Vaebn

One propulsion method I've always wondered about but have hardly seen anyone explore, is accelerator based propulsion. The idea is that in the end, (beamed energy concepts apart) what matters is how fast you can toss your propellant the other way. (Even the Orion thingies are just a trick to accelerate "propellant" really fast). So... what tosses things faster than a particle accelerator? Now, I know, this is pretty much what an ion drive is but the difference is in scale. The modern idea of an "ion drive" is constrained by the mental image of it having to look like a neat little engines, meant to be go behind something probe sized. Whilst what I am talking about is basically, you know... CERN. This is not worth imagining for probes. However, if we are talking about generation ships the fact that the vessel is going to be km long is pretty much a given. Therefore such a vessel could house such a thing running the entire thing length of it (if not wrapped in spirals around it) Accelerating particles to 0.999% the speed of light, which is a far cry from a "normal" ion engine's exhaust of 31 km/s or so. The real questions to be answered are: a) Particle accelerators such as CERN are not meant to accelerate great volumes. They just accelerate a handful of particles as opposed to the millions, of millions a "normal" ion thruster does. One question is if someone can ever make an accelerator, able to accelerate much more significant volumes, without the energy requirements and heat losses of the infrastructure doing the accelerating melts everything within a 10 mile radius. Energy! That's such a thing would need a small city of fission/fusion reactors and a small mountain of fissiles/fusiles for the journey, to power it, is a given. The question is wither something that, along with the weight and heat losses of all its reactors and reactor turbines and accelerator itself, would still be more "efficient" than, say, nuclear pulse propulsion. Keep in mind that nuclear pulse propulsion might be super awesome compared to chemical rockets, but not necessarily an efficient use of fissiles itself. Most of the nuke's energy radiates in a big spherical boom to space and the speed of the little bit of gas/plasma that collides with the pusher plate (therefore the "exhaust speed" of it) is of course much much less than the speeds a particle accelerator can archive. (albeit entire kilograms of it) It can also be hard to improve, because the pusher plate has to survive, thus providing a hard limit on how hard you can hit it, but at the same time there is also a hard limit on how small a nuke can be.

Thats a cute way of doing it, however, I have to say that as a (human) colonist, I'd be scared that the home beam would turn off. The nice thing with self-contained generation ships is that they also act as lifeboats if something happens to the home system back home (nuclear war, relativistic 99% speed of light missile from another species that didn't like our TV transmissions, apes rising to power etc). On the other a hand, a ship depending on beamed energy has a point of failure at precisely the place they are trying to escape in the first place!

^ That, although I'd go so far as to say that the regrowth bit at the end won't be needed by then. The whole ecosystem with trees and water and praires right now exist to support this weirdly complex life thing, which in turn supports brains, which in turn supports what is going on inside them. But clearly all of it, is just a fancy way of converting collected sun energy, into radiated heat energy from metabolism, "thinking" being something that happens inbetween. It is probably worth it, before thinking about anything interstellar, for a civilization to simplify the whole thing to high energy state -> thinking -> lower energy state. Aka "brain uploading" if you so wish to call it. Then you can put the entire crew in a nice solid state box or something, with a nuclear reactor on one end, and a radiator on the other. Not only this is going to be smaller than carrying a whole bunch of wheat fields, and chickens, and mitochondria, just to break down ATP just to make the electrochemical reactions in some fragile neurons. Its is probably going to be a whole lot more comfortable as well. Living inside a tiny universe of a cylinder sucks. Simulated environments on the other hand can be near infinite in experience. Of course all this has huge implications for everything. From not really wanting to colonize "planets" any more, to such ships no longer having to be "generational".

