If two Starlink satellites collide that go roughly in the same direction, it's not exactly a huge problem.
I think the biggest issue is to coordinate this and potentially disallow some excentric orbits.
The nasa is pretty scared of it, so is SpaceX.
But so far it's not anything like in Hollywood movies, it's just a graph slowly going up. There are about 12000 satellites orbiting earth. That looks like a lot on a map, but 12000 objects spread over an area larger than the surface of the earth isn't all that much
Like all exponential processes it will become a major issue if we don't address it, but this is one that starts pretty slow and is well monitored
People keep saying this, but the only way to assure there is no collision is to have non-intersecting orbits, but that is not going to work: not enough space.
It's a tell that SpaceX is now lowering the orbits, even though their satellites mostly move in flocks that maintain a formation relative to each other: because the other ways are exhausted.
Of course if they do cause a (low orbit) Kessler syndrom, then they don't have a business any more, and SpaceX will have achieved the opposite of its stated goals.
The major reason to lower these orbits is likely the risk of a terrorist state turning these constellations into a weapon, by willingly causing the Kessler syndrome. SpaceX isn't going to tell you that, just as it doesn't tell you it's the USA's most important military asset.
Hard to see how the repositioning appreciably alters this risk, since there are still thousands of satellites in the original plane to get hit by shrapnel from intentionally caused collisions, and the satellites in the lower orbit aren't invulnerable to it either
Suspect there's a rather more practical calculation that the extra thruster firings needed to main position in a lower orbit with more atmospheric drag are offset by the smaller number of conjunction avoidance manoeuvres they need to undertake in less congested space (the cost of lowering the orbit is simply deducted from their original delta-v budget for end of life deorbiting). In simple terms they get lower accidental collision risk without operations in the lower orbit shortening satellite lifetime.
Yes, but the lower the orbit, the faster atmospheric drag (which isn't zero, just low) cleans up a cascade.
The article mentions a few months at 480 km. I'm a little skeptical about this figure though, because the last tracked piece from an NRO satellite that was shot down at ~250 km by SM-3 missile in operation burnt frost, lasted 20 months in space before reentry. SpaceX is probably using a statistical cutoff percentage of fragments to calculate the time. But all the pieces are dangerous uncontrolled hypervelocity projectiles. Spain lost a military communications satellite a few days ago from a collision with a tiny undetermined space debris.
But the LEO ones like Starlink will see their orbit decay in about five years (if I'm reading things correctly) even if they run out of fuel / can no longer be controlled, according to e.g. https://space.stackexchange.com/a/59560. But it's exponential, at 600 km it takes 10 years, at 700 25 years, at 800 100 years, etc. Between 500-600 km seems to be ideal for things to naturally decay in case of issues.
But also, it won't be a hard and fast "we are confined to the earth now"; the simplest model is a "the risk of being hit by debris is now x%", more advanced is "there are debris clouds in these altitudes / inclinations so best to avoid those at these times of day".
A golf ball hitting a bowling ball or basketball, both traveling at 30 units of speed can produce quite a fast golf ball. Not all of the debris will safely burn up.
To circularize at a higher orbit you would need secondary collisions on the other side of the earth.
Let us say that you had 10 thousand people running around on Earth, including all the oceans and Antarctica, and that collision of any two would release a hail of small deadly darts into the troposphere lasting, for, at 2 years or so. Which is approximately how long debris will last on LEO, though the actual values vary.
You still wouldn't expect all those 10 thousand people to obliterate themselves like that, as the Earth's surface is pretty darn big.
The volume of the LEO-relevant space is much bigger than the volume of the entire troposphere on Earth, because a) it is further away from the Earth's center than the troposphere, b) it is much deeper.
Now, 10 million objects, that would be a different story. So would be some specific peculiar orbit which is overcrowded. But tens of thousands of objects spread all over the entire planet isn't that much. That would be like 2-5 people in total roaming the entire Czechia, how often would they come into contact? Not very often.
>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 ?
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.
Lowering the orbits just means that we get back to normal faster, not that the it's impossible.
It's not a wall. The risk from going through a dangerous orbit is much much less than the risk from staying there.
This is actually what asat weapons take advantage of. They usually don't even reach orbital velocity, just like ballistic missiles (of course, there are exceptions like the golden dome monstrosity). The kill vehicle just maneuvers itself into the path of the satellite and lets the satellite plough into it at hypervelocity.
This is like bowling, you hit one, it hits the other one etcétéras.
And its also really expensive, each sat you take down costs you far more then what you hit. So unless you can actually cause a chain reaction its a losing proposition.
As soon as a satellite is hit the rest of the fleet can start thrusting and raise their orbits to create a clear separation to the debris field.
Following such an attack the rest of the fleet would of course spread out across orbital heights and planes to minimize the potential damage done by each hit, leading to maximum cost for the adversary to do any damage. Rather than like today where the orbits are optimized for ease of management and highest possible bandwidth.
It's a massive spy network, if weaponized.
Spy satellites are more like space telescopes, but pointed at the Earth. As an example, Hubble is designed after a spy satellite, the "camera" is pretty massive and obvious.
Starlink can probably be weaponized for a variety of thing, like for communication, obviously, but I don't think earth optical observation is one of them.
https://www.independent.co.uk/news/world/middle-east/iran-in...
- 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. Again, nothing like 10,000 missiles needed.
(Or both.)
To target 10,000 satellites directly, the "obvious" weapon would be a few satellite-launch rockets, lofting tons of BB's (or little steel bolts, or whatever) - which would become a sort of long-duration artillery barrage shrapnel in orbit.