this post was submitted on 06 Nov 2025
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California-based startup Reflect Orbital aims to build a swarm of 4,000 giant mirrors in low Earth orbit to "sell sunlight" to customers at night. Experts warn that the mirrors could mess with telescopes, blind stargazers and impact the environment.

Reflect Orbital, which was founded in 2021, has recently taken the first step in a scheme to sell sunlight at night by bouncing solar rays off giant "reflectors" that can redirect the vital resource almost anywhere on our planet. By doing this, the company aims to extend daylight hours in specific locations, thus allowing paying customers to generate solar power, grow crops and replace urban lighting.

But experts say it is a wildly impractical plan that should never get off the ground. What's more, the resulting light pollution could devastate ground-based astronomy, distract aircraft pilots and even blind stargazers.

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[–] dual_sport_dork@lemmy.world 158 points 1 day ago (3 children)

In addition to being a moronic idea, this is also physically infeasible as I outlined in excruciating detail in my comment the last time this came up. The takeaway is that this is an investor scam for sure, and the side effects outlined in this article are just a fun (!) and exciting (!) sideshow if these bozos actually do mange to get a single mirror off the ground and deployed. Which they probably won't.

[–] JoshuaFalken@lemmy.world 54 points 22 hours ago (1 children)

I disagree they are bozos. I'm actually coming around on the idea. Not the mirror thing of course, but the VC grift using a flashy idea. Millions of dollars and the only thing you make is a slideshow? Brilliant.

[–] SaraTonin@lemmy.world 47 points 21 hours ago (1 children)

It’s tricky business. The idea has to be plausible enough to attract investors, but implausible enough not to get looked at too closely by clever investors. Similarly, you have to drum up enough publicity to get interest, but not enough to get scrutiny.

Get the balance wrong and you get Theranos.

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[–] Krudler@lemmy.world 22 points 23 hours ago (1 children)

I'd like to see that comment if you could link it!

I mean just on the surface of it, this is completely preposterous.

The first thing that comes to mind is you can only cover so much area. 4000 satellites would cover the dog park near me. In the scope of an undertaking like this, it's a trivial amount of energy they could possibly gather?

[–] dual_sport_dork@lemmy.world 47 points 23 hours ago* (last edited 22 hours ago) (9 children)

That's the main hurdle.

Re-finding this was a pain in the ass because I didn't save it. https://lemmy.world/post/19485246/12219336

Editing to add some more meandering. Now this is even longer than the first one.

In addition to surface area limitations, there's also a pretty obvious line of sight problem in that if your satellite is positioned such that its shiny side is facing the sun, by definition it must be facing the same direction as the Earth's currently lighted side. The further past the dusk line onto the dark side of the Earth you're trying to hit the further you have to rotate your mirror until ultimately the surface of it is perpendicular to the incoming sunlight. This is the angle of incidence, in optical terms, and it reduces the effective reflection not only off of the mirror proportionally to the increase in angle (in a roughly geometric manner, I believe) but also where that reflected beam of light hits the ground at its oblique angle. In real terms, it will be impossible to hit any target more than a few degrees past the dusk line with any meaningful amount of energy. Insofar as this harebrained scheme could possibly hit the ground with any amount of energy at all.

The diagram (which is surely not to scale) on these idiots' website seems to depict a mirror in orbit around the Earth that's about the size of Massachusetts, which is orbiting at a height that'd put it somewhere in the vicinity of the Van Allen belt, which is also a bad idea (no radio communication for you!) and would result in an orbital period of around 2.5 hours. If so, that means your mirror is whizzing over the surface at something like 14,000 MPH, and you would have some kind of line of sight to it from the ground for maybe 25% of its orbit. So even with the best will in the world and absolutely mathematically perfect rotation control it'll only be able to remain on a surface target for about 37 minutes at most, most of which would be while it's uselessly passing through the Earth's shadow and is reflecting no sunlight at all, and for the remaining handful of minutes with its effective output tapering off to uselessness as it sets over the opposite horizon.

"I'll just position my mirrors in a geostationary orbit," says Mr. Clever. "Then I'll have line of sight to a big chunk of the surface and my satellite won't move relative to it."

