trivial.
The tether system requires that the elements of the ship must be designed to climb "up" and "down" the lines, somewhat like elevators on tracks.
We can even locate the hydrogen between the tungsten shadow shield and the antihydrogen, to provide even more shielding for both the crew and the antihydrogen.
There is an irony involved in this configuration. Our "inside-out" rocket, the most highly evolved rocket yet conceived, is nothing new. We have simply come full circle and rediscovered Robert Goddard's original rocket configuration: with engines ahead of the fuel tanks and the fuel tanks ahead of the payload. Nor is the engine itself an entirely new creation.

It guides and focuses jets of subatomic particles the same way the tool of choice among most microbiologists guides streams of electrons through magnetic lenses. Valkyrie, in essence, is little more than a glorified electron microscope.
In addition to shielding against gamma shine and avoiding the absorption of engine heat, another major design consideration is shielding against interstellar dust grains. Flying through space at significant fractions of lightspeed is like looking through the barrel of a super particle collider. Even an isolated proton has a sting, and grains of sand begin to look like torpedoes. Judging from what is presently known about the nature of interstellar space, such torpedoes will certainly be encountered, perhaps as frequently as once a day.
Add to this the fact that as energy from the matter-antimatter reaction zone (particularly gamma radiation) shines through the tungsten shields and other ship components, the heat it deposits must be ejected.
Jim Powell and I have a system that can perform both services (particle shielding and heat shedding), at least during the acceleration and coast phases of flight. We can dump intercepted engine heat into a fluid (chiefly organic material with metallic inclusions) and throw streams of hot droplets out ahead of the ship.

The droplets radiate their heat load into space before the ship accelerates into and recaptures them in magnetic funnels for eventual reuse. These same heat-shedding droplets can ionize most of the atoms they encounter by stripping off their electrons. The rocket itself then shuts the resulting shower of charged particles - protons and electrons - off to either side of its magnetic field, much the same as when a boat's prow pushes aside water.
The power generated by occasional dust grains should range from the equivalent of rifle shots to (rarely) small bombs. These detonate in the shield, harmlessly, far ahead of the ship. Fortunately, almost all of the interstellar particles likely to be encountered are fewer than 20 microns across (10,000 microns = 1 centimeter), and we should expect no more than one impact per day per square meter of Valkyrie's flight path profile...

...One of the great advantages of a droplet shield is that it is constantly renewing itself. Put a dent in it, and the cavity is immediately filled by outrushing spray.

If a dust grain passes into the shield, many of the shield's droplets are bound to be exploded. Some of the scattered droplet fluid will be absorbed and recovered by surrounding droplets, but some fluid is bound to be hurled out of the droplet stream, which means that we must add the weight of droplets to be replaced to the ship's initial mass.

In addition to spare droplet fluid, our preliminary design calls for a spare engine. Both engines will be located at opposite ends of the tether. The forward engine pulls the ship along during the acceleration phase of flight. It also fires during the cruise phase, but only at one-hundredth thousandth of a gravity, keeping the tether taut and permitting recapture of forward flying droplets. At the end of the cruise phase, the rear engine kicks in for deceleration (as we cannot simply swing a ten-kilometer-long ship broadside to relativistic bombardment in order to turn the engine around and fire in reverse).

In normal use, the rear engine is turned on only to decelerate the ship, or to maneuver the crew compartment into the center of the forward engine's gamma ray shadow. Nudging the crew compartment, from behind, to one side or the other will be necessary during major course changes, because the crew compartment, much like a water skier, cannot turn simultaneously with the motor that pulls it and might otherwise drift out of the protective shadow. A spare engine also provides some insurance against the chilling possibility of irreparable damage to the leading engine or, worse, a break in the tether. In the former case, identical engine parts could be ferried up and down the tether and exchanged as necessary. In the latter, depending upon where the break occurs, with careful rearrangement of the ship's components along the tether, the remaining coil can be safely used to finish the outbound leg of the mission.

