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Does this mean the concerns about a Kessler event are greatly exaggerated?

by mickdeek86 4y ago

cwillu 4y ago
You're kinda asking if a number is too big, without saying which number you're asking about.
- mickdeek86 4y ago
  I'm asking whether Kessler syndrome is something we should be worried about
  - ghufran_syed 4y ago
    No, not until the density of objects in LEO is much higher IMO
mlindner 4y ago
I'm not an expert but I would say I've spent a lot of time looking at this. I'd say the risk is exaggerated in some ways and not in other ways. Kessler syndrome is a real effect but it's also not something that happens suddenly when some threshold is reached. It comes from statistics and generally assumes that no preventative action is taken when satellites are destined to collide with each other. It also assumes no attempts to clean up debris happens. Both of which are not the case in general. Many countries have rules that say that satellites cannot be left in orbit after end of mission (in the US for example that is currently 25 years, and there is effort right now to reduce that to 5 years). This kind of cuts the effects of kessler syndrome short. Further, Kessler syndrome is different for different altitudes. People keep talking about it with respect to Starlink, but at the altitudes where the Starlink satellites orbit, because of atmospheric drag, debris don't last longer than a decade or so so. This means there isn't enough time for that statistical effect to build up and destroy most satellites, at least at current satellite densities. There's also the argument that kessler syndrome has in fact already begun. As mentioned, it's a statistical effect that happens over time. Imagine the slowest burning smoldering campfire that takes decades or centuries to burn through it's fuel. In short, I feel like current plans to reduce the allowed maximum debris lifetimes by some countries (as long as we can get all major space launch countries to agree) will largely make the kessler syndrome not really a risk.

Does this mean the concerns about a Kessler event are greatly exaggerated?

cwillu 4y ago

You're kinda asking if a number is too big, without saying which number you're asking about.

mickdeek86 4y ago
I'm asking whether Kessler syndrome is something we should be worried about
- ghufran_syed 4y ago
  No, not until the density of objects in LEO is much higher IMO

mlindner 4y ago

I'm not an expert but I would say I've spent a lot of time looking at this. I'd say the risk is exaggerated in some ways and not in other ways. Kessler syndrome is a real effect but it's also not something that happens suddenly when some threshold is reached. It comes from statistics and generally assumes that no preventative action is taken when satellites are destined to collide with each other. It also assumes no attempts to clean up debris happens. Both of which are not the case in general. Many countries have rules that say that satellites cannot be left in orbit after end of mission (in the US for example that is currently 25 years, and there is effort right now to reduce that to 5 years). This kind of cuts the effects of kessler syndrome short. Further, Kessler syndrome is different for different altitudes. People keep talking about it with respect to Starlink, but at the altitudes where the Starlink satellites orbit, because of atmospheric drag, debris don't last longer than a decade or so so. This means there isn't enough time for that statistical effect to build up and destroy most satellites, at least at current satellite densities. There's also the argument that kessler syndrome has in fact already begun. As mentioned, it's a statistical effect that happens over time. Imagine the slowest burning smoldering campfire that takes decades or centuries to burn through it's fuel. In short, I feel like current plans to reduce the allowed maximum debris lifetimes by some countries (as long as we can get all major space launch countries to agree) will largely make the kessler syndrome not really a risk.