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http://www.technologyreview.com/blog/mimssbits/25701/

by cwan • 16 years ago

16 10 16 years ago

mikemol2• 16 years ago

Not only no on-board fuel, but no on-board propellant, either. There goes everything I learned about rockets from Heinlein. Slick!

Groxx• 16 years ago

They're covering this like it's a new thing... At least at the end they mention this:

>The rocket traveled 1.2 meters into the air - the world record for such a craft is 72 meters and 12.7 seconds of flight, accomplished in 2001.

ie, 9 years since a massively more successful demonstration. Slow science news day?

edit: the ones I've seen before were essentially two cones, one upside down and inside the other. It was spun, and lasers / masers were shot at the bottom, creating a bit of plasma near the joint of the two cones.

      /\
     /  \
    /    \
   / \  / \
    ^ \/ ^
    │    │
    └────┴── plasma

tocomment4• 16 years ago

Why don't we investigate this more? It sounds very promising. What are the primary obstacles?

Das_Bruce2• 16 years ago

Some would include that it super heats the air to gain thrust, as you get higher the air gets thinner meaning less thrust. Also there are limits to how narrow you can keep a laser beam through air and atmospheric absorption and diffusion.

All these things combine to make it more difficult to get energy to the craft as it get's further away.

tocomment4• 16 years ago

Would adaptive optics help? and/or Could the rocket carry its own propellant but get power from the beam? E.g., carry its own air.

tocomment4• 16 years ago

Gentlemen, I think I've solved our problem of air thinness at high altitudes. We use a RAM jet like shape for the rocket to funnel the air and compress it.

The rocket could like this:

  thin air
  
  \   /
   | |
   ||
  
  compressed air
  
  laser 
    |
  _____

JoeAltmaier• 16 years ago

I'm confused - I thought the idea was to use "light pressure" to propel rockets from the ground - not gas expansion. Light pressure would work all the way to space - in fact could propel a Mars mission from a stationary/orbital laser.

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