Seems like reusing some of Star Wars research could be used as well where the beam is constantly adjusted with independent mirrors to keep the beam coherent through the atmosphere. Also learned was the beam itself starts to distort the atmosphere requiring even more adjustments.

Multiple ground stations are a fine solution for backhaul, but not most end-user use cases.

So it'll never work in Scotland.

My read was that they're going to have 144 Gbps RF for both regular users and their ground station gateways, and 6 Tbps optical for satellite-satellite back haul, but then you can also buy direct ground-MEO access to a back haul link. (Presumably MEO-only because it's hard to maintain the link to a fast-moving LEO satellite?)

They don't seem to mention using optical for their own ground stations - maybe too unreliable?

It's interesting that people have a hard time visualizing this. The area in Earth's LEO is, definitionally, bigger than the Earth itself.

The SEA parking garage fits 12,000 cars in it. Two of those spread over the entire planet would be an imperceptible amount of space. You could drop a pin on a map your entire life and probably never hit one.

Speed matters a lot. You can fit a lot more walking people than speeding motorcycles in the same space.

Satellites need to travel at 8 km/s to not fall down.

By my calculations there will be an average of 500 collisions, no? Each shoebox has an effective width of 2 feet, and with 50k of them that's about 1% density. With 50k in the other direction, and about a 1% collision rate, that's 500 collisions.

This is funnily oddly specific.

Things you put in orbit at a certain elevation don't stay at that elevation forever.

Debris moves in 3D. Debris moving up will continue moving up. There is no force acting on it to bring it back down. Your comment makes it sound like an explosion would only be in 2D along the same orbit as the original object.

> According to https://www.youtube.com/watch?v=b66ZZ05wKC0 this might end very badly very soon

The paper they cite [1] estimates "the no-manoeuvre collision time" for various orbits. It has no alarming results.

That paper cites another paper [2], which raises the possibility of runaway conditions. It, in turn, runs a model developed in this paper [3].

[1] https://arxiv.org/pdf/2512.09643

[2] https://conference.sdo.esoc.esa.int/proceedings/sdc9/paper/3...

[3] https://www.researchgate.net/publication/234449150_Critical_...

> It is a very real possibility

It's really not. Not in the popularly-portrayed manner. Militaries have been researching how to intentionally cause such a cascade in even a limited orbit. To my knowledge, there isn't a solution.

I'll put that one in the toptext as well - thanks!

And my guess would be multiple beams for redundancy.

Is there even still one today?

For example, Starlink's "direct to cell" uses terrestrial-assigned 4G/5G frequencies which are already not globally coordinated.

Serving a given market from space already needs a national license anyway, and with today's small and region-dependent spotbeams for both GEO and LEO, I feel like we're going to move to a frequency regime more similar for terrestrial networks than for legacy communications satellites covering a whole hemisphere with one beam.

Fair enough, I was misremembering the higher end of Leo's bandwidth (1Gbps down/400Kbps up). Doesn't really intersect with TeraWave at all

> Starlink etc. use directed spotlight-like beams, so if you're not near a receiver (on the road) then no signal will be present. Why would they waste energy directing the signal anywhere other than where their dishes are?

You do not know how starlink downlinks work, so I can excuse your comments to ignorance. One person using a starlink antenna requires a beam from a satellite that covers about a 16 mile diameter with the power obviously being highest closest to the antenna. But anyone withing that hexagon will be exposed to mmWave radiation. It is not the "spotlight" you assume it to be. More like a flood light. "Narrow" is subjective in this case.

https://redlib.perennialte.ch/r/Starlink/comments/lwfj8v/map...

http://www.satmagazine.com/story.php?number=1026762698

This papare goes into the beam forming very expertly:

https://people.engineering.osu.edu/media/document/2022-10-12...

And it is not about only the power, it is about the effect. The same power used to push a 400 pound man vs a 40 pound child, you tell me the difference in outcome. As I said, you can be more skeptical and undecided and have a discussion with me, or just think that everyone has the same genetics and sensitivities and go on with your life.

> Correct me if I'm wrong, but aren't LEO satellites only going to reflect light from the sun when they're at low angles near sunrise and sunset? For night time stargazing, they're going to be in Earth's shadow, too.

Iridium's LEO satellites were sometimes (impressively) visible after midnight.

"value" is also a very charged term, and pollution is nearly purely a byproduct of the pursuit of value.

With the difference that cars can steer and stop to avoid collisions and aren't necessarily in your field of view every time you look at the night sky ;)

I have no idea if the number is actually a lot shrug but it's surely different than cars on a planet's surface

These satellites are low Earth orbit (LEO)

They're extremely sparse. Imagine putting 12,000 satellites randomly over the surface of the Earth. You're just not going to bump into one, statistically. Now expand that into 3D space in an orbital zone above us.

It's not a collision risk.

It is already impossible - all the remaining Space Shuttles are in a museum, not to mention all Space Shuttle missions were (and were always intended to be) to Earth orbit. No Space Shuttle ever went past 600 km hight Earth orbit.

> wonder if there's a limit to space junk beyond which leaving the Earth in a space shuttle becomes impossible

There is. We don't have the industrial capacity, as a species, to do it.

> How many causes Kessler syndrome?

Space is huge. Try this trick: the number of satellites in orbit is about the same as the number of planes in the air at any time. (~12,000 [1].)

The volume of space from the ground to 50,000 feet is about 200x smaller than the volume from the Karman line to the top of LEO alone (~2,000 km).

Put another way, we approach the density of planes in the sky in LEO when there are milliions of satellites in that space alone. Picture what happens if every plane in the sky fell to the ground. Now understand that the same thing happening in LEO, while it occurs at higher energy, also occurs in less-occupied space and will eventually (mostly) burn up in the atmosphere.

Put another way, you could poof every Starlink simultaneously and while it would be tremendously annoying, most satellites orbiting lower would be able to get out of the way, those that couldn't wouldn't cause much more damage, the whole mess would be avoidable for most and entirely gone within a few years.

There are serious problems with space pollution. Catastrophic Kessler cascades that block humans from space, or knock out all of our satellites, aren't one of them.

[1] https://www.travelandleisure.com/airlines-airports/number-of...

At the altitudes these mega-constellations operate at, kessler syndrome is not a real threat. Even if left unpowered, everything there will naturally re-enter the atmosphere in ~5 years.