How to travel to Alpha Centauri
Prohibited total or partial reproduction of the material contained in this site without permission of the author.
Intellectual property of the researcher Daniel Marin.
It's official. We know that there is at least one planet in Alpha Centauri, the closest star to the sun. And, given that Alpha Centauri is actually a system made up of three stars, it is likely that there are many more. Since we met the news of the discovery, many people are wondering how much it would take to travel to Alpha Centauri to see the new planet with our own eyes. Or rather, with the eyes of our robotic emissaries.
I would say that it is possible to carry out a mission to the nearest star with a duration of twenty or thirty years. Long, yes, but less than the average life of a human being. I would say, but I'd be lying. Sorry, folks, but there are no shortcuts. Interstellar travel is really difficult, really a feat itself evolved species and not suitable for small aggressive apes airs. Garlic and water. Although, on second thought, perhaps all is not lost. Consider the options more calmly.
 |
| Travel in the Hyperspace |
The abyss of interstellar space
The fastest human object we have launched outside the solar system is the venerable Voyager 1. This probe is away from the Sun at a speed of 17.4 km / s, ie about 540 million kilometers a year. But Alpha Centauri is 4.37 light years, or 272 000 astronomical units (AU) - a figure that drops to 4.24 light years for small Proxima Centauri. At this speed, the Voyager 1 would take about 76,000 years to reach Alpha Centauri, assuming him to travel to it (which does not). Needless to say, the Voyager is not a very suitable interstellar vehicle.
The moon Pandora Avatar movie revolved around Polyphemus, a world orbiting Alpha Centauri A. We do not know if there are habitable worlds in Alpha Centauri, but the presence of planets more than 10 Earth masses seems ruled.
With the technology available would be possible to send a ship out of five to ten times faster Solar System Voyager 1. NASA serious proposals to build capable 'interstellar' probes to study the Oort Cloud or the heliopause expect to reach a distance 150 000 million kilometers in fifteen or thirty years. Well, it looks like we're progressing ... until we realize that this distance is less than 2% of a light year. We continue to like at first.
 |
| Stellar Spaceship Enterprise |
To get to Alpha Centauri within an acceptable time, we have to reach speeds should exceed ten thousand kilometers per second. At that speed we would come in 130 years, which may involve some nuisance considering another bad habit that we have the majority of human beings we die before hundred. If we travel at 25 000 km / s, the flight time is reduced to 50 years. Half a century is not bad for interstellar travel, so this should be the speed that we should aim to achieve, a challenge if we remember that Voyager 1 is moving at less than 18 km / s.
Clearly no choice but to use different propulsion systems to standard we have, so we're better forgetting conventional chemical propulsion rockets used by the currents. Why? Because if we want to reach 1% of the speed of light (3000 km / s) using conventional chemical rockets we would need 1026 kg of fuel per kg of mass of the spacecraft. So, craft shows end up having one hundred times the mass of Earth (!).
On the other hand, if we go to Alpha Centauri in this century we must make certain sacrifices. For example, forget manned spacecraft. Automatic probes will be infinitely cheaper and durable. Furthermore, we can conceive of a mission that is limited to fly the Alpha Centauri system without having to stop and go into orbit around one of the two main stars, which would be prohibitive energy costs.
 |
| Quantum Impulse Spaceship |
Well, let's get to what propulsion systems we use? Just take a look at Wikipedia to see it is very easy to find dozens of propulsion systems to accomplish interstellar travel. However, not all are equally viable, so it is best to divide interstellar travel techniques in 'potential' (in principle achievable with existing technologies, but would have to develop much more), 'unlikely' (promising but with some severe) paste and 'science fiction' (impossible to perform with the technology available in the long term). For obvious reasons of space, we will just outline the main characteristics of each system.
Possible propulsion systems
Ionic and nuclear thermal propulsion
The -iónica electric propulsion or plasmapheresis is currently used in several spacecraft and achieves a specific -eficiencia- momentum of several thousand seconds. The nuclear thermal propulsion followed a little behind. These propulsion systems are not bad to travel the solar system, but it would take 40,000 years to reach Alpha Centauri. No, better we discard these options.
Suppose that, despite the complaints of many critics, the VASIMR former astronaut Franklin Chang Diaz is viable. In that case, a ship with VASIMR take 'only' 2200 years to reach Alpha Centauri. What is a lot? It also rule this system.
 |
| Fusion Interstellar Spaceship |
Solar sails
Here we began to move into interesting territory. A solar sail in the language of interstellar flight is not a single photon as Japanese Ikaros sail. The adjective 'solar' has a motive. A solar sail is a huge structure shaped parachute, like a photonic sail, would use radiation pressure from sunlight, and not the solar wind as sometimes erroneously thought of how to speed up ship speeds up to escape the solar system. But to take advantage of this system is necessary to deploy the sail close to the sun. Much.
Assuming that in the decades to be able to build giant sails ultralight capable of withstanding 60 g of acceleration and thousands of degrees Celsius, a solar sail could travel to Alpha Centauri in a thousand or two thousand years. Still a lot, but this system can be combined with others to reduce flight time. For example, the proposal Medusa-90s joined the nuclear pulse propulsion with a solar sail. In addition, a solar sail could be used by a starship to visit Proxima Centauri and maneuver after traveling to Alpha Centauri A or Alpha Centauri B.
