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It is particularly bad for a satellite in geostationary orbit to break up or fail. Satellites are packed as tightly as possible into that orbit due to its econo

It is particularly bad for a satellite in geostationary orbit to break up or fail. Satellites are packed as tightly as possible into that orbit due to its economic importance (it's very useful for a satellite, particularly communications satellites, to always be over the same part of the Earth), so there is a higher than normal likelihood that this could be seriously disruptive.

accrual 2y ago
Indeed, Intelsat 33e has a couple nearby neighbors in similar orbits and inclinations. ID Name Orbit Incl. 98050A ASTRA 2A 57.2 4.93 09017A WGS F2 (USA 204) 57.5 0.01 14023B KAZSAT-3 58.5 0.02 12008A BEIDOU-2 G5 58.7 2.10 16053B INTELSAT 33E (IS-33E) 60.0 0.04 <-- 20+ debris components 19014A WGS 10 (USA 291) 60.3 0.01 04007A ABS-4 (MOBISAT-1) 61.0 3.86 10008A EWS-G2 (GOES 15) 61.5 0.04 19049B INTELSAT 39 (IS-39) 62.0 0.02 https://www.satsig.net/sslist.htm https://www.satsig.net/sslist.htm
- nordsieck 2y ago
  Looks like WGS-10 is the closest. From Wikipedia, it looks like it's a USSF satellite launched in 2019 with a service life of 14 years. It provides wideband communications to DoD customers. https://en.wikipedia.org/wiki/USA-291 https://en.wikipedia.org/wiki/USA-291
  - bryanlarsen 2y ago
    It's 0.3 degrees ahead in orbit. Which means the debris needs to speed up to collide. It's possible if the break-up was explosive, but most, if not all of the debris is more likely to stay at the same velocity or slow down.
    - taftster 2y ago
      So does that mean the other satellites "behind" it are in more danger?
      - bryanlarsen 2y ago
        The one behind it is 1000km away vs 200km away for the one in front.
    - Aachen 2y ago
      Speeding up does not work, that'll just put it in a higher orbit. My understanding of these issues is that introduced eccentricity gets you: if it takes the "inside corner" (is that the English word for binnenbocht/innenkurve?) around the earth, it could then then meet you on the other side where the orbits intersect. If it sped up (flying out of the corner, in this race analogy) and thereby took a longer way around, it'd rather be a danger to those immediately behind (with each orbit, progressively further back along the circular orbital path) Disclaimer: this comes from playing a self-made orbital mechanics game, I have no training whatsoever let alone professional experience with this
      - bryanlarsen 2y ago
        Any velocity changes will only happen once so will result in an eccentric orbit where only one side of the orbit is raised or lowered -- the other side will still be in SSO.
      - panki27 2y ago
        My KSP experience supports your view :) Parts that were sped up have their opposite orbital side raised, parts that got slowed will have their opposite orbital side lowered.
      - sangnoir 2y ago
        > Speeding up does not work, that'll just put it in a higher orbit Speeding up doesn't raise the orbit; it makes it (more) elliptical while still intersecting with the old orbit (shared with neighbouring satellites)- you need at least 2 maneuvers to raise an orbit. You're also assuming a perfectly pro-grade acceleration. In an explosion, different pieces go in different directions, I suspect there is a vector that results in faster speed in the same orbit, but I'm no rocket scientist.
perihelions 2y ago
- "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 2y ago
  > 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 2y ago
    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.
    - throw4950sh06 2y ago
      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 2y ago
        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 https://en.m.wikipedia.org/wiki/Kessler_syndrome [1] https://en.m.wikipedia.org/wiki/Neutron_flux https://en.m.wikipedia.org/wiki/Neutron_flux
matrix2003 2y ago
Not to mention debris can be in GEO for a long, long time. People worry about LEO constellations causing Kessler syndrome, but the reality is that LEO debris deorbits in the order of months/years. GEO is much, much longer.
- nordsieck 2y ago
  > Not to mention debris can be in GEO for a long, long time. On human timescales, it's basically forever. Hopefully we'll develop the tech to clean up debris in space, but it's extra challenging to do it in geostationary orbit since it's so far away from Earth, both in terms of actual distance, and delta-V. > People worry about LEO constellations causing Kessler syndrome, but the reality is that LEO debris deorbits in the order of months/years. It's a little more complicated than that. The time to spontaneously deorbit is based on orbital height. Starlink can deorbit on its own in 5-10 years because it's orbiting so low. But any OneWeb satellites that malfunction[1] will take 1000+ years to deorbit because they're up at 1000+ km. --- 1. Like this one https://spacenews.com/oneweb-mulls-debris-removal-service-for-failed-satellite/ https://spacenews.com/oneweb-mulls-debris-removal-service-fo...
  - matrix2003 2y ago
    Yep! That's a great point! I forgot that LEO encompasses quite a bit of difference as well. Starlink has been in the news lately, so that's mostly where my mind was. I believe the newly announced Starlink shells are even lower, so that's good news from a failure standpoint.
  - Aachen 2y ago
    > Hopefully we'll develop the tech to clean up debris in space Rendezvousing is pretty established tech so long as you know a precise and stable orbit of your target, afaik? Which, for geo, we would I think. So taking up some grabbing mechanism probably does it, then use ion engines, burning retrograde (avoiding the need for heavy fuel) until you get it to a low LEO orbit, let loose, and let the problem solve itself within a few ~weeks. Then move on to the next piece, so you don't need a launch to orbit for every individual piece of debris. You also don't have to circularise your orbit to just rendezvous and grab it. And you probably also don't have to go out of plane even if the target object is, if I'm visualising this correctly, because there's always a node where the planes intersect and you can just start the path up to geo at the right point in your LEO orbit Grossly simplified, devil in the details, but this seems very possible with today's technology and potentially less expensive in terms of delta V than it may seem at first glance
exitb 2y ago
The most important contributor to a Kessler-like scenario is extremely high relative speed of items traveling on crossing orbits. It’s not very relevant to the situation in a single geostationary orbit shared by all the objects.
Tepix 2y ago
Note that for every 1 km at the earths surface, you get 6.61 km at geostationary orbit. So there's quite a bit of room (264,924 km circumference vs 40,075km at ground level).
idunnoman1222 2y ago
No, you cannot shift orbit with a single burn maneuver so whatever explosion unless it exploded the other way later cannot shift orbit if the pieces accelerated relative to earth they’re going into a higher orbit if they decelerated they go into a lower orbit Transverse thrust would cause a procession which should be very unlikely to hit another Geo stationary satellite in the future
- accrual 2y ago
  Without having details of the explosion, I imagine some parts will slow down and some will speed up. They'll all be clustered together around the original orbit, and will take many years to drift any considerable distance unless it was a very high velocity explosion.
  - dylan604 2y ago
    I remember this taking a second to click in high school physics class. The initial thought is that after an explosion all of the pieces fly away from a stationary point. The satellite is not stationary, so the pieces "flying away" only have their speed subtracted from the speed of the satellite. The fact that orbital speeds are faster than explosions took a bit to sink in.
    - idunnoman1222 2y ago
      That’s tangential to you not being able to fly in a straight line from one Geo stationary orbit to another
      - dylan604 2y ago
        How is it tangential? It's directly related. The satellite is moving in a straight line at a specific speed. The explosion does not negate that speed, rather it just applies a momentary bit of acceleration/deceleration along a new vector. So unless an explosion can provide more acceleration that can null out the original object's speed, the pieces will remain in orbit. That's just how fast orbital speeds are, and it took a bit for that to click
UltraSane 2y ago
It isn't great but the diameter of geostationary orbit is 84,328 kilometers so there is a lot of room.

