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Controversial startup's plan to 'sell sunlight' using giant mirrors in space would be 'catastrophic' and 'horrifying,' astronomers warn (www.livescience.com)

submitted 18 hours ago by themachinestops@lemmy.dbzer0.com to c/technology@lemmy.world

109 comments fedilink hide all child comments

https://archive.ph/3WZrp

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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[–] julysfire@lemmy.world 5 points 8 hours ago (1 children)

What are the space laws for if we nudge it into the sun?

[–] luciferofastora@feddit.org 2 points 2 hours ago

Fun fact: pushing things into the sun is really difficult. Short version: imagine spinning a pendulum, then trying to slow it down, except the pendulum is 100kg (200lbs) and moving at 87 Mach.

Long version:

Anything launching from earth will have a significant orbital velocity around the sun by virtue of starting at the earth's own velocity (~30km/s, about 67000 mph). That velocity makes it hard to actually reach the sun.

Consider that even the sun's gravity isn't enough to pull in the earth at that speed. Simply applying thrust towards the sun would have to amount to a significant portion of the sun's gravity to make a noticeable difference.

So to reach the sun, you'd ideally have to get rid of that excess orbital velocity instead. That requires a lot of force, to put it mildly. That kind of force requires powerful boosters and a lot of fuel. Of course, getting those engines and that fuel up there also takes powerful engines and a lot of fuel. But the larger the rocket, the heavier it'll be, so it'll require even more fuel...

There's a phenomenon dubbed the "Tyranny of the Rocket Equation". It describes the problem that, at some point, the extra weight required to make a rocket more powerful is greater than the extra power it provides. That basically puts a limit on how strong a given engine can get. There's a lot of work being done on getting them to be more efficient, so that limit is getting higher, but the bottom line is:

It would require an immense amount of resources to slow an object enough to toss it into the sun, and more resources to get them to that object in the first place.

Physics is a cruel mistress and a mean spoilsport.