I think using the heart's kinetic energy is a bit crude, and probably tiring and all sorts of bad. Now, assuming copious amounts of sexy biotechnology, here's how that could/ought to be done: There already readily available examples in nature of biological systems generating respectable amounts of electricity. Electric Eels/Rays! They have cells, stacked one after the other, which pretty much generate voltage and act like batteries. With a little bit of tweaking they could -easily- produce the 2.5 Watt or so a USB provides. - Keep in mind you will find a lot of sources saying that eels can produce 500-800 WATTS(!), although this is technically true, they can only sustain that for a couple of ms, before they have to recharge for 20 minutes or so. What most sources gloss over, is that they also produce near continuously low-voltage current, which they use for electrolocation, which amount hovers pretty much exactly at a USB's worth! The Christmas Tree is an example of that, (they aren't torturing the eel in order to make it shock continuously or anything). And the way those cells do these, is through the use of the same energy generating chemical thingies that animal cells use for anything else (ATP etc). So basically, the main effect having such cells would have, is burning "more calories". Which for the rich bastards reading this is probably not a problem. So theres the "source code". Such electricity generating organs are clearly possible, all is needed is some extra truckloads of, well, perfect bioengineering to add us an organ.

Have you excluded the possibility that you are picking signals from yourself in the future/past/ghost/aliens?

I wave a stick on all your aircraft, and present you with this: It's a SSTO lander/rocket. Launched from Kerbin, it can juuuuust about make it to low orbit. (Hey, no one said anything about "SSTO & Return to surface" ) However, it's true power, is that, it is a Tylo SSTO. Specifically a 70km -> surface, surface -> 70km, SSTO lander.

Well... it would largely depend on the duration of travel and so. If it is just for 1 week or so, with near instanteneous travel, I say Enceladus too. Because gaysers 10x times the size of Everest and Saturn nearby with DEM RINGS. However if it is for 10 years or something including travel time. Yeah... I think I will pick Hawaii too.

You know what I'd like to see? A nuclear powered spaceplane! It goes like this. It would combine the concept of a Nerva Engine, with the concept of a Nuclear Scram/Ram/Jet, in what would hopefully be the exact same engine. Just imagine a SR-71 with two large intakes or something (it always was so sci-fi of a design, wasn't it?) A normal jet engine sucks air in, heats it up by burning fuel, then tosses it the other way. Similarly a nuclear ram/scram/jet would suck air in, heat it up because getting hot is what nuclear reactors do, and toss it the other way. ( Such ramjets have been proposed in the past for the likes of Project Pluto and such, albeit the observant fellow might notice that they were parts of nuclear cruise missiles meant to go boom at the end and kill all of russia or something. Let's ignore that. ) The advantages of such a thing are that: a) it doesn't need "fuel" for atmospheric flight. The innate warmth of the engines themselves does all the job. it doesn't need "oxidizer" or in other words "oxygen". All it needs is to such non-discript "air" in order to warm it up and toss it the other way. Intuitively then, such a thing would be able to go much, much higher than the layers or the atmosphere where oxygen becomes scarce. And as the atmosphere would thin out, it would also go faster and faster, which it would pretty much -have- to do, so that it can still gather "air". All too convenient. I have no idea how high such a thing would operate, but I suspect it would be high. Really high. Keep in mind that a reason a lot of "normal" scramjets heat up, is because they have to confine themselves in the layers of the atmosphere with oxygen. This doesn't. If it existed you'd simply pull the stick and watch it go up and up, and going faster and faster. So, oxygen burning aircraft pretty much "stop" at 30km or so which is the world, jet flying record. (the U2 was flying at 21km). I like to think that such a thing would make, well into the mesosphere (80km) easily. Possibly higher. Somewhere along then, it would start using its engine as a Nuclear Rocket rather than a Nuclear jet, using on board propellant. Since, oxidizer is irrelevant, even that propellant mass would probably end up more efficient than any rocket's. (What would be really awesome, would be for the craft to be able to collect and store propellant in-flight. After all, with no oxidizer need, pretty much any gas will do, no? Although I guess there's reasons Hydrogen is concidered the most efficient fuel, even for Nerva style engines. Probably because of how much you can compress it or something) And that's pretty much the most awesome, futuristic, but not alien technology I can think of. Basically a Skylon, minus all the in-atmosphere flight fuel, the oxidizer, and with more specific impulse in space. And of course it will never be done, because if it went boom in low-attitude, it would irradiate everything in a 200 mile radius. So uh. I'll just select the option for rockets in the poll I guess

