[perihelions]

- "Satellites are packed as tightly as possible into that orbit due to its economic importance"

Note that that's in the sense of angular separation, as viewed from the ground. They're physically hundreds of kilometers apart.

edit: (Geostationary orbits are ~42,000 km from the Earth center-of-mass; each degree of angle is an arc of ~700 km).

[naikrovek]

> They're physically hundreds of kilometers apart.

That’s pretty close when your neighbor just exploded and there’s almost exactly zero air resistance to prevent debris from reaching you.

[ben_w]

Yes there's no air resistance, but also most of the fragments aren't going your way.

If you have a 25 m^2 cross section in the direction of the explosion, at that distance you have a roughly 1 in 246 billion chance of any given bit of debris hitting you.

[anjel]

It might not place neighbors at appreciable risk but wouldn't debris still prevent replacing the failed satellite with another one at the same precious original address?

[ethbr1]

Wouldn't debris at the same address (after some time) therefore have zero relative motion?

[user32489318]

No, because the debris = tiny pieces of aluminum, will be pushed around by solar radiation. Also, there’re tiny meteorites, and other pieces of debris colliding with it, which adds energy to the system, if you like. TLEs are not maintained for small debris, so you can’t really predict conclusively. But my hunch is that eventually, the orbit will become a bit more parabolic, precession of which could put it into a trajectory of a S/C and cause a collision.

[verzali]

Things in geo orbit aren't perfectly stable, since the Earth's gravitational field is not perfectly uniform. Without active station keeping things tend to gather at two particular longitudes over the equator. So eventually that debris will probably end up at those points.

[throw4950sh06]

What is the chance of getting hit by further broken pieces of that satellite and other satellites?

When calculating risk, you have to take into account how many are there and what is the chance that any will be hit. Then you have to calculate what's the chance this will happen again, etc - and only then you can calculate the risk to your own satellite.

It's true that the chance of getting hit by one broken satellite is small. But that assumes there are exactly 2 things on the orbit.

[ethbr1]

Aka Kessler syndrome [0] or neutron flux / cross-section (and associated equations, if you want to model it that way) [1].

[0] https://en.m.wikipedia.org/wiki/Kessler_syndrome [1] https://en.m.wikipedia.org/wiki/Neutron_flux

[throw4950sh06]

That's if the risk comes out at 100%, but there's some space below that.

[randmeerkat]

> If you have a 25 m^2 cross section in the direction of the explosion, at that distance you have a roughly 1 in 246 billion chance of any given bit of debris hitting you.

Source?

[a1369209993]

  $ units
  You have: 25m2 / 2tau(700km)^2
  You want: /billion
    * 0.0040600751
    / 246.30086

[Tepix]

Getting hit by debris that flies away directly from an explosion would very bad luck indeed. Just think about how well you would have to aim to hit someone 10km away.

But some debris (in particular slower pieces) will probably oscillate around the geostationary orbit giving it countless chances of hitting other satellites.

Has someone modelled this for example in Kerbal space program?

[lupusreal]

> But some debris (in particular slower pieces) will probably oscillate around the geostationary orbit giving it countless chances of hitting other satellites.

Almost all of the debris will have orbits which intersect their orbit of origin.

[blkhawk]

well while that is true only debris that has the right speed will stay there. the issue is that debris will probably have gotten some impulse that turns it orbit elliptical. that means it will slowly ratchet along geo touching it every day or so at a different place. so you get a changes every day for every piece to hit something. And even a big piece that might just have a delta of 30km/h might damage your panels on your working Sats.

[naikrovek]

Yes, exactly.

It almost certainly won’t hit you directly, but that stuff is in orbit with you now, and it is uncontrolled.

[furyofantares]

That doesn't seem very close in terms of the area traced out by each object in relation to the area of the sphere? (And less if you consider volume since they won't be at exactly the same altitude.)

[bryanlarsen]

It can reach you, sure. But the chances of hitting are miniscule. If you could throw a basketball a few hundred kilometres you're still likely to miss the net.