At the end of the cruise phase, with nearly half of the ship's fuel exhausted, empty fuel tanks can be ground up into ultrafine dust, for dumping overboard (we see no reason to expend extra energy decelerating tons of equipment, no longer in use, which can easily be remanufactured and replaced at the destination solar system). At up to ninety-two percent the speed of light, the dust will fly ahead of the decelerating ship, exploding interstellar particles and clearing a temporary path (trajectories must be such that the relativistic dust will fly out of the galaxy without passing near stars and detonating in the atmospheres of planets).

This fist of relativistic dust is the first line of defense against particles encountered during final approach. With the rear engine firing into the direction of flight, droplet shields will be come useful only for expelling heat from the rear engine, for along the tether, "up" has now become "down," and droplets can only be sprayed "up" behind the engine, where, traveling at uniform speed, they will fall back upon the decelerating ship. To shield against particles ahead of the ship, ultrathin "umbrellas" made of organic polymers similar to Mylar and stacked thousands of layers deep are lowered into the direction of flight. This is the second line of defense - against particles moving into the ever-lengthening space between the ship and the fist. The umbrellas will behave much like the droplet shield and, in like fashion, they will be designed with rapid self-repair in mind. Throughout the ship, repair and restructuring will be assisted (where such repair abilities as self-annealing filaments are not already built into ship components) by small, mouselike robots capable of climbing up and down tethers and rigging.

chances are that after a few 1000,s years they would forget why they where on the space ship or that they where even on one. and they would become religious friut cups

END OF PELLEGRINO DUMP

ANOTHER PUBLIC SERVICE BY CCM

>>3069486
Thanks, that was pretty awesome.

>>3069484
ONE MUST NOT DIRECT THEIR STARE DIRECTLY AT THE HAL.

>>3069488

You're most welcome!

>>3069492
o and you would know what a hal is if you where born on the ship and know nothing other then that. now would you?

Radiation shielding will be performed by materials that absorb radiation, converting it into electricity.

And apparently graphene may be capable of "creating" mass. Whether it would be enough to simulate gravity is another question.

Aging may actually be able to be stopped completely, within our lifetimes (assuming you're relatively young).

This is all speculative and some of it may not come to fruition even after centuries pending leaps in scientific discovery. However, nothing is impossible given time and human ingenuity.... given that we do not destroy ourselves or that the world ends via supernatural means in 2012 or sometime this month.

You don't need to spend fuel decelerating from large fractions of the speed of light. Since you're moving at a good clip relative to the interstellar medium, you only need to increase your friction on it.

There are many ways to do so: a loop of superconducting wire could function as a parachute in the partially ionized medium.

On another level, there are many practical issues with the Bussard ramjet design, but the worst of them go away if you only try to scoop matter and generate power while decelerating.

It is entirely possible that hydrogen scooped during deceleration could be used to generate sufficient fuel to accelerate back up to speed.

Actually a pulsed nuclear "Orion" vessel using modern hydrogen bomblets would be able to accelerate to 1/10th the speed of light within 36 days and reach Alpha Centauri within about 47 years. Young children placed abord such a vessel, entrusted to automated caretaking and education systems, would reach that star system by the time they were middle aged.

Alpha Centauri appears to offer conditions ideal for the formation of earthlike planets:

http://www.sciencedaily.com/releases/2008/03/080307121613.htm

but none are yet known to exist around any of the three stars, so it would be a huge gamble to send people there. If we did, it would be their children manning the vessel on its return voyage. The round trip would take just under a century, although we could receive transmissions from them just a few years after they arrived and therefore close-up images of any planets that may be orbiting Proxima Centauri or Alpha Centauri A/B as well as readings they could take from their position that we cannot take from ours.

Really, there's a better case to be made for sending a probe first. If there's some method faster than nuclear pulse for doing this I'd like to hear about it, but that's reliable, well understood tech that we know how to build and which would certainly do the job.

