NASA Administrator Charles Bolden and his wife Alexis lay a wreath at the Tomb of the Unknowns as part of NASA's Day of Remembrance, Friday, Jan. 31, 2014, at Arlington National Cemetery. The wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Bill Ingalls)

NASA Administrator Charles Bolden and his wife Alexis lay a wreath at the Tomb of the Unknowns as part of NASA's Day of Remembrance, Friday, Jan. 31, 2014, at Arlington National Cemetery. The wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Bill Ingalls)

NASA Administrator Charles Bolden and his wife Alexis participate in a wreath laying ceremony at the graves of Apollo 1 crewmembers Virgil "Gus" Grissom and Roger Chaffee as part of NASA's Day of Remembrance, Wednesday, Jan. 28, 2015, 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/Joel Kowsky)

Taps is played by the Honor Guard after NASA Administrator Charles Bolden, left, and his wife Alexis laid a wreath at the Tomb of the Unknowns as part of NASA's Day of Remembrance, Friday, Jan. 31, 2014, at Arlington National Cemetery. The wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Bill Ingalls)

NASA Administrator Charles Bolden and his wife Alexis watch as Tomb guards with The Old Guard, the 3rd U.S. Infantry Regiment, perform a changing of the guard prior to a wreath-laying ceremony as part of NASA's Day of Remembrance, Wednesday, Jan. 28, 2015, at Arlington National Cemetery in Arlington, Va. The wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Joel Kowsky)

NASA Administrator Charles Bolden and his wife Alexis lay a wreath at the Tomb of the Unknowns as part of NASA's Day of Remembrance, Wednesday, Jan. 28, 2015, at Arlington National Cemetery in Arlington, Va. The wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Joel Kowsky)

NASA personnel watch as a wreath is laid at the Tomb of the Unknowns by NASA Administrator Charles Bolden and his wife Alexis as part of NASA's Day of Remembrance, Wednesday, Jan. 28, 2015, at Arlington National Cemetery in Arlington, Va. The wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Joel Kowsky)

NASA Administrator Charles Bolden and his wife Alexis lay a wreath at the Tomb of the Unknowns as part of NASA's Day of Remembrance, Wednesday, Jan. 28, 2015, at Arlington National Cemetery in Arlington, Va. The wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Joel Kowsky)

NASA Administrator Charles Bolden (right), his wife, Alexis Walker, and other guests watch the launch of the Orbital Sciences Corporation Antares rocket, with the Cygnus cargo spacecraft aboard, Sunday, July 13, 2014, at NASA’s Wallops Flight Facility in Virginia. Cygnus will deliver over 3,000 pounds of cargo to the Expedition 40 crew at the International Space Station, including science experiments, experiment hardware, spare parts, and crew provisions. Photo Credit: (NASA/Aubrey Gemignani)

NASA Administrator Charles Bolden (right), his wife, Alexis Walker, and other guests watch the launch of the Orbital Sciences Corporation Antares rocket, with the Cygnus cargo spacecraft aboard, Sunday, July 13, 2014, at NASA’s Wallops Flight Facility in Virginia. Cygnus will deliver over 3,000 pounds of cargo to the Expedition 40 crew at the International Space Station, including science experiments, experiment hardware, spare parts, and crew provisions. Photo Credit: (NASA/Aubrey Gemignani)

Taps is played by the Honor Guard after NASA Administrator Charles Bolden and his wife Alexis laid a wreath at the Tomb of the Unknowns as part of NASA's Day of Remembrance, Friday, Jan. 31, 2014, at Arlington National Cemetery. The wreaths were laid in memory of those men and women who lost their lives in the quest for space exploration. Photo Credit: (NASA/Bill Ingalls)

NASA Administrator Charles Bolden (left), speaks with Gina Burgin, Deputy Secretary of Administration, Commonwealth of Virginia, prior to the launch of the Orbital Sciences Corporation Antares rocket, with the Cygnus cargo spacecraft aboard, Sunday, July 13, 2014, at NASA’s Wallops Flight Facility in Virginia. Cygnus will deliver over 3,000 pounds of cargo to the Expedition 40 crew at the International Space Station, including science experiments, experiment hardware, spare parts, and crew provisions. Photo Credit: (NASA/Aubrey Gemignani)