#USSPACECOM deputy cmdr, Lt Gen John Shaw at @ascendspace on Russian DA-ASAT test: We are still characterizing this event. We expect the debris will grow over time. #Perigee, #apogee event will widen. "It will become a threat that we will have to deal with." #ASAT #Russia

Shaw: This isnt' the beginning of such activity. #Russia conducted a similar test in April, though it didn't target a #satellite. Russia is showing "disregard of the sustainability of #space."

Shaw likens tracking objects in #space to book version of #JurassicPark: Scientists had automated sensors to track dinosaurs & algorithm to count the expected number of dinos. Problem is, it didn't account for the population of dinos rising. ...

I think the #KesslerSyndrome is too often presented as a tipping point or a threshold we have yet to cross, so I wanted to use some aspects of my paper at the 8th European Conference on #SpaceDebris to explain why I think that is wrong [1/n]

The starting point of my thinking was to look at how natural populations grow. The simple exponential model is a standard model that describes the growth of a single population [2/n]

If we know the initial number of individuals in the population N(0) then this model allows us to estimate the number of individuals at any future time t. Here, r is the intrinsic rate of natural increase, which depends on the birth rate, b, and death rate, d [3/n]

I am seeing some ill-informed takes on today's near-miss in orbit so would like to offer some trajectory corrections if I may. Firstly, the chance that a single collision would trigger a catastrophic 'chain reaction' that would sweep through LEO is tiny.

For every close pass involving catalogued objects in orbit we can estimate a collision probability, or Pc. The Pc is between 0 and 1. If it is 1 we can say that a collision is certain. If it is 0 then we can say that a miss is certain.

The event today may have had a Pc between 0.02 & 0.2. In any case, the Pc was relatively small (compared to a Pc of 1) so a miss was the most likely outcome. For a chain reaction to occur a long & sustained sequence of collisions would need to take place.