How Long Would it Take to Travel to the Nearest Star?
Written by Ian O'Neill
We've all asked this question at some point: How long would it take to travel to the stars? And could I do it in my lifetime? There are many answers to this possibility, some very simple, others in the realms of science fiction. To make this easier to answer, we'll address how long it would take to travel to the nearest star to the solar system, Proxima Centauri. Unfortunately, any route you take to the stars will be slow, even if you are powered by the most powerful nuclear propulsion technology…
In April, I examined how long it takes to travel to the Moon. We took the fast-track with New Horizons Pluto mission, powering past Earth's only natural satellite in a mere eight hours and 35 minutes. We also had the leisurely ion drive-propelled SMART-1 mission that trundled its way to the Moon for 13 months. So, from the speedy rocket-propelled spacecraft to the economical ion drive, we have a few options open to us when flying around local space (plus we could use Jupiter or Saturn for a hefty gravitational slingshot). But say if we build a dedicated mission to somewhere a little more extreme?
The nearest star to Earth is our Sun. It is a fairly "average" star in the Hertzsprung – Russell diagram's "Main Sequence." Our Sun is surprisingly stable, providing Earth with just the right sunlight for life to evolve on our planet. We know there are planets orbiting other stars near to the Solar System, but could they support life as efficiently as our Sun? In the future, should mankind wish to leave the Solar System, we'll have a huge choice of stars we could travel to, and many could have the right conditions for life to thrive. But where would we go and how long would it take for us to get there?
First choice would probably be Proxima Centauri, the closest star to the Solar System. Part of a triple star system called Alpha Centauri; Proxima is 4.22 light years from Earth. Alpha Centauri is actually the brightest star of the three in the system, and so the system is named after this star. Alpha Centauri is part of a closely orbiting binary about 4.37 light years from Earth, but Proxima Centauri (the dimmest of the three) is an isolated red dwarf star 0.15 light years from the binary. Red dwarf stars generate far less energy than our Sun, so we'd have to find a planet in a closer orbit to this red dwarf to sustain life as we know it.
Interstellar travel probably conjures up some outlandish theories about the technology we could use to get there. Star Trek's warp drive will have to wait and stay in the "sci-fi" category for now, it is more likely any deep space trip will take generations rather than a few days. So, starting with one of the slowest forms of space travel, how long will it take to get to Proxima Centauri? Remember, this is all conjecture as there is currently no benchmark for interstellar trips…
Slowest: Ion drive propulsion, 81,000 years
Ion drive propulsion was considered to be science fiction only a few decades ago. In recent years however, the technology to support ion propulsion has moved from theory and into practice in a big way. The ESA SMART-1 mission for example successfully completed its mission to the Moon after taking a 13 month spiral path from the Earth. SMART-1 used solar powered ion thrusters, where electrical energy was harvested from its solar panels and used to power its Hall-effect thrusters. Only 82 kg of xenon propellant was used to propel SMART-1 to the Moon. 1 kg of xenon propellant provided a delta-v of 45 m/s. This is a highly efficient form of propulsion, but it is by no means fast.
One of the first missions to use ion drive technology was the 1998 Deep Space 1 mission to Comet Borrelly. DS1 also used a xenon-powered ion drive, consuming 81.5 kg of propellant. Over 20 months of thrusting, DS1 was designed to reach a cometary flyby velocity of 56,000 km/hr (35,000 miles/hr).
Ion thrusters are therefore more economical than rocket technology as the thrust per unit mass of propellant (a.k.a. specific impulse) is far higher, but it takes a long time for ion thrusters to accelerate spacecraft to any great velocity. As the maximum velocity of ion thruster-powered spacecraft depends on the amount of fuel it can carry and the amount of electricity it can generate, although slow, if ion thrusters were to be used for a non-time critical mission to Proxima Centauri, the ion thrusters would need a huge source of energy production (i.e. nuclear power) and a large quantity of propellant (although not as large as less-economical forms of space travel, such as rockets). As interstellar ion engines do not exist yet, I will quickly calculate how long it would take for an interplanetary ion engine spacecraft, like Deep Space 1 to travel to our nearest stellar neighbour.
Assuming all the 81.5 kg of xenon propellant translates into a maximum velocity of 56,000 km/hr (assuming there is no other forms of propulsion, such as a gravitational slingshot, and this velocity remains constant for the duration of the journey), Deep Space 1 would take over 81,000 years to travel the 4.3 light years (or 1.3 parsecs) from Earth to Proxima Centauri. To put that time-scale into perspective, that would be over 2,700 human generations. So I think we can categorically say, interplanetary ion engine mission speeds are far too tiny to be considered for manned interstellar missions. But, should ion thrusters be made bigger and more powerful (i.e. ion exhaust velocity would need to be higher), with enough propellant for the spacecraft's entire 4.3 light year trip, the 81,000 years would be greatly reduced.
