January 8th, 2011, 03:37 PM
A more for the fun of it article based about how much energy it would take before we even launch such a mission.
"Interstellar travel won’t be possible for at least 200 years, according to a former NASA propulsion scientist who has some new calculations"
http://www.popsci.com/science/articl...w-calculations
January 8th, 2011, 04:55 PM
A while ago I did some back-of-the-envelope calculations on transit time for a rocket of reasonable size and thrust (chemicalropulsion) to go to the nearest star. The estimate was about 30,000 years. That is considerably longer than the funding periods usually aurhorized by Congress.Originally Posted by Lynx_Fox
You can cut that down a bit if you assume exotic propulsion, but not by enough to make the trip feasible.
Nevertheless I think we should launch almost immediately -- and I have suggestions regarding who should go.
January 8th, 2011, 05:01 PM
ROFL!
My personal belief is that 200 years is too short. We got to the moon 40 years ago and it will probably be at least 20 years more till we get to Mars. At this rate in 200 years we might get to visit the moons of Jupiter and maybe even Saturn's.
Probably.
In the 1960's we pretty much knew how to get to the moon, so the problem was mostly in assigning sufficient resources to the task.
At this time we have no clue as to how to do practical interstellar travel. Light speed is a significant limitation, and we have no technology capable of propelling anything macroscopic at any significant fraction of c.
We won't be on Mars in 20 years. At the rate the space program is regressing we may not be there in 100 years. Constellation is alive only because the budget is kept going by a continuing resolution, and Constellation will hardly put a man on Mars.
Unfortunately cost escalation is outpacing technological innovation. Our best propulsion system is still the chemical rocket 50 yrs later. The associated costs are probably 100s of times higher.
We were a simpler people back in the early sixties, who believed their government could do no wrong and we rallied to the opportunity to get to the moon no matter the sacrifices. Today we're not willing to make personal sacrifices for the benefit of mankind. Look at how we agonize over a few deaths in Afghanistan ( I'm Canadian ) when we lost thousands in each of WW1, WW2 and Korea.
Interstellsr travel will have to involve a paradigm shift ( always wanted to use that word ) in the way we travel, and possibly to where and when, we travel.
The rocket is a fairly small part of the total launch cost. The big piece is the standing army at the launch site, and government regulations that drive the pre-launch processes and size of that standing army.
Chemical rockets will not get you interstellar travel. Neither will anything else currently known or under study -- arc jets, ion propulsion, nuclear. solar thermal, solar sails, ....
yup, due to these limitations, science fiction(well at least for the present) kicks in, so we are looking at controlled antimatter collisions, a possibility of a wormhole transit etc etc...Chemical rockets will not get you interstellar travel. Neither will anything else currently known or under study -- arc jets, ion propulsion, nuclear. solar thermal, solar sails, ....
I think we should start by colonizing our own solar system, and maybe build a super-giant telescope, before focusing on sending a ship to another system.
Before 200 years pass, nanotechnology, genetic engineering, ec, may make it possible to launch a self-contained colonyship in which a Martix like simulation has the duplicatation of human minds live in a virtual world for a few hundred years(thousands of years earth time), while receiving messages about scientific discoveries or events from our solar system(as long has humans arent extinct or something), and when it gets to another planet these simulated minds could transfer to an android body and explore and possibly create an automated outpost, and if desirable use stored DNA and cells to rebuild human bodies and teach the kids about the ancient earth left behind and the new colony they are about to build.
When that civilization gets around to building starships, they travel and find other civilizations that are conveniantly human and speak english.
As soon as we figure out how to manipulate space like the UFO's
we should be able to get to the nearest star almost instantly.
Because if we can manipulate space we can eliminate space.
Space is made of ZPE(zero point energy). As soon as we figure
out how to control this subatomic energy we should be able to tunnel
across space to anywhere we want to go by eliminating the space
between you and your destination.
What have you been smoking ?
January 14th, 2011, 01:20 PM
Well it will not happen for a very long time has we first must find a way to bring the space cost down before we can try to go to other star system.
Just bringing the space cost down will be a problem.