>>3069567

>1/10th

Wait wait what.

For one thing, isn't the top velocity for a 150km-long Orion .05c? Also, a constant one gravity of acceleration for a month?

Simple fission rockets are theoretically sufficient for us to build unmanned probes that reach near-light speed.

Thanks Colonel Coffee Mug for that enormous post. What I read of it (about half) was interesting.

One concern I just thought of:

The transport from the interstellar vessel to their future home would have to be pretty good right? I mean, it would have to be guaranteed to work right? If they got there and their transport doesnt work, or if they got there and it burnt up in the atmosphere or something, that would be a catastrophic loss.

Not only that, but I am assuming it has to be reusable. In that it can go from the ship to the surface many times autonomously.

Seems like we would need a pretty awesome ship, and one designed to be extremely reliable. What if they spent hundreds of years in space. This vessel has to just hang out on the generation ship for decades and not deteriorate or anything, and remain fully functional once they arrive.

For Bussard ramjets, has anyone done much research on light hydrogen fusion reactors?

I mean manmade ones, not stars -- like, how much harder it would be to make an efficient CNO cycle fusion reactor than, say, a D-D reactor.

>>3069648

>The transport from the interstellar vessel to their future home would have to be pretty good right? I mean, it would have to be guaranteed to work right? If they got there and their transport doesnt work, or if they got there and it burnt up in the atmosphere or something, that would be a catastrophic loss.

They're going to need transatmospheric vehicles, and they have to be reusable like some sort of Hydrogen-powered spaceplane that can simply fuel up with a bunch of solar panels and a pond of water. If the ship has nanotechnology, then you could just drop a few robots with assemblers mounted on top and build launch and resupply facilities (Along with the whole colony, so it's ready for colonists once they descend) and maybe even build the reentry vehicles with the local resources. And due to the whole thing about friction with the interstellar medium, the TAV's are going to have to be very well shielded against stray cosmic rays and such. Alternatively you could assemble them out of whatever Carbon you salvage from the half-burnt remains of the ship once it's reached its destination.

The only flaw with pic related is that the damned things are just hanging there, Jesus Christ.

>ignoring saltwater rockets hydrogen-boron aneutronic nuclear engines
>taking antimatter engines seriously

>>3069712

>maybe even build the reentry vehicles with the local resources.

Isnt that a bit optimistic? You are basically dropping these humans off on a planet and you expect them to be able to turn around an construct a space ship? I would think they would need to spend some time actually developing some amount of civilization before they can even worry about the technology it would take to build a transatmospheric vehicle.

>ignoring saltwater rockets and hydrogen-boron aneutronic nuclear engines
>taking antimatter drives seriously

>>3069731

Well if they can travel among the stars at 80% the speed of light I assume they carry quite advaced robotics & nano.

>>3069731
If they can sustain themselves for generations in the vehicle en route in barren interstellar space, they can sustain themselves for further generations in the vehicle within the destination solar system while they gather up comets and meteors and expand the vehicle and its industrial capabilities.

I mean, it's not like we're expecting an Earthlike planet with spacefruit trees and spacechicks to land on, right?

There are some advantages to landing on a barren planet, and terraforming an extrasolar world is a nice dream, but there are also major practical advantages to just building in space.

>>3069438
>>3069434

While I applaud the forward thinking dream of this, we'd need a hell of an energy boost to synthesize antimatter on any kind of scale for this to be feasible.

And the max speed of a 100m diameter Orion pulse propulsion ship using fusion bombs is about 0.1c. That's right out of an episode of Cosmos.

>>3069802

The guy mentions Asimov Arrays somewhere.

Speaking of proton-proton fusion, I was just reading this fairly crackpottish stuff about low-energy nuclear reactions which sounded really awesome, if you could only believe it.

