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Beaming into Space

Posted by michael on from the do-not-look-into-beam-with-remaining-eye dept.

HobbySpacer writes "At this week's 1st Int. Symposium on Beamed Energy Propulsion in Huntsville a wide range of laser and microwave propulsion schemes are being presented. The big news so far is the announcement by Gregory Benford of plans for a test of microwave propulsion with the Cosmos Sail, due to fly early next year. The possibilities of using lasers to deflect incoming asteroids & comets are also under discussion."

4 of 124 comments (clear)

  1. Re:Asteroid Deflection how? by wd40 · · Score: 2, Informative

    Vapourising asteroid mass causes thrust by virtue of the gaseous ex-rock moving away from the body of the asteroid.

  2. Re:Just how much? by saskboy · · Score: 2, Informative


    Look just above your post. It shows that the vapourized asteroid is the factor, not the "momentum" of photons from a laser.

    --
    Saskboy's blog is good. 9 out of 10 dentists agree.
  3. Re:Asteroid Deflection how? by jamesc · · Score: 2, Informative
    Yeah, how would that even work in space? I thought lasers could push things on Earth because it heats the projectile, and the heat difference causes some reaction with the atmosphere, but there is no air in space to interact with. What gives?

    Simple. The "reaction with the atmosphere" is that the air is so strongly heated by the beam that it ionizes, expands, and shoots out the bottom of the projectile. Turn off the beam. Wait for the ionized air to get out of the way. Repeat tens or hundreds of times per second.

    The asteroid deflection plan would work much the same way. Very high energy pulsed beams would vaporize some of the asteroid material from one side of the rock. That jets off into space, creating a small amount of thrust. Keep the beam on the asteroid until it has enough velocity to miss us.

    (Delivering that much energy accurately to the target over astronomical distances is left as an exercise for the student. ;^)

    --
    "You've crossed my Line of Death!" "What? No! Where is it?" "Here in the fine print...."
  4. Re:A simple proposal by descentr · · Score: 4, Informative

    Well there's a slight problem with the space elevator idea. That requires you to have a large mass at the end of the cable for a counterbalance, like an asteroid. So using a space station attached to a a space elevator to build a ship capable of bringing an asteroid back to balance the elevator is kind of a chicken and the egg problem =)

    More info here:
    http://science.nasa.gov/headlines/y2000/ast 07sep_1 .htm