Ax-4 astronauts set to return from ISS with over 500 pounds of research samples

After nearly two and a half weeks conducting science aboard the International Space Station (ISS), the Ax-4 private astronaut crew is preparing to return to Earth, bringing back more than 580 pounds of research samples and equipment.

The four-person mission, led by veteran NASA astronaut Peggy Whitson, is scheduled to undock on Monday, July 14, at 7:05 a.m. EDT.

This Axiom Mission 4 (Ax-4), flown aboard a SpaceX Dragon spacecraft, marks a historic international effort.

Whitson was joined by Shubhanshu Shukla (India), Sławosz Uznański-Wiśniewski (Poland), and Tibor Kapu (Hungary) — the first astronauts from their respective countries to reach the ISS. Over their stay, the team completed more than 60 experiments across biology, technology, and human health in microgravity.

NASA confirmed the crew maintained a packed research schedule during their final days in orbit. On Friday, the astronauts collected blood samples for future medical studies and cultivated microalgae, which could be used as a sustainable food and oxygen source for long-term space missions.

Their investigations also included testing wearable nanomaterials designed to monitor health in space.

Saturday’s focus shifted to human physiology.

The team trialed electrical muscle stimulation devices, evaluated new fabric technologies for exercise clothing, and documented daily life aboard the station for behavioral health research. By Sunday, the astronauts began organising and stowing equipment and samples into Dragon for the journey back to Earth.

Expedition 73 crew members provided key assistance during the Ax-4 crew’s wrap-up. NASA’s Anne McClain helped prepare equipment and contributed to final experiments. Fellow astronauts Nichole Ayers and Jonny Kim processed blood samples using a centrifuge, secured them in the station’s science freezer, and conducted final spacesuit water checks.

Meanwhile, Japan’s Takuya Onishi handled saliva sample processing and station upkeep, while Russian cosmonauts Sergey Ryzhikov and Alexey Zubritskiy monitored fitness data using the station’s cycling machine.

Once undocked, the Dragon capsule will transport the Ax-4 team and their 580 pounds of cargo - including research samples and hardware - back to Earth.

The mission will conclude with a splashdown off the California coast.