NASA astronaut Mark Vande Hei speaks about his time onboard the International Space Station during a presentation to students at Walt Whitman Middle School, Thursday, June 14, 2018 in Alexandria, Va. Vande Hei and astronaut Joe Acaba answered questions from the audience and spoke about their experiences aboard the International Space Station for 168 days as part of Expedition 53 and 54. Photo Credit: (NASA/Joel Kowsky)

NASA astronauts Mark Vande Hei, right, and Joe Acaba answer questions during a presentation to students at Walt Whitman Middle School, Thursday, June 14, 2018 in Alexandria, Va. Acaba and astronaut Mark Vande Hei answered questions from the audience and spoke about their experiences aboard the International Space Station for 168 days as part of Expedition 53 and 54. Photo Credit: (NASA/Joel Kowsky)

NASA astronaut Mark Vande Hei speaks about his time onboard the International Space Station during a presentation to students at Walt Whitman Middle School, Thursday, June 14, 2018 in Alexandria, Va. Vande Hei and astronaut Joe Acaba answered questions from the audience and spoke about their experiences aboard the International Space Station for 168 days as part of Expedition 53 and 54. Photo Credit: (NASA/Joel Kowsky)

NASA astronaut Joe Acaba speaks about his time onboard the International Space Station during a presentation to students at Walt Whitman Middle School, Thursday, June 14, 2018 in Alexandria, Va. Acaba and astronaut Mark Vande Hei answered questions from the audience and spoke about their experiences aboard the International Space Station for 168 days as part of Expedition 53 and 54. Photo Credit: (NASA/Joel Kowsky)

NASA astronaut Joe Acaba listens to a question from a student during a presentation at Walt Whitman Middle School, Thursday, June 14, 2018 in Alexandria, Va. Acaba and astronaut Mark Vande Hei answered questions from the audience and spoke about their experiences aboard the International Space Station for 168 days as part of Expedition 53 and 54. Photo Credit: (NASA/Joel Kowsky)

NASA astronauts Mark Vande Hei, left, and Joe Acaba answer questions during a presentation to students at Walt Whitman Middle School, Thursday, June 14, 2018 in Alexandria, Va. Acaba and astronaut Mark Vande Hei answered questions from the audience and spoke about their experiences aboard the International Space Station for 168 days as part of Expedition 53 and 54. Photo Credit: (NASA/Joel Kowsky)

NASA astronaut Joe Acaba speaks about his time onboard the International Space Station during a presentation to students at Walt Whitman Middle School, Thursday, June 14, 2018 in Alexandria, Va. Acaba and astronaut Mark Vande Hei answered questions from the audience and spoke about their experiences aboard the International Space Station for 168 days as part of Expedition 53 and 54. Photo Credit: (NASA/Joel Kowsky)

NASA astronauts Mark Vande Hei, left, and Joe Acaba answer questions during a presentation to students at Walt Whitman Middle School, Thursday, June 14, 2018 in Alexandria, Va. Acaba and astronaut Mark Vande Hei answered questions from the audience and spoke about their experiences aboard the International Space Station for 168 days as part of Expedition 53 and 54. Photo Credit: (NASA/Joel Kowsky)

NASA astronauts Joe Acaba, left, and Mark Vande Hei, right, present Walt Whitman Middle School Principal Craig Herring with a montage from their Expedition 54 mission, Thursday, June 14, 2018 in Alexandria, Va. Acaba and astronaut Mark Vande Hei answered questions from the audience and spoke about their experiences aboard the International Space Station for 168 days as part of Expedition 53 and 54. Photo Credit: (NASA/Joel Kowsky)