the imcpse-4 meeting continued the discussions started in 1992 when this conference series was started. the proceedings of imcpse-4 conference contain the latest developments in the area of the effects of the space environment on materials and structures in the low earth orbit and on ways to prevent and/or reduce them. the main mandate of the meeting, as in the past years was to: promote the dissemination of experimental data and experience among research organizations, and scientists gathered in ground and flight experiments; provide a tool for engineers, material scientists, and management in space and aerospace sectors to learn about the latest advances in the field of materials and structures protection in leo environment and to provide a basis for interaction and utilization of each others capabilities in cross pollenization of ideas; review the latest research and development in topics such as: effects of leo environment on materials and structures, predictive models for interaction of materials with leo environment factors, and alternative ways for protection from leo environment.