Astronauts stuck on ISS as undocking manoeuvre fails

An attempt to undock a Russian Soyuz capsule from the International Space Station failed this morning, leaving two Russian and one American astronauts stuck there for another day.

Three departing Expedition 24 crew members will spend at least another day on the International Space Station following an unsuccessful attempt to undock their Soyuz spacecraft overnight.

At 12:12am EDT today, the Mission Control Centers in Houston and Moscow agreed to give up the attempt and reopen the Soyuz hatches to allow Alexander Skvortsov, Tracy Caldwell Dyson and Mikhail Kornienko to reenter the station.

The undocking was unsuccessful because commands being sent to disengage the hooks and latches holding the Soyuz TMA-18 spacecraft sent a false signal indicating that the seal between capsule and station wasn’t complete. It’s the first time this has ever happened.

Engineers are continuing to examine the problem. Expedition 25 commander Doug Wheelock and flight engineers Shannon Walker and Fyodor Yurchikhin snapped still photos and video of a small star-shaped gear with two broken teeth, and ground-based experts are examining whether this could be related to the commanding problem.

A second time-slot for undocking last night was missed while engineers examined the problem. The team aims to try again at 10:02pm this evening, which would result in a landing in Kazakhstan at 1:21am tomorrow.

It’s the second docking problem at the ISS in three months: in July, the unmanned Progress supply ship failed to dock due to a telemetry failure.