Expedition 73 Settles In: Snowy Japan From Orbit, New Crew Orientation and Ongoing Science (Dec. 1–5, 2025)

Expedition 73 — Dec. 1–5, 2025

During Dec. 1–5, 2025, newly arrived and soon-to-depart members of Expedition 73 spent their final full week together aboard the International Space Station (ISS), carrying out science, maintenance and crewmember orientation before upcoming spacecraft movements.

From Orbit: A Nighttime View of Japan

"Last night, I went to bed early and woke up once in the middle of the night to film a video of the Japanese archipelago," JAXA astronaut Kimiya Yui posted on Dec. 4. "Even from space, it looked very cold. There were many areas where it seemed to be snowing or places where it had snowed afterward, and while it looked beautiful from space, I became a little worried when I thought about all of you."

Research Highlights

• CIPHER Human Research: NASA astronauts Zena Cardman and Jonny Kim collected Cardman’s blood samples, tested cognition and logged exercise data to track health before, during and after flight. Cardman prepared samples in a centrifuge for freezer storage and later analysis on the ground.
• Astrobee Robotics: Ground teams and on-orbit crewmembers evaluated Astrobee free-flying robotic assistants to help automate routine tasks and enable astronauts to spend more time on science.
• Zero Boil-Off Tank Noncondensables: Flight Engineer Mike Fincke swapped cameras inside a microgravity science glovebox to photograph cryogenic fluid behavior, work that informs improved spacecraft fuel-tank design.
• European Exploration Exercise Device (E4D): NASA astronauts Jonny Kim and Chris Williams inspected and cleaned the newly installed E4D in ESA’s Columbus lab. The device combines bicycling, rowing and resistance training to protect crew muscle, bone and cardiovascular health in microgravity.

Station Operations & Crew Familiarization

Newly arrived NASA astronaut Chris Williams completed orientation briefings and hands-on familiarization led by veteran crewmembers Mike Fincke (NASA) and Kimiya Yui (JAXA), covering station hardware, operations and systems. Russian flight engineer Oleg Platonov conducted a "closet" inventory in the Russian segment, documenting clothing and towel locations and quantities to help logistics planning.

Where The Vehicles Were Docked

In imagery and operational notes from the week, Northrop Grumman’s Cygnus XL cargo vehicle, the S.S. William C. "Willie" McCool, and the newly arrived Soyuz MS-28 spacecraft were clearly visible near the station.

Crew And Visiting Vehicles (As Of Dec. 5, 2025)

• Crew Aboard (10): Expedition 73 commander Sergey Ryzhikov and flight engineers Oleg Platonov, Sergey Kud-Sverchkov, Sergey Mikaev and Alexey Zubritsky (Roscosmos); NASA astronauts Zena Cardman, Mike Fincke, Jonny Kim and Chris Williams; and JAXA astronaut Kimiya Yui.
• Crewed Spacecraft Docked: SpaceX Dragon "Endeavour" at Harmony (space-facing), Soyuz MS-27 at the Prichal node (Earth-facing) and Soyuz MS-28 at Rassvet (Earth-facing).
• Cargo Vehicles Berthed/Docked: Progress MS-31 (92P) at Poisk (space-facing), Progress MS-32 (93P) at Zvezda aft, Northrop Grumman Cygnus XL S.S. William C. "Willie" McCool at Unity CBM, and Japan's HTV-X1 at Harmony CBM.

Milestone: As of Friday, Dec. 5, 2025, the ISS had been continuously crewed for 25 years, 1 month and 3 days.

Why It Matters

The mix of science, maintenance and hands-on orientation highlights how the ISS balances cutting-edge research (from human physiology to robotics and cryogenics) with the daily work of keeping a complex international laboratory running. The work done this week supports future missions and helps preserve crew health for longer-duration spaceflight.