Fastest: Gravitational assists, 19,000 years
The 1976 Helios 2 mission was launched to study the interplanetary medium from 0.3AU to 1AU to the Sun. At the time, Helios 1 (launched in 1974) and Helios 2 held the record for closest approach to the Sun. However, to this day, Helios 2 holds the record for fastest ever spacecraft to travel in space. Helios 2 was launched by a conventional NASA Titan/Centaur launch vehicle (the craft itself was built in Germany) and placed in a highly elliptical orbit. Due to the large eccentricity (e=0.54) of the 190 day solar orbit, at perihelion Helios 2 was able to reach a maximum velocity of over 240,000 km/hr (150,000 miles/hr). This orbital speed was attained by the gravitational pull of the Sun alone.
Gravitational assists are a very useful spaceflight technique, especially when using the Earth or massive planets for a much needed boost in velocity. The Voyager 1 probe for example used Saturn and Jupiter for gravitational slingshots to attain its current 60,000 km/hr (38,000 miles/hr) interstellar velocity. Technically, the Helios 2 perihelion velocity was not a gravitational slingshot, it was a maximum orbital velocity, but it still holds the record for being the fastest manmade object regardless.
So, if Voyager 1 was travelling in the direction of the red dwarf Proxima Centauri, how long would it take to get there? At a constant velocity of 60,000 km/hr, it would take 76,000 years (or over 2,500 generations) to travel that distance. And what if we could attain the record-breaking speed of Helios 2's close approach of the Sun? Travelling at a constant speed of 240,000 km/hr, Helios 2 would take 19,000 years (or over 600 generations) to travel 4.3 light years.
Again, these speeds are prohibitively slow for any quick forms of transportation to the stars. Other technologies are required (wormholes, warp drives and teleportation will remain in the "sci-fi" drawer for now)…
Fastest (theoretical): Nuclear Pulse Propulsion, 85 years
Nuclear pulse propulsion is a theoretically possible form of fast space travel. Very early on in the development of the development of the atomic bomb, nuclear pulse propulsion was proposed in 1947 and Project Orion was born in 1958 to investigate interplanetary space travel. In a nutshell, Project Orion hoped to harness the power of pulsed nuclear explosions to provide a huge thrust with very high specific impulse. It is a major advantage to extract maximum energy from a spacecraft's fuel to minimize cost and maximize range, therefore a high specific impulse creates faster, longer-range spaceflight for minimum investment.
For archived prototype video of pulsed propulsion using conventional explosives, watch this video »
The Partial Test Ban Treaty of 1963 is largely attributed to the cancellation of Project Orion (due to the obvious design flaw that huge amounts of radioactive waste would be pumped into space), but what kind of velocities could a nuclear pulse propulsion spaceship attain? Some estimates suggest a ballpark figure of 5% the speed of light (or 5.4×107 km/hr). So assuming a spacecraft could travel at these speeds, it would take a Project Orion-type craft approximately 85 years to travel from the Earth to Proxima Centauri.
In conclusion, if you were hoping to travel to the nearest star within your lifetime, the outlook isn't very good. However, if mankind felt the incentive to build an "interstellar ark" filled with a self-sustaining community of space-faring humans, it might be possible to travel there in a little under a century if we developed nuclear pulse technology. So your descendents may touch down on a planet closely orbiting Proxima Centauri, but unless we make a breakthrough in interstellar travel (and science fiction becomes more like science fact), we'll be stuck with long-term, pedestrian transits for the foreseeable (and distant) future…
Filed under: Space Exploration
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July 8th, 2008 at 2:27 pm
Excellent article, as usual. I'll go out on a limb and sound like a wingnut. But what about theoretical aspects? We seem so hopelessly confined to conventional understandings of space travel, but I still wonder about the possibilities of interdimensional travel. Mathematics suggests the existence of a multi-dimensional universe. Could they be utilized to get from point a to point b in this dimension? What about alterations in space time, a-la black holes and worm holes? I understand gravity would prove a nasty foe to using these monsters, but is there still a possibility of creating one or finding one that could be used for human use? At least in our present understanding, we appear to have hit a wall in long distance space travel. Even if we utilize the above, even with suspended animation…our efforts would seem rather existential at best given that the round trip would return us to a home where we would not know anyone, where all our friends and family would long since have expired. It would seem we need to return to imagination in our theoretical constructs or resign ourselves to being confined to the solar system.
July 8th, 2008 at 2:34 pm
Well, some people are already seriously thinking of going way beyond nuclear pulse drives…
http://arxiv.org/pdf/astro-ph/0410511
July 8th, 2008 at 2:54 pm
David, I think reaching a black hole would take longer than it'd take to reach the star, so using one of those would be counter-productive? Unless we made our own temporarily, or something.