January 14th, 2011, 01:25 PM
Cost is not the problem. We don't have a clue how to go there in any vaguely reasonable time at any cost.
January 14th, 2011, 01:45 PM
What I'm trying to say is we are having hard time to find way to bring space cost down and he wants us to go to other star system it is beyond the science and technology level today.
First thats find a way to bring space cost down than we can look into space mining and space colony do to it is cheap than we can look into harder stuff like how to go to other star system.
By that time science and technology will be more advance to how to find a way to go to other star system.
the biggest problem in traversing the stars with current technologies is the enormous amount of fuel required. realistically we'd not be able to reach our destination alive if we weren't travelling at least 10% lightspeed. the fuel required for this is absolutely vast. even at 1g accelleration for half the trip to proxima centauri would require us to expend the size of a small asteroid worth of energy.
realistically nuclear fusion seems destined in our future of space travel
it's gonna be at least 300 years before we figure out how to get a bit more go for the gram of fuel expended
It is not just the amount of fuel required, it is specific impulse and mass fraction. With current technology we could not get to any significant fraction of c is fuel were no constraint.
yes you're right, but again, we are many orders of magnitude below the specific impulse required. technically some past ideas would work, such as project Daedalus. but then we are assuming we will have sufficient technology to fuse materials such as deuterium. and again, would still require vast amounts of fuelIt is not just the amount of fuel required, it is specific impulse and mass fraction. With current technology we could not get to any significant fraction of c is fuel were no constraint.
Wow...
Such optimism of everyone for technological breakthrough before the stated times.
True interstellar travel (millions of light years) would never happen unless there is a shortcut.
The nearest star could be reached within a lifetime with conventional rockets.
Maybe this means giant colony ships, but I strongly disagree with this idea- humans mentally evolve so fast the colonists wouldn't be human when they reached their destination (if it is many generations).
Huh? I think our brians aren't much different than they were 20,000 years ago. Evolutionary change to another species takes a lot more than a few generations.
Sorry for not being clear. I meant cultural evolution rather than actual physical evolution. Although they would share our genes, their culture would have adapted to fit their surroundings. Just think of the difference between today's culture and that of the 1900's.
what about if we were able to exploit magnetic energy i mean whit huge magnets wouldn't that work?
How ?
well i been thinking about something but i do not know for sure if it is even possible and i need someone with general knowledge of magnetism. if you have knowledge i would be glad to tell you how we can produce enough energy for a space travel if i sit and think a little it is almost infinite
My best bet is least 500 - 1k years. Any propellant system won't get us to another star in a lifetime, unless we create babies aboard a spacecraft, or on a space colony created by robots/androids. Else the last alternative is if we could prolong life to absurd extent and at the same time could put the astronauts in a hybernation.
First we have to create commercial interest in populating Mars and mine the planets, then the space programwill really evolve.
Another potential problem is that the greater the speed (in fractions of light speed) you get to reach, wouldnt collisions with a big chunk of rock somewhere in between be a problem? wouldnt it be the equivalent of being stationary and be on the receiving end of a hyper velocity mass driver cannon?
Maybe in the distant future nanotechnology can be used to send a smaller probe that contains a brain simulation of people, knowledge bases, nanobots and such a probe could drop like a seed and start replicating nanobots that can assemble into a collony node, once the infrastructure is in place and environmental systems functional it can replicate dna and seeds to be planted in automated hydroponics hub, then human looking androids can be manufactured where the brain simulation of the people(now long dead) become simili sentient en start making the colony functional. And if they so desire, they could clone humans to be brought up by the artificial parents, and then go from there.
At any speed characteristic of space travel, orbital speeds for instance, if you hit a big chunk of something you are toast. Additional speed doesn't add hazard. Dead is pretty much dead.
who votes for anti-matter propulsion?
The movement towards commercialization of space is a good sign. I suspect that as we gradually build infrastrucure and human presence in near-Earth space there will be a self-reinforcing mechanism that will prompt more infrastructure and human presence.
The big hurdle now is to find ways to reduce the cost of getting from Earth to low Earth orbit. Once this cost is brought down by new approaches, or just by economy of scale, things will move along at a quicker pace than what we've seen so far.
