Beaming into Space

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."

Comments

Not creative enough

[cscx]

I'm waiting for when they can do this using one of those medieval catapults.

Microwave propulsion systems?

[Anonymous Coward]

10... 9... 8... 7... 6... 5... 4... 3... 2... 1...

Ding!

One thing to not worry about.

[karmavore]

The inflight meal will not be cold.

A simple proposal

[sam_handelman]

1) Lock all the air and space engineers and astrophysicists together in a big building (with lab equipment, and access to journals and suchnot.) That building at MIT with the mile long hallways would do nicely.
2) Don't let them out until they have a prototype design for FTL.

Physics has become boring and I think we, as a species, have to put our collective foot down as regards this whole no FTL business. You can worry about whether or not black holes emit radiation later, I want a warp drive and I want one yesterday!

Re:A simple proposal

[TheOnlyCoolTim]

What we really need to do is convince some multi-billionare (like Bill Gates, Warren Buffet, or one of those Middle East Oil Sheiks) to jumpstart humanity's expansion into space out of their own pockets.

Start with a space elevator, price tag 10 - 40 Billion dollars. Then maybe build a *NICE* space station on top of it, which should cost much less. Use the space station to build a spaceship for the purpose of bringing an insanely mineral rich asteroid back to Earth orbit. Establish a mining base on the asteroid.

3. Profit.

Tim

Great a propulsion system that flashes 12:00

[Sagarian]

but if it has a "Popcorn" button, it's gold!

Give them a break.....

[vvikram]

I think you are being way to skeptical here .

Look, you can say all you want but you are talking about something which can basically wipe us. Not to be a controversialist but wherein AIDS and hunger if you aren't there in the first place. Yes, I agree maybe its not top priority as much as the folks quote but its bloody well important. You think even if we spot an asteroid we can do anything about it.....throw a few nukes doesnt solve it. Want us to be sitting ducks and pray ? Maybe you should take a look again about Schu-Levy?

Also how many times will the AIDS+hunger thing come up ? If your view is right then we should stop all technological innovation and start feeding everyone. It doesn't work that way - we should try to fight AIDS, hunger but at the same time its _very_ important to look forward

No offence. Thanks,
vv

Re:Most immediate space challenge? Riiight....

[Anonvmous Coward]

"... at least low enough that ther are probably better things to spend one's time addressing... say, hunger, AIDS, yadda yadda yadda."

You're talking about different areas of science here. Scientists aren't exactly being pulled off AIDS research to work on this problem. However, a tragic asteroid impact would mean that AIDS and world hunger wouldn't be on everybody's top lists.

Microwave Beams: Phased Array Antenna

[spiro_killglance]

One of the nice advantages of Microwaves over
lasers, is that is really easy to make a stearable
beam of Microwaves using the phased array technique. I you make a dipole antenna and feed a
microwave single into it, the signal goes pretty much everywhere, if you put another dipole antenna, next to the first, the two signal interfere results in a more direction beam. If you
have a square grid of antennas, you get a narrow
beam which becomes more focused as the density of
the grid increases.

If all the signals are in phase then the beam goes straight ahead (also straight behind, so you put a microwave mirror, a metal plate behind the antennas at a (half) integer number of wavelength in distances.

To stear the beam, you just put a slight phase difference between each dipole antenna and the ones next to it, so that the phase difference increases with the distance between the each dipole antenna and the first one, thus the beam is stearable electronically. Because there a lots a seperate dipole antenna, the power in each does need to be to large, so you can use fairly ordinary electronic components to produce the beam.

Imagine, building a simple block of antenna, consisting of a 100 by 100 dipole antenna, each
feed by its own 100W oscillator, and with its own
control and stearing computer inside. That should
be fairly cheap to build. Now mass produce these.

Now lets put a hundred of these side by side in a square, you
get a stearable 100 MegaWatt beam and its only 10meter by 10meters big.
You can use this idea to build with conventional
technology a microwave beam as powerful as you like.

Now you don't get much thrust from just reflecting
the energy, 6.7 Newtons per gigawatt. But a constant accelation over time can quickly build up speed in space. You can get a lot more thrust out of the system by using the microwaves to heat a reaction mass, say water in the target craft. I haven't done the calculations, put a powerful enough beam could be used to launch a steam rocket from the earths surface at very little cost.