Thread by @mikeclindsay

A thread about satellite collision probability 🛰️💥🛰️

The FCC & others consider "satellites equipped with propulsion capability to have a collision risk of zero or near zero."

So let's ask ourselves: is that a reasonable assumption?

docs.fcc.gov/public/attachm… (see paragraph 20)

Well, if met with a collision risk (Pc) of 1/1000, an operator might avoid it with a maneuver (they don't have to), thus buying the risk down to 1/1,000,000.

But if Pc is initially 1/100,000, the operator likely won't maneuver at all! That's not zero risk, but is it "near zero?"

Depends on the # of times you take that risk!

Math tells us that the probability of having NO collisions = (1 - Pc)^N, where N is the # of times you "roll the dice."

So if Pc = 1/100,000 and you roll the 🎲 100 times, the probability of no collisions = 99.9%.

Not bad, right?

Well, according to estimates, we could be rolling the 🎲 8 times/hour soon.

https://twitter.com/SineadOS1/status/1186675327801667589

In other words, that's 70,000 times/year. And the probability of NO collisions with a Pc = 1/100,000? About 50%.

A coin flip. Every year.

So, it's not "near zero" either.

What do you think is an acceptable collision risk level, when considering all satellites in orbit, on an annual basis?

(I suppose I don't have enough followers to justify a poll, but oh well!)