Some short googling says they have lasers that clear a path for a data carrying beam, but that seems wasteful/infeasible for commercial uses
"Even Earth’s atmosphere interferes with optical communications. Clouds and mist can interrupt a laser. A solution to this is building multiple ground stations, which are telescopes on Earth that receive infrared waves. If it’s cloudy at one station, the waves can be redirected to a different ground station. With more ground stations, the network can be more flexible during bad weather. SCaN is also investigating multiple approaches, like Delay/Disruption Tolerant Networking and satellite arrays to help deal with challenges derived from atmospheric means."
https://www.nasa.gov/technology/space-comms/optical-communic...
Some more info on Optical Communications for Satellites: https://www.kiss.caltech.edu/workshops/optcomm/presentations...
Which then also means you have to build ground stations in this range yet far enough apart that they experience different weather yet close enough that you can redundantly link all the sites.
Aside from government and massive telecommunications companies who would this serve?
It's just really cool sci-fi tech that I want to see used in something other than DLP chips!
JWST and other observatories with segmented primary mirrors kind of use the segment alignment one time to get the correct alignment once. Then there is Adaptive Optics. It's kind of the opposite direction though as they are using a laser to detect the distortion so it can be compensated in the image. From learning about SDI when I was a kid/teen, it's just always been about controlling the laser itself in my mind.
may be something like this - a high-power impulse making a channel through whatever clouds, mist, dust and after that information carrying ray/impulse through the channel, rinse and repeat
They don't seem to mention using optical for their own ground stations - maybe too unreliable?
Twenty of them at 100,000 birds each to start approaching the density of planes in the sky [1]. Not around an airport. In all of the sky. Oceans and all.
Practically speaking, this is not a pressing concern for our generation.
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.
Satellites need to travel at 8 km/s to not fall down.
Not really. You're correct inasmuch as it increases collision energies. But it also increases momentum, which maintains orbital integrity within predictable bounds. Nobody is maneuvering around satellites, they–and their debris–stay where the math tells them to.
Not how orbital mechanics work.
Planes maneuvers, get tossed around and have hubs they circle. A plane under my left wing can’t be relied on to continue in a straight line. The satellite can.
The other underestimated dimension is that satellite manoeuvres use up a finite supply of expensively-launched propellant. That's tolerable when Starlink is doing 50k conjunction avoidance manoeuvres in six months across its constellation, but once it becomes each satellite moving at least weekly you either need bigger satellites carrying more propellant or have to accept significantly higher collision risk than they currently do.
This is something people unfamiliar tend to misconceive in their limited thinking on the subject. You can't just tap the breaks to slow down. Changing altitude of satellites is done by speeding up to increase altitude and slowing down to lower altitude. Once you change the velocity and reach the desired altitude, you have to then undo that acceleration to get back to orbital velocity. Fuel is required in both directions. The less fuel used the better for the maneuver. Most satellites EoL is defined by remaining maneuvering fuel vs functionality of the hardware.
My first understanding of accelerating in space was from the old Asteroids game. To slow down, you had to rotate 180° and start accelerating in that direction. Others might learn it from Kerbal.
I have a background in astronautical engineering. While you can't tap the brakes to 'slow down', you can impart miniscule amounts of impulse which, over the course of hundreds of orbits, will change your plane by an imperceptible amount from a distance, but tens or hundreds of kilometers up close. OM being OM, you can predicts these collisions in advance.
I had a professor who referred to orbits not in altitude but in expected decay time. We're currently in the months to single-digit years orbits. (We will stay there for telecommunications due to latency.) If we were doing at decades or centuries what we're doing in LEO, this would be a problem. At LEO, it's a nuisance and barely more.
right. this is what is counter-intuitive for those that are not familiar with space. they don't just light the burner and boost to a new altitude. the part about stopping the acceleration with an opposite burn is often not considered. most think you can fly a space ship like a jet fighter, but in space. can't blame them since that's how sci-fi portrays it. real life space flight is really boring in comparison. jumping out of FTL to land in orbit around a planet makes me laugh every. single. time.
I'm not arguing against collisions becoming more likely. I'm arguing aginst it becoming commonplace to the point that it becomes a commercial concern.
> satellite manoeuvres use up a finite supply of expensively-launched propellant
Nobody is plane changing out of a collision. And for the foreseeable future, in LEO, the birds are not propellant constrained. (And launch is getting cheaper.)
> you either need bigger satellites carrying more propellant or have to accept significantly higher collision risk than they currently do
We're decades away from this being a problem. That gives ample runtime to developing e.g. magnetic station-keeping (if we go reactionless) or more-efficient engines.
I've not kept up for decades now .. what's the state of solar powered magnetorquers these days? I'd quietly assumed it would be more commonplace.
I dimly recall a couple of small satellites magnetically locking fifteen or so years past?
Academic. We don't currently have a pressing need for reactionless thrust in the magnetosphere. Each of semiconductors, launch vehicles and telecommunications standards are moving faster than satellites last.
> Each of semiconductors, launch vehicles and telecommunications standards are moving faster than satellites last.
That's certainly a pragmatic cost based argument for not using them in the fast moving world of commercial magnetosphere constellations.
> Academic.
I feel they've moved past academic and transitioned to deployed .. at some evolution of implementation. Not commercially relevant is certainly one state of play.
I guess I was more interested in the nonlinear control issue in a field of highly variable intensity.