Well, the further you park your mirrors from the surface, the harder they are to aim. You can't have it both ways. A geostationary orbit is about 22,000 miles from the surface, a distance from which even the tiniest error in alignment will result in you hitting the wrong target. You can use some middle school trig to calculate this for yourself: At a distance of 22,000 miles, an alignment error of just 0.01 degrees will result in the centerline of your beam missing the target by four miles, which in terrestrial terms is what we refer to as kind of a lot. Maintaining an alignment precision that high especially taking into account gravitational perturbation by the moon, etc., is a rather tall order. To maintain targeting precision within 223 feet, which is probably already unacceptable, you need a constant alignment precision of 0.0001 degrees, and you need to hold it there 100% of the time.

I don't care how big your rocket is, that's not happening.

All of this also assumes perfectly flat and 100% reflective surfaces on the mirrors, which never degrades or gets scuffed up or punctured by space debris. Which is also impossible.

To recap:

  • You can't reflect any more energy than strikes the surface area of your mirrors, end of story. The mirrors will be tiny, relative to the size of the Earth, and the Earth is huge, relative to the size of any mirror we can launch.
  • The efficacy of your mirrors diminishes geometrically with how far you must angle them relative to the direction of incoming sunlight.
  • Most of the time your mirrors will either be in the Earth's shadow, where they are useless, or over the already illuminated side of the Earth, where they're pointless. In easily achievable low Earth orbits, their time on target will be very short.
  • Positioning the orbits high enough to mitigate either problem will make aiming mathematically impossible, and also magnify any imperfections in focus, which are certain to be vast. That won't work either.

TL;DR: The whole thing won't work.

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[–] UnderpantsWeevil@lemmy.world 90 points 23 hours ago

"We're a startup"

"What's your plan?"

"Giant mirrors in space to control the sunlight that hits the earth's surface."

"Wow, sounds incredibly expensive and of dubious technical merit. What are you asking to make this happen?"

"We need whatever money you have in your wallet right now."

"And the return on investment?"

"Infinity zillion dollars."

"I guess I'd be a fool not to hand you all my money."

"Absolutely. Now... that's a really nice watch. And shoes. We could get you an amazing return if you gave us those, too."

[–] toiletobserver@lemmy.world 72 points 1 day ago (3 children)
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[–] philycheeze@sh.itjust.works 62 points 22 hours ago (3 children)

You don’t even have to be an expert to see that this is one of the stupidest ideas ever conceived.

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[–] dalekcaan@feddit.nl 55 points 21 hours ago (2 children)
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[–] _lilith@lemmy.world 52 points 19 hours ago (6 children)

collapsed inline media

Joking aside this is a horrible idea even if it were possible to get right. Anything with circadian rhythm is going to get fucked up real fast and that includes people. This is like angry mob outside the corporate office level bad. Torches and pitchforks, the whole thing

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[–] axx@slrpnk.net 40 points 6 hours ago (1 children)

The future we hoped for: Dyson sphere, free unlimited energy

The future silicon valley shitlords are hoping for: let us sell you sunlight (or maybe lack thereof, wink wink)

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[–] FireWire400@lemmy.world 35 points 14 hours ago (3 children)

It's nice how, in theory, some crackhead silicon valley startup would be allowed to single handedly fuck up just about everything

[–] 1984@lemmy.today 11 points 13 hours ago* (last edited 13 hours ago)

Next idea : Shining ads in space, powered by sunlight, so people always have something to look at. /puke

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[–] krooklochurm@lemmy.ca 31 points 9 hours ago (1 children)

If I was going to build death ray mirrors in space this is how I would pitch it.

Tf are people gonna do once you've built the death ray?

It's not about selling sunshine, it's about melting your enemies with the power of the sun.

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[–] baronvonj@lemmy.world 28 points 1 day ago

See my vest! See my vest! It's authentic gorilla chest!

[–] Naevermix@lemmy.world 26 points 3 hours ago (2 children)

This is obviously a scam directed at venture capitalists. There's no way this is going to happen.

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[–] thenose@lemmy.world 25 points 21 hours ago (1 children)

Why is this not an Onion piece????

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[–] slaacaa@lemmy.world 25 points 8 hours ago
[–] xxce2AAb@feddit.dk 25 points 23 hours ago (1 children)

"We also plan on patenting atmospheric air and granting reasonably priced usage licenses for limited daily volumes to every man, woman and child on the planet. It'll be great!"

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[–] Surp@lemmy.world 25 points 7 hours ago

Rich people should not have the choice to have fucking sunlight in the middle of the night.