As for the other theoretical things, for all we know now we could say we could get there before we even left using interdimensional/time travel. Nobody knows for sure, though, and this article just sticks to conventional methods we've got down (or theories with a definitive speed like nuclear pulse propulsion). Maybe one day traveling anywhere in the universe can happen in the blink of an eye with those other ideas!
This article is cool, I love seeing answers to unorthodox questions like this.
One thing I always think of, though, is how people tend to think we'll pick up the whole human race and relocate them. But in the actual case of us inhabiting another planet, only a few people would really go (at least, that's how we'd do it now). Taking more than a few vital people would be too much added weight and supplies and the mission would never work out!
July 8th, 2008 at 3:16 pm
Hmm, not sure Nuclear Pulse would be a valid form of travel for us lowly humans. Wouldn't the g force from such a pulse transform us into small piles of goo? Though for probes it would be nice.
Also, how do theoretical antimatter engines stack up? If we can eventually find a way to produce the stuff in sufficient quantity, that may be able to get us there.
July 8th, 2008 at 3:25 pm
im most interested in the last one
85 years , ok
but
does that include i mean , i would imagine to actually arrive there you would need to slow down , and any slowing down at those supposed speeds would take a long ass time ,
so is that factor in , when you say it'll take 85 years to arrive to our closest star?
July 8th, 2008 at 4:35 pm
Great article.
I believe they figured out the g force problem for Project Orion. Something about a shock absorber. Smart, imaginative people back then I suppose.
July 8th, 2008 at 5:20 pm
Before we think about sending people to Alpha Centuari, we need to send a robot probe. Our government did a study and made a plan. There are a few problems to solve yet:
http://en.wikipedia.org/wiki/Project_Longshot
July 8th, 2008 at 5:36 pm
Jorde Says:
July 8th, 2008 at 3:16 pm
"Hmm, not sure Nuclear Pulse would be a valid form of travel for us lowly humans. Wouldn't the g force from such a pulse transform us into small piles of goo? Though for probes it would be nice."
>>>>Google Project Orion. The space craft was designed to utilise a thrust plate and massive shock absorbers that reduced the apparent acceleration to something manageable for humans. You can actually see the concept drawing in this article – it's the very first picture. The thrust plate is the big dish at the back of the craft near the explosion, and the shocks are those linear-looking poles between the plate and the spacecraft…
What we really need to do is get ourselves a technology that will get us up near the speed of light. Then good old Lorentz contraction will shorten the distance we need to travel considerably… Hmmm – easier suggested than done, me thinks.
July 8th, 2008 at 5:39 pm
I am sorry for the criticism, but unlike what told above, I think that this article is really of a exceptionally low quality, that I am surprised to see here on this blog. Not only it completely ignores that such long travel necessarily includes accelerating and decelerating phases (likely half of the journey each), it ignores maximal possible long-time acceleration and deceleration (which could not be much higher than 1G for human flights), but it also looks like the author completely misunderstood the principle of ion drive propulsion, and of gravitational assist.
At ion propulsion (or any other similar one), the thrust results in acceleration force, and that again in the acceleration. You need to dimension the propulsion according to available power and propellant supplies, and the mass that needs to be accelerated (including the propellant). The time the propulsion is active plays a role too, of course (ideally it would be accelerating 1/2 way, and decelerating the other half). And of course, as already written, you are limited by the maximal acceleration (at human travels it could not be much more than 10m/s2, but also at robotic probes there would be limits). So basing the calculation on the constant maximal speed achieved by DS1 is a nonsense. You can scale it up (technologically no big issue) to get higher acceleration, and let it on much longer (both for the acceleration and the deceleration), but you are limited by the power supply and by the weight of the entire system (including propellant tanks). The calculation would be much more complex, but the result would be quite different from the one shown in this article.
And as for the gravitational assist – you cannot use the Sun for assisting a space ship – the boost it gives the ship when it falls to the Sun, the vessel loses again when flying away. You can only use assist of planets that gravitationally pull the ship behind them, but that force is quite limited and not of a big interest for interstellar trips. You could only use pull of the Sun if you made huge spirals in the galactic space around the Solar system, using it relative speed to the galaxy center, but that would make the travel many times longer.
July 8th, 2008 at 5:48 pm
Yeah, the Orion designed called for a 'pusher plate', effectively a giant shock absorber at the back of the craft. The nuclear charges would be fired out the back, through an opening in the pusher plate, detonating behind the ship, and the pusher plate would convert the sudden impulse into a longer, gentler push, solving the 'strawberry jam problem'.
