The low Earth orbit (LEO) environment exposes spacecraft materials to atomic oxygen, UV light, meteroid impact and thermal cycling. The purpose of this paper is to report on progress towards evaluating damage done to candidate space materials, and ways to protect materials on future long-term space missions in LEO. Specifically, we prepared and characterized sets of samples for flights on the US Space Shuttle missions STS-46 and STS-51, and evaluated samples returned from STS-46. In addition, laboratory simulations of the LEO environment are shown to present interesting problems and challenges.