[–] kazerniel@lemmy.world 24 points 8 hours ago (2 children)

Capitalism is at it again 🤦 What are they selling next? Air?

[–] Blackmist@feddit.uk 13 points 8 hours ago (2 children)

Are we talking Spaceballs or Total Recall?

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[–] ZILtoid1991@lemmy.world 18 points 10 hours ago (2 children)

New startup idea: iAir. Pay a certain amount of subscription for air, or we will choke you to death!

[–] Mrkawfee@feddit.uk 12 points 10 hours ago (2 children)

Mel Brooks had this covered in Spaceballs.

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[–] echodot@feddit.uk 17 points 18 hours ago

Why are all the experts going on about the fact you might blind pilots but not talking about the fact that it won't actually do anything.

It would have to be an astonishingly vast megastructure for it to have any effect at all. If we were talking about a structure 100 km across or more they might actually have some sort of point.

[–] rob_t_firefly@lemmy.world 15 points 6 hours ago

Last time some rich fuck started screwing with people's access to natural sunlight, it didn't end well for him.

collapsed inline mediaTwo screenshots from the "Who Shot Mr. Burns" episode of "The Simpsons" showing Mr. Burns with a gunshot wound, and then collapsing onto a sundial.

[–] otacon239@lemmy.world 14 points 22 hours ago (4 children)

I think there’s a couple of Bond villains with similar setups. Not sure how I feel about that, but felt it was worth mentioning.

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[–] ILoveDurians@lemmy.cafe 14 points 8 hours ago (2 children)

Does anyone else remember the scene in the movie called "The Core" where a giant beam of light started frying people and melting bridges?

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[–] lightsblinken@lemmy.world 14 points 6 hours ago

please stop fucking with the delicate balance of nature, its the only nature i've found that works for me

[–] _cryptagion@anarchist.nexus 14 points 19 hours ago (1 children)

I almost wish this was not a practical impossibility just so we could get to see the headlines when some misalignment fries an island of billionaires like bacon.

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[–] nondescripthandle@lemmy.dbzer0.com 13 points 23 hours ago* (last edited 23 hours ago)

Oh fuck we're in a Futurama episode.

[–] Quexotic@infosec.pub 13 points 6 hours ago (9 children)

Yes. Let's make the planet even hotter... Fucking morons.

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[–] proper@lemmy.world 12 points 22 hours ago

simpsons did it!

[–] iAvicenna@lemmy.world 11 points 9 hours ago (1 children)

this startup's CEO and finding members should be trialed for crimes against humanity

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[–] cycadophyta@lemmy.world 11 points 21 hours ago

Throw these guys in a volcano. Add the billionaires and tech capitalists while at it.

[–] drosophila@lemmy.blahaj.zone 10 points 23 hours ago
[–] drascus@sh.itjust.works 10 points 6 hours ago (1 children)

I just imagine the first places that put in in-door lightnig like "here now you can work later in the day" now they will be like "Oh look you can work 24/7 now it's never dark anymore".

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[–] Arkthos@pawb.social 9 points 13 hours ago (1 children)

Very useful on the off chance that vampires are real. Otherwise.... Less so.

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[–] SethTaylor@lemmy.world 9 points 11 hours ago (1 children)

Cut to: man watching in shock as his "mirror satellite" burns people like ants under a magnifier

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[–] Pacattack57@lemmy.world 9 points 20 hours ago

This isn’t even possible and the cost even if it was would be ASTRONOMICAL.

[–] fodor@lemmy.zip 8 points 11 hours ago (4 children)

Oh, I think it's a wonderful plan for the startup. They don't own space, they don't have any control over space, they're selling something that they know they can't possibly deliver because they would have to get people to agree that they're allowed to steal sunlight and space, and that would never happen. It's great for them. They can get some cash.

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[–] TORFdot0@lemmy.world 8 points 19 hours ago (2 children)
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[–] Jax@sh.itjust.works 8 points 23 hours ago (3 children)

Hey so, this might seem pretty extreme but um....

People who even attempt to steal sunlight should die. I don't care how, they should just be dead.

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[–] thespcicifcocean@lemmy.world 8 points 11 hours ago (1 children)

they'll start by selling sunlight at night, but we know that it'll end up being that we have to either pay to have sunlight in the daytime OR pay to not have sunlight at night.

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[–] Arghblarg@lemmy.ca 7 points 22 hours ago* (last edited 22 hours ago)
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