The real reason is because of the fear that someone will turn it into dust and spread it all over the place. Plutonium would actually be really safe, if people weren't assumed to be dicks. It's alpha radiation can be stopped by wrapping it in newspaper or something. However "easily stopped" in terms of radiation is just another way of saying "the subject next to it, absorbs the entirety of it". This is not a problem if it is newspaper, this is a problem if it is cells. Much like a toxic heavy metal, it also has a tendency to accumulate in the bones and liver. At which point, you have a sort of dust that irradiates what is right next to it.

How quickly they forget that inflatable thing from Bigelow...

I approve.

You don't *have* to target the hole... If the asteroid rotates, you can target any spot you like as long as it pushes at the right direction. If the asteroid doesn't, you can target the hole to make a bigger hole, or anything else reasonably nearby. I only said that to keep a certain mental aesthetic of a rock having a single designated "nuclear engine point". You can of course just rain freely down on it without any sort of hole hitting obligation, as long as all explosions eject, ejecta the right way.

The image of Gilly certainly puts into perspective. However, here's another cool image: I don't know how big Gilly actually is, but I stretched it's image so that it was 26000 pixels, wide, then made a 390 pixel hole in it. A 390 pixel hole, simulates the crater made by the Sedan test in 1962. http://en.wikipedia.org/wiki/Sedan_(nuclear_test) Keep in mind, that was the result of a 100 kiloton warhead, but an 1 megaton warhead would be considered today pretty average. Keep also in mind that the dinosaur killer asteroid is though to have been about 13km in diameter, so talking about 26km is quite generous. 26km, means that something the size of Phobos (which is the bigger one of the two martian moons) is coming towards us. Now that might not look much, however... it is actually visible. You have actually altered geography by doing that in a picture containing the entire thing. I actually find that pretty impressive. In the Sedan test, 11 million t of soil were displaced. 11 MILLION t of rock and dirty rose vs the earth's gravity and fell again someplace which is not the crater. Now, it's almost impossible to find the speed this happened, but on Phobos, any of those that exceeded 11m/s would never return to it. Frankly, I am rather sure that all of it was much, much speedier than that (a jumping cat is speedier than that), so being ultra conservative, I wouldn't be surprised to learn that 10 million tones of material wouldn't return to the asteroid ever again. At that point, all that rock is acting like a propellant, and the entire thing is just a fancy mass drive, nuke doing the driving. And that's just the effect of 1 nuke. Obviously if we are talking about an extinction event, we ought to have no qualms to use, you know, ALL the nukes. So imagine that hole, targeted 200, or 2000, or 20000 times. (2000 explosions ejecting, say, 50 million tonnes of, material each due to larger warheads would equal 50 billion tonnes of "propellant" ejected... right?) Imagine, nuke, after nuke, after nuke, slamming at near the same spot, each one creating a huge plume of material to space. And that's what I mean with "nuke it until it goes away". Project Orion gives the right visual, but the numbers in wikipedia are VERY wrong to go by! Our nukes are a lot more powerful than that. Project Orion had to be survivable and not have the ship go boom, or even have the pusher plate ablate after hundreds of explosions. It was pushed only by a tiny amount of material which the nuke vaporized in its own container. In this case, we'd have no reason not to go balls to the wall, "we must move this NAO". Now, there are some details regarding how fast that exhaust is (it only has to be faster than 11m/s to impart some change), but by plugging those numbers to one of those delta-v calculators and taking into account: I am sure that you'll find that we aren't nearly as powerless as a species!