The catalyst that's needed is the so-called "killer app" (to borrow a term from the early days of the computer). Once someone figures out how to make a lot of money in space, there will be a rush of well-heeled investors wanting to get in on the ground floor of the next "big thing". In a way we're already moving in that direction with the numerous privately launched and operated communications and imaging satellites. In this regard space-based solar power satelites have long been touted as the leading candidate.
I see a slow progression outwards from Earth to near-Earth orbit, to the Moon, and subsequently to the outer planets or their moons, and the asteroid belt. Only once we've exploited the immediate neighborhood of the solar system will people seriously turn their attention to relatively nearby stars. By that time the technology needed to live in space - and to live in orbiting colonies will be mature. As it stands, orbiting space colonies (or generation ships, if they're intended to transport people) seem to be the most likely method for leaving the solar system. If the type of colony envisioned for structures such as the Stanford Torus or the O'Neil Cylinder come to pass, living in space won't be much different that living in most urban terrestrial settings.
In reply to the OP, I think we're looking at several hundred years before serious consideration is given to sending people outstide our own solar system (barring the invention of warp drive, of course).
Chris
Definitely agree. Commercial interest would be the key. Once we're up there harvesting and making use of in-situ materials in large quantities, building huge giant rockets in space will be much more practical.
I think what would be more practical than trying to build a cylinder or toroid shaped space station is just to build it however you want, then divide the space station into two parts and tether them together with a long cable.
It would be the two ends of a bolo.
The most economical design depends on ths size of the ship. For large populations () it seems that a variation of the O'Neil cylinder is most economical overall.
(ref. http://www.nss.org/settlement/space/2007KalpanaOne.pdf )
Chris
Good point. I guess if the floor space is going to be large enough, then it might as well be laid out so that it curves around into a loop. Then we don't need a big long cable.
The cable design would be great for smaller ships, but probably an interstellar flight would not be a smaller ship.
If it's going any respectable speed it would only be safe if there was a lot of mass in the front of the vessel to ablate and absorb inevitable impacts with stray atoms and molecules. We'd probably need centrifugal force but I'm not sure how much really or when humans need it. Could we work in 1G during the day but sleep in near 0 G for example and still remain healthy? Do the reverse?
approaching fractions of the speed of light does increase the risk of impacts being disastrous. but take when we get past our solar system, theres very little debris, and very little anything really, so i dont think this would be the main issue.
realistically if we were to make somethin it would almost certainly be nuclear. people seem to think you can hop in a little ship and go, but the fuel required to approach say 10% the speed of light is simply vast, much more than humanity is capable of supplying right now, the fuel consumption is exponential, the faster u go, the more fuel required, the more fuel u require means u carry more mass, and in turn, the more mass u carry, the more fuel required to get it up to speed.
it's sickening to think that the status of our ability to travel to the stars has not changed in 50 years, since we first proposed the idea
My guess for achieving interstellar flight is never.
What do you want to do on another star? If you just want to observe it then probes and surface robots will be able to do everything, yes, including making decisions on where to look, tirelessly and incomparably cheaper than sending people.
If we want to live there then how many people do you send? The mass that you'd have to accelerate is ridiculous. Even if you send just frozen eggs, you have to somehow recreate an entire functioning civilisation. Even if this was possible, what's the point? They won't be like us, are we expected to instill in them our culture by virtual teachers? What is the point? the world will be so different and they'll have to develop their own culture anyway.
In my opinion interstellar travel is a modernist's dream, the claims that we have always wanted to go to the stars, or that it is our destiny are nonsense. 100 years ago people dreamed of travelling to the centre of the earth, 200 years ago they dreamed of adventures against huge kraken and elephant eating birds. It's just a dream. It happens to have been given some credibility by USA spending billions getting one over on the communists by having people play golf on the moon
This passage, apparently from East Africa 200,000 years ago, fell through a time warp and was translated by a colleague:
My guess for achieving intercontinental travel is never.
What do you want to do on another continent? If you just want to observe it then look at what plants wash up on the shore from that other continent, or what birds and animals migrate from it.
