Robert Behnken and Douglas Hurley are the astronauts who will be aboard the SpaceX Crew Dragon capsule when it launches on Wednesday.
Both men are experienced astronauts and engineers who joined NASA after achieving the rank of colonel as military pilots, but their lives and careers have mirrored each other’s for two decades.
Their historic launch, scheduled for 9.33pm on Wednesday, will be the first manned spaceflight to launch from the US since the space shuttle was retired in 2011.
Eight things you need to know before the historic lift-off
Behnken will be the joint operations commander for the mission, responsible for the SpaceX Crew Dragon’s rendezvous with the International Space Station, as well as docking and undocking.
He has previously completed two space shuttle flights and performed three spacewalks, and before joining NASA was a test flight engineer with the US Air Force.
Hurley will be the spacecraft commander, responsible for launch, landing and recovery.
He also has completed two space shuttle flights, including the final mission in 2011, and before joining NASA was a fighter pilot in the US Marine Corps.
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They were both selected as astronauts in 2000, and both of them met their wives – who are also astronauts and part of NASA’s class of 2000 – while undergoing training.
Behnken’s wife, Megan McArthur, is an oceanographer and NASA astronaut who has flown one space shuttle mission. She is currently the deputy chief of NASA’s Astronaut Office
Hurley’s wife, Karen Nyberg, is a mechanical engineer and was a NASA astronaut who completed two space missions before recently retiring.
Doug and Bob as they are almost always referred to are close friends and they attended each other’s weddings. They also both have sons and have trained together for this mission for five years.
In a promotional video for NASA which shows the close bond between the two, Behnken said what he was most looking forward to was “actually ending up in the water, safely, at the end of the mission”.
“Seeing how we both go through that experience of, I’m expecting, a little bit of vomiting.
“When we get to that opportunity to do that in the water together, it’s kind of a weird thing to say, but I’m looking forward to that kind of celebratory event.”
Hurley added: “For me it’s just actually getting to fly the mission with Bob.
“We’ve been close friends since we started as astronauts almost 20 years ago, so being lucky enough to get to fly with your best friend is, kind of a, I think there’s a lot of people that wish they could do that. We’re lucky enough to do it.
“We spent a ton of time together. We could have gone two directions with that – we could have gotten to the point where we didn’t want to be around each other, or we’re closer.
“I think just the whole experience for me is what we’re looking for. And then, yes, the celebratory vomiting at the end of the mission will be excellent,” he added.