Applications to the European Space Agency (ESA) opened Wednesday, seeking candidates for its new space crew for the first time in a decade.

Applications close on May 28, with the application process including six steps through late 2022.

ESA said earlier it is looking for four to six astronauts, who would be employed full-time as part of a space crew to be sent on missions. ESA is also looking for another 20 astronauts as back-up.

An ESA official said last month that the agency is looking to recruit more female astronauts.

The requirements for potential applications are high: They have to have completed at least a master's degree in a natural science, medicine, engineering, maths or informatics and have at least three years' worth of job experience.

A pilot license is not required, but applicants should fulfill the conditions to be able to get one, including providing a medical assessment report.

Very good English and proficiency in another language are also required.

There are also some physical conditions: People should be between 1.5 and 1.9 meters tall, and at most 50 years old.

In the first month of the training, astronauts have to do a swimming test, and should therefore be good swimmers. They have to be ready to train underwater for longer periods of time and own a driver's license.

People who have worked in risk management before are at an advantage, as being an astronaut is risky and dangerous, according to ESA.

The agency is also explicitly looking for one astronaut with a physical disability, to help people with disabilities break down barriers. It was, however, unclear if that astronaut would be sent into space.