If we want to live there then how many people do you send? The number you would have to move is ridiculous. And how are you going to move the children and the old folk? Even if this was possible, what's the point? They won't be like us. The people in the next valley have some weird ideas can you imagine what they would be like if they lived on another continent. What is the point? the world will be so different and they'll have to develop their own culture anyway.
In my opinion intercontinental travel is a witch doctor's dream, the claims that we have always wanted to go to the other places, or that it is our destiny are nonsense. 100 years ago people dreamed of travelling to the Big Hill With a White Top. Two hundred years ago they dreamed of travelling down The River that is Wider Than My Mother In-Laws Ass. It's just a dream.
It happens to have been given some credibility by the Fukawi tribe who have made water bottles out of antelope bladders so they can roam into desert regions for days at a time.
The point is to honor the only real purpose in life which is shared by all species....to survive.
Given the gulf in time even if we had "fast ships" of say 10% of the speed of light, the colonist will essentially be on their own and develop their own cultures as humans have always done when separated from their homeland by long travels.
Thanks for the analogy Ophiolite, the problem is that analogies should be reasonably similar, but when the distance is different by a factor of 10^13, the gap in energy levels is even larger, it is not a convincing comparison, it only reinforces the known fact that sometimes we can do things we don't think possible today.
While we dream of space travel, here's the reality:
- Within 10 years oil will likely be on terminal decline, and that includes rocket fuel.
- Advances in space propulsion beyond rocket fuel can't circumvent the astronomical energy required to move civilizations between the stars.
- With a rising population and larger demands for energy from the developing world, together with limited sustainable alternatives to oil, we will be hard pushed to sustain our own world let alone a massively risky mission to a poorly understood distance planet
For interstellar travel to be likely there needs to be a concrete reason that is better than the cheaper alternatives:
To colonise to expand population or escape earth problems:
- space stations in own solar system immeasurably easier
To learn about suspected alien life and report back
- robotic probes immeasurably cheaper / faster / less risky
To experience living on strange new worlds
- virtual reality and simulation will not only be hugely realistic in future, but will allow all sorts of simulated planets and plants... a planet 50 light years away will seem far too boring
To survive:
- possibly we might want to colonise another star when the sun becomes a red giant, however most species don't live that long and if we did live that long, we would have evolved, split and changed such that anything resembling a human would have died out millions of years prior, i.e. it wouldn't be 'us' doing any travelling.
In my opinion it is just a dream, we have dreamed of living in floating houses in the clouds, and dreamed of cities under the sea and voyaging to the centre of the earth, and we dream of living on other planets. The first three are far far far more modest dreams but we don't do them because there are easier alternatives.
Intergalactic space travel by humans has already been done- Long ago in a galaxy Far, Far away. (Begin Yellow scrolling text explaining current status of the galaxy)
It would take over a 200 years.
There are many more hurdles than just having the required drive technology.
No one is going to send a ship with humans in it without knowing what we are sending them to. Probes will be sent first which will take decades to get there, data will need to be sent back, which even at the speed of light will still take at minimum over 4 years to arrive. Currently we can not detect earth like planets so we would be sending them blindly in to a solar system hoping for the best. Just the research of where to send the ship will take considerable time.
The building of the ship itself will probably not really start until at least one probe has been sent and reported back with positive results. Even then we lack the knowledge of how to build a ship of that complexity. It will need to provide the needs of all the humans aboard for years. It is a completely closed system. All the food needs to be grown, waste taken care of, air recycled. If we say it was basically a huge garden the complexity is massive. It would take a lot of space to provide the required food even with hydroponics.
Then you need all the resources we take for granted. What if something breaks? You need the ability and parts to fix it, you can't take spares of everything. What about energy for the habitat? Energy for heat and lights for the plants as well as the humans. How do you power the ship?
Who do we send and how many? What are the psychological requirements of the explorers? This is unlike anything ever done before and mental health will be a huge factor. How do we get the explorers back? Etc.
About ten years ago, a couple of NASA scientists wrote an article for Scientific American on interstellar travel. Their view is that it will take 500 to 1000 years before humanity can send a vessel to Alpha Centauri.