What they were claiming is that some feature of hydrogen absorption into certain types of porous metals with a certain electric potential or current or something greatly increased the rate of weak interactions that convert protons into neutrons, in a way that generates ridiculously cold neutrons that immediately get sucked into any neutron-hungry nucleus nearby, thus enabling a lithium-beryllium-helium catalysed fusion cycle at low temperatures.

Like I said, cold fusion stuff, very crackpottish, but they make it sound so plausible, and you really want to believe it's that easy.

ok, so lets say we got a form of propulsion that lets us travel at 50% of light speed, that way we could get to Alpha Centauri in "only" 2.5 years. do you know hof fucking fast that is? if you collided with a tiny particle of spacedust, it would rip the whole ship up like a 7.62 trough a soda can

>>3069856

On the plus side, if we meet hostile aliens, we can throw four or five sandbags out the window at 0.5c and evaporate their planets.

>>3069618

Check the source on the orion vessel wiki. The math predicting a 47 year one way trip works out, assuming modern thermonuclear explosives.

I'm not saying there aren't hypothetically better methods, just that this is the only one we are certain we can build with modern technology at a reasonable price point.

>>3069865

Did anyone say relativistic war-themed story time?

>>3069865

i think it would vaporize in the atmospheric entry stage

>>3069865
0.5 c is fast, but not that fast.

>>3069877

ooo, I did!

Lemme check my stockpile from /tg/'s assorted HFY threads...

Placeholder for now. Falling Stars.

>>3069884
>>3069887

It would partially vaporize, but at that speed air friction wouldn't have a long time to act.

Even assuming it all vaporizes, the energy released would set the atmosphere on fire.

>>3069895

Physics are fucking awesome

>>3069895

I think, at more or less 10 kilometers above the surface (Earth density) the thing is likely to stall and finally explode. The trail it leaves through the atmosphere would radiate "trillions of watts per square meter" (Pellegrino).

So "set the atmosphere on fire" is a very good description regardless of the atmosphere's composition.

Pic tangentially related.

50% the speed of light converting 1/2 its mass into 50% pure energy
Amidoinitright

>>3069895
At 0.5c, the kinetic energy is only equal to about 15.5% of the mass of the object.

So each kilogram at 0.5c would have about 14 petajoules of kinetic energy, equivalent to about a 3 1/2 megaton nuke. For reference, the Tsar Bomba (biggest nuke ever tested) was a 50 megaton bomb.

Big boom, but hardly planet-cracking or enough to "set the atmosphere on fire". In fact, it's about one hundred millionth of the amount of energy that falls on the Earth each day from solar radiation.

As stated above, 0.5 c is fast, but not that fast.

>>3069901
Yeah, but you have to actually do the math.

>>3069567
Yeah, actually. Too bad most people still have no fucking CLUE, that we today have the capability to build a ship capable of interstellar travel at significant portions of the speed of light, and it would've been possible 50 years ago.

Im disgusted that people still believe in something like "DuRr we has no capability for interstellar travel, as trip take millions of years" or something along that line.

Not to mention the several theories that could get us around the ultimate speed limit and allow us, by all practical means, to travel faster than the speed of light.

Following article originally from newscientist.com (viewing fully required registration at newscientist)
http://www.scribd.com/doc/6990323/Burkhard-Heim-Take-a-Leap-Into-Hyper-Space

And stuff that may be related to the predictions of Heim Theory.
http://en.wikipedia.org/wiki/Eugene_Podkletnov
http://www.esa.int/esaMI/GSP/SEM0L6OVGJE_0.html

>>3069618

The maximum speed for nuclear pulse propulsion is around 0.1-0.2c, which should be attainable with increased specific impulse and thrust (using larger bombs, or making a smaller ship) as the models for the more bigass Orions only include the same 1MT bombs as the smaller ones. The larger ones could be fitted with bombs more appropriate for their size, so they could reach 0.1c.

