Composite materials have gained popularity for aerospace applications thanks to their low weight and out-standing mechanical and thermal properties. However, space environment at low earth orbit (LEO) can be very hazardous to polymers. LEO environment conditions such as atomic oxygen, high vacuum, UV radiation, and thermal cycling, and their synergistic effects affect composites by changing their mechanical and thermal properties, and causing outgassing, which may lead to mission failure. Therefore, composites with high resistance to space environment are necessary. In this work, the effects of reduced graphene oxide (rGO), which is a strong, high purity and cost effective material that approaches the structure of pristine graphene, were studied on epoxy exposed to LEO environment. Nanocomposites were manufactured using the solvent method for uniform dis-persion, and were exposed to simulated LEO environment. As a result, rGO/Epoxy had higher tensile properties than neat epoxy before and after LEO exposure. However, nanocomposites suffered higher mass loss than neat epoxy due to residual solvent. By thermally treating the cured samples, the mass loss was reduced compared to neat epoxy and GO/Epoxy. Finally, the rGO/Epoxy nanocomposite was tested as a coating for CFRP, and it resulted in a decrease of mass loss compared to uncoated CFRP.