I'm surprised Robert Forward's solar-laser sail design didn't rate a mention. It's a little beyond our technology right at the moment, but could get a ship up to around 0.2c in reasonable time…
July 8th, 2008 at 5:52 pm
I'll propose a possible scenario. Lets say we develop, in the not too distant future, say a highly focused beam of energy that could be transmitted to our craft, or perhaps fission drive with a hydrogen scoop for fuel/thrust. The important thing is we have a craft that can accelerate/decelerate to proxima all the way there ( decelerating at 1g halfway there). So our craft (freighter) can carry a crew and supplies and can accelerate/decelerate at a constant 1g. How long would it take? As a matter of fact lets skip this first model and go straight to a second model which has the ability to accelerate/decelerate at up to 8g, but would only be used as a reasonably healthy crew could withstand for short periods, then 1g.
July 8th, 2008 at 5:56 pm
The gravitational assist one stood out to me as wrong.
You can get a boost from a planet, by a hyperbolic fly-by. You end up moving away from the planet with the same relative velocity you had on approach (with comparatively minor course adjustments if necessary). This gives a boost in velocity with respect to some other reference point, due to the motions of the planet. You effectively grab a little bit of momentum from the planet. That can't work with the Sun.
July 8th, 2008 at 6:28 pm
If you go 1g half-way and brake 1g the other half, you can calculate the necessary time with the following formula:
t = 2*SQRT(0.5*d/a)
where t is the time, d is distance, and a is the acceleration. In this case the a would be equal to g, which is 10m/s2. So you get these numbers:
t = 2*SQRT(0.5*4.37*365*24*60*60*300,000,000 / 10) = 90932608 s = 2.88 years
However, that's impossible, because with 1g you would get close to the speed of light pretty soon, and there the relativistic laws apply, increasing the mass and decreasing the accelaeration. It would require a more complex formula to get the real time needed, but likely the journey would not be that long even with a more moderate acceleration rate (assuming sufficient energy for the propulsion is available during the entire flight).
July 8th, 2008 at 6:39 pm
>> The nuclear charges would be fired out the back, through an opening
>> in the pusher plate, detonating behind the ship, and the pusher plate
>> would convert the sudden impulse into a longer, gentler push
I did not see the numbers, so I do not know in what force and acceleration the nuclear explositions would result, but my very raw guess is that the absorber would need to be several miles long to allow for sufficient aborbtion. And that again would represent huge mass that needs to be accelerated, hence requiring much more additional energy.
July 8th, 2008 at 7:01 pm
A planet that can support life will have life, and we will have zero immunity to it. It's better to just send our genetic information so if there is intelligent life they can simulate us and perhaps send back some suggestions.
July 8th, 2008 at 7:37 pm
Unless we discover a potentially life-sustaining planet about Alpha Centauri, I doubt we will attempt to send any spacecraft there until it can be done in less than 100 years — and that's a long way off. I just don't think there will be any incentive to invest in a multi-century mission unless there is some other factor involved, like a critical threat to our existence on Earth.
As for a manned mission, I reckon 40 years (averaging 0.1c) will be the longest attempted. I believe that fast a ship is theoretically possible, but again we're a long long way off.
So for the next few decades at least, we are better pouring our resources into better and beefier telescopes to do long range surveys of the nearer solar systems. My guess is that before we set foot outside our own system, we will have a catalog of tens of thousands of exoplanets from which to choose from to visit first.
July 8th, 2008 at 8:02 pm
Instead of trying to force the universe to act how we think it should act(something we do here on earth), the whole of science would benefit greatly by working with natures grain not against it. Nature has already figured everything out for us, we just need to learn how we can tap into the inherant knowlege in such a way that we join with it in a "natural"manner.
The broader our perception becomes the more we need to keep in mind that all things interact.
An infant has a narrow understanding of what it sees. As it learns that understanding spreads to include bits of information that previously were isolated and not related in perception. This concept can be true when compared to science as a whole, humanity has not put much energy into trying to blend all scientific disceplines together to create a GUT.
Renniassance man= multi discepline learning= potential for great understanding.
I know we have the ability, I know we do not yet have the focus or long sightedness it would take to achieve any great things, such as interstellar travel or world harmony.
July 8th, 2008 at 8:17 pm
I think some of you are taking the article too seriously. He just answered a question, providing us with nothing other than the answer of 'how long would it take us to reach our nearest neighboring solar system?"
This article doesn't suggest any of them are that logical, nor that we need to invest in it. Because obviously right now it'd take way too long to reach it.
It was just food for thought, really.
In regards to the life on another planet, there are 3 possibilities.
1) Neither affect eachother
2) They lack immunity and some of them die off (perhaps all of them?)
3) We lack immunity and some of us die off (perhaps all of us?)
Of course, when the time comes to study other life, we'll assume that #3 to be what we're dealing with, to prevent getting stuck in a worst-case scenario, #2 to be of slightly-less-but-still-great importance, and #1 to be how we hope it turns out.
The way you spoke of it, you make it seem like you know 100% we'll get destroyed by the life we find.
Again, the article is using estimations to just give us a general idea. You guys are like 'MAN SENDING A SHIP TO ANOTHER STAR NEXT YEAR WOULD BE DUMB." Yeah, obviously.
