One, NASA astronaut Bob Behnken, has taken a pair of spacewalks.

On May 30, the pair became the first NASA astronauts to launch on a commercial rocket to the station, hitching a ride on vehicles manufactured by Elon Musk’s SpaceX, not NASA.

A day after lifting off from the Kennedy Space Center, their Dragon spacecraft, which they named Endeavor, docked with the station autonomously, and the duo were greeted on the station by fellow NASA astronaut Chris Cassidy, as well as Russian cosmonauts Anatoly Ivanishin and Ivan Vagner.

“Certainly, the highlight for both Doug and I was the initial arrival at space station, coming through the hatch again and being on board after several years of working on a new spacecraft,” Behnken said in an interview from the station this week.

During the spacewalk, they were able to see the Dragon spacecraft docked to the station, and Cassidy turned and took a photo.

President Trump and Vice President Pence were at the Kennedy Space Center for the launch, and afterward, Trump heralded it in a speech as a victory for the country.

SpaceX launch of NASA astronauts provides a chance to compare the new and old.

The Trump campaign sought to seize on the launch with an ad titled “Make Space Great Again.” But the ad was quickly criticized by Democrats, who pointed out that NASA’s “commercial crew” program — the hiring of private companies to fly its astronauts — began under President Barack Obama.

The entire mission is a test to see how SpaceX’s Dragon capsule performs, and while NASA said its ascent went flawlessly, there still are many risks ahead.

“Parachutes are way harder than they look,” Musk said in an interview with The Post before the launch.

American astronauts have not splashed down in the water since 1975 — the space shuttles landed on land, as do the Russian Soyuz spacecraft.