Undocking Problems Delays Soyuz, Station Crew Return to Earth

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Two Russian cosmonauts and an American astronaut were forced to call off their scheduled departure from the International Space Station because of a failure of the undocking system. Hooks on the space station's Poisk module docking interface failed to release for the scheduled departure at 9:35 p.m. EDT Thursday, sending astronaut Tracy Caldwell-Dyson and Russia's Alexander Skvortsov and Mikhail Kornienko back inside the ISS from the Soyuz, where they were strapped in, ready to return to Earth. NASA and the Russian Space Agency are hoping to try again, with the hatch closing at 6:45 pm EDT on Friday; undocking at 10:02 pm and landing in Kazakhstan at 1:22 am.

"The preliminary analysis, according to the technical commission, showed that a false signal appeared in the onboard computer system about the lack of a hermetic junction after closing the hatch on the station," said Roscosmos head Anatoly Perminov.

This type of undocking problem has never happened before and comes three months after a Russian Progress resupply vehicle had problems docking to the ISS when a transmitter for the manual rendezvous system accidently activated, overriding the usually reliable automated system.

In trouble shooting the problem, Expedition 25 flight engineer Fyodor Yurchikhin on board the station removed a cover from the docking mechanism and found a small gear floating away. But the station crew couldn't confirm the object came from the docking system or had anything to do with the failure.

Nancy Atkinson

Nancy Atkinson

Nancy Atkinson is a space journalist and author with a passion for telling the stories of people involved in space exploration and astronomy. She is currently retired from daily writing, but worked at Universe Today for 20 years as a writer and editor. She also contributed articles to The Planetary Society, Ad Astra (National Space Society), New Scientist and many other online outlets.

Her 2019 book, "Eight Years to the Moon: The History of the Apollo Missions,” shares the untold stories of engineers and scientists who worked behind the scenes to make the Apollo program so successful, despite the daunting odds against it. Her first book “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” (2016) tells the stories of 37 scientists and engineers that work on several current NASA robotic missions to explore the solar system and beyond.

Nancy is also a NASA/JPL Solar System Ambassador, and through this program, she has the opportunity to share her passion of space and astronomy with children and adults through presentations and programs. Nancy's personal website is nancyatkinson.com