Immunity and exercise science continued aboard the International Space Station on Wednesday giving doctors insight into how the human body adjusts to weightlessness. The Expedition 73 crew is also packing a cargo craft before the end of its mission and maintaining a variety of orbital lab hardware.

Flight Engineer Kimiya Yui of JAXA (Japan Aerospace Exploration Agency) picked up the cellular immunity research he began on Monday spending the first half of his shift collecting and processing his blood and saliva samples for the Immunity Assay study. The specimens were both preserved in a science freezer for later analysis and stowed in a research incubator for further processing. Scientists on Earth will analyze the samples to understand how living in space affects cellular immunity and improve health monitoring in space.

Yui also took turns with NASA Flight Engineer Mike Fincke pedaling on the Destiny laboratory module’s exercise cycle for an aerobic health study. Fincke began the first run of the experiment strapping himself onto the cycle, wearing electrodes and breathing gear measuring his heart and respiratory rate, and pedaling for about an hour. Fincke later spent the rest of his shift on hardware inspections and electronics replacement work behind the thermal control system rack in Destiny.

Next, Yui took over and recalibrated the exercise cycle’s instruments, wore new sensors, and pedaled on the bike as doctors on the ground monitored his workout in real-time. The data will help doctors ensure astronauts stay in shape to handle sustained physical activities such as long spacewalks or the return to Earth’s gravity after several months in space.

NASA Flight Engineer Zena Cardman contributed to the ongoing exercise research on the station by working out on the Tranquility module’s advanced resistive exercise device, or ARED, that mimics free weights in microgravity. She performed isometric mid-thigh pulls, or static dead lifts, measuring how much force she can produce on the ARED for the CIPHER human research investigation. She also exercised her back, shoulders, biceps, and triceps on ARED before jogging on the COLBERT treadmill while wearing a heart monitor. The insights gained from the workout studies adds to the growing knowledge into cardiorespiratory fitness, muscle strength, and physical endurance in space.

NASA Flight Engineer Jonny Kim swapped out a Bio-Monitor headband and vest for a spare set on Tuesday to continue measuring his cardiovascular health for a 48-hour monitoring session for another portion of the CIPHER study. Kim also set up the Columbus laboratory module’s European Drawer Rack-2 in preparation for the installation of research hardware then measured airflow throughout the station’s U.S. segment.

Cosmonauts Sergey Ryzhikov and Alexey Zubritsky, station Commander and Flight Engineer respectively, partnered together again packing trash and outdated gear for disposal inside the Progress 91 resupply ship. Progress 91 is nearing the end of its six-month stay in September and will undock from the Zvezda service module’s rear port and descend into Earth’s atmosphere for a fiery, but safe demise above the South Pacific Ocean.

Roscosmos Flight Engineer Oleg Platonov began his shift downloading multispectral imagery of Asian and Pacific Ocean landmarks captured automatically during the crews’ sleep shift. Afterward, he began a new Earth photography session photographing landmarks himself including the Swiss Allalin Glacier, Africa’s Mount Kilimanjaro, and Brazil’s Amazon delta.

Learn more about station activities by following the space station blog, @space_station on X, as well as the ISS Facebook and ISS Instagram accounts.

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August 19, 2025

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