July 8th, 2008 at 8:31 pm
Todos alguna vez nos preguntamos cuánto tiempo tomarÃa viajar a las estrellas y si ese viaje serÃa posible en el transcurso de la vida propia. Hay muchas respuestas para esta posibilidad, de las cuales algunas son muy simples y otras pertenecen al reino de la ciencia ficción. [...] Fuente: Ian O'Neill para Universe Today.
July 8th, 2008 at 8:49 pm
sera la imaginacion que nos lleva a un lugar tan lejo , pero no se puede decir , que lo que se saca de la imaginacion no puede existir , si no , es de la imaginacion que encontramos la inspiracion de hacer lo imposible , de ciencia a realidad y ficcion a lo mismo
July 8th, 2008 at 9:03 pm
Maybe I'm just dense, but you say Alpha Centauri is the dimmest, yet on the Hertzsprung – Russell diagram it's by far the brightest (highest on the vertical luminosity scale) of all Centauri stars, second brightest on the whole diagram. The scale isn't of apparent luminosity, is it?
July 8th, 2008 at 9:06 pm
Oops.. I made a typo myself. The error I'm pointing out is that you say Alpha is the brightest, whereas the diagram puts Proxima/Beta Centauri as brightest star, brighter than even both Alpha Centauri A and B put together.
July 8th, 2008 at 9:17 pm
Nevermind.. I found Proxima on the chart.. Nothing to do with "Beta" Centauri.
July 8th, 2008 at 9:29 pm
I fancy the idea of a very long rail gun myself. Granted this would be a one way trip for a probe but I like the fact that a system of rings could be set in a line and a probe would pass through them.
As the probe approaches the ring, the ring's magnetic attraction increases around the probe drawing the two objects closer together then as the probe reaches the ring the Magnet is deactivated and the Probes inertia carries it onward.
You might even reverse the polarity of both so that magnetic repulsion occurs inspiring an even greater boost to velocity.
The More Rings you have placed in a straight line, the higher velocity you might potentially achieve and best of all, your ship needs not carry any sort of fuel except for navigational corrections.
July 8th, 2008 at 10:07 pm
Considering you're traveling at 5% the speed of light, would there be a slow-down in time for the passengers of the ship?
In other words, would the trip be 85 years viewed by the people of Earth or would the trip seem to last 85 years for the people on board? Or would the time seem the same for both????
July 9th, 2008 at 12:09 am
Actually, these figures would only be true if the Alpha Centauri system was stationary relative to the solar system.
It ain't!
Radial velocity is 22 km/sec in approach and proper motion 5 km/sec – almost toward us.
Can anyone do the trig and work out when Alpha Cent system will be closest to us and by how far? Then we could do the trip in much less time.
Martin
July 9th, 2008 at 12:30 am
Excellent article, but "The Partial Test Ban Treaty of 1963 is largely attributed to the cancellation of Project Orion (due to the obvious design flaw that huge amounts of radioactive waste would be pumped into space)" sort of misses the point. That waste, injected into the near-total vacuum of interstellar space, would very quickly become an extremely tenuous, rapidly expanding mist of particles whose intense radioactivity would be far and away offset by the egregiously low density of the mist. Something like one atom of the stuff for every, what, 10,000 cubic miles? Anywhere near Earth, of course, that waste would definitely be a liability — but we could build the craft somewhere in the Solar System where Earth wouldn't be in the firing line, and send it on its way from there. Other than that, great article.
July 9th, 2008 at 12:44 am
As far as The time issue goes I believe it is relative. Anything accelerating away from the earth appears to slow down while anything accelerating toward the earth appears to be faster. This throws the whole idea of a maximum velocity out the window though and our scientists seem to be stuck on that idea.
This also puts a kink in space travel in that we still have to aim our craft to intercept the object we are aiming for and its relative speed trajectory and now relative time difference into account.
But to make a long story short it would seem like 80 years to the people on board but to the people of earth it will look like it takes at least the amount of time the light from that object takes to reach earth no matter what speed we reach.
Oh and SUGARAT I agree completely and belive we should talk. I have been saying the same thing for years to all the people I know and wish more people would realize it.
July 9th, 2008 at 3:56 am
Sadly at the moment we might as well tie bungy rope around 2 trees and call it a launcher. Hopefully we'll come up with something better soon
July 9th, 2008 at 5:15 am
I've been wondering what the chances are of hitting a solid object between here and there (where ever "there" may be). How much stuff is out in the Oort Cloud? How about dust, debris and larger objects in interstellar space?
Seems to me that a good strategy is to send a fleet of highly miniaturized (or even nano) robots with the understanding that there will be losses on the trip. Perhaps if they were smart machines they could join up at the destination and construct some sort of a transmitter to send information back to Earth.
