This photo provided by NASA shows the crew of SpaceX entering the International Space Station, Sunday, May 31, 2020. The Dragon capsule arrived Sunday morning, hours after a historic liftoff from Florida. It's the first time that a privately built and owned spacecraft has delivered a crew to the orbiting lab. (NASA via AP)

In this image taken from NASA TV video, the SpaceX Dragon crew capsule, with NASA astronauts Doug Hurley, left, and Robert Behnken aboard docks with the International Space Station Sunday, May 31, 2020. It was the first time a privately built and owned spacecraft carried astronauts to the orbiting lab in its nearly 20 years. (NASA TV via AP)

A SpaceX Falcon 9, with NASA astronauts Doug Hurley and Bob Behnken in the Crew Dragon capsule, lifts off from Pad 39-A at the Kennedy Space Center in Cape Canaveral, Fla., Saturday, May 30, 2020. The two astronauts are on the SpaceX test flight to the International Space Station. For the first time in nearly a decade, astronauts blasted towards orbit aboard an American rocket from American soil, a first for a private company. (AP Photo/David J. Phillip)

Spectators watch from a bridge in Titusville, Fla., as SpaceX Falcon 9 lifts off with NASA astronauts Doug Hurley and Bob Behnken in the Dragon crew capsule, Saturday, May 30, 2020, from the Kennedy Space Center at Cape Canaveral, Fla. The two astronauts are on the SpaceX test flight to the International Space Station. For the first time in nearly a decade, astronauts blasted toward orbit aboard an American rocket from American soil, a first for a private company. (AP Photo/Charlie Riedel)

In this image provided by NASA, the SpaceX Dragon crew capsule, with NASA astronauts Doug Hurley and Robert Behnken aboard, docks with the International Space Station Sunday, May 31, 2020. It was the first time a privately built and owned spacecraft carried astronauts to the orbiting lab in its nearly 20 years. (NASA TV via AP)

In this photo provided by NASA, a SpaceX Falcon 9 rocket carrying the company's Crew Dragon spacecraft is seen in this false color infrared exposure as it is launched on NASA's SpaceX Demo-2 mission to the International Space Station with NASA astronauts Robert Behnken and Douglas Hurley onboard, Saturday, May 30, 2020, at NASA's Kennedy Space Center in Cape Canaveral, Florida. (Bill Ingalls/NASA via AP)

This photo provided by NASA shows Bob Behnken and Doug Hurley, far right, joining the the crew at the International Space Station, after the SpaceX Dragon capsule pulled up to the station and docked Sunday, May 31, 2020. The Dragon capsule arrived Sunday morning, hours after a historic liftoff from Florida. It's the first time that a privately built and owned spacecraft has delivered a crew to the orbiting lab.(NASA via AP)

In this image provided by NASA, a view of SpaceX's Crew Dragon spacecraft with NASA astronauts Douglas Hurley and Robert Behnken onboard is seen on monitors in firing room four of the Launch Control Center at NASA's Kennedy Space Center in Florida, as the spacecraft approaches the International Space Station for docking, Sunday, May 31, 2020. The Dragon capsule arrived Sunday morning, hours after a historic liftoff from Florida. (Joel Kowsky/NASA via AP)

NASA astronauts Douglas Hurley, left, and Robert Behnken walk out of the Neil A. Armstrong Operations and Checkout Building on their way to Pad 39-A, at the Kennedy Space Center in Cape Canaveral, Fla., Saturday, May 30, 2020. The two astronauts will fly on a SpaceX test flight to the International Space Station. For the first time in nearly a decade, astronauts will blast into orbit aboard an American rocket from American soil, a first for a private company. (AP Photo/John Raoux)

In this image taken from NASA TV video, the SpaceX Dragon crew capsule, with NASA astronauts Doug Hurley and Robert Behnken aboard, docks with the International Space Station Sunday, May 31, 2020. It was the first time a privately built and owned spacecraft carried astronauts to the orbiting lab in its nearly 20 years. (NASA TV via AP)