accrual 2y ago

Indeed, Intelsat 33e has a couple nearby neighbors in similar orbits and inclinations. ID Name Orbit Incl. 98050A ASTRA 2A 57.2 4.93 09017A WGS F2 (USA 204) 57.5 0.01 14023B KAZSAT-3 58.5 0.02 12008A BEIDOU-2 G5 58.7 2.10 16053B INTELSAT 33E (IS-33E) 60.0 0.04 <-- 20+ debris components 19014A WGS 10 (USA 291) 60.3 0.01 04007A ABS-4 (MOBISAT-1) 61.0 3.86 10008A EWS-G2 (GOES 15) 61.5 0.04 19049B INTELSAT 39 (IS-39) 62.0 0.02 https://www.satsig.net/sslist.htm https://www.satsig.net/sslist.htm

nordsieck 2y ago
Looks like WGS-10 is the closest. From Wikipedia, it looks like it's a USSF satellite launched in 2019 with a service life of 14 years. It provides wideband communications to DoD customers. https://en.wikipedia.org/wiki/USA-291 https://en.wikipedia.org/wiki/USA-291
- bryanlarsen 2y ago
  It's 0.3 degrees ahead in orbit. Which means the debris needs to speed up to collide. It's possible if the break-up was explosive, but most, if not all of the debris is more likely to stay at the same velocity or slow down.
  - taftster 2y ago
    So does that mean the other satellites "behind" it are in more danger?
    - bryanlarsen 2y ago
      The one behind it is 1000km away vs 200km away for the one in front.
  - Aachen 2y ago
    Speeding up does not work, that'll just put it in a higher orbit. My understanding of these issues is that introduced eccentricity gets you: if it takes the "inside corner" (is that the English word for binnenbocht/innenkurve?) around the earth, it could then then meet you on the other side where the orbits intersect. If it sped up (flying out of the corner, in this race analogy) and thereby took a longer way around, it'd rather be a danger to those immediately behind (with each orbit, progressively further back along the circular orbital path) Disclaimer: this comes from playing a self-made orbital mechanics game, I have no training whatsoever let alone professional experience with this
    - bryanlarsen 2y ago
      Any velocity changes will only happen once so will result in an eccentric orbit where only one side of the orbit is raised or lowered -- the other side will still be in SSO.
    - panki27 2y ago
      My KSP experience supports your view :) Parts that were sped up have their opposite orbital side raised, parts that got slowed will have their opposite orbital side lowered.
    - sangnoir 2y ago
      > Speeding up does not work, that'll just put it in a higher orbit Speeding up doesn't raise the orbit; it makes it (more) elliptical while still intersecting with the old orbit (shared with neighbouring satellites)- you need at least 2 maneuvers to raise an orbit. You're also assuming a perfectly pro-grade acceleration. In an explosion, different pieces go in different directions, I suspect there is a vector that results in faster speed in the same orbit, but I'm no rocket scientist.