Just nuke it 'till it goes away Orion thingies having already been mentioned, I'd like to note that you wouldn't actually need a properly build orion engine, with a pusher plate and stuff. The asteroid would be the "pusher plate". So basically you'd just have to lob nukes at it one after the other. I suppose either some sort of standardized, cheap, booster section for existing ICBMs would have to be quickly made and mass produced, or bigger rockets carrying many warheads at once, and releasing and spacing them out with tiny rockets of their own, before impact. Preferably both.

Or you could use a $1 cable from a Laptop's HDMI port to a TV's HDMI port I am more interested in, is the word "Linux", combined with the word "2.500 games of Steam", because I am not actually very sure how that is possible. On the other hand, if that means that SteamOS, will include some sort of properly developed and supported library emulating whatsamathingy, like wine then that is a more significant announcement than people realize.

Yes, but not yet. Unless you count single celled things as animals as well, in case it has kind of, already been done ( Mycoplasma Laboratorium ) The problem with such biology is that it deals with huge amounts of information. Not to mention that the DNA, courtesy of it's evolution, is not only fully obfuscated, but also a case of the worse spaghetti code in existence. Considering that computers have only recently become "good" (aka, think of what our fathers had) the information age had to happen first before a true age of biology can begin.

Use them as liquid boosters for an even bigger rocket.

Already been to Eeloo once, and I was going to do so again as I "took for a spin" a variant of my main in-system ship to test if it is Eeeloo capable. So I might as well show it off here Here's the two ships in formation flying. The ship in the foreground has been used so far to plant a flag on every solid body in the system except Eve & Tylo, without changing a single thing ever since it's original design (originally made for Duna. I overengineered a bit). They are also fully reusable and under 100 parts each. The ship in the background, is the light, sport's version version of it, featuring a variety of revolutionary features, like: - a pointier nose - better handling - better acceleration - 10.000 of delta-v Sexy promotion shot of the sport model. And away it goes. Kerbin Escape burn. Now, this being a toy for rich Kerbal Billionaires, the ship doesn't really have many scientific instruments on board (just a smartphone really). As a result, my mission pretty much is to pop to Eeloo, spray some rude stuff over Hejnfelt's stuff and go back. Instead I'd like to wave you away from the scoring system and point out that the ship features a private cabin per Kerbal. Does yours? A couple more gracious burns, courtesy of our lady the atomic engine and the ship does arrive to Eeloo entering a 8700km "low orbit". No problem, the lander, is completely overpowered anyway and can do the rest itself. Speaking of the lander, in case you have been wondering where that one is, it's time for... SAUCER SEPERATION! Had I had... a saucer. And there's the lander. It had been pushing the ship all along. Engineering section heads to Eeeloo. Aaaaaand... Touchdown! Yay, Eeloo! For some reason the Kerbals don't want to touch the ground that has been thoroughly irradiated by the nuclear engines, despite our reassurance that no local bioinfectant can possibly survive the touchdown. Weird. Time to head back, and after the tiniest of inclination errors... Back in one piece! Also another shameless promo shot. Now, at this point the ship runs so low on fuel that it is basically operating on the lander's fuel supply worth. Acceleration has gone up to 6. We leave no comfy cabins behind however and will carry them back to Kerbin. Some minimal aerocapturing might be required in order to enter Kerbin LEO though... Approaching Kerbin in order to perform minimal aerocapturing. Aaaaaaaaarh, thisburnsomuch. Notice the altitude from the surface Pointy nose man. It makes all the difference. And back to Kerbin LEO. Awaiting for the local automated fuel tanker. :]

