14 DAY TRIAL // It is the closest star system to Earth, located only 4.4 light years away, and best of all, it may also have rocky planets like Earth orbiting around it. Alpha Centauri represents a triple system, composed of two average stars relatively similar to the Sun, and a red dwarf. It is argued whether we will be able to go there in the future, because even if it is the closest star system to us, the task looks rather impossible today. First of all, the distance of travel is very large although it might appear infinitely small in the big picture of the universe.
Conventional rockets, dead in the water
To give you an idea what 4.4 light years really means in more common terms, you should probably know that it is equivalent to more than 276,000 times the distance from Earth to the Sun, to be more precise about 40 trillion kilometers. Let's say we launch a conventional rocket from the Earth towards the Alpha Centauri system at a speed of 29,000 kilometers per hour. A short calculation reveals that we would reach the Alpha Centauri system in about 165,000 years. Now, why would anybody spend his whole life in a spacecraft traveling through space a short distance towards a star? It makes no sense.
Secondly, we wouldn't go very far with conventional rockets, since just carrying an amount of fuel requires more fuel which also requires fuel to power the spacecraft through space, so in the end one would need an infinite amount of fuel to travel through such a large distance.
The anti-matter dilemma
The solution would be to scrap the conventional engines and develop more efficient ones, which would provide the power and speed to shorten the trip as much as possible. One of these would be anti-matter engines, which rely on the energy released by the decay reactions when matter and anti-matter interact. As it turns out, eventually we would reach the same conclusion as that related to conventional engines, first we would have to create and store enough anti-matter for the trip.
At least we know that anti-matter exists, because fabricating it is out of the question for now. Even the largest particles accelerators in the world are only capable of producing minute quantities of anti-matter. On the other hand, storing anti-matter is not as easy as anybody might think. NASA physicist Geoffrey Landis argues that only to store one gram of anti-matter would require the combined magnetic field of about one ton of magnets, not exactly the efficiency scientists first had in mind.
Alternatively, the problem of containing anti-matter with the help of magnetic fields could be resolved just by freezing the anti-matter. However, if even the smallest amount of frozen anti-hydrogen leaks and comes in contact with regular matter, a catastrophic explosion could destroy the vehicle in an instant. However, it is the only valid solution we have so far. Anti-matter could theoretically be used to trigger nuclear reactions, which could produce the massive amount of power needed with the input of small quantities of anti-matter.
Gather fuel!
Late Robert Bussard proposed some time ago that instead of carrying large amounts of fuel all the way to the next star, one could possibly build a ship that gathers it while traveling through space. With the help of a powerful electromagnetic field, it would be possible to collect hydrogen to power a nuclear engine. However, Bussard missed two little details when proposing this design; one, the interstellar space could be less dense than the required density for such a process, and two, by collecting gas the ship would actually be slowed down by the drag of the gas.
But even if we don't take into consideration these two 'small' problems, the design immediately hits a fundamental question. Where will we find pure hydrogen gas? Landis approaches this dilemma, by proposing the use of a mix of deuterium-tritium and deuterium-helium-3, to avoid the difficulties posed by pure hydrogen reactors.
When nothing works, use light
Light siles would resolve most of the problems encountered with all the previous proposition, as long as there is light. Reflective sails focus the energy provided by the beam of light into a region of space to produce thrust. The weight of the spacecraft is considerably reduced, and can harness both natural light emitted by stars and laser beams created by the ship. This way, phenomenal speeds could be reached, as the spacecraft never stops accelerating. When too far away from a star to provide with the required light, the crew could then fire laser beams for the spacecraft itself to give it a boost of speed.
A similar design involves the use of a powerful beam of particles fired from the Earth in the direction of travel, which the spacecraft could convert into energy. However, the problem with lasers is that they tend to diverge with distance, spreading the particles' beam over a large volume of space, thus becoming totally inefficient after traveling a certain distance.
Bombs away!
Further still, scientists have proposed over time the use of bombs to propel spacecraft to distance stars. A well-placed bomb in the back of a ship could provide the required energy to push it a little further through space, maybe even nuclear bombs, why not? A ship carrying about 1,000 people could easily travel through space on nuclear pulse propulsion.
Technical consultant Jordin Kare believes the way to go is by using both light sails and pulsed nuclear propulsion system, which could put a manned spacecraft into the Alpha Centauri system in about 60 to 70 years.
However, none of all these proposed propulsion systems really takes into consideration an important factor in space travel. The human factor, or getting the spacecraft to the designated location within its lifetime, thus the probability of procreation in space, so that in case the original crew doesn't make it, at least their offspring would get there.
We can only dream of the advantages brought by the invention of a warp drive, traveling at speeds higher than that of light. We could get to Alpha Centauri in no time!