perihelions 2y ago

- "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 2y ago
> 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 2y ago
  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.
  - throw4950sh06 2y ago
    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 2y ago
      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 https://en.m.wikipedia.org/wiki/Kessler_syndrome [1] https://en.m.wikipedia.org/wiki/Neutron_flux https://en.m.wikipedia.org/wiki/Neutron_flux

matrix2003 2y ago

Not to mention debris can be in GEO for a long, long time. People worry about LEO constellations causing Kessler syndrome, but the reality is that LEO debris deorbits in the order of months/years. GEO is much, much longer.

nordsieck 2y ago
> Not to mention debris can be in GEO for a long, long time. On human timescales, it's basically forever. Hopefully we'll develop the tech to clean up debris in space, but it's extra challenging to do it in geostationary orbit since it's so far away from Earth, both in terms of actual distance, and delta-V. > People worry about LEO constellations causing Kessler syndrome, but the reality is that LEO debris deorbits in the order of months/years. It's a little more complicated than that. The time to spontaneously deorbit is based on orbital height. Starlink can deorbit on its own in 5-10 years because it's orbiting so low. But any OneWeb satellites that malfunction[1] will take 1000+ years to deorbit because they're up at 1000+ km. --- 1. Like this one https://spacenews.com/oneweb-mulls-debris-removal-service-for-failed-satellite/ https://spacenews.com/oneweb-mulls-debris-removal-service-fo...
- matrix2003 2y ago
  Yep! That's a great point! I forgot that LEO encompasses quite a bit of difference as well. Starlink has been in the news lately, so that's mostly where my mind was. I believe the newly announced Starlink shells are even lower, so that's good news from a failure standpoint.
- Aachen 2y ago
  > Hopefully we'll develop the tech to clean up debris in space Rendezvousing is pretty established tech so long as you know a precise and stable orbit of your target, afaik? Which, for geo, we would I think. So taking up some grabbing mechanism probably does it, then use ion engines, burning retrograde (avoiding the need for heavy fuel) until you get it to a low LEO orbit, let loose, and let the problem solve itself within a few ~weeks. Then move on to the next piece, so you don't need a launch to orbit for every individual piece of debris. You also don't have to circularise your orbit to just rendezvous and grab it. And you probably also don't have to go out of plane even if the target object is, if I'm visualising this correctly, because there's always a node where the planes intersect and you can just start the path up to geo at the right point in your LEO orbit Grossly simplified, devil in the details, but this seems very possible with today's technology and potentially less expensive in terms of delta V than it may seem at first glance

exitb 2y ago

The most important contributor to a Kessler-like scenario is extremely high relative speed of items traveling on crossing orbits. It’s not very relevant to the situation in a single geostationary orbit shared by all the objects.

Tepix 2y ago

Note that for every 1 km at the earths surface, you get 6.61 km at geostationary orbit. So there's quite a bit of room (264,924 km circumference vs 40,075km at ground level).

idunnoman1222 2y ago

No, you cannot shift orbit with a single burn maneuver so whatever explosion unless it exploded the other way later cannot shift orbit if the pieces accelerated relative to earth they’re going into a higher orbit if they decelerated they go into a lower orbit Transverse thrust would cause a procession which should be very unlikely to hit another Geo stationary satellite in the future

accrual 2y ago
Without having details of the explosion, I imagine some parts will slow down and some will speed up. They'll all be clustered together around the original orbit, and will take many years to drift any considerable distance unless it was a very high velocity explosion.
- dylan604 2y ago
  I remember this taking a second to click in high school physics class. The initial thought is that after an explosion all of the pieces fly away from a stationary point. The satellite is not stationary, so the pieces "flying away" only have their speed subtracted from the speed of the satellite. The fact that orbital speeds are faster than explosions took a bit to sink in.
  - idunnoman1222 2y ago
    That’s tangential to you not being able to fly in a straight line from one Geo stationary orbit to another
    - dylan604 2y ago
      How is it tangential? It's directly related. The satellite is moving in a straight line at a specific speed. The explosion does not negate that speed, rather it just applies a momentary bit of acceleration/deceleration along a new vector. So unless an explosion can provide more acceleration that can null out the original object's speed, the pieces will remain in orbit. That's just how fast orbital speeds are, and it took a bit for that to click

UltraSane 2y ago

It isn't great but the diameter of geostationary orbit is 84,328 kilometers so there is a lot of room.