The effects of meteoroid protection weight requirements on space exploration costs are examined. A basis is developed for selecting upper and lower bounds to the acceptable risk. The quality of present knowledge of the meteoroid environment and of hypervelocity impact penetration is reviewed. This information is synthesized and criteria are developed that are suitable for selecting methods of designing simple and composite barrier systems. Techniques are established for controlling damage to spacecraft components. Short and long term goals are recommended to improve present design capability.