Two Russian cosmonauts on the International Space Station spent six hours on a space walk on Wednesday to retrieve an explosive bolt believed the cause of the dangerously high-speed descent and landing on two recent resupplying missions of the Soyuz capsule.
The Astronauts Removing the Pyro Bolt
While US flight engineer Greg Chamitoff monitored the spacewalk from inside the Soyuz capsule, ISS Commander Sergei Volkov and Flight Engineer Oleg Kononenko attached themselves to the Strela hand-powered crane which moved them to the Soyuz.
They cut back insulation to safely get to the pyro bolt, which was then secured in a protective blast-proof case to be sent back to Earth for examination. It was a risky operation requiring them to first remove the electrical cables that fire the bolts, to avoid sparking a firecracker-sized explosion that could damage their space suits.
Russian space officials believe that the pyro bolts, which help separate the Soyuz from its docking position ahead of its trip back to Earth, were failing to operate correctly. The error caused the Soyuz to enter the atmosphere at an incorrect angle and excessive speeds on the two most recent missions.
The off-track re-entry subjected the cosmonauts to uncomfortably high G-forces (“It usually refers to the reaction force resulting from an acceleration, with the causing acceleration expressed in g”), and also caused the spacecraft to land heavily hundreds of kilometers off of the estimated course.