Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Interstellar propulsion systems

  1. Sep 28, 2010 #1
    Ever since I saw stephen hawkings universe doc's, I've been wondering about one creative senario he presented.

    surround our sun with solar energy satellites.
    Draw and store the energy in the satellites.
    satellites fire this energy in beams (synchronized) into
    one satellite which then fires the combined energy in one beam through space.

    Hypothetically, Do you think this could warp space enough for something to travel though behind the beam.

    If you think this method woudl be unsuccessful, please feel free to discuss other theoretical, breakthough propultion systems ... vacuum energy? nuclear?

    I'm almost certain that whatever the propultion type, it will involve 'farming' energy from stars
  2. jcsd
  3. Sep 29, 2010 #2


    User Avatar
    Science Advisor
    Gold Member

    Alcubierre has proposed a reasonable theory for warp drive, but, it requires an unimaginable amount of energy. The same is true for sublight propulsion. The energy required to travel even to the nearest star is also unimaginable.
  4. Sep 29, 2010 #3
    There's no warping of space here. You just shine a massive laser at a light sail. The good part about this technique is that it's an engineering issue. It may be hundreds of years before you get all of the laser satellites together, but it doesn't rely on any new laws of physics.

    There is a reason why beaming a light sail is an interesting idea. The big problem with rockets is that not only do you have to carry fuel to pull the payload, but you have to carry fuel to move the fuel, and then fuel to move the fuel to move the fuel. The problem is that with interstellar travel, you end up with a spaceship that is all fuel and no payload.
  5. Sep 29, 2010 #4
    Only unimaginable when comparing it to chemical energy. Nuclear fission or fusion allow not unreasonable trip times to the nearer stars for relatively small fuel masses. Only cramming up close to lightspeed requires Kardashev II scale efforts, but plausible arguments can be made for the eventual feasibility of that scale too. The Sun puts out ~4.3 million tons of energy per second, enough to launch thousands of starships to ~0.87c per year, even if we use but a fraction.

    As for "warp drive" it probably allows arbitarily close-to-lightspeed travel (cf. Ursula LeGuin's Nearly-As-Fast-As-Light starships in her Hainish novels), but seems to run into intense Hawking-like radiation if it tries to achieve or exceed lightspeed. I suspect the Alcubierre metric will allow development of "space-drives" which can achieve rapid sub-light travel, but will prove unphysical for super-luminal configurations.
  6. Sep 29, 2010 #5
    You just gave me an idea, what if solar satellites, orbiting the sun were able to send energy through beams down to powerplant on earth, wouldn't that cut carbon emissions?

    it would also be a fine line to the weaponization of space, i suppose
  7. Sep 29, 2010 #6
    Drop something from orbit fast enough and it's a pretty hefty weapon. Most solar power satellites use very diffuse power-beams thus are unlikely weapons. But any kind of directed energy device does have that liability, of possible misdirection for evil purposes. If we need such energy systems, then we'll develop security to match.
  8. Oct 1, 2010 #7
    The solar satellite are useful, I have idea this my suggestion in that case, Madlahulika Guhatharkurta. lead of scientist in NASA telling that the "solar will observe the sun faster, deeper and in greater detail than any previous observatories," she said, "breaking barriers of space, time and clarity that have long blocked progress in solar physics."
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook