Meteoroids and small sized debris in Low Earth Orbit and at 1 au: Results of recent modelling

We present consolidated flux data from the Long Duration Exposure Facility (LDEF) and develop an isotropic meteoroid model applicable to predicting damage to the LDEF surfaces. The model is shown to work well, and is used to derive the resultant component of orbital debris incident on the LDEF east (ram) and west (wake) faces. Overall, orbital debris dominates the measured fluxes at small sizes (aluminium penetration depth F-max < 30 mu m) whereas meteoroids dominate above this size (see also McDonnell et al., 1997). The east and west face comparison shows that at least 2 distinct populations of debris exist with different size distributions. Analysis of data from the European Retrievable Carrier (EuReCa) shows the interplanetary meteoroid flux to he biased towards the Earth-apex direction (in the measured size regime). An enhanced meteoroid model is derived which is consistent with both EuReCa and LDEF data, and which does not affect the debris fluxes derived from LDEF data. (C) 1999 COSPAR. Published by Elsevier Science Ltd.