Expedition 73

Expedition 73 was the 73rd long-duration expedition to the International Space Station (ISS). The expedition began with the departure of Soyuz MS-26 on 19 April 2025 with JAXA astronaut Takuya Onishi taking over the ISS command and concluded with the undocking of Soyuz MS-27 on 9 December 2025.^[1] It continued the extensive scientific research conducted aboard the ISS, focusing on various fields, including biology, human physiology, physics, and materials science. The crew members also maintained and upgraded the space station systems.

The expedition commenced with a crew consisting of NASA astronauts Anne McClain, Nichole Ayers, and Jonny Kim, JAXA astronaut Takuya Onishi, and Roscosmos cosmonauts Kirill Peskov, Sergey Ryzhikov, and Alexey Zubritsky.

The expedition saw three spacewalks. On May 1, 2025, McClain and Ayers performed a 5-hour, 44-minute EVA to install a modification kit on the port side of the station’s truss structure enabling the future installation of its seventh iROSA and relocated an antenna that communicates with approaching and departing commercial crew and cargo spacecraft.

On June 26, 2025, the crew was joined by the staff of Axiom Mission 4's Crew Dragon Grace: commander Peggy Whitson of the United States, pilot Shubhanshu Shukla of India, and mission specialists Sławosz Uznański-Wiśniewski of Poland and Tibor Kapu of Hungary.^[2][3] Their mission marked India, Poland, and Hungary's return to crewed spaceflight for the first time in over 40 years.^[4] During their two-week stay aboard the ISS, the astronauts carried out 60 experiments planned by 31 different countries.^[3][5]

SpaceX Crew-11 arrived at the ISS on August 2, transporting NASA astronauts Zena Cardman and Michael Fincke, JAXA astronaut Kimiya Yui, and Roscosmos cosmonaut Oleg Platonov. The mission featured a handover with Crew-10 of six days. Onishi handed over command of the space station to Ryzhikov on August 5. Crew-10 departed with McClain, Ayers, Onishi, and Peskov on August 8.

On October 16, Ryzhikov and Zubritsky performed a 6-hour, 9-minute spacewalk to install the Ekran-M payload onto the Nauka module frame, jettisoned some cameras and a mounting platform, cleaned the windows on Zvezda service module, and removed a SSK panel and a Biorisk container.

On October 28, Ryzhikov and Zubritsky performed a 6-hour, 54-minute spacewalk to install the final set of payloads onto the Nauka module frame the IPI plasma injector into slots two and three, relocate the ERA control panel, clean the Nauka science window, and replace a cassette in the Ekran-M payload.

Soyuz MS-28 arrived at the International Space Station (ISS) on November 27, 2025, transporting NASA astronaut Christopher Williams and Roscosmos cosmonauts Sergey Kud-Sverchkov and Sergey Mikayev.

On December 1, 2025, following the reberthing of Cygnus NG-23 to the Unity module, all eight ISS docking ports were simultaneously occupied for the first time in the station's operation. Cygnus had been temporarily positioned on Canadarm2 on November 24 to clear the approach corridor for Soyuz MS-28 at the Rassvet nadir port. At this time, the station hosted eight visiting vehicles: two SpaceX Dragon 2 spacecraft (Crew-11 and CRS-33), the Northrop Grumman Cygnus XL freighter (NG-23), the JAXA's HTV-X cargo ship (HTV-X1), Roscosmos Soyuz MS crew vehicles (MS-27 and MS-28), and two Progress MS cargo spacecraft (MS-31 and MS-32).^[6]

After a handover period, Ryzhikov transferred command of the ISS to Fincke on December 7. The expedition concluded on December 9 with the departure of Ryzhikov, Zubritsky, and Kim aboard Soyuz MS-27.

Events involving crewed spacecraft are listed in bold.

Previous mission: Expedition 72

19 April 2025 - Soyuz MS-26 undocking, official switch from Expedition 72

22 April 2025 - CRS SpX-32 docking

1 May 2025 - EVA 1 (US-93) McClain/Ayers: 5 hrs, 44 mins

23 May 2025 - CRS SpX-32 undocking

26 June 2025 - Axiom Mission 4 docking (Non-Expedition crew)

1 July 2025 - Progress MS-29 undocking

5 July 2025 - Progress MS-31 docking

14 July 2025 - Axiom Mission 4 undocking (Non-Expedition crew)

2 August 2025 - SpaceX Crew-11 docking

5 August 2025 - ISS Expedition 73 change of command from Takuya Onishi to Sergey Ryzhikov

8 August 2025 - SpaceX Crew-10 undocking

25 August 2025 - CRS SpX-33 docking

9 September 2025 - Progress MS-30 undocking

13 September 2025 - Progress MS-32 docking

18 September 2025 - CRS NG-23 capture and berthing

16 October 2025 - EVA 2 (VKD-64) Ryzhikov/Zubritsky: 6 hrs, 9 mins

28 October 2025 - EVA 3 (VKD-65) Ryzhikov/Zubritsky: 6 hrs, 54 mins

29 October 2025 - HTV-X1 capture and berthing

24 November 2025 - CRS NG-23 unberthing

27 November 2025 - Soyuz MS-28 docking

1 December 2025 - CRS NG-23 reberthing

7 December 2025 - ISS Expedition 73/74 change of command from Sergey Ryzhikov to Michael Fincke

9 December 2025 - Soyuz MS-27 undocking, official switch to Expedition 74

Next mission: Expedition 74

The Prichal aft, forward, starboard, and aft ports all have yet to be used since the module originally docked to the station and are not included in the table.