Minimising collision risk already is a commercial concern, and the number of conjunction avoidance manoeuvres SpaceX takes in order to achieve this has been growing exponentially (which presumably is a major factor driving their move of 4k satellites to a lower orbit which involves more station keeping) Obviously this gets harder when most of the satellites avoiding their orbits coming too close don't have the same owner, particularly if some of the other megaconstellations aren't even particularly cooperative (hi China!)
> Nobody is plane changing out of a collision. And for the foreseeable future, in LEO, the birds are not propellant constrained. (And launch is getting cheaper.)
No which is why I mentioned the fact that constellations pre-emptively plane change to avoid conjunctions. The frequency with which they have to do this scales superlinearly with the number of satellites operating in or intersecting the orbital plane. Ultimately propellant use for those manoeuvres and station keeping defines the satellite lifetime: agree it's not a huge problem when a satellite is only making small orbital changes a handful of times a year and its got a decent sized delta-v budget for station keeping and EoL deorbiting anyway, but another 70k satellites in the same plane would require quite a lot more adjustments, never mind them operating at aircraft density as proposed earlier.
> We're decades away from this being a problem. That gives ample runtime to developing e.g. magnetic station-keeping (if we go reactionless) or more-efficient engines.
Depends how fast the satellites get put up there (and also whether orbital megastructures become a reality, although non-trivial numbers of them actually might be decades away). There's some scope to improve propulsive efficiency (hi colleagues!), but within the power/mass constraints of a smallsat, you're not likely to see orders of magnitude more improvement in specific impulse over current gen EP, and we are forecast to need orders of magnitude more avoidance manoeuvres, which is generally going to mean more reaction mass. Sure, if we get reactionless propulsion suited for precise orbital changes in LEO then we can forget all about the tyranny of the rocket equation, but hey, if we perfect flying cars we won't have to think about the implications of congestion on the roads!
Randomly place 50,000 shoe boxes up and down the entire eastern seaboard.
Randomly place 50,000 shoe boxes up and down the entire western seaboard.
Send them in straight lines towards the other side of the country.
See if any collide. Almost certainly none of them will. Edit: They will almost certainly
For reference, if you placed all 50k boxes next to each other on the same beach, it would be about 10 miles wide. The total shoreline on either side would be ~1800 miles wide.
And that's only 2D.
It may seem counterintuitive, but if something in orbit gets a push that isn’t strong enough to make it totally escape orbit, it will stay in a new elliptical orbit. That new orbit will pass through the point where the push happened, so it will come back through that location again, just with a different speed and direction.
Gravity?
But also orbital dynamics (at least as I understand it) means debris that debris that is flung up is going to have a more oval orbit, so the high point (apogee) increases and the low point (perigee) decreases. And a lower perigee means more atmospheric drag, which will help deorbit the debris.
Not quite.
If you are at apogee and accelerate, your perigee will be raised. If you are at perigee and accelerate, your apogee will be raised. You can't increase your apogee and perigee at the same time.
If the impulse is in the direction of orbit, then the altitude of your orbit 180 degrees from your current position will raise. If the impulse is against your orbital direction, your height 180 deg away will be lowered. Once you complete an entire orbit (360 degrees) you will pass through your current position again.
If you wish to move to a higher, circular orbit two impulses are required, 180 deg apart.
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_...
https://en.wikipedia.org/wiki/Kessler_syndrome
... It is a very real possibility, but less of a problem below 550km altitude because the decay time is much shorter (and why all of these mega constellations tend to stay at lower altitude, even though ~1000km is generally better for a communications satellite).
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.
https://www.blueorigin.com/news/blue-origin-introduces-teraw...
>The TeraWave architecture consists of 5,408 optically interconnected satellites in low Earth orbit (LEO) and medium Earth orbit (MEO).
https://arstechnica.com/space/2026/01/blue-origin-we-want-to... ("Another Jeff Bezos company has announced plans to develop a megaconstellation")
Before the "new wave", in 2010-2015 or so, Earth had around 1500 active satellites in orbit, and another 2,000-2,500 defunct ones.
Starlink now has almost 9,500 satellites in orbit, has approvals for 12,000 and long-term plans for up to 42,000. Blue Origin has added 5,500 to that. Amazon plans for 3,000. China has two megaconstellations under construction, for a total of 26,000, and has filed for even larger systems, up to 200,000 satellites.
We might be the last generation that is able to watch the stars.
I'm not convinced this is a major issue, but I'd like to hear arguments for why it is.
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.
The amount of light they reflect back is also small. They can be seen if you look closely at just the right time, but I don't understand how this is supposed to be so much light that it starts raising the overall background light level considerably. The satellites are small and can only reflect so much.
Is it just annoyance that they're up there and showing up in photos?
Iridium's LEO satellites were sometimes (impressively) visible after midnight.
I have no idea if the number is actually a lot shrug but it's surely different than cars on a planet's surface
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.
There is. We don't have the industrial capacity, as a species, to do it.
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...
For a given period of time, a single satellite will travel through a vastly larger volume of space than a single plane.
Same as with any dropped packet.
Bezos can't even build his first constellation and already planning his second... Possibly the real play here is snapping up more frequency licenses on earth (we need them because we're launching any day now promise). They are the real constraining resource and could be used to keep others out of the market for a while.
I'd love to see a betting market on a unified, global licensing regime lasting for another ten years.
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?
(I personally don't believe in the harms of low power non-ionising radiation sources, but this comment is written in the context of avoiding them.)