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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

#151

Post by lenkite »

kadoban wrote: post #105
lenkite wrote: post #92

Earlier quoted context omitted.

At some point, nations are going to claim the orbital space above them as national territory and develop technology to shoot down violators.

That would be fairly nonsense. There's _very_ few orbits that can stick over a particular place, and it's only places on the equator. We'd be giving up 99+% of useful orbits.

If Russia had been the one to launch over ten thousand satellites in mega-constellations occupying LEO space, there would have already been a dozen senate hearings all talking about extraordinary and imminent threat to US national security and urgent need to eliminate the problem.

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

#152

Post by peeters »

consp wrote: post #96
peeters wrote: post #91

The fact that they're spelling this Earendil, not Earendel, makes me think this is a direct reference to Tolkien's work. It's pretty weird for dystopian industrial initiatives to be named after characters in a work whose most unambiguous message was that rampant industrialization was ruining the world.

Sounds like a morning star reference (via some obscure Christian texts) which I will draw further towards Lucifer via Latin. Do with this idea as you please.

Tolkien's Earendil was definitely a reference to the morning star, but outside his legendarium I don't know of anyone spelling it "dil" instead of "del". If it was supposed to be a non-Tolkien reference I would've expected them to spell it accordingly.

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

#153

Post by semi-extrinsic »

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…

Anything that can explode if overheated in a refinery is covered with passive fire protection. This is designed to withstand jet fire exposure, meaning a heat load of at least 1100 °C and at least 250 kW/m2. Ordinary sunlight at peak is about 1 kW/m2, so your mirror needs to cover 250x the visual extent of the sun in the sky.

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

#154

Post by kadoban »

wildzzz wrote: post #39
datakan wrote: post #21

Earlier quoted context omitted.

Someone tried to recruit me back in 2000 for a startup that would sell a box you connect to your computer allowing you to smell things over the internet. I'll let you guess what industry he was targeting.

Ah yes, the best part of human intimacy: the smells!

You're being sarcastic but you're not far wrong. Scent is a big part of attraction and sex. It's somewhat subtle, but important.

Artifically capturing that sounds...doomed though.

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

#155

Post by Robotbeat »

ben_w wrote: post #49
Robotbeat wrote: post #34

Earlier quoted context omitted.

Launching a gossamer thin mirror in space is not very expensive. Broad strokes claiming anything launched to space is going to be a more expensive solution has to level with the fact that GPS and quite a lot of telecommunications and Earth observation seem to have incredible leverage if launched to space instead of just using ground based solutions.

For this use, "gossamer thin" is unlikely. You want to control where you point the mirror, it needs a structure that not only doesn't flop around when you torque your spacecraft, but also doesn't have surprise vibrational modes that squeeze and expand the illumination zone. (Things I'm learning while researching what is now looking like an eight thousand or more word blog post about why a different space thing, data…

I know for a fact it is gossamer thin. It does need structure, but there’s a fundamental limit to how small your spot size is anyway due to Conservation of Etendue, so small deformations aren’t a huge problem.

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

#156

Post by ben_w »

Robotbeat wrote: post #155
ben_w wrote: post #49

Earlier quoted context omitted.

For this use, "gossamer thin" is unlikely. You want to control where you point the mirror, it needs a structure that not only doesn't flop around when you torque your spacecraft, but also doesn't have surprise vibrational modes that squeeze and expand the illumination zone. (Things I'm learning while researching what is now looking like an eight thousand or more word blog post about why a different space thing, data…

I know for a fact it is gossamer thin. It does need structure, but there’s a fundamental limit to how small your spot size is anyway due to Conservation of Etendue, so small deformations aren’t a huge problem.

You know "for a fact" anything about a tech which is currently in the experimental stage (or even "press release before first experiment" stage), in a field which has a famously large gap between theory and practice, confidently enough to assert it will definitely not suffer from the problems that mean the large sheet materials we already launch to space (space-qualified PV arrays) are much heavier than bare cells?

> Conservation of Etendue,

Sounds like you think I have in mind something like an Archimedes' heat ray. I do not see anything close to that for the presented satellites.

I would aver that the presented design is so far from being useful that making it useful requires solving enough engineering challenges to also enable an Archimedes' heat ray; but again: what is actually shown is not that.

The numbers I see from Reflect Orbital suggest they have an expectation of the apparent brightness fluttering by 5x from internal motion of the reflector. At the scale involved, may be easier to consider the imperfections/ripple as behaving the same as if some of the specular reflection becomes diffuse reflection.

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

#157

Post by Robotbeat »

ben_w wrote: post #156
Robotbeat wrote: post #155

Earlier quoted context omitted.

I know for a fact it is gossamer thin. It does need structure, but there’s a fundamental limit to how small your spot size is anyway due to Conservation of Etendue, so small deformations aren’t a huge problem.

You know "for a fact" anything about a tech which is currently in the experimental stage (or even "press release before first experiment" stage), in a field which has a famously large gap between theory and practice, confidently enough to assert it will definitely not suffer from the problems that mean the large sheet materials we already launch to space (space-qualified PV arrays) are much heavier than bare cells? >…

I know for a fact because I’ve dug deep into the field, colleagues work on it every day, and I’ve met and talked to the founders of Reflect, saw material samples of their mirror tech.

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

#158

Post by brookst »

ben_w wrote: post #43
brookst wrote: post #38

Earlier quoted context omitted.

Illuminating a solar farm for 24 hour power generation?

At the orbits they're talking about, at best 30 minutes before dawn and after sunset. Earth gets in the way, have to go much much higher to get 24 hour coverage, and if you can focus that well over that distance you've got the optics for a super-weapon. And as this is optical, won't go through clouds. This is why beamed power discussions often talk about converting to microwaves instead, though that comes with an eve…

Yeah, fair points. Thanks!

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

#159

Post by kube-system »

kadoban wrote: post #116
kube-system wrote: post #110

Earlier quoted context omitted.

I think most current wars in progress have much less logical reasons for happening

It's possible, it would just be _very_ dumb. It'd also turn into just...shooting them all down, restrictions of who anything is over wouldn't survive.

It wouldn't be an all-or-nothing type scenario -- and in fact there is already no common international agreement about where a nation's boundary extends to in the z-axis. The observed limit is "however high that country can detect and shoot something down"

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

#160

Post by b112 »

bunderbunder wrote: post #67
b112 wrote: post #25

Earlier quoted context omitted.

With global warming, trillions upon trillions of acres of immensely fertile bogland, in Northern Canada is thawing. The problem is, global warming doesn't affect daylight. 4 hours of "the sun barely makes it over the horizon" means no crops, no matter if the temp is above 0C in September. Obviously this satellite isn't viable, but all things start small. Large tracts of land could be illuminated. But of course, I que…

Though I have to ask the value of illuminating large tracts of mostly uninhabited land. Lighting areas where no humans are around to want the light seems like a proposition that’s mostly useful for further disturbing nocturnal wildlife. What might be more useful is to illuminate just the areas where a human currently needs to see well. It would hypothetically be both more useful - you can concentrate more light in ju…

Though I have to ask the value of illuminating large tracts of mostly uninhabited land.

Crops means farmland. Farmland means food. Food prevents people from starving to death.

With global warming, existing croplands will become unusable. We'll need new farmland.

That was the whole point of my post, which also discusses other concerns.

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