On April 9 at 07:42 UTC, a Soyuz 2.1a launched with the Soyuz MS-18 spacecraft carrying two Russian cosmonauts and one NASA astronaut to the International Space Station.

Both the spacecraft and the rocket are named Soyuz, which means “Union” in Russian. Why?

A Soviet tradition was to name the rocket after the first payload it carried into orbit. The first payload of this version of the R7 (for the rocket nerds, that’s the standard core and boosters with a new Blok I upper stage) carried into orbit in 1966 was a Soyuz, so that’s what they named it. You also see this with the Proton rocket after it launched the astrophysics satellites of the same name.

This marked the 1,937th launch of an R7-derived Soyuz rocket. JAXA astronaut Soichi Noguchi took a picture of the rocket’s contrail as it ascended, which he posted to his Twitter account.

The spacecraft was successfully placed into orbit on the new three-hour rendezvous trajectory, arriving at the station’s Rassvet module at 11:05 UTC. Soyuz MS-18 is only the second crewed Soyuz to use this trajectory, with Soyuz MS-17 being the first back in October 2020. It was demonstrated on several uncrewed Progress spacecraft first, in the Russian philosophy of incremental testing. The three-hour rendezvous requires exceptional orbital insertion accuracy from the launcher, and the ISS has to be in a very specific orbit.

Roscosmos goes to all of this trouble because the Soyuz is a very cramped spacecraft and prefers the crew to spend as little time in the confined space as possible. Back in the 1970s, the standard rendezvous to the Salyut stations took two days or more.

After two hours of leak checks, Mark Vande Hei, Oleg  Novitsky, and Pyotr Dubrov entered the ISS and joined Expedition 64, temporarily increasing the number of crew members on the ISS up to ten.

This is Vande Hei’s second spaceflight, Novitsky’s third, and Dubrov’s first. The trio will spend the standard six months in orbit before returning. Notably, Dubrov and Novitsky will perform a series of spacewalks to integrate the Nauka module to the ISS when it finally docks to the ISS later in 2021.

Soyuz MS-18 was originally slated to fly with three Russian crew members for the arrival of Nauka, the next Russian module for the ISS. At the last minute on March 9, American astronaut Vande Hei was added to assure the backup capability in the event of a problem with any crew spacecraft or an emergency aboard the station that requires a crew to return to Earth sooner than planned.

Vande Hei’s seat was procured under unusual circumstances. When I talk about a seat, I don’t mean the physical seat that the astronauts ride in; it’s just a shorthand way of saying a ride to and from the space station. Axiom Space had bought a seat on a Soyuz from Roscosmos with the intention of sending one of their engineers up to their future module. That module will be attached to the ISS sometime between now and 2024. But because Vande Hei was needed on the station and the Axiom Space module isn’t in space, NASA proposed a trade: this seat on the Soyuz in exchange for a seat on a future Crew Dragon or Starliner mission.

Soyuz MS-17 will return to Earth on April 17. SpaceX’s Crew-2 will launch in late April while Crew-1 is still at the station. This will increase the station’s population from seven to eleven. Crew-1 will return to earth once Crew-2 has arrived and settled in.

More Information

NASA press release (launch)

NASA press release (contract)

Launch video