Thirty-one astronauts have made a return-trip to Mars. Well, not quite – but they have put in the requisite hours in space. That’s just one of the surprising insights to come out of a recent attempt to chart humanity’s 52-year history in space.

Gilles Clément and Angelia Bukley of the International Space University in Illkirch-Graffenstaden, France, used publicly available information from the US, Russian and Chinese space programmes. Between 12 April 1961, when Yuri Gagarin took a single orbit around the Earth on board the Soviet Vostok-1 craft and December 2013, they counted the humans who have flown to space, how long they collectively spent there and who they were.

We picked out our favourites six insights, then put them in context with data from elsewhere.

1. Astronauts are as common as Nobel prizewinners


As of 31 December 2013, 539 individuals had been to space, defined as reaching an altitude of 100 kilometres or more. That’s a rate of about 10 per year, and roughly equivalent to the 566 people who have ever won a Nobel prize in a science subject (physics, chemistry, or physiology/medicine).

(Note: Clément and Bukley’s analysis does not include the two commercial astronauts who piloted the SpaceShipOne test flights in 2004, who were in space for just a few minutes each.)

2. Space trips last days, months… but rarely years

Gagarin’s single orbit of the Earth lasted just 108 minutes. Clément and Bukley found that of a total of 1211 person-flights, defined as a single crew member flying one mission, most last less than a month. Presumably these short hops were trips to the moon and missions spent inside NASA’s now-retired space shuttle, to build and repair the International Space Station. But a significant minority spent five or six months, representing stays on board the ISS.

3. Many astronauts spend more than a year of their life in space

Though no single trip has been longer than Valeri Polyakov’s 437 days aboard the Soviet space station Mir, if you count total time in space over a lifetime, the figures are quite different.

4. Thirty-one astronauts have been to Mars and back, sort of

One of Clément and Bukley’s most surprising observations is that 31 travellers have spent over a year in total in space, enough to make a trip to Mars and back – though the exact travel time depends on relative positions of Earth and the Red Planet.

5. Like many adventures, space is sexist

Last year, a private foundation announced plans to send a man and woman on a 501-day round-trip to Mars, to “represent all of humanity”. Spaceflight so far has been far from representative when it comes to gender, though it is not the only extreme pursuit with a skew.

6. Space travel is not as dangerous as you might expect

Clément and Bukley also examined the risks of space travel. Counting two lost shuttles and two lost Soyuz capsules, the pair calculated that the chance of dying on a space mission is 1.5 per cent, markedly less than the percentage of people who die attempting to reach the summit of Mount Everest.

Journal reference: Acta Astronautica, DOI: 10.1016/j.actaastro.2014.04.002