Abstract: A GUI based meteoroid and orbital debris risk assessment system(MODRAS) is developed for assessing risks to spacecraft from meteoroid and debris impact. Instance a spacecraft as an example for M/OD risk assessment is conducted. The distribution of debris flux, exposed area of spacecraft and impact data are obtained. The results show that the relative impact possibility for a spacecraft depends on the spacecrafts altitude and orbital inclination, as well as debris size. Changes in shuttle mission operations, flight rules, and flight planning were adopted to reduce meteoroid and debris risks.