5 ms·

This is important correction. But a high-speed collision at a very low orbit can trow debris to not-so-low orbit. How big of a problem this can be is something

• cogman10 6y ago
  I don't see how that's a major issue, It'd take a pretty odd angle for a high speed collision to push something into a higher orbit. That seems like a pretty rare event.
  • bodhiandphysics 6y ago
    Not really. High speed collisions are high entropy events, so debris fills state space, and you get SOME debris at high altitudes (usually in highly eccentric orbits). That being said, low altitude is much safer since you don’t get as many long lived dead satellites
    • jerf 6y ago
      From super-low Earth orbits, more of the orbits that go really high also impact Earth or its atmosphere on the other side, so they only are up there once, rather than over and over and over.
      • bodhiandphysics 6y ago
        Yep!
• fooker 6y ago
  > But a high-speed collision at a very low orbit can trow debris to not-so-low orbit. This seems wrong, from what I understand of orbital mechanics.
  • bdamm 6y ago
    Yeah, the terminology is wrong. It's not a high orbit, it's a high ballistic trajectory, which then is terminated on the low side. But if that object improbably happens to collide with a high-orbit object then you could get a spreading of the consequences to higher orbit.
• arjunnarayan 6y ago
  A high speed collision in low orbit can change a circular low orbit into an elliptical eccentric orbit that intersects a higher circular orbit, but unless there is an additional accelerating event at that higher altitude, it cannot recircularize its orbit at that higher altitude. There are thus two takeaways: 1. By definition, this means that part of the orbit will always be at low altitude, regardless of the collision dynamics. So this means that it will continue to decay over time, albeit perhaps at a slower rate (decay being proportional to the time spent at lower altitude). 2. While that eccentric orbit will intersect with a higher circular orbital plane, it does so in a predictable fashion that can be routed around. The higher orbits are also much sparser, so the chance of this intersecting with a satellite that is already present is very, very small.
  • IlliOnato 6y ago
    Thank you, others pointed this out too. Proves that "celestial mechanics" is trickier than I thought. I guess if a collision is messy enough, there would be secondary collisions between debris pieces, and it sounds like these in principle can push some junk into higher orbits. But I think the probability is really low; this should not be a concern.
• nharada 6y ago
  Curious how big of an issue this actually ends up being since they can't be put in a stable higher orbit without a second burn/collision to circularize. Without a change to the orbit perigee it would still decay, just more slowly?
  • deleted 6y ago
    [deleted]
• hypertele-Xii 6y ago
  > a high-speed collision at a very low orbit can trow debris to not-so-low orbit How so? According to my understanding of orbital mechanics, if an object begins its orbit at a certain altitude, it will return to that altitude exactly one orbit later. While a collision can change the shape of the object's orbit, it can't change the spot of collision - which it will return to every cycle of its orbit.
  • simonh 6y ago
    Some of the debris will be thrown into eccentric orbits reaching significantly higher altitudes as part of the orbit. If these fragments hit objects in these higher orbits, that will create further debris clouds in more stable high orbits, etc, etc. That way you can get a runaway chain reaction that could escalate to arbitrarily high orbits and debris cloud lifetimes.