NASA Associate Administrator for Legislative and Intergovernmental Affairs Suzanne Gillen, portrait, Thursday, Jan. 31, 2019 at NASA Headquarters in Washington. Photo Credit: (NASA/Bill Ingalls)

NASA Associate Administrator, Human Exploration and Operations William Gerstenmaier, left, NASA Associate Administrator for Legislative Affairs Suzanne Gillen, center, and NASA Special Assistant to the Administrator Mark Sirangelo, confer prior to the start of the House Subcommittee on Space and Aeronautics hearing titled "Keeping our sights on Mars: A Review of NASA's Deep Space Exploration Programs and Lunar Proposal", Wednesday, May 8, 2019 at the Rayburn House Office Building in Washington. Photo Credit: (NASA/Bill Ingalls)

NASA Associate Administrator, Human Exploration and Operations William Gerstenmaier testifies during the House Subcommittee on Space and Aeronautics hearing titled "Keeping our sights on Mars: A Review of NASA's Deep Space Exploration Programs and Lunar Proposal", Wednesday, May 8, 2019 at the Rayburn House Office Building in Washington. Photo Credit: (NASA/Bill Ingalls)