It is also their view that maximum achievable speed would be 10% to 20% of light speed. I think this was to be done with highly efficient ion accelerator drives.
If we assume 10% light speed, and a ten year period to accelerate to that, plus 10 years to decelerate down again, then to get to Alpha Centauri would take 55 years.
Obviously, sending a vessel before that time would be idiotic. If a vessel left Earth 250 years from now, at 1% light speed, it would take about 500 years to get there. In the mean time a second vessel leaves Earth after 500 years at 10% light speed, and their descendants have been living on the Alpha Centauri planets for 200 years when the first one arrives!
I am sure that any scientist (or other expert) is far better qualified, than the layperson, to predict future developments in their field. This is certainly true for what I would call the short run (next hundred years or so) but I am less convinced that predictions about what can be achieved, in the long run, have any accuracy.
The NASA scientists are probably right, about interstellar travel, but trying to work out scientific/technological developments 500 to 1000 years hence is difficult, if not impossible, even for these experts.
I just feel I have read and listened, too often, to those (some of them scientists) who seem to believe they have an insight into what can and cannot be achieved, by a certain time, in the distant future.
Halliday
I am sure you are correct with respect to timing. If we look at predictions in the past, the would-be scientific prophets nearly always get the timing wrong. so if NASA scientists predict interstellar travel in 500 to 1000 years, we should probably add a big error factor. Maybe 200 years to 10,000 years??
Whatever. It is irrelevent to us, anyway, since it is so far in the future - so long after we are dead - that it matters not at all to us personally.
I am more interested in theoretical capability. Barring some breakthrough, allowing us to do what the currently understood laws of physics permit, the question becomes, what cruising speed can an interstellar craft, of very advanced design, reach?
I read somewhere that the Voyager spacecraft would take something like 80,000 years to get to Alpha Centauri (if that was where they were headed). Since the aforementioned NASA scientists claim we will one day be able to travel at 0.1c to 0.2c, then any spacecraft sent off in the near future, at our current very slow speeds, will be comfortably overtaken by future and faster space craft.
"They that go down to the sea" has long been an important subject of scifi.
Any interstellar mission launched in the next fifty years will be of necessity one way and profoundly uncertain of success.
It will have to be a "generation's" style mission. The original mission cosmonauts will long have been soylent green before their descendants even think of arriving around their target star where there might, or might not, be a habitable planet.
I also strongly suspect that if such a mission attempt were announced today, there would be no shortage of volunteer's.
quite frankly none of this that anyone has been talking about will happen in our current system of artificial scarcity. only till our nations evolve to a post scarcity or "resource based economy" will many of these technology's be adequitly (srry spelling) funded. search post scarcity on wiki if you're curious and watch zeitgeist addendum on youtube as an example of a post scarcity system if you want to
Ophiolite gave perspective.
For the scale and significance of the venture, I don't find 30,000 years very long. Or, what advantage could there be in colonizing quickly?
The main problem is sustaining life, both in transit and arrival. If we can do one we can do the other.
As I mentioned, we should colonize our own solar system first. Once we have a space civilization necessity should increase the exposure and focus of space travel technology within our own solar system. Eventually we can send Seed Ships to other solar systems but the priority should be our own system.
I agree with somfooleishfool, in that the best way to acheive a space civilization is to upgrade and reboot our social and economic system to something that resembles a ressource based economy or a system that ends up along the lines of what Star Trek's creator envisioned.
May 24th, 2011, 02:34 PM
i firmly believe that the key to intersteller travel is the abandoning of fossil fuels and the primary focus of reactor-produced energy. we will then be free to experiment with electromagnetic propulsion. it is believed that using electromagnetic field tensor theory, one can propell a craft off of the magnetic fields of planetary bodys. though this would only be usefull in a solor system, and there would need to be some astonishing advances in enertial dampeners, this is the logical next step in propulsion theory. the only restriction is power, a mind-boggling power source would be required, and channled into the most advanced and sensitive electromagnet ever designed.
P.S. the same would hold true for interplanetary flight. allthough the power demanded would be reduced dramaticly for inside a atmosphere. then, the only concern is crashing a vehicle with a reactor in it, into a house or highrise, and vaporizing several city blocks when containment is breached.
