Soyuz MS-24
Soyuz MS-24 is a Russian crewed Soyuz spaceflight launched from Baikonur on September 15, 2023 to the International Space Station. Crew
The original three-Russian member crew for this scenario was named in May 2021. American astronaut Loral O'Hara replaced Andrey Fedyaev as a part of the Soyuz-Dragon crew swap system of keeping at least one NASA astronaut and one Roscosmos cosmonaut on each of the crew rotation missions. This allows continuous space station occupation by US and Russia and keep backup crew scenarios to prevent vehicle either vehicle grounding like Soyuz MS-10 launch failure or to compensate for delays in launch of crew rotation missions of either vehicles like SpaceX Crew-3, that was delayed due to unfavorable launch weather conditions. They were originally assigned to Soyuz MS-23 mission, but were moved to MS-24, due to Soyuz MS-22 coolant leak accident that required MS-23 to be launched uncrewed as its replacement. Oleg Kononenko is assigned for an one year long mission with his MS-24 crewmate, Nikolai Chub that started on September 15, 2023. If the mission lasts 300-365 days, Kononenko will have spent a total of 1,036-1,101 days in space, exceeding the current record of 878 days by Gennady Padalka. He will thus also become the first person to stay 1,000 days in space. Primary Crew

Backup crew

References 

Crewed Soyuz missions
Future human spaceflights
2023 in spaceflight
2023 in Russia