NASA astronaut Bob Behnken and Doug Hurley arrive at the International Space Station aboard SpaceX's Crew Dragon capsule in this still image taken from video May 31, 2020. Nearly 24 hours after launching from Florida, SpaceX's Crew Dragon capsule delivered NASA astronauts Bob Behnken and Doug Hurley to the International Space Station on Sunday. NASA/Handout via REUTERS

NASA astronaut Bob Behnken and Doug Hurley arrive at the International Space Station aboard SpaceX's Crew Dragon capsule in this still image taken from video May 31, 2020. NASA astronauts Bob Behnken and Doug Hurley on Sunday climbed aboard the International Space Station after a 19-hour flight aboard the SpaceX Crew Dragon capsule. NASA/Handout via REUTERS

NASA astronaut Bob Behnken arrives at the International Space Station aboard SpaceX's Crew Dragon capsule in this still image taken from video May 31, 2020. The two Americans received a warm welcome from the current crew on board the ISS, after executing an hours-long critical spacecraft docking. NASA/Handout via REUTERS

NASA astronaut Bob Behnken arrives at the International Space Station aboard SpaceX's Crew Dragon capsule in this still image taken from video May 31, 2020. NASA/Handout via REUTERS

NASA astronaut Bob Behnken arrives at the International Space Station aboard SpaceX's Crew Dragon capsule in this still image taken from video May 31, 2020. NASA/Handout via REUTERS