Ax-4 Astronauts to Return from ISS with 580 Pounds of Science Cargo

NASA’s SpaceX Dragon spacecraft is pictured approaching the International Space Station in June 2025, carrying the Ax-4 crew. Mission managers have given the “go” to undock this private astronaut mission (Axiom Mission 4) on Monday, July 14 at 7:05 a.m. EDT. The four-person crew, led by veteran astronaut Peggy Whitson, has spent about two and a half weeks aboard the orbiting lab conducting science. Whitson’s crewmates are Shubhanshu Shukla (India), Sławosz Uznański-Wiśniewski (Poland) and Tibor Kapu (Hungary), the first astronauts from their countries to visit the ISS. Together they performed dozens of experiments in microgravity before packing up for the ride home.

Completing the Research Mission

According to NASA, the Ax-4 team kept a busy schedule of science activities in their last days on station. On Friday they collected blood samples for later medical analysis and grew microalgae as a potential food source and life-support organism in space. They also studied special nanomaterials that could become wearable health monitors.

On Saturday the crew worked on human health investigations: testing electrical muscle stimulation, trying new exercise suit fabrics for thermal comfort, and filming their daily routines for a behavioural health study. By Sunday they began stowing research gear and packing science samples and personal cargo inside Dragon for return to Earth.

Preparing for the Return Journey

Expedition 73 station crew members pitched in to help finalize the departure. NASA astronaut Anne McClain helped gather hardware and supplies for packing Dragon and assisted with Ax-4’s ongoing experiments. Colleagues Nichole Ayers and Jonny Kim spun the astronauts’ blood samples in a centrifuge and stowed them in the science freezer, then transferred water into the spacesuits during pre‐return checks. Japanese astronaut Takuya Onishi processed saliva samples and carried out routine maintenance, and Russian cosmonauts Sergey Ryzhikov and Alexey Zubritskiy ran a final fitness test on the station’s exercise bike.

The SpaceX Dragon will carry the crew and roughly 580 pounds of cargo – including hardware and data from over 60 experiments – back to Earth. Upon undocking on Monday, Dragon will eventually splash down off the California coast, returning the Ax-4 crew and their research samples after this historic international mission.