In-situ impact detection techniques, interplanetary dust, and future Mars exploration : proceedings of the B1 Symposium of COSPAR Scientific Commission B and the B1.1 and B1.3 meetings of COSPAR Scientific Commission B which was held during the Thirtieth COSPAR Scientific Assembly, Hamburg, Germany, 11-21 July, 1994 / edited by Ph.L. Masson, J. Kissel and J.A.M. McDonnell