Space Debris

The United Nations Committee on the Peaceful Uses of Outer Space defines space debris as “all man-made objects, including fragments and elements thereof, in Earth orbit or re-entering the atmosphere, that are non-functional”. Approximately 21,000 objects larger than 10 cm are known to exist, whilst the population of particles between 1 and 10 cm is estimated to be 500,000 and the number of smaller particles likely exceeds tens of millions. The sources of this debris population are space launches, on-orbit operations and fragmentations, with the latter accounting for over half of the trackable objects in the current catalogue.


Space debris is now widely known to represent a significant risk to operational spacecraft due to the collision hazard it represents. Indeed, the first collision between two intact objects in February 2009 led to the loss of Iridium 33 (as well as a defunct Russian satellite) and generated over 1500 fragments 10 cm or larger.


Orbital speeds are such that even small particles carry sufficient kinetic energy to cause significant damage to or even catastrophic break-up of operational spacecraft. The Iridium 33-Cosmos 2251 event is only the most recent collision involving trackable orbiting objects. The European Space Agency’s Database and Information System Characterising Objects in Space (DISCOS) describes the occurrence of four other collisions since 1991 and The Union of Concerned Scientists suggest that a further four may have taken place. As the population of debris continues to grow, the probability of further collisions will consequently increase.

Space Debris Research at Southampton

The Astronautics Research Group has been involved in work on space debris modelling since 1992 and is currently led by Dr Hugh Lewis. We have developed a number of models, including DAMAGE, a state-of-the-art evolutionary model, and FADE. Our space debris research has been supported by the EPSRC, the Faculty of Engineering and the Environment at the University of Southampton, the former Defence Evaluation and Research Agency (DERA), QinetiQ and the European Union Framework 7 Programme. Members of the Astronautics Research Group represent the UK Space Agency on the Inter-Agency Space Debris Coordination Committee (IADC), the intergovernmental forum for discussing space debris issues....