July 9th, 2008 at 6:41 am
I'm a bit conservative as well when it comes to the point of "human" exploration. With so many technological advances in robotics I see no reason for putting anyone in harm's way. Even though a pair of human eyes is always better in the observational sense the risk is just to great for that particular astro/cosmonaut and the space community as a whole can you imagine the moral problem we would face if someone were to die. There would'nt be another try for a 20 years or so.
July 9th, 2008 at 6:47 am
Even if we could travel close to the speed of light, surely this would be impractical.
At, say, around 20,000 km/sec or faster, any subatomic particle would manifest itself as a highly enegetic cosmic ray particle with disastrous consequences.
July 9th, 2008 at 7:55 am
We are thinking too small and too short term. Also Proxima Centauri is doo-doo. For another .17 light years, you may as well go to Alpha and Beta.
Too short term: witihin the next 50 years, we should have effective immortality for humans through medical advances. That changes all the rules about how long you can take to get there.
Too small: don't muck about with ships. Take a planet. Mars might be big enough. Either live underneath the surface or make an artificial sun. Plan B, consider taking the Sun and all the major planets. It can be done, it's the space tug idea on a grand scale.
Well, that's enough mind boggling ideas for today. Remember, you heard it here first.
July 9th, 2008 at 7:58 am
Everyone needs to pause a bit and think about the motivation for the article. The article is a valid discussion of the distances and times it would take to travel to another star using diffenert technologies. Remember, around 200 years ago, a fast ship would take about 9 months to travel from England to Australia. Now it's about day in a plane.
I often wondered about this very question – so thank you to the author. The article didn't assert to predict the future, only discussed the present times to open further discussion. It seems so simple at first – only four point something light years away – but we all know that is still a very long way.
Currently, travel at, or remotely near, the speed of light is not realistic, so our fastest 'feasible' travel speed must be only a small fraction of light speed within the foreseeable future. There are obviously undiscovered 'faster' travel methods that we will hopefully discover in the near future, but others have decided to discuss the human challenges. I point to the technical, ethical and financial constraints that surround the present day discussions of travelling to the Moon or Mars to stress my point.
One-way trips to Mars are contriversial enough, so I say again – thanks for the article; others needn't loose sight of the original purpose of the article was to simply discuss the times it would take using present technology, and to give us laypeople some 'perspective'. Therefore I suggest we should debate always, but not ovely slant the debate towards the technical challenges of humans travelling to the stars when the 'walk in the park to Mars' is proving difficult enough.
Finally, a point I recall on this topic came up at school 20+ years ago. The teacher replied – it's not currently worthwhile to travel to the starts, because say you could build a ship today that takes 1000 years to get there – in 100 years, a much faster ship would be built (say it took just 300 years), so you would have traveled for over 100 years (1/10th distance) and then some more, when a newer mission would follow, which would 'pick you up' as they passed by, to save you wasting your time. and then the story repeats – so wait until the times are realistic – and you know what is out there…
July 9th, 2008 at 8:38 am
I think our first step is to colonize the solar system, that will give us better experience in developing faster propulsion systems. I'd say at least 50 to 100 years from now will be a more realistic attempt to send a probe to the nearest star system. I hope its within our life time.
Joe
July 9th, 2008 at 9:26 am
Imagine travelling 80 to 1,000 years to the nearest star, and then finding out there is absolutely nothing of interest there.
Fuel is gone, next nearest star is another 80 to 1,000 years away.
It seems to me that for Humans and all the other alien species out there, we are all stuck in our own little solar systems.
Every 1,000 years, we will receive a communication that says …
… "Hi, how are you. We are fine. Nothing really happened since our last communication 2,000 years ago. We received your communication 1,000 years ago and we are glad you are fine. I guess you are not coming to visit and we won't be able to visit you either."
July 9th, 2008 at 12:50 pm
Yes I agree first lets settle our own backyard then figure out what the hell to do about our neighbors yard
July 9th, 2008 at 2:12 pm
By 2020 we should know whether or not there would be habitable planets around Alpha Centauir A and B. They are both very close to what our star, the Sun is.
Forget Proxima. It is too tiny, and way too much unlike our Sun for humans too survive.
If we can discover other "Earth like planets" within 1 to 2 centuries of space travel using the Orion method, we should go for it.
Manifest Destiny
July 9th, 2008 at 2:20 pm
" It would seem we need to return to imagination in our theoretical constructs or resign ourselves to being confined to the solar system."
Some do:
http://www.thespaceshow.com/detail.asp?q=968
http://archive.thespaceshow.com/shows/968-BWB-2008-06-24.mp3 (52.4mb podcast)
http://www.aiaa-la.org/flyers/Adv%20Space%20Propulsion%20for%20Interstellar%20Travel%20-%
As for the nuclear-pulse Orion, the Test Ban Treaty simply didn't allow exceptions for nuclear detonations in space that were clearly *not* weapons tests, so they had nowhere else to go with the concept.
