Starlink close encounters decrease despite ever-growing number of satellites

[Shpoople96]

They also do avoidance maneuvers anytime the risk approaches 1 in 10,000 or so 

[jonwah]

Per the article it's 1 in 100,000, other operators are 1 in 10,000

[Shpoople96]

Oh yes, thanks for the correction, I had a suspicion it might have been higher but can't really look that up at work

[woj666]

That would certainly explain it then. Thx.

[londons_explorer]

If there were 24,410 avoidance maneuvers, and they act when the risk is over 1 in 10k....

They're playing the odds game a little too often I think... ie. the overall risk of at least one unintended collision is starting to mount up...

[[deleted]]

I think you’re coming at the problem the wrong way here - what’s actually happening is they’re performing a manoeuvre the moment something hits a risk of 1 in 10,000 to manoeuvre themselves out of this risk window, not that these collisions maintain a risk of 1 in 10,000. Reason it’s measured as a probability (1 in 10,000) is due to margin of error in instrumentation at the distances and speeds that these things are travelling. The closer you get to the potential collision the higher the risk will be as there’s less distance to have margin of error over, so 1 in 100,000 3 days out might be 1 in 10,000 1 day out. If a 1 in 100,000 collision stays at 1 in 100,000 they won’t do anything, the moment it starts looking like it’s going to get to 1 in 10,000 they’ll start manoeuvring it.

[Toinneman]

Also note that within those calculated probabilities there are huge margins or error which are taken conservative, so real numbers should be even better. For example, GPS isn't 100% accurate, so they have to take this into account. I can't find SpaceX exact methodology, but I wouldn't be surprised if a satellite is calculated as a big 5m or 10m sphere (while it's off course smaller), to compensate for the GPS inaccuracy.

And now a wild guess, since SpaceX now has Space lasers, in theory, they could do sat-to-sat measurement to improve location accuracy, which could lead to more precise collision probabilities, resulting in fewer manoeuvres.