Space structures that are ultra-lightweight, and have gas barrier property, space durability, radiation resistance and high impact resistance are desirable to improve the reliability and provide a safe resting environment for astronauts and equipment operation. Some of the components currently in use such as stations or habitats use double-wall thick films with high internal pressure. Some components are in thin film form and the specific rigidity and dimensional stability needs improvement. Components of landers and vehicles are subject to dust impact. All these solid or hollow components are vulnerable in space because of the foreign object impact or radiation attack. In this Phase I project, we propose to develop ultra-lightweight, microcellular nanocomposite foams and sandwich structures that possess all the desirable properties mentioned above. The structural module can be compacted into a small volume to facilitate launching. The proposed microcellular nanocomposite foam and sandwich structures do not involve or release any toxicity and will have much higher specific mechanical properties than foams and sandwich structures processed by the conventional techniques. They can be used to either replace or supplement to the inflatable technology for improvement in reliability, durability, and safety in space operation. Preliminary research results are very encouraging.