this post was submitted on 15 Feb 2024
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(page 4) 20 comments
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[–] [email protected] 5 points 1 year ago (1 children)

Are those mirrors curved to a focal point? If theyre flat mirrors which they probably would be, i think it could work

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[–] [email protected] 15 points 1 year ago (1 children)

Patrolling the Mojave wasteland almost makes you wish for a nuclear winter.

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[–] [email protected] 11 points 1 year ago (1 children)

Someone get this person a defense contract stat

[–] [email protected] 9 points 1 year ago (2 children)
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[–] [email protected] 61 points 1 year ago (19 children)

tell my why this thing should not be able to melt satelites that cross over during the day

[–] [email protected] 6 points 1 year ago

Because it's always nighttime in space.

[–] [email protected] 102 points 1 year ago (7 children)

My scientific research of squinting at the poster says a spy satellite is probably about as long as a pickup truck which is probably about 20 feet long.

xkcd says space is 100 km away and I'm sure there's nothing else I need to understand about that.

At 100 km away, the change of angle that will move your beam by 20 feet (enough to make the difference between hitting or not, if the thing and the flat mirror are both about 20 feet long I guess) is (20 feet / 100 km / pi) radians or 0.0000194 radians, meaning you raised or lowered one edge of the mirror by 0.004 inches or around the width of pretty-thick hair. I would be a little surprised if the mirrors even stayed within that tolerance just from flexing around in the wind for as big as they are.

On the other hand, you wouldn't have to hit the spy satellite with every mirror; you could probably heat it up significantly just by hitting it with a bunch of the beams as they were swinging wildly around and mostly missing it. And if it was specifically a spy satellite, you could probably fry its optics with not really a lot of mirrors for not a long time actually managing to hit it.

On the other other hand the thing would be flying along at around 8 km/s, so you'd have to get your mirrors positioned accurately enough, and then start moving them at a relatively insane speed while still keeping their absolute positioning dead accurate when their motors and overall construction clearly weren't designed for either of those tasks at the required level of precision.

TL;DR Let's try it

Also there's this

[–] [email protected] 21 points 1 year ago (1 children)

You still have a crap-ton of atmosphere you have to get through, and the beams being reflected aren't coherent. So the light reflected is subject to the inverse square law, which means that the energy diminishes as the inverse square of the distance. So the actually energy reaching the satellite would be minuscule. If you want to effectively use light to punch all the way through the atmosphere, you'll need beam coherence.

[–] [email protected] 8 points 1 year ago* (last edited 1 year ago) (36 children)

The difference in the angles of the beams is the angle difference of a beam that came from an object 149,597,871 km away at a separation of 20 feet i.e. basically fuck-all. For this purpose I think they're effectively (edit: ~~coherent~~) parallel. And I think the atmospheric reduction would be significant but not defeating-to-the-purpose; I mean the sunbeam on its way in still had plenty of effectiveness after getting through the same atmosphere. If you did it on a cloudy day or something then yeah it wouldn't work at all.

(Edit: Wait, I don't understand optics; I mean parallel, not coherent. I don't think coherence enters into it?)

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[–] [email protected] 35 points 1 year ago (1 children)

and then start moving them at a relatively insane speed while still keeping their absolute positioning dead accurate when their motors and overall construction clearly weren't designed for either of those tasks at the required level of precision.

That's what they want you to think.

Props on your Internet math and research. It was a fun read.

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[–] [email protected] 13 points 1 year ago (2 children)

Uh… losses from transmitting through the atmosphere a second time?

Damn. I wonder what its operational range would be.

[–] [email protected] 6 points 1 year ago (1 children)

this thing is big enough to alter the average reflective index of a whole state if it swings around its mirrors

the focus spot in theorie could be set to any range, just as u go more far the precision of each mirror angle will be the limiting factor amongst atmospheric losses distortions.

[–] [email protected] 7 points 1 year ago* (last edited 1 year ago) (1 children)

Even if the actuators had enough precision, which they almost certainly do not, there's no way the mirrors are flat enough to keep the light collimated that far out. The angular spread would make the intensity much lower at orbital altitudes.

[–] [email protected] 3 points 1 year ago

True, however even if you get nearly 400MW of energy focused roughly, that's going to be well outside the operating parameters of satellites. The only thing that would save them would be the fact that they're moving at orbital speed and would only be subject to that beam for milliseconds.

[–] [email protected] 7 points 1 year ago (3 children)
[–] [email protected] 4 points 1 year ago

Some laws were made to be broken 😎

[–] [email protected] 27 points 1 year ago (1 children)
[–] [email protected] 10 points 1 year ago (1 children)

That is 300 ft, not 600-1,200 miles.

The Sun puts more energy on a spy satellite than the array could do.

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