And
"Imagine travelling 80 to 1,000 years to the nearest star, and then finding out there is absolutely nothing of interest there."
Imagine doing the best telescopic study from this solar system you can, first. And possibly sending robotic probes after that, befor committing people…just like here.
And define 'nothing of interest.' Some people (sadly) don't care what probes are doing on Mars at this moment.
July 9th, 2008 at 3:21 pm
Along the lines of Marcellus regarding Proxima Cen as a viable destination for humans, the star ( a red dwarf) much less luminous than Sol, is classified as a 'flare star' (as are most magnetic dwarf stars) capable of producing flares intense enough to create copious amounts of X-rays (see Wiki listing for Proxima Cen for details). Alpha Cen A and-or B would seem more stable, luminous stars with a better likelihood of habitable planets (or moons orbiting gas giant planets). In any case, a great article on interstellar flight & great food for thought.
July 9th, 2008 at 7:02 pm
May I suggest reading the Chapter "You can get Here from There" in my new book "Flying Saucers and Science". The author has ignored the Nerva and Phoebus nuclear rocket engines for upper stages and the D-He-3 fusion reaction to provide 10million times as much energy per particle as in chemical systems.See John Luce and John Hilton paper. Far more efficient than Orion. Soviets have
operated 3 dozen nuclear reactors in space for electricity production. At 1G it only takes a year to get to near c.
July 10th, 2008 at 2:14 am
Thank You Stanton, I was thinking about your work on the Nerva & Phoebus systems when I read this. We could learn a lot by just looking at all the fantastic space technology that was developed 50 years ago.
July 10th, 2008 at 3:49 am
Are there any theories relating to what space would be like between solar systems? would it be more of a vacuum so maybe more acceleration could be reached? or maybe you would get stuck in the spin of the milky way outside of the protection of our solar system and never get anywhere… (random thought i know)
July 10th, 2008 at 5:26 am
Great article! Great posts!
July 10th, 2008 at 7:27 am
MC, both ideas go kablooie. Space is a near vacuum anywhere you go, even in a nebulae. There are no meteor storms to watch out for in interstellar space. (Nothing to keep them together) It would be like watching out for meteorites while you are driving…not a major concern. The Milky way affects us here the same way it would outside our solar system. The heliopause affects atomic size particles, not spaceships. The Oort cloud is invisible mostly because "cloud" poorly defines it. It's far more tenuous than whales in the ocean. How many times have you dived in to land on one's back?
I personally think it's hilarious anyone is worried about radioactivity in space. It's got to be a red herring or simply the worries of bureaucrats with little astro-education. There is a radioactive belt or two surrounding the earth even now. Space is filled with radioactivity. Nasty place. As described in one post, bomb detritus would spread to near nothingness in little time. It would probably take off from moon orbit anyway. Too big to launch from earth surface.
And the blast absorbtion plate would have to be enormous? Where does that thinking come from? The blasts are smallish and continuous. It doesn't have to be a Hiroshima every ten minutes. And whatever distance from the ship that works, doesn't have to be just 15 metres away.
I think anti-matter will probably be the answer that gets us there. Massive energy from smallest quantity, and lacking in need for extra-dimensional travel which will probably always remain a tantalizing theory at best.
July 10th, 2008 at 5:25 pm
Here's my suggestion:
Within two or three decades, we should have sufficient molecular manufacturing technology to create extremely efficient, small, light and highly intelligent robots, as well as small nanofactories capable of creating any object from patterns stored in computer memory. Sending them out to the nearest stars would take far less energy than sending humans.
If a robot arrived at a suitable exoplanet, it could use the nanofactory to construct a laser receiving station (or similar device), as well as living accommodations for humans.
The same technology that would allow the construction of the robots and nanofactories should allow us to disassemble human beings and reassemble them. This may allow us to store entire humans as digital information.
We could then beam the information to the receiving station on the exoplanet. The nanofactory would reassemble the human patterns, creating exact duplicates of the original human templates, and those humans would have living accommodations already waiting for them.
Of course that would still take a while: probably hundreds or thousands of years to get the robots to the exoplanets, then at least a few years to establish a connection with Earth (beaming info at lightspeed), and then a few more years to beam the human patterns to the exoplanets.
By that time we'll likely have populated the entire solar system and probably won't resemble modern humans in mind or body much at all.
So…forget it. At least for now. Maybe some AI will come up with a way to shorten the trip, so just wait a few decades and find out.
July 11th, 2008 at 9:51 pm
Thanks so much for the article and reader comments. Exciting visions. Always dreamt of such possibilities as a small boy.
Unfortunately, nowadays, the negative consequences of global warming accelerate faster than the development of interstellar propulsion engines.
