Feeling overwhelmed by all the things I need to fight this morning before a 6 hour drive across the north island of NZ for my next talk in New Plymouth.
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ALSO speaking of awesome people I work with, my collaborators redid the CRASH Clock calculation for several years in the past, so you can see how it has dropped to shorter and shorter values: https://outerspaceinstitute.ca/crashclock/
The CRASH Clock is the likely time to first collision if all collision avoidance maneuvers in orbit suddenly stopped, and is a measure of how much stress we're placing on orbit and how reliant we are on 100% perfect operations in orbit to keep using our satellites
@sundogplanets I suppose the next question to consider is what are the statistical chances that any two satellites on a collision course suffer maneuvering /avoidance failure at the same time - remembering that some of these objects have no maneuvering capacity to begin with as they're space junk.
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ALSO speaking of awesome people I work with, my collaborators redid the CRASH Clock calculation for several years in the past, so you can see how it has dropped to shorter and shorter values: https://outerspaceinstitute.ca/crashclock/
The CRASH Clock is the likely time to first collision if all collision avoidance maneuvers in orbit suddenly stopped, and is a measure of how much stress we're placing on orbit and how reliant we are on 100% perfect operations in orbit to keep using our satellites
3.8 days currently...
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@sundogplanets I suppose the next question to consider is what are the statistical chances that any two satellites on a collision course suffer maneuvering /avoidance failure at the same time - remembering that some of these objects have no maneuvering capacity to begin with as they're space junk.
@sundogplanets That 3.8 day time window is pretty chilling by itself. Gets you thinking about the situation where some computer spits out that a collision is possible, realize the objects can't get out of the way of each other, and you don't have enough time to launch some Hollywood astronauts-avert-disaster-in-space rescue mission. There is literally no answer other than sitting there in passive horror while a clock ticks down and praying that the objects make a near pass without colliding.
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ALSO speaking of awesome people I work with, my collaborators redid the CRASH Clock calculation for several years in the past, so you can see how it has dropped to shorter and shorter values: https://outerspaceinstitute.ca/crashclock/
The CRASH Clock is the likely time to first collision if all collision avoidance maneuvers in orbit suddenly stopped, and is a measure of how much stress we're placing on orbit and how reliant we are on 100% perfect operations in orbit to keep using our satellites
@sundogplanets Is CRASH intended to represent a realistic scenario (i.e. all satellites disabled by solar activity), or is it primarily a way to put a number on the stress?
It might be interesting to have a sort of satellite equivalent of LD50, i.e. a measure of how many satellites would need to become uncontrollable before a collision within some specified time period (say 1 year, or 1 month) becomes inevitable. Obviously a related metric, but maybe easier to interpret in terms of likelihood?
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@sundogplanets Did you do any post CRASH estimations? By this I mean, did you look at how fast subsequent crashes might occur after the first one?
Yes, that seems like a highly imprecise, even guess-like, calculation. But my imagination suggests that there could well be a rapid, and increasingly rapid cascade of secondary, tertiary... etc collisions with fragments.
If you're not familiar with the concept, then kudos to you for recognizing it on your own.
It's often discussed using the name "Kessler Syndrome" after Donald Kessler, one of the NASA scientists who first wrote of the risk in 1978. (Also called "ablation cascade" among other terms.)
We're on the brink of the nightmare scenario where a major collision could trigger a cascade which makes near earth orbit impassable, possibly for centuries.
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@sundogplanets Is CRASH intended to represent a realistic scenario (i.e. all satellites disabled by solar activity), or is it primarily a way to put a number on the stress?
It might be interesting to have a sort of satellite equivalent of LD50, i.e. a measure of how many satellites would need to become uncontrollable before a collision within some specified time period (say 1 year, or 1 month) becomes inevitable. Obviously a related metric, but maybe easier to interpret in terms of likelihood?
@angusm Sounds good, you should write that paper
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@ctwardy No no no, the avoidance maneuvers are happening every 2 minutes in Starlink's orbit, but they're making the maneuvers at really low collision probabilities, which is probably the only reason we haven't had a crash yet. The 3.8 days is how long until you expect a collision to happen.
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@sundogplanets So would a retired person with no knowledge of satellite systems, space regulation, or astronomy BUT who has free time willing to contribute to a cause like writing to agencies, politicians, etc. be of any help to you?
@leslore Yes! I will post information on how to write the FCC soon, and it would be lovely if you can follow it and express your opinions to them
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@leslore Yes! I will post information on how to write the FCC soon, and it would be lovely if you can follow it and express your opinions to them
@sundogplanets Gladly! I look forward to your directions.
So many things disguised as "progress" or "job creating" have been permitted without consideration of negative downstream effects.
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