To develop a modernised statistical model characterising collision break-ups on orbit, by exploiting numerical simulation results

 

All missions in Earth-bound orbits rely on space debris and meteoroid flux models. These models are used to assess the mission risk and design shielding concepts (for manned modules). The flux predictions have been found to have a remarkable sizing effect. Collision break-ups are the major source of debris >1mm and are poorly understood. This needs to be improved significantly.

On Agency level, collision break-up modelling is decisive to define the Agency's position towards international agreements on space debris mitigation. Current models will be misleading.

Today, 4 traceable collision events have been taken place on orbit. Out of these, only one showed the expected characteristics of a catastrophic collision break-up. The reasons for the mismatch of the other 3 could be manifold. It could be related to a lateral impact geometry, impact into appendices or other. A high-fidelity collision break-up model is required to understand the effect of these parameters. A correct description of such collisions is essential for correct environmental projections, that drive mitigation standards.

 

The following steps are to be taken:

- The numerical models established in the previous GSP study "Numerical Simulations for Spacecraft Catastrophic Disruption Analysis" shall be validated and calibrated with the help of existing results of small scale hypervelocity impact tests (re-using data gained within CD02, CD07 and CD10).

- The models shall be systematically used to characterise collisions between large structures in space in terms of fragment numbers, size distribution, delta-velocities as a function of impact geometry and energy.

- where necessary, repeat selected tests adding optical tracking to get insight in the fragmentation processes, e.g. The fragments clouds dimensions and their temporal evolution.

- a first characterisation of the effect of impacts into appendices is to be established.

- Finally, a simpler statistical model shall be fitted that (from its computational performance) is suited to replace the outdated NASA collision model in the many tools used in Europe to analyse on-orbit risks and long-term environmental projections.