May 24th, 2011, 02:59 PM
there is also another theory, this would require that stephen hawkings theory, disproving "Aether" is wrong. it is theorized that space is actualy not the lack of substance, but instead is full of a substance called "Aether" this is the reason that Einstein's Theory of Relitivity does not govern the speed of light. because the "Aether" is not at a constant density, and therefore slows the speed of light as per the observers possition in a Actual Fixed Spacial Location. as the source of light must still uniform to "line of sight" and therefore to get an actual messurment of the speed of light, one must not be on a planetary body (because a planetary body is always in motion), and not have anything, "Aether" included, in between the observer and the source of light. therefore every messurment of the speed of light, theoreticly, cannot be correct. keep in mind that all spacial possitions on a planetary body is never fixed. if one was to cup there hand, and call the center of the void, possition X, then 1 second passes, that means that possition X is actualy about 12 miles away from your hand, from the rotational concept of our planetary body. this is the basis that there is no concept of "Absolute Space". also bear inmind that it is proven that the known universe is expanding at a finite speed and new space, or "Aether" is constantly generated. the cause for this is currently unknown.
with this same concept in mind, in theory, if "Aether" has a density, and it can be messured, then theoreticly, one can find a way to propell themselfs throughout the "Aether" with a engine of some kind.
I doubt that electromagnetic fields in interplanetary space would be strong enough to use as a basis for any significant thrust. I have seen no serious scientific discussion of this possibility.
My own view is that space travel will, in the long run, be an outcome of social and technological evolution, rather than specific policies or decisions. We have already begun with a few small orbital habitats.
Since it will take decades or centuries rather than years for interstellar travel, we need massive space habitats (space cities?) which are largely self contained before this movement will occur. A rotating and shielded habitat which is carrying out economic activity somewhere in the solar system could easily be adapted to travel to another star system.
The most logical drive system, to me, would be a linear particle accelerator, which sends its reaction mass out the rear at close to light speed. Very slow acceleration over a period of years, but a rather high potential top velocity - a significant fraction of light speed.
i find what you said especialy interesting, because to my knowledge there has been no research into what that would actualy do to space. for instance, if the theory of "Aether" as previously mentioned is correct, then that could prove for a very interesting ride indeed. since there has been no experimentation on high yield particle accelerators in a Zero-G non-Atmospheric enviornment. it very well could cause a tear in space, as some of Eienstein's Theorys would suggest.
This must be some new theory of "aether" I was previously unaware of, as all the older aether variations have so far come to nothing. Literally.
You build a giant mass driver on the moon, 600 km long, accelerating a missile with an orange sized nanofactory-seed payload, an extractable communication anteana, a deployable solar sail and a miniaturized ~whatever~ propulsion system. The missile is lauched like a torpedo into space and accelerates with its propulsion system to the best speed possible. As it travels new and improved data is sent by radio signals. Hundreds, or thousands of years later, the missile reaches a nearby solar system and deploys the solar sail to slow down as it heads for a suitable planet or moon. The nano-factory is launched and lands. It assimilates molecules and grows, creating a base hub, then a base which sends the ready signal back to our solar system. In our solar system a large automated comunication array receives the message, re-activates and sends digital data to the new planet colony on a trip at light speed that will take a few years. The data will include a complete neurological map and bio-chemical neural simulation program of the various volunteers that may or may not still be alive, along with historical records, technological schematics and digital creations(artwork, movies, etc). The colony receives the data and uploads the artificial conciousness of the virtual travellers into androids.
Then the androids build a replication chamber and on earth a disintegration chamber is built. You step in the disintegration machine, and your olecules are analyzed and you are destroyed. The data is sent to the replication chamber where you(or someone exactly like you that thinks hes you) are recreated at the molecular level and voila! , you just made a trip at light speed in a teleportation machine! ta da! Simple isnt it?
Not only is there no evidence of a 'tear in space', but the vacuum of space is by far the best place to operate a linear accelerator.
