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FCC approves test of space mirror to light night sky

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Re: FCC approves test of space mirror to light night sky

#51

Post by blooalien »

gcr wrote: post #24

Wonder what would happen if a hacker focused all ten thousand of them on a single area for an hour or two. Sounds like a really energy-efficient way to demolish a city. X Wing: Wedge’s Gamble (1996) by Michael Stackpole shows the rebel alliance using similar tricks during the battle of Coruscant.

> "Wonder what would happen if a hacker focused all ten thousand of them on a single area for an hour or two. Sounds like a really energy-efficient way to demolish a city."

I'm far more concerned about the people who own/build stuff like this using it as you suggest (or any of the government pets that they own) than I am about "hackers" doin' such things (although, you're entirely right to have that concern as well, because there's obviously those type of folks out there doin' bad things even with the technology we have already).

Re: FCC approves test of space mirror to light night sky

#52

Post by appplication »

8cvor6j844qw_d6 wrote: post #28
ben_w wrote: post #10

They seem to be talking about each satellite managing the luminosity of the full moon over a few square kilometres, and getting a few tens of thousands of them. Even if you ignoring how much drag these must have, and hence how much electrical power you'd need for an ion drive just to keep them up, each spot being a few km across (and only getting light while the satellite is over your horizon) is just not compelling.…

> relatively easy to redesign as weapons There is a fiction I've read years ago that mentioned satellites becoming makeshift weapons by overheating exposed objects (think reactors, gas trucks, oil refineries) by acting as a solar furnace [1] via mirrors. Not sure/don't recall how it deals with practical issues such as clouds and distance/intensity, but good enough for a story I guess. [1]: https://en.wikipedia.org/wi…

> The temperature at the focal point may reach 3,500 °C

I thought this was interesting because it doesn’t really seem like an applicable top level claim, surely this is referring to a specific furnace, not all solar furnaces?

Then this got me thinking if there is some universal upper bound constraint to these temperatures. E.g. if I recall a telescope can’t make a source object brighter than it actually is, and this just seems like a thermal telescope, so I wonder if that principle applies here or not.

Re: FCC approves test of space mirror to light night sky

#53

Post by reader9274 »

gcr wrote: post #24

Wonder what would happen if a hacker focused all ten thousand of them on a single area for an hour or two. Sounds like a really energy-efficient way to demolish a city. X Wing: Wedge’s Gamble (1996) by Michael Stackpole shows the rebel alliance using similar tricks during the battle of Coruscant.

First, they don't exist and 10k of them will never exist. Second, nothing would happen, the power will be minuscule and last for a very short time focused on such a small patch.

see: https://youtu.be/lkjyeI0ykGM

Re: FCC approves test of space mirror to light night sky

#55

Post by ben_w »

appplication wrote: post #52
8cvor6j844qw_d6 wrote: post #28

Earlier quoted context omitted.

> relatively easy to redesign as weapons There is a fiction I've read years ago that mentioned satellites becoming makeshift weapons by overheating exposed objects (think reactors, gas trucks, oil refineries) by acting as a solar furnace [1] via mirrors. Not sure/don't recall how it deals with practical issues such as clouds and distance/intensity, but good enough for a story I guess. [1]: https://en.wikipedia.org/wi…

> The temperature at the focal point may reach 3,500 °C I thought this was interesting because it doesn’t really seem like an applicable top level claim, surely this is referring to a specific furnace, not all solar furnaces? Then this got me thinking if there is some universal upper bound constraint to these temperatures. E.g. if I recall a telescope can’t make a source object brighter than it actually is, and this…

> I wonder if that principle applies here or not

It applies, but also in practice the maximum temperature is lower than the theoretical upper bound.

https://what-if.xkcd.com/145/

Re: FCC approves test of space mirror to light night sky

#56

Post by brynnbee »

goda90 wrote: post #54

So we've got this problem of the atmosphere trapping too much heat from solar radiation hitting the surface and the plan is to increase the amount of solar radiation hitting the surface?

It's fine just setup mirrors on the ground to bounce the light back to the satellite! (/s)

Re: FCC approves test of space mirror to light night sky

#57

Post by blooalien »

swasheck wrote: post #40

somebody watched die another day ( https://en.wikipedia.org/wiki/Die_Another_Day ) and thought, “hmm. great idea.”

It's actually more'n a little bit scary how much of modern "politics" seems as if it could be driven by having watched any of a number of movies and thinking "We should do that!" When I hear people talk about politicians bein' like spoiled brat children in adult bodies, I tend to think that sounds like exactly the type of mentality that could see something all messed up and scary in a movie and want to try to do it in the real world. What makes it even more scary in my mind is that we've allowed those type of people to gather entirely too much money and power such that they have the option available to them to seriously consider trying such horrible ideas.

Re: FCC approves test of space mirror to light night sky

#58

Post by appplication »

ben_w wrote: post #55
appplication wrote: post #52

Earlier quoted context omitted.

> The temperature at the focal point may reach 3,500 °C I thought this was interesting because it doesn’t really seem like an applicable top level claim, surely this is referring to a specific furnace, not all solar furnaces? Then this got me thinking if there is some universal upper bound constraint to these temperatures. E.g. if I recall a telescope can’t make a source object brighter than it actually is, and this…

> I wonder if that principle applies here or not It applies, but also in practice the maximum temperature is lower than the theoretical upper bound. https://what-if.xkcd.com/145/

Oh funny, my intuition when I was writing that was “there’s probably an xkcd what if about this”, but I imagined it be about surrounding the sun with mirrors. Same idea though in the end

Re: FCC approves test of space mirror to light night sky

#59

Post by dheera »

gcr wrote: post #24

Wonder what would happen if a hacker focused all ten thousand of them on a single area for an hour or two. Sounds like a really energy-efficient way to demolish a city. X Wing: Wedge’s Gamble (1996) by Michael Stackpole shows the rebel alliance using similar tricks during the battle of Coruscant.

I don't think 50000 60-ft mirrors at the height they intend to fly would cause that to happen. Not enough light gathering power.

50000 60-ft mirrors is about the same area as a single mirror 2.5 miles across. So the area of the mirrors is about the area of a city. You gather as much light as the city itself in regular daytime. If you focused all of that perfectly efficiently onto a city, that city would just look like daytime.

Re: FCC approves test of space mirror to light night sky

#60

Post by moralestapia »

Robotbeat wrote: post #26
moralestapia wrote: post #22

Earlier quoted context omitted.

Rescue operations, etc... I saw a presentation by one of the founders where he talked about several use cases where the benefit is just phenomenal. They don't fool me for a second, however. The end goal of this is to build a weapon that can fry people/places on demand (but only the bad guys, of course).

orbital mirrors make very poor weapons because Conservation of Etendue means you fundamentally cannot concentrate very high unless your fill factor is very high (which would require millions of tons in orbit). Lasers are far more effective as weapons as a single aperture launched on a single rocket is sufficient to get high concentration. Microwaves also. The military application would just be illumination.

You don't need to go "very high", 80C is more than enough to wreak havoc.

I'm sure that's attainable with a few hundred sats.

Can someone do the math?

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