NASA astronaut Ricky Arnold speaks about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold speaks about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold speaks about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold speaks about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

A student shakes a glass of water with an Alka-Seltzer tab in it while conducting an experiment on effervescence, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. NASA astronaut Ricky Arnold helped them carry out the experiment which he also conducted during his 197 day mission onboard the International Space Station (ISS) during Expeditions 55/56. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold is introduced to speak about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold speaks about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold poses for a photo after presenting the Challenger Center with a montage of images from his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold speaks about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold speaks about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold poses for a photo with students after speaking with them about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold presents the Challenger Center with a montage of images from his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold speaks about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold speaks about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold speaks about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold speaks about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold poses for a photo with students after speaking with them about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold is seen during a talk about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold watches a timer while students conduct an experiment on effervescence, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the International Space Station (ISS), and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

Students are seen in the audience as NASA astronaut Ricky Arnold speaks about his time onboard the International Space Station (ISS) during Expeditions 55 and 56, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the space station, and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

A student holds up a glass of water with an Alka-Seltzer tab in it while conducting an experiment on effervescence, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. NASA astronaut Ricky Arnold helped them carry out the experiment which he also conducted during his 197 day mission onboard the International Space Station (ISS) during Expeditions 55/56. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold watches a timer while students conduct an experiment on effervescence, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the International Space Station (ISS), and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)

A student observes a glass of water with an Alka-Seltzer tab in it while conducting an experiment on effervescence, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. NASA astronaut Ricky Arnold helped them carry out the experiment which he also conducted during his 197 day mission onboard the International Space Station (ISS) during Expeditions 55/56. Photo Credit: (NASA/Aubrey Gemignani)

NASA astronaut Ricky Arnold watches a timer while students conduct an experiment on effervescence, Friday, May 3, 2019 at the Challenger Center in Lanham, MD. During Expedition 55/56, Arnold completed three spacewalks for a total of 19.5 hours outside the International Space Station (ISS), and concluded his 197 day mission when he landed in a remote area near the town of Zhezkazgan, Kazakhstan in Oct. 2018. He also flew to the space station on shuttle mission STS-119 to deliver the final pair of power-generating solar array wings. Photo Credit: (NASA/Aubrey Gemignani)