tell my why this thing should not be able to melt satelites that cross over during the day
That is 300 ft, not 600-1,200 miles.
The Sun puts more energy on a spy satellite than the array could do.
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
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.
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?)
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.
The mirrors are flat, and the sun has an apparent diameter of about half a degree, so at 100 km, the spot diameter would be 900 meters.
You could use concave mirrors, but since you’re moving them independently, you’d also have to consider the diffraction limit for each one.
Fine fine fine fine fine fine OH GOD WHY
For some reason it’s really funny to me. It would be in the beam for a vanishingly small time: 762 microseconds, which if every mirror in the 392-megawatt array were properly focused, is still enough to receive a burst of 300,000 joules of radiant energy. I have not enough physics to tell you if that’s a big deal or not, but I feel like it would be and I don’t think the cameras would work after.
I realize we’ve had disagreements in other regards but this is excellent
I think solar-powered lasers would be a better bet. That would eliminate any surface irregularities of the mirrors and reduce the effective focus area . This would also reduce the number of moving parts required for focusing.
On the other hand, the amount of particulate diffusion within the atmosphere would complicate both the accuracy of the beam and the effective beam area, so who knows.
Let’s try it.
Uh… losses from transmitting through the atmosphere a second time?
Damn. I wonder what its operational range would be.
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.
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.
The suns angular diameter is about 0.01 radian, so at a distance of 100km, the suns reflection will spread out to a disc about 1km across.
392MW over a disc that size is 500w/m2, which is weaker than direct sunlight.
Yes; it is well known that if you look at yourself in a flat mirror, and then back up, your reflection will spread out bigger and bigger and get dimmer and dimmer, the further away you get.
Wait
“You” are the sun in this scenario.
As you back up, you fill a smaller and smaller fraction of the mirror. The reflection becomes less sun and more space.
It’s the plural form.
One axis, two axes.
https://www.splashlearn.com/math-vocabulary/geometry/axis-plural-axes
If you’re going to be pedantic and annoying, the least you could do is not be wrong.
Satellite is surrounded by vacuum. Thus insulated from getting rid of heat that way. So just pump heat into it and watch the temperature rise.
And you don’t need to melt it. Just cook it till its electronics overheat.
Well all things (human) in space have special paint in order to modify their blackbody radiation and maintain a trade off between disipation heat by EM radiation and keeping a temperature that allows semiconductors to work.
The point is that satellites do disipate heat. Convection disipation is the worst disipation of heat. The best disipation of energy (heat) is by radiation. Thats why the thermal blankets look shinny weird, just like the satellites. You would need a realiable source of heat in order to overcome the satellite disipation and saturate the satellite.
i’ve never thought about that before.
isnt that untrue though given that objects freeze instantly in space? Also that would mean you would only need to heat the ISS (rip) once, during its conception.
What mariusafa said is correct, but I wanted to point out that objects in space do not freeze immediately. Dissipation via blackbody radiation is much slower than convection and it can take a long time for something to cool down without the latter. In other words, a vaccuum does function as a very effective insulator, which can sometimes make it more challenging to get rid of heat in space than it is to keep something warm. The ISS, for example, needs to use radiators to keep cool. The same goes for many (most? all?) satellites that are at least as close to the sun as the earth.
It’s just not true. Disipation by convection effect is one of the ways of disipating energy. Dissipation by blackbody radiation is where most of the energy goes.
For example infrared heaters transmits most of it’s heat by radiation. Efficient heaters do not use convection mechanisms, well or not only.
*Jesse, what the hell are you talking about?
With one ?, he’s not scared or anything.
Are those mirrors curved to a focal point? If theyre flat mirrors which they probably would be, i think it could work
