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Energy Requirements

  1. May 7, 2006 #1
    If we have a 1 pound Satellite with Solar Sails orbiting the Sun reflecting Energy through Solar Pressure from the Sun at a safe distance, (How much would the total Energy be) to reach 50% the speed of Light and (how big would the Solar Sails need to be) to reach this Velocity in exactly 1 Year.:bugeye:

    also, Is there any Data on stepping up this process with added EMP's vs. a Highly Diamagnetic Solar Sail?
  2. jcsd
  3. May 8, 2006 #2


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    Well, the energy required is easy, E=(1/2)m*v^2

    For the rest of it, you're on your own...
  4. May 8, 2006 #3


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    Yikes, I was thinking about it and as the satellite gained speed, it's orbit would have to decrease in distance from the sun (to retain a stable orbit), and because the distance would be decreasing, the energy hitting the sails would be increasing... helping you acceleration I suppose but would you hit 0.5C before you got too close to the sun?

    Mercury orbits at 47.89 km/s, MUCH slower than C which is about 300 km/s (1/6260 C) to be exact, so for 0.5 C the orbital distance would have to be 1/3130 that of the orbital distance of Mercury... OUCH. That would mean instead of 57.9 million kilometers away you would only be 18500 km away, OR IN THE SUN since the diameter of the sun is about 1.4 million kilometers...

    I think I may have discovered a problem with this... Basically, you can't have a stable orbit of 0.5C around our sun... but perhaps a black hole or very small neutron star?

    Perhaps an eccentric orbit like a comet where at your minimum distance you hit 0.5C... no that wouldn't work either.

    I don't know, I don't think this could work, you couldn't achieve a stable orbit... somebody jump in if I'm wrong...
    Last edited: May 8, 2006
  5. May 8, 2006 #4


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    Well, I think for that reason, the satellite would spiral out of orbit. Solar sails don't work like sails on boats - the force is always directly away from the sun.

    More info to go on, intuitive: at 1AU, the solar flux is about 1400 w/m^2.
  6. May 8, 2006 #5
    All the more reason why I think linear Speed is not the answer to space travel.:bugeye:
  7. May 22, 2006 #6


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    Well, solar sails are not a very good option for attaining a large linear speed anyway.
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