What’s the plan as the solar maximum returns?
Adjust them again as needed ..
SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake
81–90 of 105 posts
Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake
#82Earlier quoted context omitted.
If it's WWIII, and you're using ballistic missiles against satellite constellations, then either: - You are not targeting individual satellites; you're setting off nuclear warheads in space, and relying on the EMP to disable all satellites within a large radius of the blast - https://en.wikipedia.org/wiki/Nuclear_electromagnetic_pulse or - You're nuking the ground-based command & control centers for those satellites.…
The BB idea doesn’t really work either- if they are in orbit they circle with the satellites and don’t hit anything, if they are at different speeds they are in different orbits and fly above and below the satellites and miss, if they cross the orbit SpaceX just moves the satellites to miss.
"Circle with the satellites" is not how orbits work. Do a Google image search for satellite ground tracks, and observe how those tracks repeatedly cross each other. In LEO, a 90 degree orbital crossing represents a relative velocity of >10km/s. (Normally, collisions do not happen because the satellites are under control, and everyone is making ongoing efforts to avoid collision. Kinda like how cars & trucks normally don't hit pedestrians.)
BB's - https://www.amazon.com/bulk-bbs/s?k=bulk+bbs - run roughly 3,000 to the kg. And are far too small to individually track in orbit - https://clasp.engin.umich.edu/2023/12/06/tracking-undetectab...
Bottom line - a "3 tons to LEO" satellite launch vehicle could put ~10,000,000 untrackable little metal objects into orbit, crossing satellite orbits at lethal velocities. Trivial methods, such as dispersing the BB's with small explosive charges, could randomize their individual orbits.
The satellite operators have very good reason to be concerned about such "low tech" anti-satellite weapons.
Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake
#83From a comment : >The first move in the coming WWIII, where the emperors try to expand their empires militaril,y will be to wipe out any orbit with Starlink satellites. I find this highly unlikely, given Starlink is soon to reached 10k satellites and will continue to grow. Why expand 10 000 ballistic missiles to bring down one of many communications networks ?
If it's WWIII, and you're using ballistic missiles against satellite constellations, then either: - You are not targeting individual satellites; you're setting off nuclear warheads in space, and relying on the EMP to disable all satellites within a large radius of the blast - https://en.wikipedia.org/wiki/Nuclear_electromagnetic_pulse or - You're nuking the ground-based command & control centers for those satellites.…
> - You're nuking the ground-based command & control centers for those satellites. Again, nothing like 10,000 missiles needed.
With Starlink's peer-to-peer capabilities, hitting every single ground station and keeping the satellites from working through new ground stations may actually be quite difficult.
Starlink orbits close enough that they're looking into offering LTE coverage from "space". You don't need a giant dish to access the satellites, which means building new ground stations and reprogramming the network from an unassuming-looking ground device to use them is quite feasible.
The paths of the satellites are rather predictable, though, so your shrapnel attack executed with some precision should clear out enough of them.
The moment you launch a nuke (even if just to set off an EMP), you can expect nukes to come your way in retaliation before your nuke even detonates. Unless whatever war is going on has already gone full nuclear, I don't think nuclear weaponry is a viable move to take out satellites.
Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake
#84Earlier quoted context omitted.
> Hard to see how the repositioning appreciably alters this risk, since there are still thousands of satellites in the same plane to get hit by shrapnel from intentionally caused collisions, and the satellites in the lower orbit aren't invulnerable to it either Yes, but the lower the orbit, the faster atmospheric drag (which isn't zero, just low) cleans up a cascade.
Feel like I'm repeating myself here, but they're moving less than half of them , which is going to have a negligible impact on a state with sufficient ASAT weapons' ability to create a massive mess with the many thousands of Starlink satellites operating in their original plane. Not even like the satellites in the lowest orbit are insulated from the effects of debris cascades set off in higher reaches of LEO either P…
If that's the only risk, sure. But there's modelling and observation that suggest the required number of ASAT weapons to cause a Kessler cascade is currently zero, i.e. we're already in the early stages of one.
Because physics of orbital dynamics is less dramatic than shown in film, lowering orbits of satelites is an effective way to mitigate this.
Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake
#85Can anyone explain how does one technically lower a satellite?
Let me see if I can. Before we go to space, let's try something on the ground. Imagine pitching a ball horizontally. What do you expect if you pitch it too slow? The ball will curve more towards the ground and meet it early, won't it? (In other words, it doesn't go very far and doesn't stay airborne for long). Going from ground to space, this action remains the same. You need to 'lower an orbit'? Reduce its forward v…
>[10]..
From the looks of it, you still are teaching. Very informative read!
Extra points for non-referenced footnotes! =)
Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake
#86Earlier quoted context omitted.
Looking at the price of industrial lasers, right now the only thing stoping a random 3rd world terrorist cell from being able to afford to destroy all of them is the adaptive optics to compensate for atmospheric turbulence. Well, that and the fact that so much of the stuff on Amazon etc. that's listed as "welding laser" is actually a soldering iron.