>>3069956
>giggle.
>One cannot speculate with math alone

>>3069956

why only 15.5%?

>>3069918
Close, but not quite.

The relationship is a right-angle triangle. The total energy (etot) of the object is the hypotenuse. One leg is the rest (mrst) mass of the object (in joules, converted by e=mc^2), while the other leg is the... I don't know the right word, let's call it "luminal mass" (mlum).

So etot^2 = mrst^2 + mlum^2.

And the "luminal mass" divided by the total energy is the speed (v) as a fraction of the speed of light (c).

v/c = mlum/etot

Kinetic energy (ekin) is the increase in total energy over the rest mass:
ekin = etot - mrst

Momentum (p) is the total energy (not the rest mass!) times the speed:
p=etot*v

Also, the rest mass divided by the total energy is the "rate of internal evolution" (rivo) as a fraction of the rate of the passage of time (trat).

rivo/trat = mrst/etot

A totally stationary object has 0 speed and 1 rivo/trat, so a totally stationary clock would tick at one second per second and have no kinetic energy (as a whole moving object, disregarding its internal bits moving), while a photon has c speed and 0 rivo/trat (if there was a clock on it, it wouldn't tick at all; photons undergo no internal evolution between origin and destination).

Clear now? From there, it's just simple algebra.

>>3070051
why not just (weight of object) x (speed of light in m/sex) /2?

>>3070024
See: >>3070051

v/c = 0.5 = mlum/etot
mlum=0.5*etot
etot^2 = mlum^2 + mrst^2 = (0.5*etot)^2 + mrst^2
0.75*(etot^2) = mrst^2
etot^2/mrst^2 = 1/0.75
etot/mrst = sqrt( 1/0.75) ~ 1.15

ekin=etot-mrst
ekin/mrst = etot/mrst - 1
ekin/mrst ~ 1.15 - 1 = 0.15 = 15%

Thus kinetic energy is equal to about 15% of rest mass.

>>3068410
become robots. That's the only valid way I see humans doing anything in space.

Unpatentable doesnt mean they cant make money off it. Right?

>>3070071
Because that's not the way the universe works.

The way most physicists like to say it is that every object's velocity through spacetime is an equal-magnitude 4-vector.

The way I like to say it is that everything is made up of stuff that only goes at the speed of light. The stuff can be going entirely in a direction all together (a photon), or entirely in loops and whirls around each other (a perfectly stationary massive particle), or in some compromise between the two. You can simplify all of the loopy whirly internal evolution stuff as if it were all one other single direction at right angles to all of the others (in the very short term, a loopy whirly bit might be going forward, up, or sideways, but in the long term it doesn't get anywhere, so we just say it's going timewise or, as I prefer, clockwards).

Just as the relation between going north and east is a right-angle triangle (moving on the surface of the Earth, the square of your speed is equal to the square of your rate of going northwards plus the square of your rate of going eastwards), so is the relation between going forwards and clockwards.

So that's time dilation.

As for relativistic mass, the rest mass is the amount of stuff going all loopy whirly and not getting anywhere. We have to assume that's a constant. To actually make it move somewhere, you have to add stuff (energy, the same stuff as mass) to it, which goes in a straight line (such as having an atom absorb a photon) to increase its luminal, or light-like mass.

(too long)

cont. >>3070326
But remember, the true amount of stuff (conserved quantity) is the total energy. The luminal mass is an abstraction. So there are various complications in adding luminal mass (and therefore speed) without changing the rest mass, but we manage somehow.

So to accelerate a massive object what we're really adding is kinetic energy: the amount by which the total energy exceeds the rest mass.

(we could imagine timetic energy or somesuch, which would be the portion of the total energy which is greater than the luminal mass, and treat rest mass as the abstraction -- except that in our universe we don't ever put energy into decelerating photons and making their clocks tick, whereas we do put energy into accelerating all sorts of sluggish ticking things and making them go places)

Making sense?