ENHANCEMENT AND VALIDATION OF THE IDES ORBITAL
DEBRIS ENVIRONMENT MODEL
, P.H. STOKES
, J.E. WILKINSON
and G.G. SWINERD
Space Department, Defence Evaluation & Research Agency, Farnborough, Hants., GU14 0LX, UK;
Department of Aeronautics & Astronautics, University of Southampton, Hants., SO17 1BJ, UK
(Received 9 October 1998; Accepted 18 April 1999)
Abstract. Orbital debris environment models are essential in predicting the characteristics of the entire
debris environment, especially for altitude and size regimes where measurement data is sparse. Most models
are also used to assess mission collision risk. The IDES (Integrated Debris Evolution Suite) simulation
model has recently been upgraded by including a new sodium–potassium liquid coolant droplet source
model and a new historical launch database. These and other features of IDES are described in detail. The
accuracy of the IDES model is evaluated over a wide range of debris sizes by comparing model predictions
to three major types of debris measurement data in low Earth orbit. For the large-size debris population, the
model is compared with the spatial density distribution of the United States (US) Space Command Catalog.
A radar simulation model is employed to predict the detection rates of mid-size debris in the ﬁeld of view
of the US Haystack radar. Finally, the small-size impact ﬂux relative to a surface of the retrieved Long
Duration Exposure Facility (LDEF) spacecraft is predicted. At sub-millimetre sizes, the model currently
under-predicts the debris environment encountered at low altitudes by approximately an order of magnitude.
This is because other small-size debris sources, such as paint ﬂakes have not yet been characterised. Due to
the model enhancements, IDES exhibits good accuracy when predicting the debris environment at decimetre
and centimetre sizes. Therefore, the validated initial conditions and the high ﬁdelity future trafﬁc model
enables IDES to make long-term debris environment projections with more conﬁdence.
Keywords: debris measurements, low Earth orbit, model accuracy, modelling and simulation, orbital debris
The ultimate test of any simulation model is a comparison with the real world that the model
is designed to represent. For a model such as IDES, this validation process should com-
pare model predictions with reliable measurements of the debris population. The validation
process is essential in determining the accuracy of the model, and can serve to improve
accuracy in later model upgrades, once the potential reasons for the discrepancies are iden-
tiﬁed. Conﬁdence in the model predictions is strongly dependent upon a rigorous validation
programme, particularly for simulations of future debris population evolution where no
comparison with measurement data is possible.
The most deterministic debris measurement data currently available is the US Space
Command (USSPACECOM) Catalog which contains the orbital elements of over 8500
Published with the permission of the Defence Evaluation and Research Agency on behalf of the Controller
Space Debris 1, 1–20, 1999.
© 2000 British Crown. Printed in the Netherlands.