28 May 2025

Life science was back on the schedule for Wednesday as the Expedition 73 crew studied how living in space affects eye structure and cellular immunity. The International Space Station residents also maintained the upkeep of exercise gear, life support components, and orbital plumbing hardware.

The ongoing space biology investigations aboard the orbital lab constantly informs doctors how astronauts adapt to months of living and working in weightlessness. Scientists extrapolate the continuous research data and are using the insights to protect future crews on longer spaceflight missions to the Moon, Mars, and beyond.

Doctors are exploring potential space-caused changes to crew eye structure and function since vision is critical whether piloting a spacecraft, conducting advanced space science, or performing other mission critical tasks. NASA Flight Engineers Jonny Kim and Nichole Ayers kicked off their shift with a test measuring the electrical responses of the retina to light stimuli. Kim attached electrodes to his forehead and around his eyes and Ayers operated the specialized, data-collecting hardware to understand how the eye adjusts to long-term weightlessness. The study is just one part of the CIPHER suite of 14 human research investigations to learn how to keep crews healthy in space.

Kim later collected and stowed his urine samples in a science freezer for later analysis then swapped a pair of research incubators in the Columbus laboratory module. Ayers moved on to the Tranquility module and replaced orbital plumbing gear that removes inorganic impurities from the station’s water.

Station Commander Takuya Onishi of JAXA (Japan Aerospace Exploration Agency) continued studying how the stress of spaceflight affects cellular immunity helping doctors defend crews against infections. Onishi started his day his processing his blood samples that were incubating for 24 hours inside the Kubik research incubator. Next, he stowed the samples in a science freezer to later analyze the blood cells for signs of space-caused cellular stress or tissue damage. Onishi finally inspected and cleaned an experimental carbon dioxide removal device that also recovers water for oxygen generation.

NASA Flight Engineer Anne McClain spent her day inside Tranquility servicing and inspecting the COLBERT treadmill. The regularly scheduled maintenance activities take place every six months as McClain greased axles, cleaned components, and measured the acoustic volume of the workout device while operating with a crew member. McClain wrapped up her shift in the Quest airlock preparing spacesuit hardware for stowage.

Earth observations were back on the schedule as Roscosmos Flight Engineer Alexey Zubritskiy pointed a camera out a station window and photographed islands in the Pacific Ocean and other landmarks across the Pacific coasts of Asia and North America. Veteran cosmonaut Sergey Ryzhikov deactivated imaging hardware that observes Earth’s nighttime atmosphere in ultraviolet wavelengths. Flight Engineer Kirill Peskov wrapped up several days of training, checkouts, and inspections on the European robotic arm (ERA) attached to the Nauka science module. The ERA can be used to maneuver spacewalkers, payloads, and external hardware on the orbital outpost’s Roscosmos segment.

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(From left) Expedition 73 Flight Engineers Anne McClain and Nichole Ayers, both NASA astronauts, take a break and pose for a portrait aboard the International Space Station’s Destiny laboratory module.