Trying to be realistic, I only hope that there will be human astronauts after 2050 or so to board space ships.
July 11th, 2008 at 9:57 pm
Maybe we could travel to other planets with our mind rather than our bodies. OOBE's anyone?
July 12th, 2008 at 7:24 am
To: Peter K., While space is a near vacuum, I suspect there are chunks of unknown quantity and material within this near vacuum that can easily destroy a space vehicle. A couple of probes NASA has lost contact with over the years comes to mind. Another thought, for mankind to do any serious space traveling, it would be necessary to develop a means to exceed the speed of light several magnitudes. Attempting a trip to the Alpha C system, at just a fraction the speed of light, doesn't make much sense.
July 14th, 2008 at 5:40 pm
Maybe we need to learn to live on this planet before we go to another?
Planet starbucks haha….drill for oil on planet exxon…kinda reminds me of several sci fi films where the lifeforms are called a disease or virus, they jump from planet to planet destroying each in the process and the only solution is to find another host.
Did anyone mention suspension, cryonic or other?
Wake up 20,000 years later orbiting a strange planet …
August 20th, 2008 at 1:11 am
"Imagine travelling 80 to 1,000 years to the nearest star, and then finding out there is absolutely nothing of interest there."
You miss the point of space travel. The trip between the stars is the interesting part.
I would love nothing more than the chance to travel alone in a spaceship to another star, even knowing I would die of old age before making it to that star, just for the chance to be out there, every day, watching the stars from outside of Earth's atmosphere, knowing I am that much closer to another star.
If you have ever had the chance to look at stars through an actual telescope, not the internet pictures, taking the time to just look at some random name-unknown group of stars, it is fascinating. I am enthralled by the fact that I am looking at real suns live (minus light year distance of course). There is something about it that overwhelms.
I am not one who would immediately plant a carbon copy of human society on another planet. What difference does it make what planet you watch TV on?
It is the chance to leave this society behind and be out there with no one else except the stars that draws me like nothing else in life. Pick any one star, no matter how far, and head for it. Reaching it doesn't matter, the chance to be out there does.
November 4th, 2008 at 11:00 pm
well for the G forge thingy you can be put in a room filled with some sort of material that dampens the effect of the inertial forces… or some sort. easy to be done, and there are some results in achieving this kind of material, for example Asics (shoe manufacturing) uses some kind of rubber on which u can drop an egg from 3-5 meters and it won't break (the layer was just 1-2" thick). so it can be done the means of propulsion must be developed more.
November 5th, 2008 at 3:22 pm
Intersting article. And even more interesting comments.
Aside from the fact that you've neglected to mention beamed power, it's okay. But I'm sure that 80 year figure can be improved. Perhaps by launching the nukes ahead of the starcraft, or maybe by some other means.
"I would love nothing more than the chance to travel alone in a spaceship to another star, "
Agreed. Although I'd quite like to have someone with me on the Starcraft.
November 28th, 2008 at 5:41 am
We could always build a massive coil gun, preferably orbiting one of the outer planets. Build it in an elliptical shape, like a particle accelerator, accelerate a small craft to the maximum % of c we can get from storing power from nuclear generators and solar power in superconducting capacitors and then let it fly, using nuclear pulse propulsion or some other form of propulsion for additional thrust. Realistically, we can get a lot higher speeds and lower mass crafts by using robotics rather than manned voyages.
This method reduces the problem of on-board fuel. It all depends on how much power we can store, and what velocity we can accelerate the projectile to.
December 15th, 2008 at 2:54 pm
OK. We now can accellerate a stream of particles to 99.99% the speed of light. granted, these particles have very low mass and are easily pushed around CERNs tubing. How much energy would it take to accelerate a larger object to those speeds. Also the G forces from just the curvature of the earth would be enough to destroy any device we send around. But I propose that we create an orbital TRACK, one that works just like a particle accelerator that pushes an object around untill we reach the right velocity then it opens upon on end to let it fly. We could get a robot or transmitter to a distent star pretty fast, however there would be NO way to slow it down. in fact something going the speed of light that had any mass to it at all would literaly pass straight through ANything unscathed. We would need on accelerator to throw and another at the destination, to catch. But heaven forbid we should miss. lol. see ya
January 3rd, 2009 at 2:02 pm
I suggested the coil gun over at NewMars. The unfortunate thing about it is how long it takes to get up to speed without killing its occupents and such.
So I suggested launching Ion beams instead. Others suggested Aluminum pellets. Those could work to, if they could perhaps be vaporised to form high speed Ions hitting the craft.
Decelerate at the target system using a combination of MagSail and Orion. Aim for a top speed of say maybe 25% of c, although I'm fine with 5% (extended lifespan, remember), But 20 years to Alpha Centauri would be good. Although I'd trade it in for 50 years to Tau Ceti or Epsilon Eridani (much more promising places).