MODELLING OF EJECTA AS A SPACE DEBRIS SOURCE
M. BARITEAU and J.-C. MANDEVILLE
ONERA/DESP, 2 avenue E. Belin, 31400 Toulouse, France
(Received 19 June 2001; Accepted 20 March 2002)
Abstract. When a micro-debris or a micrometeoroid impacts a spacecraft surface, a large number of secondary
particles, called ejecta, are produced. These particles can contribute to a modiﬁcation of the debris environ-
ment: either locally by the occurrence of secondary impacts on the components of complex and large space
structures, or at great distance by the formation of a population of small orbital debris. This paper describes
ﬁrstly, the ejecta overall production, and secondly, the lifetime and the orbital evolution of the particles.
Finally the repartition of ejecta in LEO is computed. Some results describing the population as a function of
size and altitude are presented.
Keywords: hypervelocity impact, modelling and simulation, orbital debris, secondary ejecta
When a micrometeoroid or a micro-debris impacts the surface of a spacecraft, secondary
particles, called ejecta, are usually produced. In addition of the local interaction of these
particles with nearby surfaces, they contribute to the overall production of small space debris.
Most current orbital debris models however, with the exception of MASTER 99 (Wegener
et al., 2000) do not take into account secondary fragments produced upon impact of high
velocity particles on space objects. The purpose of this paper is to present the mechanism
of the production and of the orbital evolution of the ejecta. Functional forms, similar to the
ones used for ORDEM 96, are derived in order to compute the ﬂux of ejecta in LEO.
The main sources of micro-debris identiﬁed until now are the following:
– Small fragments of spacecraft break-up (with a size from 100 µm to 20 cm);
– Na/K droplets (leaks of Russian satellites Rorsat, 100 µm to 5 cm);
– Paint fragments and degradation products of spacecraft (from 5 µmto200µm);
– Propulsion residues (SRM Al
particles, size <20 µm and from 100 µm to 3 cm);
– Secondary particles called ejecta (from 1 µm to 5 mm).
This last population of particles is produced when a micro-debris or a micrometeoroid
impacts a spacecraft surface. Then, these ejecta become an integral part of the space envi-
ronment. In order to compute their contribution as a space debris source, the method outlined
in Figure 1 is used.
For every orbit, the surface of solar arrays and painted surfaces is estimated, and the
primary ﬂux received by these surfaces is computed using the ORDEM 96 model (Kessler
et al., 1996) for debris and the Gr
un model (Gr
un et al., 1985) for meteoroids.
Author for correspondence: ONERA/DESP, Dept. De Technologie, BP 4025, 31055, Toulouse Cedex,
France (Tel.: 5 62252741; Fax: 5 62252569; E-mail: firstname.lastname@example.org)
Space Debris 2, 97–107, 2002.
© 2002 Kluwer Academic Publishers. Printed in the Netherlands.