The Expedition 74 crew aboard the International Space Station (ISS) concluded a busy week of operations, balancing preparations for an incoming crew with a series of experiments in space physics and human health. The orbital laboratory is now readying for the arrival of the SpaceX Crew-12 mission, expected to launch next week.
While logistical tasks took priority, the three-person crew also dedicated significant time to scientific research. This included testing new methods for managing spacecraft fuel and studying the long-term effects of microgravity on the human respiratory system.
Key Takeaways
- The ISS crew is preparing for the arrival of the SpaceX Crew-12 mission, which is scheduled to launch no earlier than Thursday, February 11.
- NASA Flight Engineer Chris Williams conducted experiments to better control cryogenic fuel pressure in spacecraft tanks.
- Roscosmos cosmonauts performed respiratory tests to understand how microgravity affects lung function.
- The crew also managed cargo transfers, inventoried supplies, and conducted simulations for returning to Earth.
Preparing for Crew-12 Arrival
A significant portion of the week's activities focused on getting the space station ready for four new crew members. NASA Flight Engineer Chris Williams led the preparations, which involved managing cargo and equipment aboard a SpaceX Dragon spacecraft that docked with the station on August 25, 2025.
Williams was responsible for transferring completed scientific experiments and used hardware into the Dragon vehicle for its eventual return to Earth. He also moved trash and unneeded items into the spacecraft to clear space on the station.
In addition to clearing out old cargo, Williams staged a variety of fresh gear that the incoming Crew-12 astronauts will need shortly after they arrive. These preparations are crucial for ensuring a smooth and efficient transition as the station's population temporarily increases.
Advancing Spacecraft Technology
Beyond the logistical tasks, the crew engaged in vital research aimed at improving future spaceflight technology. Williams conducted a physics experiment inside the Microgravity Science Glovebox, a sealed container that allows astronauts to safely work with materials that could be hazardous in the open cabin.
What is Cryogenic Fuel?
Cryogenic fuels are substances, like liquid hydrogen or liquid oxygen, that are stored at extremely low temperatures to remain in a liquid state. They are highly efficient propellants for rockets but pose engineering challenges, as even small amounts of heat can cause them to boil and turn into gas, increasing pressure inside fuel tanks.
The experiment involved injecting gas into specialized hardware to test methods for controlling pressure buildup in fuel tanks. This is a critical issue for long-duration space missions, where cryogenic propellants can evaporate due to ambient heat, a phenomenon known as "boil-off."
By finding better ways to manage this pressure, engineers can design more efficient and safer fuel systems for spacecraft traveling to the Moon, Mars, and beyond. Williams' work contributes directly to developing these next-generation systems.
Monitoring Astronaut Health in Orbit
Human research remains a cornerstone of the ISS mission. The crew participated in several activities designed to monitor their health and gather data on how the human body adapts to the unique environment of space.
Roscosmos Respiratory Study
Station Commander Sergey Kud-Sverchkov and Flight Engineer Sergei Mikaev, both Roscosmos cosmonauts, collaborated on a respiratory test. The experiment required them to take turns wearing tracheal acoustic sensors while performing a series of controlled breathing maneuvers.
The sound data collected from these tests will be used by researchers on the ground to assess how the absence of gravity impacts a crew member’s respiratory function over time.
This research is vital for understanding and mitigating potential health risks for astronauts on long-duration missions. Changes in fluid distribution and muscle use in microgravity can affect lung capacity and function, and this data helps develop countermeasures.
Maintaining Research Capabilities
On the U.S. Orbital Segment, Williams also worked to ensure ongoing biomedical research could continue without interruption. He resupplied the station's Human Research Facility kits with essential supplies, including:
- DNA oral swabs
- Blood sample tubes
- Gloves and other collection materials
These kits are used for a wide range of studies that track everything from genetic changes to immune system responses in astronauts, providing a comprehensive picture of health in space.
Routine Operations and Training
Alongside the major preparations and scientific experiments, the crew also performed routine maintenance and training. After the respiratory study, Commander Kud-Sverchkov conducted an inventory of tools throughout the Roscosmos segment of the station.
Astronauts and cosmonauts regularly practice emergency procedures and piloting skills using computer simulators. This ensures they are always prepared for off-nominal situations, including a rapid return to Earth if necessary.
Later, he refreshed his piloting skills for the Soyuz spacecraft, using a computer simulator to practice operations for returning to Earth. Mikaev joined him for these descent simulations after configuring data processing hardware that controls a variety of experiments in materials science and plasma physics.
Mikaev also managed cargo transfers in and out of the Progress 92 resupply ship, another routine but essential task for keeping the station well-stocked and organized. These combined efforts highlight the multifaceted nature of life on the ISS, where astronauts serve as scientists, mechanics, and pilots all in a single week.