Roger Walker

The long-term implications of operating satellite constellations in the low earth orbit debris environment

Abstract DRAs Integrated Debris Evolution Suite (IDES) model is used in this study to predict the future evolution of the orbital debris environment for two distinct scenarios. For the first case, a pre-generated background debris population for 1995 and ‘business as usual’ future launch/explosion rates are used as input to the model. IDES then employs its collision event prediction algorithm to simulate evolution from 1996 to 2020 as a baseline. The second scenario uses the same initial conditions and future trends, but in addition, a large constellation is introduced into the simulation process from year 1998 onwards. The additional contribution of the constellation to the temporal variation of key environment/population parameters is presented; including enhancement from any long-term collision coupling effects.

Introducing “PLATFORM”—A new software program to simulate debris and meteoroid impacts on space platforms

Abstract We describe a new software program called PLATFORM, which is being developed to simulate the risk and potential damage to spacecraft from debris and meteoroid impacts. The program first generates an accurate 3D solid model representation of a space platform. Debris and meteoroid impacts are simulated by sampling directional collision flux data, derived from environment models such as IDES, and firing test particles at the platform. The location of each impacting particle and the resultant damage, including the production of secondary ejecta, are calculated. A versatile query method is used to analyse impact distributions and their effect, thereby enabling potential damage to subsystems to be assessed. Alternative shielding strategies are then considered, leading to an enhancement of the platforms survivability.

Interactions between space systems and the orbital environment

This paper introduces a strategy for minimizing the growth of orbital debris by controlling the collision hazard that it represents to operational satellites. Applying the theory of Kessler, an analytic tool can be developed to set target survivability levels for operational satellites, to determine the individual contributions of different missions to the debris hazard, and to manage the debris environment by assessing the efficacy of different mitigation measures.

Characterization of the potential impact of space systems on the orbital debris environment: satellite constellations

In this paper we consider the implications for the orbital debris environment of introducing a constellation of satellites into low Earth orbit. We consider not only the impact that the orbital debris population will have on the satellites, but also the possible effect of the space system on the environment. Using standard population models we estimate the collision risk that the current orbital debris environment will present to a variety of generic constellation designs, and investigate the consequences of a collision-induced breakup of one of the constellation elements for operational satellites residing both within, and outside, the constellation. We apply state-of-the-art developments in the method of probabilistic continuun dynamics to estimate the short term collision hazard, and the classical Kessler approach to estimate the long term collision risk. We assess the probability of a collision-induced cascade fragmentation occuring within the system and its possible consequences for the extermal satellite population. We find that for large constellation sizes, the likelihood of a collision- induced breakup of a satellite is significant, although the probability of a collisional cascade within the constellation remains small by comparison.