NASA Administrator Jim Bridenstine, left, helps place a lei at the Space Shuttle Columbia Memorial with Kristy Carroll, center, and daughter Vivian Carroll, who were friends of Space Shuttle Columbia pilot William McCool, during NASA's Day of Remembrance, Thursday, Feb. 7, 2019, at Arlington National Cemetery in Arlington, Va. Wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Aubrey Gemignani)

NASA Administrator Jim Bridenstine places a wreath at the Space Shuttle Columbia Memorial with Kristy Carroll, left, and daughter Vivian Carroll who were friends of Space Shuttle Columbia pilot William McCool, during NASA's Day of Remembrance, Thursday, Feb. 7, 2019, at Arlington National Cemetery in Arlington, Va. Wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Aubrey Gemignani)

From left to right, Chuck Resnik, brother of Challenger Mission Specialist Judith Resnik; June Scobee-Rodgers, widow of Challenger Commander Dick Scobee; Kristy Carroll, friend of Space Shuttle Columbia pilot William McCool, daughter Vivian Carroll; Vice President Mike Pence, and NASA Administrator Jim Bridenstine visit the Space Shuttle Columbia Memorial after a wreath laying ceremony that was part of NASA's Day of Remembrance, Thursday, Feb. 7, 2019, at Arlington National Cemetery in Arlington, Va. Wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Aubrey Gemignani)

Vice President Mike Pence observes the grave marker of Virgil "Gus" Grissom from Apollo 1, after a wreath laying ceremony that was part of NASA's Day of Remembrance, Thursday, Feb. 7, 2019, at Arlington National Cemetery in Arlington, Va. Wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Aubrey Gemignani)

Vice President Mike Pence hugs June Scobee-Rodgers, widow of Challenger Commander Dick Scobee at the Space Shuttle Columbia Memorial after a wreath laying ceremony that was part of NASA's Day of Remembrance, Thursday, Feb. 7, 2019, at Arlington National Cemetery in Arlington, Va. Wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Aubrey Gemignani)

Vice President Mike Pence and NASA Administrator Jim Bridenstine lay a wreath at the grave markers of Virgil "Gus" Grissom and Roger Chaffee, from Apollo 1, as part of NASA's Day of Remembrance, Thursday, Feb. 7, 2019, at Arlington National Cemetery in Arlington, Va. Wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Aubrey Gemignani)

Vice President Mike Pence observes the grave marker of Virgil "Gus" Grissom, from Apollo 1, after family and friends of astronauts lost in the Challenger and Columbia missions, former NASA Administrators, and other NASA staff participated in a wreath laying ceremony that was part of NASA's Day of Remembrance, Thursday, Feb. 7, 2019, at Arlington National Cemetery in Arlington, Va. Wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Aubrey Gemignani)