NASA Administrator Jim Bridenstine, second from left, answers a question during a discussion with Todd Harrison, director of defense budget analysis and the aerospace security project, and senior fellow in the international security program at the Center for Strategic and International Studies, left, and former NASA Administrators Sean O'Keefe, second from right, and Charles Bolden, right, during an event celebrating NASA's 60th anniversary at the Center for Strategic and International Studies on Monday, July 23, 2018 in Washington. Bridenstine, O'Keefe, and Bolden answered questions about the past and future of the agency. (Photo Credit: NASA/Joel Kowsky)