Nasa has announced it will be accepting applications for astronauts to pave the way for a new generation of space exploration. Sadly, only alpha Americans may apply. But space isn’t just about America. Next month, Tim Peake will become the first British astronaut to travel in space for more than 20 years. A dozen other nationalities have boldly gone. The cosmos has never been so, er, cosmopolitan.

Nice view, shame about the loos. Photograph: Nasa/REX Shutterstock

But how to get there? Becoming an astronaut is not easy, and most of us with a case of extraterrestrial wanderlust will have left our runs at the profession too late. But for those young and keen enough, here is a guide to becoming an astronaut (astro-naut, from the Greek words astron and nautes, meaning star sailor).

Need motivation to help launch your career? Give it a rocket boost with this special astronaut playlist

Academic qualifications

Astronauts are smart people. Nasa and the European Space Agency (ESA) each require a minimum of a bachelor’s degree in a field such as engineering, biological or physical sciences or mathematics. As well as this, pilot astronauts (who are primarily responsible for flying the rockets) must have at least 1,000 hours’ flight time in a jet aircraft and usually come from a military background.

This is all as a minimum, though. To give you a sense of how accomplished you need to be, in 2013 Nasa recruited a new group of potential astronauts. Of the eight candidates who were chosen out of 6,100 applicants, one was a naval aviator with a PhD in physics, one the station chief of the National Oceanic and Atmospheric Administration in American Samoa, and another an emergency physician and flight surgeon for the US special ops team. You get the picture. You have to be impressive.

Physical attributes

In order to apply to a space agency you need to be a citizen of that country. That’s good news for Peake and other starry-eyed Britons: the UK is one of the 20 member countries of the European Space Agency and so UK citizens are eligible to apply to the ESA.

Astronaut Tim Peake. Photograph: Marie Schmidt/The Guardian

If your country does not have its own space agency then you need to be willing to take up dual citizenship in order to get on a shuttle. The first naturalised citizen astronaut to fly for Nasa was Costa Rican Franklin Chang-Diaz in 1981 and of the 47 currently active Nasa astronauts, seven are naturalised citizens.

You also need to be the right age. Nasa does not have age restrictions, but in the past has selected candidates aged between 26 and 46, with an average age of 34; whereas the slightly more ageist ESA prefers applicants aged 27 to 37. You also need to be in prime physical condition: Peake said the physical examination during the application process culled half of the otherwise qualified candidates from the pool, mostly on the grounds of cardiovascular endurance and eyesight. You also need to have excellent mental health and to be the right height - between 1.53 metres and 1.9 metres for the ESA.

In terms of other specifications, while there have been female astronauts – the first Briton in space was female chemist Helen Sharman - women still face extra barriers. In September, Helena Serova, the first female Russian cosmonaut in 17 years, faced a barrage of patronising questions from journalists at a press conference about how she would maintain her hairstyle while on the mission.

The process

For Peake, the process to becoming an astronaut candidate was long. The ESA called for applicants in May 2008. Of the more than 10,000 who applied, 8,413 qualified for the selection process in Hamburg, which involved the candidates being given computer-based tests on everything from psychological profiling to memory. Then came a very thorough medical examination, which Peake said contributed to making the testing period “the most invasive week of my life”. Andrew Thomas, the only Australian astronaut to have been in space, similarly said that the Nasa physical examination involved being “poked and prodded in ways you couldn’t imagine”.

I was poked and prodded in ways you couldn’t imagine Australian astronaut Andrew Thomas

After these tests, candidates were whittled down 22. They were invited to a series of formal interviews, and the final 10 were asked to meet the director general of the ESA, Jean-Jacques Dordain. From them, five men – Peake, an Italian, a Frenchman, a Dane and a German – and one woman, another Italian, were chosen as the new ESA astronaut candidates and began training in September 2009.

Preparations are intense, with everything from scuba instruction to Russian language courses, exposure to high and low atmospheric pressures, and flights in the “vomit comet”, which is able to simulate zero gravity conditions for periods of up to 20 seconds.

Finally, an astronaut candidate trains and works on Earth providing assistance with other missions until they are assigned to a space mission, which can take years. Peake’s place on the ISS mission was announced in 2013 and he has been training for it ever since.

Get the timing right

This is the bit of chance that has made or devastated the ambitions of potential astronauts. Hiring windows at space agencies are a bit like a comet: they come around rarely and if the agency is hiring when you’re the wrong age, that’s probably it for you. While Nasa hires every few years, the ESA has held just three European astronaut selection processes, the first in 1978, the second in 1992 and a third in 2008/2009.

“We don’t hire astronauts all the time,” says Frank Dansey, head of human resources at the European Space Operations Centre. “Today I wouldn’t be able to say when the next selection campaign will occur. But what I can say is that of those who became astronauts they prepared perpetually, as though the next campaign was just around the corner.”