FIB-SIMS analysis of micro-particle impacts on spacecraft materials returned from low-earth orbit S. Kettle a , R.J. Chater a,* , G.A. Graham b , D.S.McPhail a , A.T. Kearsley c a Department of Materials, Imperial College, London SW7 2AZ, UK b IGPP, Lawrence Livermore National Laboratory, Livermore, CA 94551, USA c Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK Available online 25 May 2004 Abstract Returned materials from spacecraft that have had a long exposure in low earth orbit have been examined for residues by liquid metal ion source (LMIS) sputtering and SIMS. It has been possible to distinguish between res the underlying substrate in impact sites as well as the origin of the residue, man-made or extraterrestrial. This allowed examination of the sub-micrometer internal structures of residue remnants. # 2004 Elsevier B.V. All rights reserved. Keywords: Micro-particle; Impacts; LEO; FIB-SIMS; LMIS 1. Introduction Spacecraft in low-earth orbit (LEO) are prone to hypervelocity collisions with metre- down to micro- meter-sized artificial orbitaldebris. While the larger material can be monitored using ground-based tele- scope and radar techniques [1], the post-flight labora- tory investigation of retrieved spacecraft materials enablesthecharacterization of the sub-millimetre population of debris,and also samples impacts by naturalextraterrestrial dustparticles. However, the repository ofretrieved materials is fairly limited due to the difficulties in cost and logistics of recovery. It is important that the maximum yield of information is obtained from analytical investigation, in terms of both the origin and fate of the hypervelocity projec- tiles and their effect on collision with the spacecraft. The long duration exposure facility (LDEF) con- tained a number of experiments including metallic foils specifically designed to capture micro-particles [2],and was exposed in LEO for 5.7 years, prior to retrieval in 1990. The multi-layer insulation (MLI) foil is aluminized Kapton from Japan’s space flyer unit (SFU) mission. SFU was retrieved in January 1996 after being in LEO for 10 months [6]. The foil formed one of the internal layers of a particle capture cell. Th solar array panel of silicon solar cells and supporting material from the hubble space telescope (HST) was recovered in 1993, after 3.62 years of LEO exposure. Materials recovered from LDEF, SFU and the HST havebeen extensively examined previously using electron microscopy and X-ray microanalysis techni- ques to characterise preserved impact features and distinguish remnant projectile residues in terms of extraterrestrial versus artificial orbital debris [2,3]. Aluminium foils from LDEF, SFU and the HST solarcells have been re-analysed using a gallium Applied Surface Science 231–232 (2004) 893–898 * Corresponding author. E-mail address: r.chater@imperial.ac.uk (R.J. Chater). 0169-4332/$ – see front matter # 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2004.03.161