There has been a lot of interest recently regarding the destroying of an inert US payload in low-Earth orbit. Some of the animations that were shown by the news services were created using STK. More specifically, Astrogator and Integration were used to create a correctly defined debris field that could then be accurately modelled until reentry.

The solution is to use a script to create objects in Astrogator with a distribution of masses, densities and cross-sectional area in order to be able to then propagate these ‘debris-sats’ and predict when they become atmospheric. Usually, propagating the orbit until an altitude of 50km-100km is enough. Below this altitude you start to get complex lift and drag forces that make any realistic/deterministic calculation unfeasible (although probability analysis are usually used below this point).

 Once the debris cloud has been generated, these are all fed into STK using MTO (Multi-Tracked Objects) to enhance the graphics performance. If you use less than 50 debris objects, then MTOs might not be needed. In the study for the satellite hit, the number of objects was in the order of thousands.

You can download the scenario as a vdf (Viewer Definition File) here.

There’s a good paper written by the Carricos (Tim and John in this case), Lisa Policastri and Mike Loucks regarding how to model debris events. The paper is titled “Investigating Orbital Debris Events Using Numerical Methods with Full Force Model Orbit Propagation”.

You can download the paper here.