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Interstellar Travel

  1. Feb 1, 2004 #1
    How long will it be before we reach alpha centauri, i was on a thread on Fark.com yesterday about going to mars and it interstellar travel came up. I figured you guys (and girls) would prob have a better idea on what ideas are out there right now. this was my post:

    do you know how impossibly difficult it would be to send a prob to alpha centauri? The experimental engine in our deep space probe headed for 1992 kd goes 2.38*10^6 kmph (67,000 mph) alpha centauri is 3.8*10^16 m away, with these figures it would take us about 43,475 years to get there. NOt to mention the 4 years of lag time for sending and recieving data to said probe once it gets there. Oh and that ion engine i spoke of, runs off solar power. In deep space solar power is not a good idea. MMMMMkkkayyyy

    Some of the other people on the board were saying that with nano probes, and ion engines we could reach speeds of .9 c, is this really feasible.
  2. jcsd
  3. Feb 1, 2004 #2


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    Final speed is merely dictated by type of engine and percentage of fuel.

    It is possible, but not practical (requires an enormous fuel tank) to get a probe up to a (very) small fraction of the speed of light with existing technology. It'll still take several hundred years to get to AC like that though. Just try to convince congress to fund a research project which won't produce results until their great-great-great-great-great-great-great-...-great grandkids are old, if it still works after all that time (which isn't likely).

    You won't be able to get a nanoprobe to get there until we find out how to build nanoengines. I don't see it anytime in the near to medium future.
  4. Feb 1, 2004 #3


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    tripping the light fantastic

    On the other hand, it is feasible, with today's technology, to build a 'light-sail' starship. It would have to have sails several thousand km across (maybe much more?), and for power beyond the solar system, we'd have to build very powerful lasers to fill the sails with enough light (I'm speaking somewhat loosely here). Getting it to slow down as it reached Alpha Cen wouldn't be too hard, but coming back to Earth may be tricky [b(]

    Even for that, however, there are some ideas around ...

    Now, would the ESA fund the building of a powerful enough laser? And keep funding its operation??
  5. Feb 1, 2004 #4
    will somebody please explain to me what excatly solar wind is? And how it could be produced with a laser? Light has no matter, it is just electromagnetism right, thats why it can travel at C. Mmmkaayyyy so if light has no mass then it can have no inertia right? And with no inertia how can it run into a sail and transfer this non-existant inertia?????????
    i think i'm probably looking at this all wrong, somebody please help.
  6. Feb 2, 2004 #5
    just googled solar sail and discovered that solar wind is just super heated particles flying away from the sun at 400 kmps, how would we produce these with a laser? It doesn't look to me like solar wind has anything to do with light, oh and at 400 kmps it would take 3012 years to get there.
  7. Feb 3, 2004 #6


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    Solar sail is not just charged particles. It is also direct photonic pressure. (ie. photons have momentum, which they transfer to the sail)

    Things can have no rest mass, yet still have momentum. Look up wave-particle duality.
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