NASA astronauts Joe Acaba, left, and Mark Vande Hei, right, meet with the Honor Guard at the Tomb of the Unknowns, Friday, June 15, 2018 at the Arlington National Cemetery in Arlington, Va. Photo Credit: (NASA/Aubrey Gemignani)
NASA astronauts Joe Acaba, left, and Mark Vande Hei, right, meet with the Honor Guard at the Tomb of the Unknowns, Friday, June 15, 2018 at the Arlington National Cemetery in Arlington, Va. Photo Credit: (NASA/Aubrey Gemignani)