Nuclear pulse propulsion
Project Orion popularized by '60s, this system sounds crazy, but the truth is that associated technologies have already been tested. A pulsed nuclear ship moves detonating nuclear devices near the vehicle. The shock wave is absorbed by a special plate with dampers, which transfers some energy to the ship so that it accelerates steadily. Orion was a very promising to travel the solar system car, but interstellar distances this system is not as attractive.
 |
| Ionic Spaceship |
For starters, you should use about 300,000 artifacts -and not fission and fusion in interplanetaria- version, which may well exceed our technological possibilities. Orion manned interstellar should have a mass of around 400 000 tonnes (!) And a plate of hundred meters across. And even with these monstrous dimensions would take about 150 years to reach Alpha Centauri. Not bad for a generation ship, but may not be best suited for a mission automatic recognition. Still, it is a system to keep in mind if we join with other forms of propulsion.
Laser sails
Laser candles are a case of propulsion systems with energy beams. Basically consist of a giant sail-powered photonic not by sunlight but by a set of super-power lasers located on land or solar orbit. Several versions of this system, some masers using particle beams or instead of lasers, or sails of fissile material. If we had a set of spatial lasers 25 gigawatts of power we could send a ship of 100 kg (including 33 kg payload would rest and sail) to Alpha Centauri in just 40 years.
Lasers should work constantly during the four decades that the mission would last and sailing would simply fly over the system, but we are obviously facing a form of propulsion that is within the technological possibilities of our civilization. 100 kg is clear that very little, but if we use a slightly more massive ship, the flight time would soar to a hundred years if we do not increase the power of lasers. Still, it is the most promising method in the short, medium and long term. And as a bonus ball, you can build lasers candles stages -Proposals Robert L forward- able to stop before reaching its target, although in this case the technological difficulties are considerable.
 |
| Nuclear Fusion Spaceship |
Unlikely propulsion systems
Ships nuclear fusion
Nuclear fusion is a favorite for interstellar travel, both in reality and in fiction propulsion systems. Daedalus and Icarus famous projects are based on this system. Other proposals, such as Project Longshot 80s, using a ship design fusion with other systems. However, and very famous they are, the truth is that nobody knows how to build a fusion engine operating. There are many designs (motors continuous melting, melting pulses, fusion by laser beams or electron beams, magnetic confinement fusion, etc.), but none has passed the conceptual phase on paper.
As land controlled fusion reactors, fusion engines seem to be just around the corner, but nothing indicates that it is. To complicate matters, the efficiency of a fusion engine depends strongly on the used fuel: deuterium, tritium and helium-3. The reactions of deuterium with helium-3 are the most efficient, but the problem is that the helium-3 isotope is a very, very low. Extract helium-3 from Jupiter or the Moon, as has been proposed repeatedly, there seems to be a practical option, nor cheap.
Terrestrial fusion reactors using deuterium and tritium as fuel, but this reaction generates neutrons which can not be directed to propel a spacecraft and create a serious problem of induced radioactivity (the He3-deuterium reactions generate protons, whose electrical charge It makes more compliant). In any case, a ship melting stages as Daedalus will take 30 years to reach Alpha Centauri (the initial target was Barnard's star, then the 70- years-the only star in suspected that there could be planets ).
 |
| Wormholes Space Travel |
Antimatter
Antimatter annihilates with ordinary matter releasing pure radiation. The reaction is so efficient that a few kilograms of antimatter would allow us to reach other stars. You can create a propulsion system that directly take light and particles resulting from annihilation-called 'fotónico'- rocket or to heat a propulsive fluid (water, methane, hydrogen, etc.). The big drawback is that we lack the ability to produce large amounts of antimatter and also nobody knows how to store safely for decades. Many consider a propulsion system of science fiction, but I preferred to leave it in this category because the truth is that every day antimatter is created in several accelerators throughout the world, even in minute quantities. In addition, certain concepts of starships (AIMStar or ICAN-II) make a more rational use of antimatter, mixing it with "normal" fusion or fission systems.
Propulsion Systems science fiction
The ramscoop Bussard is undoubtedly the most impressive spaceship conceived by the human mind. Able to use hydrogen as an inexhaustible interstellar fusion drive for fuel, in principle there are no limits to what this ship could get. Even travel to the other end of the universe! It is no wonder it is one of the favorite concepts of science fiction writers (as in the mythical Tau Zero of Poul Anderson). But the difficulties associated also appear to be science fiction. While there are many who believe that this system is simply a chimera. Other versions of more modest ramscoop such as Augmented Interstellar Rocket (RAIR) could be viable for more advanced civilization like ours, but not for us. The ramscoop Bussard is a ship to gods, not for mere mortals.
 |
| Star Trek Spaceship |
Star Trek
This category wormhole, superluminal propulsion systems and all mechanisms of distortion of spacetime (or warp). Sorry, but until proven otherwise, Einstein's relativity is sacred.
Chariots of the Gods
So how do we travel to Alpha Centauri? In principle, and until viable fusion engines, laser sailing or ship Orion nuclear pulse rate appear to be the only realistic short-term options (and with 'short' I mean 'this century'). Of course, you can combine several of these techniques for even faster mission, but the truth is that the final choice of propulsion system depends on progress in many key technologies that have not yet occurred. Another reason to get you started development.
Venture ship Star of the movie Avatar uses a combination of laser sailing and antimatter engine also hibernate for the crew.
 |
| Venture Star over Pandora |
Even if we do not discover planets, or moons like Pandora in the habitable zone of the stars of the Alpha Centauri system, a trip to the nearest star it is a key challenge for mankind. A challenge that would allow us to better understand the processes of planet formation in the Milky Way and, incidentally, to ourselves.
As Carl Sagan said, when we are able to visit other stars, we will have changed. Only a mature and truly intelligent species will be able to face the huge abyss of interstellar space and overcome it. If we are to survive in the vastness of the universe and not fall into oblivion, mankind must travel to the stars. In our hands to make this dream come true. Will we be able to meet the challenge?
Copyright Daniel Marin (2012)