A smaller version of a linear accelerator is known as a rail gun, which uses electromagnetic fields to fire bullets at enormous velocity at the enemy. Rail guns are popular science fiction gadgets for use when at war in space. They will not work anywhere nearly as well in atmosphere. However, in space, there is no clear cut upper limit for the velocity of the bullets, and they could be effective at massive distances, and be quite devastating.
Between small rail guns and a giant accelerator, there are numerous possibilities for a device to expel reaction mass at high velocity, thus providing acceleration. I would suspect that our interstellar craft would have an accelerator at least ten kilometres long, and expel ionised gas out the back at perhaps 99.9% of light speed. Such a device would permit slow acceleration to about 0.1C or even 0.2C. No faster, since a large part of its reaction mass has to be used for deceleration.
As also pointed out, a light sail might also be a part of initial acceleration and deceleration when near the goal. Two propulsion systems are better than one.
As said, I see no advantage in getting to another star quickly. Moreover it occurs to me that an impatient start bodes ill for the long-term mission. The mission, ultimately, must welcome an eternity of independence from Earth's civilization. If colonists lack the self-reliance to accept a lengthy voyage, how will they cope in orbit of a lifeless star?
But if fast travel is a must, the best way is to use fuel thrown ahead of the engine, before you even got underway. Then your craft isn't burdened with an enormous mass of fuel and burning fuel to accelerate the fuel mass. Use something like Skeptic's rail gun to shoot the fuel ahead, then build your craft a century later.
So, for the sake of costs, the going rate for positrons (anti electrons) is 25 million per milligram.
http://en.wikipedia.org/wiki/Antimatter#Cost
And that does not include the costs of long term storeage. A cardboard box is not gonna work.
So who pays the very very high costs of this ?
The guys now who have no hope of making the trip ?
The guys who are going to go who won't be born for decades ?
Have you written your check ?
Here's the kicker with long slow voyages, Since technology will presumably increase as time goes on, we will be able to make faster and faster ships which will overtake and pass the earlier ones. I know that it is an worn out cliche, but it is an issue.
For instance, let's start with a 30,000 year trip to Alpha Centauri. And we'll assume that technology increases at a rate such that final achievable velocity of our ships increase by a modest 1% per century.
This means that a ship launched 100 years after the first ship will shave ~300 years off the trip and arrive 200 years before the earlier ship.
Wait another century and you trim ~297 years off the second ship's time and arrive ~197 yrs before it.
Another century trims another ~294 years of the third ship's time...
Finally, after 11,000 yrs have passed since launching the first ship, you will have a ship that will arrive after the ship that was launched in the in the previous century rather than before it.
It doesn't make much sense to start launching ships before then, except where noted below.
Reasons to even start launching ships eariler would be:
A propulsion breakthrough occurs that reduces trip time so significantly that we get "ahead of the curve".
A Noah's ark type scenario occurs. we won't be around to or will be incapable of
launching ships in 100+ yrs.
We "hit the wall" as far as propulsion technology goes and we can no longer expect to increase speed's by 1%/century anymore.
Yeah. I wonder how we would contain it in space. Would it work to just generate a really big magnetic field and then just have the positrons orbit around the outside of the space ship in a big ring or disk? (This would be a good time for me to admit that I'm out of my depth. I'm really bad with magnetism and charge questions.)And that does not include the costs of long term storeage. A cardboard box is not gonna work.
Cosmic rays would still hit them, which are less than 1% composed of electrons, so it couldn't stay out there forever without gradually getting annihilated. I don't know how dense those rays are, though. It would be interesting to try and figure out what their half life would be under those circumstances.
Anti-hydrogen is 62.5 billion per milligram, if that's any easier.
this makes me refer to Stephan Hawkings, "Into The Universe" part 3.. look into that =)So who pays the very very high costs of this ?
The guys now who have no hope of making the trip ?
The guys who are going to go who won't be born for decades ?
Have you written your check ?
My vote is a bunch of naive rich dudes. You know, the kind that are willing to pay to have their heads/bodies frozen after they die. You just convince them that, when the technology to bring them back is discovered, someone will send a a radio signal to their ship so the colonists onboard can use it on them.
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