NASA and Boeing have announced changes for the inaugural crewed flight of the CST-100 Starliner launching to the International Space Station in 2021 after Boeing astronaut Chris Ferguson decided not to fly.
As Ferguson withdrew for "personal reason", veteran NASA astronaut Barry "Butch" Wilmore will join astronauts Mike Fincke and Nicole Mann for the Boeing crew flight test, the US space agency said on Wednesday.
Wilmore has been training side-by-side with the crew since being named the sole backup for all flight positions in July 2018.
He now will shift his focus specifically to the spacecraft commander's duties in preparation for the flight to the space station.
The flight is designed to test the end-to-end capabilities of the new Starliner system.
"Butch will be able to step in seamlessly, and his previous experience on both space shuttle and space station missions make him a valuable addition to this flight," said Kathy Lueders, Associate Administrator of NASA's Human Exploration and Operations Mission Directorate.
Wilmore has spent a total of 178 days in space over the course of two missions. In 2009, he served as the pilot of space shuttle Atlantis on STS-129, helping to deliver 14 tons of spare parts for the space station.
In 2014, he returned to the space station via a Russian Soyuz spacecraft for a 167-day mission, during which he performed four spacewalks.
Ferguson will assume the role of director of Mission Integration and Operations, as well as director of Crew Systems for Boeing's Commercial Crew Program, where he will focus on ensuring the Starliner spacecraft meets the needs of NASA astronauts, the US space agency said.
In this role, he will be one of the last people the crew sees before leaving Earth and one of the first they see upon their return, as well as supporting them throughout their training and mission.
Ferguson has been an integral part of the Starliner program since 2011, after retiring from NASA as a three-time space shuttle veteran, including as commander of STS-135, the final space shuttle flight to the space station.
Boeing had signed a contract with NASA's Commercial Crew Program to fly operational missions to and from the space station with Starliner in 2014.
Its debut uncrewed orbital flight mission in 2019 did not go exactly as planned, requiring it to make another try before putting astronauts on board for the crewed flight test.