Astronaut Alexander Gerst suffered a frustrating nose-scratching fail during extreme g-force training for his upcoming mission to the International Space Station (ISS).

Gerst, a German ESA astronaut currently training to return to the ISS as a commander in 2018, shared footage of his intensive training on social media Tuesday which, he says, “only went to 5g.”

“Trained this so much that I only really noticed the g load when I wanted to scratch my nose - and couldn’t,” wrote Gerst on Twitter.

Just had my exams on how to fly a space ship completely manually. Bizarre thought by itself. Today only went to 5g. Trained this so much that I only really noticed the g load when I wanted to scratch my nose - and couldn’t. (last secs of video) #SoyuzMC09pic.twitter.com/zRCdkfukdb — Alexander Gerst (@Astro_Alex) November 21, 2017

Gravitational force is the measurement of acceleration that causes weight. Earth has gravity force of 1g, anytime we accelerate, that force increases.

Astronauts on manned missions normally experience a maximum g-force of around 3g when talking off. It’s important astronauts endure high levels of acceleration to prevent loss of consciousness during flight. Most humans black out at around 9g, an untrained individual can blackout between 4 and 6 g.

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Gerst is scheduled to launch into orbit on board the Soyuz MC-09 in April, 2018, from Yuri Gagarin’s launchpad for Expedition 56 and 57, taking over as commander of the Space Station for Expedition 57, in what has been dubbed the ‘Horizons’ mission.

Gerst said the name and logo of the mission was based on the scientific experiments they plan to run on the space station; “we want to broaden our horizons as humankind," he said.

The astronaut and geophysicist will be the first of ESA’s class of 2009 to enter space for a second time – he had a stint on the ISS already from May to November 2014.