What Does Undocking from Orbit Really Mean for Astronauts?

Space · Published 4 October 2026 Swipe more like this →

In short: Leaving the International Space Station after months in orbit is a complex procedure. Understanding the precise sequence of undocking, hatch closures, and the journey back to Earth reveals much about the engineering mastery required for deep space travel. It is a carefully choreographed return.

The departure of Expedition 48, which included NASA astronaut Jeff Williams and Roscosmos cosmonauts Alexey Ovchinin and Oleg Skripochka, involved several precise steps. The crew had spent a total of 172 days conducting research and operational tasks aboard the ISS. Williams was noted for capping off a record-breaking mission, having accumulated the most cumulative time in space among the group. The return journey began with the crew undocking from the orbital outpost on September 6th. The spacecraft, a Soyuz TMA-20M, was involved in this transit.

The timeline of the departure was highly structured. The hatch between the International Space Station and the Soyuz TMA-20M was sealed at 2:30 p.m. EDT (1830 GMT). Later that day, at 5:51 p.m. EDT, the trio officially undocked from the station to commence their trip back to Earth. The crew had arrived at the station on March 18th and had been occupied with maintaining numerous scientific experiments and executing multiple spacewalks throughout their six-month tenure.

The planned landing site for the crew was southeast of the remote Kazakh town of Dzhezkazgan. If all procedures proceeded as scheduled, their arrival was anticipated for 9:14 p.m. EDT (0114 GMT on September 7th). Upon landing, Russian recovery teams were responsible for assisting the crew in exiting the Soyuz spacecraft and helping them readjust to Earth's gravity. This entire sequence underscores the meticulous planning required for crew safety during trans-Earth transfers.

The mission provided opportunities for scientific study, including observing life science while the station passed over Hurricane Matthew in the Caribbean Sea. The coordination between NASA and Roscosmos, involving the Soyuz TMA-20M, highlights the international collaboration underpinning long-duration space missions.

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