When people attack satellites with lasers, what they're trying to do is blind surveillance sats. To actually physically damage a satellite would take enormous amounts of power and accurate tracking tied into powerful radars. That's something a state might do, but too many resources are involved for terrorists.
Previously, perhaps.
I'm saying the only limit to damaging them now is the optics.
Radar is pointless here. Both for crude and precise positioning. For crude, we already know roughly where the satellites themselves are because those are well-advertised.
For precise, you still wouldn't use radar, physics prevents high enough resolution ever. Even for tracking, angular resolution is k(λ/D), i.e. you care about aperture size in wavelengths, and radar uses wavelengths much much larger than visible or IR laser light. But even with arbitrarily large equipment, you get a spot size ~= wavelength, which wastes a lot of power as the wavelength is much larger than the necessary spot size for a critical component on a satellite.
So you'd use optical targeting and tracking, i.e. you'd look through the exact same system that the laser also fires through, with the exact same adaptive optics, and say "this specific point on this satellite".
The hard part is focussing a spot size order of cm scale (it can't be the same size as you find in a welding system for same reason radar is useless, k(λ/D) gets you ≥300m telescope and that's obviously a no). This requires adaptive optics (and also a wide telescope). Adaptive optics is the really hard part here.
Getting a 12 kW industrial laser is relatively easy, and putting that power into a spot on the joint between the PV and the main body, that has a decent chance[0] of weakening or severing it while also causing catastrophic loss of control, even with just a few minutes over the horizon. Weakening is still important, see all 9/11 memes about steel beams and why they miss the point. Severing is plausible but only because of space design constraints, see [0] again.
As I understand it, PV cells themselves have a much lower threshold for catastrophic damage, a 12 kW system is basically guaranteed to cause irreparable damage to that even in a few minutes even though the spot size here is much much larger than you'd find in a welding system.
The prices I see for 12 kW industrial lasers are significantly lower than the estimated cost per missile for most of what the Houthis used to attack shipping last year, and they fired quite a lot of those missiles.
[0] can't say for sure without detailed plans that it would be genuinely insane[1] for me to have access to; but do consider that everything in orbit is mass constrained, even with SpaceX pricing, and designed without expectations of e.g. wind or needing to support its own weight, so the thickness of structural elements is likely much lower than you'd expect from anything you see on the ground
[1] the world is currently going insane, so if it turns out they are available, either deliberately or via a leak, this is just more evidence of insanity rather than a contradiction
Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake
#87Earlier quoted context omitted.
Looking at the price of industrial lasers, right now the only thing stoping a random 3rd world terrorist cell from being able to afford to destroy all of them is the adaptive optics to compensate for atmospheric turbulence. Well, that and the fact that so much of the stuff on Amazon etc. that's listed as "welding laser" is actually a soldering iron.
I think you severely underestimate the amount of power you would need to damage some Starlink satellites in the 4 minutes they would be visible while tracking them at ridiculous speeds.
Modern welding lasers are pretty powerful. Hard part is focussing them, especially given need for adaptive optics for atmospheric turbulence. Movement is almost irrelevant, they only deviate from a fixed path while their engines run, and even then those engines are pretty weak.
I'm saying the only real limit now is the adaptive optics.
Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake
#88From a comment : >The first move in the coming WWIII, where the emperors try to expand their empires militaril,y will be to wipe out any orbit with Starlink satellites. I find this highly unlikely, given Starlink is soon to reached 10k satellites and will continue to grow. Why expand 10 000 ballistic missiles to bring down one of many communications networks ?
Because Kessler syndrome means you don't need to hit all 10k yourself. Lowering the orbits just means that we get back to normal faster, not that the it's impossible.
> Kessler syndrome means you don't need to hit all 10k yourself
Kessler is useless for LEO constellations. The timeframes of the cascades exceed the useful lives and dwelling times at those altitudes.
I am not aware of a military solution to prompting a cascade over even a limited area. Instead, you’d use repeated high-atmosphere nuclear detonations to fry birds in a region.
Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake
#89There are so many satellites in orbit that there is a pretty good chance that if even one was to be hit by something and explode in many pieces, it would crash another one and then another one until there is nothing left. The nasa is pretty scared of it, so is SpaceX.
> there is a pretty good chance
No;, there is not, particularly in LEO.
Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake
#90Earlier quoted context omitted.
Feel like I'm repeating myself here, but they're moving less than half of them , which is going to have a negligible impact on a state with sufficient ASAT weapons' ability to create a massive mess with the many thousands of Starlink satellites operating in their original plane. Not even like the satellites in the lowest orbit are insulated from the effects of debris cascades set off in higher reaches of LEO either P…
If that's the only risk, sure. But there's modelling and observation that suggest the required number of ASAT weapons to cause a Kessler cascade is currently zero, i.e. we're already in the early stages of one. Because physics of orbital dynamics is less dramatic than shown in film, lowering orbits of satelites is an effective way to mitigate this.
> there is a pretty good chance
Source?