1. 1) Belvin, W. K., Watson, J. J. and Singhal, S. N.: Structural Concepts and Materials for Lunar Exploration Habitats, AIAA Space 2006 Conference & Exposition, AIAA 2006-7338, 2006.
2. 2) Cichan, T., O'Dell, S., Richey, D., Bailey, S. A. and Burch, A.: Mars Base Camp Updates and New Concepts, 68th International Astronautical Congress, IAC-17-A5, 2017.
3. 3) International Space Exploration Coordination Group: The Global Exploration Roadmap, January 2018, https://www.globalspaceexploration.org/wordpress/wp-content/isecg/GER_2018_small_mobile.pdf (accessed March 20, 2018)
4. 4) Brophy, J. R., Etters, M. A., Gates, J., Garner, C. E., Klatte, M., Lo, C. J., Marcucci, M. G., Mikes, S., Mizukami, M., Nakazono, B. and Pixler, G.: The Dawn Ion Propulsion System-Getting to Launch, 30th International Electric Propulsion Conference, IEPC-2007-083, 2007.
5. 5) Polk, J. E., Brinza, D., Kakuda, R. Y., Brophy, J. R., Katz, I. and Anderson, J. R.: Validation of the NSTAR Ion Propulsion System on the Deep Space One Mission: Overview and Initial Results, 35th Joint Propulsion Conference and Exhibit, AIAA 99-2274, 1999.