Crew-1 docking
The Crew Dragon spacecraft "Resilience" after docking with the International Space Station Nov. 16. Credit: NASA TV

WASHINGTON — NASA has selected three astronauts for a future SpaceX commercial crew mission to the International Space Station as it leaves open the possibility of exchanging seats with Russia.

NASA and the European Space Agency jointly announced Dec. 14 they had assigned NASA astronauts Raja Chari and Tom Marshburn and ESA astronaut Matthias Maurer to the SpaceX Crew-3 mission. That commercial crew mission is scheduled for launch in the fall of 2021.

Chari, who will serve as commander of the mission, joined the astronaut corps in 2017 and will be making his first spaceflight. He is also part of NASA’s “Artemis Team” of astronauts announced Dec. 9 who are eligible for future Artemis lunar missions. Marshburn, a NASA astronaut since 2004, flew on the STS-127 shuttle mission in 2009 and spent nearly five months on the ISS in 2012 and 2013. Maurer, who joined ESA’s astronaut corps in 2015, will be making his first spaceflight.

The agencies did not announce who will occupy the fourth seat on the Crew Dragon spacecraft for this mission. “A fourth crew member will be added at a later date, following a review by NASA and its international partners,” NASA stated in a release about the crew assignments.

So far, only astronauts from NASA, ESA and the Japanese space agency JAXA have been assigned to commercial crew missions. The Crew-1 mission currently at the ISS includes three NASA astronauts and one JAXA astronaut, while the Crew-2 mission expected to launch in the spring of 2021 will fly two NASA astronauts and one each from ESA and JAXA.

NASA, however, has expressed its interest in what it calls “mixed crews,” flying Russian cosmonauts on commercial crew vehicles in exchange for allowing NASA astronauts to fly on Soyuz spacecraft. Those exchanges, done on a bartering basis, would ensure there is at least one NASA and one Roscosmos astronaut on the ISS should either the Soyuz or commercial crew vehicles be out of service for a time.

Roscosmos, though, has been skeptical about flying its cosmonauts on commercial crew missions. At a March meeting of the ISS Advisory Committee, former astronaut Tom Stafford, chair of the committee, said Russian officials would consider flying cosmonauts on commercial crew vehicles eventually, but would not fly on the first missions of those spacecraft.

Discussions to enable mixed crews are ongoing. “We’re looking to fly on each other’s vehicles, probably later in 2021,” said Joel Montalbano, NASA ISS program manager, at a Nov. 13 briefing about the Crew-1 mission, which launched two days later. The first step for doing so, he said, is a government-to-government “implementing agreement” that was being drafted at the time of the briefing.

The launch of Crew-3 will overlap with Crew-2, just as Crew-2 will overlap with Crew-1, NASA said. That means that the first operational mission by Boeing’s CST-100 Starliner commercial crew vehicle, called Starliner-1, will likely be delayed until at least the spring of 2022. NASA announced in August it had selected astronaut Jeanette Epps for that mission, joining Sunita Williams and Josh Cassada, who had been assigned to the flight in 2018.

At the time of the announcement, NASA said that Starliner-1 would launch by the end of 2021, but did not give a more precise date. The agency said Dec. 9 that a second uncrewed test flight of the spacecraft, called Orbital Flight Test 2, had been scheduled for March 29. That will be followed by a crewed test flight with three NASA astronauts on board in the summer of 2021.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...