In brief: SpaceX astronauts Doug Hurley and Robert Behnken will receive the Congressional Space Medal of Honor on Tuesday. Both are former NASA astronauts who flew space shuttle missions before the program's retirement. The awardees went on to work for SpaceX.

The Congressional Space Medal of Honor is a civilian award, not to be confused with the Medal of Honor for military members. It was introduced in 1969 and awarded to Neil Armstrong and Buzz Aldrin for being the first humans to set foot on the moon.

Traditionally, the medal is handed out to those who marked a first in space exploration. Congress also awarded it posthumously to the crews of the space shuttle disasters Challenger and Columbia. The last time it was awarded was in 2006, when Robert L Crippen piloted the first shuttle mission.

So for the first time in 17 years, the White House will recognize Hurley and Behnken with the award as being the first commercial space crew to berth with the International Space Station, putting an end to US astronauts having to hitch rides on Russian craft. Their milestone mission was the SpaceX Demo-2. It was initially planned for May 27, 2020 but got weather delayed until May 30, 2020.

Demo-2 took them to the ISS aboard SpaceX's Crew Dragon spacecraft Endeavor. The pair joined the ISS Expedition 63 crew and stayed aboard the station for about two months, conducting various science experiments. They also installed "a new European Drawer Rack Mark 2 in the space station's Columbus module."

Interestingly, the Demo-2 mission directly resulted from NASA's commercial crew program. SpaceX and Boeing received a combined multibillion-dollar grant from the space agency in 2014.

As we have seen, SpaceX's development and deployment of crewed spacecraft has been far faster and more efficient than Boeing's still-struggling Starliner spacecraft, which has yet to get off the ground. Since Hurley's and Behnken's milestone flight, SpaceX has flown five other crews to the ISS, including astronauts from Europe and Russia.

Despite being a civilian award, the Space Medal of Honor is authorized to be worn as a military decoration when appropriate. Since Hurley is a retired colonel in the Marines and Behnken is likewise a former colonel in the Air Force, they can add the badge to their uniform lapels.

Vice President Kamala Harris is scheduled to present the medals at the White House later today.