New Soyuz Crew Arrives at ISS — Six Months Later Than Planned

A new Russian-American crew has arrived on the International Space Station as part of a rather unusual crew rotation. The three people aboard Soyuz MS-24 were supposed to launch six months ago on Soyuz MS-23, but that spacecraft had to be launched empty because of a technical problem with Soyuz MS-22 already docked at ISS. They are finally aboard, but unlike most crews that arrive and leave together, this time the American will return as usual after six months, but the two Russians will stay for a year.

Roscosmos cosmonauts Oleg Kononenko and Nikolai Chub and NASA astronaut Loral O’Hara lifted off from the Baikonur Cosmodrome on September 14 at 11:44 am EDT and docked about 3 hours later at 2:53 pm EDT.  This is Kononenko’s fifth trip to the ISS. Chub and O’Hara are rookies.

Liftoff! @LunarLoral of @NASA_Astronauts and two cosmonaut crewmates are on their way to the @Space_Station. They’ll dock about three hours from now. pic.twitter.com/4JTtfcgQZC

— NASA (@NASA) September 15, 2023

The trio’s launch was delayed six months because the spacecraft that took the Soyuz MS-22 crew — Sergey Prokopyev, Dmitri Petelin and NASA’s Frank Rubio — to the ISS last year leaked all its coolant into space and was not safe to return them to Earth. Roscosmos decided to launch the Soyuz MS-23 spacecraft empty so it can bring them home. They’ve had to stay in space those extra six months and are scheduled to land on September 27 after more than a year in space — 371 days.

Year-long missions are rare and unanticipated for Prokopyev, Petelin and Rubio. However, the two Russians on Soyuz MS-24 are planning to stay that long, while NASA’s O’Hara will follow the usual schedule and come home after six months.

International crews rotating on roughly 4-6 month assignments have permanently occupied the ISS for almost 23 years, but both shorter and longer duration missions are interspersed throughout that history. Russia has been sending  visitors — non-professional astronauts often referred to as space tourists — to ISS for approximately 10-day stays since 2001. The United States started doing so last year.

Ordinarily Kononenko, Chub and O’Hara would be replaced by a new crew on Soyuz MS-25 next March, but Russia is using that flight for a tourist, Marina Vasilevskaya from Belarus. She can only stay for a short mission, so will ride up to ISS with Roscosmos cosmonaut Oleg Novitskiy in command. O’Hara’s replacement, Tracy Dyson, will be in the third seat.

Novitskiy and Vasilevskaya will return to Earth with O’Hara in Soyuz MS-24, leaving the fresh Soyuz MS-25 for Kononenko, Chub and Dyson to use for their trip home a year from now. Soyuz spacecraft are certified for only six months in space.

The permanent ISS crew complement is seven, three launched on Russian Soyuz spacecraft and four on U.S. Crew Dragons, which have a similar on-orbit lifetime.

The astronauts and cosmonauts conduct a wide range of scientific research during their expeditions to ISS and are themselves subjects. Understanding how humans adapt physically and psychologically to long durations in space is critical for eventual trips to Mars. Year-long missions, whether planned like Kononenko and Chub’s, or unexpected like Prokopyev, Petelin and Rubio’s, will add considerably to that database.

Despite the grim geopolitical situation on Earth, the international ISS partnership among the United States, Russia, Japan, Canada, and 11 European countries working through ESA remains strong. As has been true since the first crew arrived in November 2000, Russians and Americans have launched on each others’ spacecraft to ensure at least one of each nationality is aboard to operate their respective segments of the 420 Metric Ton facility.