Marco Alain Sieber was born in 1989 in Switzerland.

Marco graduated from the Gymnasium Burgdorf in Switzerland in 2007.

In 2009, Marco joined the paratrooper training with the Swiss Special Forces Commando at the Swiss Army, where he achieved the military rank of Sergeant.

In 2015, he received the degree of Doctor of Medicine from the University of Bern, Switzerland. His doctoral thesis was on robotic surgery and he was awarded best final exam for his physician diploma.

In 2021, he earned his specialist diploma in pre-clinical emergency and rescue medicine (SGNOR).

Next to his mother tongues German and Swiss German, Marco also speaks English and French.

Between 2009 and 2015, Marco was working as an assistant teacher for anatomy and physiology courses at the faculty of medicine at the University of Bern. At the same time, he was also a skydiving instructor for pre-military paratrooper courses.

Between 2015 to 2017, he was a general surgery/traumatology, as well as an intensive care unit resident in Interlaken, Switzerland.

After becoming chief medical officer with Swisscoy (Swiss Army) for KFOR (Kosovo) in 2018, Marco worked as an emergency medicine resident at the University Hospital of Bern, Switzerland, until 2019.

Between 2019 and 2021, he was an anaesthesiology resident in Interlaken, Switzerland.

Since 2020, Marco is working as a helicopter rescue emergency medical doctor and also joined the hospital in Biel, Switzerland as an urology resident one year later.

Marco holds a private pilot license. He enjoys outdoor and adventure sports such as skydiving, paragliding, scuba diving, skitouring and kitesurfing.

In November 2022, Marco was selected as an ESA astronaut candidate. He commenced his one-year basic training programme in April 2023 and attained astronaut certification at ESA’s European Astronaut Centre on 22 April 2024, rendering him eligible for spaceflight assignments.