The two crew members were on their way to the International Space Station when the Russian-made Soyuz rocket (the only way to ferry humans to the ISS at this point in time) aborted about a minute and a half after takeoff. An official report detailing the cause of the failure is due to be published today, but Russian officials told news agencies yesterday that the problem was an on-board sensor used to track the separation of the rocket’s boosters.
The Soyuz is a multistage rocket, meaning it uses groups of engines that fire one after another to push the vehicle out of the grip of Earth’s gravity. At the end of the video released by Roscosmos below you can see the first of these engine stages detaching:
Usually, the four boosters fall away perfectly symmetrically (creating a visual phenomenon sometimes referred to as a “Korolev Cross,” after Soviet rocket engineer Sergei Korolev). But here you can clearly see one of the boosters clinging to the rocket, sending it into a spin.
The two crew members aboard the Soyuz sustained no injuries from the aborted launch, but did experience extreme G-forces (up to 6.7 times normal Earth gravity) on their unexpected, 31-mile trip back home. NASA astronaut Nick Hague told reporters that the pair experienced a brief moment of weightlessness after the failure, before beginning what’s known in the business as a ballistic descent.
“It’s like tossing a ball high into the air,” said Hague. “At some point gravity takes over and starts bringing it back down.”
The Soyuz rocket is currently grounded and it’s not clear when it will next fly (although some time in December is suggested). And at the moment, there are three crew members onboard the ISS. Although they can return safely to Earth whenever needed using a capsule attached to the station, NASA wants to avoid leaving the ISS uncrewed for too long.