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Nazi Scientists Proposed Creating a Giant Space Mirror to Burn Enemy Nations



An issue of Life magazine published on July 23, 1945 includes an article about a secret weapon proposed by some Nazi scientists toward the end of World War II. It was a huge mirror that, if placed in orbit, would focus sunlight on enemy nations and burn them:

Plausible schemes to build a station in space were engineered on paper long before the war. European rocket enthusiasts, including Dr. Hermann Oberth, who may have been the designer of the V-2, had planned to use the space station not as a weapon but as a refueling point for rockets starting off on journeys into space. ... The only major obstacle: constructing a rocket powerful enough to reach a point where a space station could be built. If the modern German scientists had been able to make such a rocket, they might have ben able to set up their sun gun. Whether the sun gun would have accomplished what they expected, however, is another matter."

The German idea of using the sun as a military weapon is not new. There is an ancient legend that Archimedes designed great burning mirrors which set the Roman fleet afire during the siege of Syracuse, in which Archimedes later died. This legend, and the German plan for building may be proved physically impossible by a simple axiom of optics. This is that light cannot be brought to a sharp, pointed focus with lenses or mirrors unless it comes from a sharp, pointed source. Since the sun appears in the sky as a disk and not as a point, the best any optical system can produce is an image of this disk. At very short focal lengths, the image is small and hot but as the focal length is increased the image becomes progressively bigger and cooler. At the distance the Germans proposed to set up their mirror (3,100 miles) the image of the sun cast on the earth would be about 40 miles in diameter and not hot enough to do any damage.


Link via blastr | Image: Life

I guess the editors of Life Magazine thought, "If we're going to furnish propaganda about the evil Germans, we might as well dream big."

This ranks right up there with the History Channel's shows about Nazis and UFOs. Wait...maybe it's all connected! I can't wait to discuss the intricacies of WWII with someone who starts bellowing about aliens helping Hitler put a death ray on the moon.
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What matters is the amount of energy delivered, not the size of the image. If you deliver 100 times the normal flux of sunlight, you'll do damage.

The Nazis would have discovered the Van Allen radiation belts the hard way.
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It was based on an idea first proposed by astronautics pioneer Hermann Oberth in the 1920s...who realized more quickly than Life magazine did that the focus would be too large to do any harm.
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@ Steve

They basically did, but 20 years later

Don't forget it was former SS Sturmbannführer Werner Von Braun's Redstone (which is basically a slightly upgraded V2)which launch the satellite that discovered the radiation belts
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Somebody needed to study physics a little harder.

It's true that a *spherical* lens or mirror can only reproduce an image of the source, but a parabolic mirror will easily focus light to a single point.

Well, technically a parabola only focuses /parallel/ incoming rays to a single point, but given that the sun is about 92 million miles away, all light hitting the surface of a 40-mile mirror would be close enough to parallel that it doesn't matter.

There are a bazillion reasons why a giant killer space mirror would be an extremely difficult technical challenge.

- The orbital velocity at 3100 miles up (roughly 5 million meters) is about 13,000 miles per hour. The orbital period (the time it takes to go all the way around the Earth) is about 3-1/2 hours. The Earth, meanwhile, spins at about 1000 miles per hour, probably not in the plane of the mirror's orbit.

- A circle 40 miles in diameter has an area of roughly 1250 square miles. Lifting 1250 square miles of *anything* to that kind of orbit would take a huge number of lifts, and would be hideously expensive.

- A structure 40 miles in diameter would be floppy as hell if it were made of 10' steel beams, and there's no way you could begin to lift that much mass into orbit. It's far more likely that you'd have a bubble of mylar that would make 'fragile as a soap bubble' look downright rigid by comparison.

- Even a stiff, light mirror 40 miles in diameter would turn very slowly. Anything flexible would have to move even slower to keep from A) ripping itself apart, and B) twisting out of a useful shape.

- At a distance of 3100 miles, getting within a mile of the target means you have to be accurate to about 1/50th of a degree.

For something that big and that hard to move, trying to hit something that far away, at those speeds, would be a bitch to say the least. And that says nothing of the whole 'turning it off so it doesn't roast your own country on the way past' issue.

Focal limits aren't even a theoretical problem though.
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Whoops.. just reread the OP on the point that the theoretical focal image would be 40 miles in diameter.. not that the proposed mirror was that size.

Even taking a 40-mile scale out of the equation, most of the problems remain: The focus has to be much smaller than the mirror in order to generate heat. Any mirror even a few hundred feet in diameter would still be fragile, and would still move slowly. Having a smaller focus means your aim has to be that much better in order to hit anything at all. And you're still trying to hit something moving 1000 miles per hour from a platform moving 13,000 miles per hour.
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Such a pity the Germans didn't pursue this more vigorously... the war would have ended so much faster, what with the wasted resources on such a ludicrous plan.
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Why use only one mirror?
Many mirrors would be:
- Much easier to control individually.
- One can keep the focus while the other moves on.
- Much less fragile.
- Hard to shoot down.
- Cheaper to bring up.

Very expensive though. Beside what is the point? If disruption is requested then terrorism is way more effective. If killing people is requested then neutron bombs are far cheaper, and they leave behind usable infrastructure.

But using such a construct to beam down power! now that would be a fine idea.
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