Astronaut preps purple kefir for a vitamin boost | On the International Space Station Sept. 8-12, 2025

As their research activities continued, the Expedition 73 crew had a busy week on the International Space Station with the departure of a cargo vehicle and preparations for the arrival of two more.

Orbital observation

Japan Aerospace Exploration Agency (JAXA) astronaut Kimiya Yui, an Expedition 73 flight engineer, hammed it up with kids from his home country this week aboard the International Space Station (ISS).

“I was able to talk with the children of Takacho in Hyogo Prefecture via HAM! This is the first time talking with Japanese children during a mission!” said Yui in a social media post on Thursday (Sept. 11).

Amateur radio has been used in Earth orbit since the early 1980s aboard the U.S. space shuttle. Crew members can use it to connect with people all around the world without interfering with other communications between Earth and the space station.

“I gained energy from interacting with the children, and it helped me get through the subsequent work smoothly! Thank you very much!” said Yui.

Science status

Among the research that was conducted by the Expedition 73 crew aboard the space station this week was:

CIPHER — NASA astronauts Mike Fincke, Zena Cardman and Jonny Kim focused on studies relating to eyesight and balance, using VR goggles, electrodes and other specialized optical equipment to gauge how spaceflight affects their sense of balance and the shape of the retina, among other changes to the ability to see and steady themselves.

Cardman also used a ultrasound to monitor signs of arterial stiffness and changes in her cardiac function, while Kim processed bone stem cell samples for their later return to Earth as part of a study into bone density loss during long-duration space missions.

Plant Cell Division and Cell Biology Experiment Facility — Yui prepared and placed under study tobacco plant and algae cell samples to add to the experience and knowledge base of growing crops on future missions to the moon and Mars.

BioNutrients-3 — Fincke used a research incubator to test ways to use yeast, yogurt and samples of the fermented milk drink kefir to produce additional vitamins and nutrients to benefit future crews’ health. The astronaut showed off a tray of purple kefir used in the experiment; you can see a photo of it above.

Station keeping

The Expedition 73 crewmates also took part in activities to maintain the space station’s systems and prepare for future research.

Progress MS-30 (91P) — Having completed repacking the Russian cargo craft with refuse last week, the crew saw the departure of Progress MS-30 on Tuesday (Sept. 9).

Progress M-32 (93P) — Cosmonauts Sergey Ryzhikov and Alexey Zubritsky trained for the arrival and docking of Progress M-32, which is scheduled to dock to the aft port of the station’s Zvezda service module on Saturday (Sept. 13).

NG-23 “S.S. Willie McCool” — The crew also began preparations for the arrival of Northrop Grumman’s first “XL” Cygnus cargo craft, which is scheduled to be captured with the Canadarm2 robotic arm and berthed to the Earth-facing port on the Unity node on Wednesday (Sept. 17).

Astronaut activity

Astronaut Discusses Life In Space With MIT’s Technology Review Magazine – Tuesday, September 9, 2025 – YouTube

Watch On

Expedition 73 flight engineer Mike Fincke, a NASA astronaut, discussed life on orbit with MIT’s Technology Review Magazine during an interview on Tuesday (Sept. 9).

“I I think me and my crewmates on board Expedition 73 here are very focused and dedicated to science,” said Fincke. “We’re supporting the scientists on the ground, so we go above and beyond to give them best results that we can. I take great pride in that.”

You can watch the full interview above.

By the numbers

As of Friday (Sep. 12), there are 7 people aboard the International Space Station: Expedition 73 commander Sergey Ryzhikov of the Russian space agency Roscosmos; fellow cosmonauts Alexey Zubritsky and Oleg Platonov; Jonny Kim, Zena Cardman and Mike Fincke of NASA; and Kimiya Yui of JAXA, all flight engineers.

There are two docked crew spacecraft: SpaceX‘s Dragon “Endeavour” attached to the zenith port of the Harmony module and Roscosmos’ Soyuz MS-27 attached to the Earth-facing port of the Prichal node.

There are two docked cargo spacecraft: Roscosmos’ Progress MS-31 (92P) docked to the space-facing port of the Poisk module and SpaceX’s CRS-33 Dragon spacecraft is docked to the forward port of Harmony Node 2.

As of Friday, the space station has been continuously crewed for 24 years, 10 months and 10 days.