Hi AletzN1! I've actually accidentally done a couple of those in my explorations for a SSTO Tylo lander (I don't like my ships littering like *some* people) Here's one, full stock, minus the mechjeb: I call it the "The Space Booth". In fact, this silly thing not only makes it to an 100km orbit, but if you do a Hoffman transfer it has enough fuel to crash on the moon. So I guess you could call it it a Single Stage to Moon Impactor or something Craft file to confirm: http://www.sendspace.com/file/ud9ois And yes, for that matter, it is a fully a capable 100km to surface, surface to 100km, SSTO Tylo lander as well, if interested. Or don't mind carrying a 80tn "lander" around. And here's another one! (told ya I have lots). This is not exactly a lander design, but a derivative of one which I figured could make it to Kerbin Orbit with a couple of tweaks. It makes it to 70km Kerbin Orbit, again full stock, minus Mechjeb: Wat. LV-Ns? I know that these make no sense on Kerbin but in makes more sense on Tylo. Notice the aerospike in the middle. This actually starts with a terrible TWR on Kerbin of, uh, 1.04, but as it consumes fuel it improves. At about 30km, I shut down the aespike and LV-Ns can do the rest alone. Craft file to confirm: http://www.sendspace.com/file/98dve1 Remember that you are looking at lander design derivatives so none of those are really meant to carry any payload or land again, they are however "rocket fuel only, stock parts, SSTO"s ^^

Anyway. The answer, which I give very intuitively, is none. Minus radioactive elements whose half life has caused them to decay ever since the initial creation of all heavy elements. Said heavy elements were created in a nova (or novas?), which in turn seeded/were part of the hydrogen cloud that made the solar system. So if you can find it on earth, you can find it in asteroids too. It was the same cloud everywhere! The only reason planets seem to be "poor" in them, is because during planet formation most of the heavier stuff settled within, like a sexy planet sized layered cocktail.

Hm, I think I'll throw my little ship in this thread as well. =] Behold, the Bacteriophage. It's a minimalistic, 91 part, two-person space yacht. It does include some RP elements however, like each Kerbal getting it's own cosy cabin for the duration of the trip. It's main party trick is that it doesn't push a lander, the lander pushes the ship. The aft section in this picture detaches and lands. And yep, it's Moho capable.

Technically speaking, radiation doesn't sound like something -that- hard to deal with, so a different evolution path could perhaps be more resistant to it. The reason I am saying its not that hard, is because it goes like this. Already cells have some limited self and DNA repairing abilities, however a main problem with that process is that it seems to only take into account the information inside its own cell. DNA for example will use "the other strand" to repair itself, but when both strands happen to get damaged its screwed. Yet, radiation only damages a couple of cells which means that usually, you'd have a lot more cells that are radiation un-damaged, than radiation damaged. All of them containing a perfect copy of their original DNA (incidentally the concept of a "DNA" for a product of a different evolution process is probably bs, but nod along) What an organism could have, is a way for a cell to "statistically sample" the cells nearby, for their own copy of DNA! So, if in 1000, or 10000 cells said copy is one way, and in 1, with both strands damaged, another, then a process ought to be able to figure out, that, that's how it ought to repair it even if the cells itself doesn't know it. Or kill it. That would make an organism significantly more radiation resistant. So resistant that part of the reason it doesn't exist, might be that being able to get DNA "easily" damaged, kinda helps evolution, whilst such a thing would basically stop evolving. (such a process could even fix damage from free radicals and such) I can perfectly imagine such a system working for a different biology though. For example, perhaps some random "damage" could be introduced only during reproduction, in which case an organism could both evolve, and have radiation resistance. Such a system could develop in a system where "radiation resistance" is a much more important factor, than on earth (where things -don't- usually die from cancer before reproduction, so it's hardly an advantage). (Keep in mind that ultra-high doses that kill many cells at once would still kill you. The same way we have "UV resistance", but it you stand in the path of a huge UV laser, you'd still be toast)

Create... creative outlets! Sorry couldn't resist.

You know... with a really good electromagnetic launcher, the satellite could de-orbit the rod merely by tossing it really really fast no? Of course that would accelerate the satellite the other direction, but technically you'd save on the weight of having to give the rods separate engines. The satellite then (who probably already has a nuclear reactor on board and tons of capacitors for said launcher ) could use a much more efficient way, like ion engines, to fix its orbit. See! It all makes sense.

Yes, No, Maybe