The 169-day marathon of Expedition 40 concludes in Kazakhstan

Space · Published 9 October 2026 Swipe more like this →

In short: Spending half a year in orbit is a test of human endurance and engineering. Expedition 40 just wrapped up a grueling 169-day mission, completing a record-breaking week of science and orbiting the Earth over 2,700 times before touching down on the Kazakh steppe.

Expedition 40 served as a critical bridge toward long-duration human spaceflight. A primary focus for NASA and Roscosmos was human health management, specifically studying bone and muscle physiology to prepare for the 2015 goal of having two crew members spend a full year aboard the International Space Station. To achieve this, the crew engaged in intensive research, including a record-breaking 82 hours of scientific work in a single week during July. Their work also spanned Earth remote sensing and studies on human behavior and performance in microgravity.

The mission was a logistical feat of coordination and heavy lifting. During their tenure, the crew welcomed five cargo spacecraft, including two Russian Progress vessels and the European Space Agency's Automated Transfer Vehicle, named after Georges Lemaitre. They also managed the third of at least 12 planned commercial resupply missions by SpaceX's Dragon and the third of at least eight missions by Orbital Sciences' Cygnus. These missions were essential for maintaining the $100 billion laboratory, providing tons of supplies and equipment for the crew's ongoing research.

Beyond pure science, the station functioned as a high-stakes technology test bed. The crew monitored the carbon dioxide removal system, which behaved unexpectedly compared to ground tests, providing vital data for next-generation life support. Commander Steve Swanson also performed a spacewalk to replace a failed backup computer relay box. This combination of routine maintenance, emergency repairs, and complex experimentation highlights the ISS as a living laboratory where every action—from monitoring air quality to extravehicular activity—contributes to the future of human exploration.

The mission concluded on September 11, local time, with the Soyuz TMA-12M spacecraft undocking from the Poisk module. The three-person team, consisting of Swanson and Russian engineers Alexander Skvortsov and Oleg Artemyev, traveled over 71.7 million miles before a descent that lasted less than 3.5 hours. They landed southeast of Dzhezkazgan, handing over command to Maksim Suraev as Expedition 41 began.

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