Bosses of the Mars One project have whittled the number of candidates down from 200,000 to just 100 as the applicants move one step closer to becoming the first humans to settle on the Red Planet.

The privately funded project, which has been ongoing since 2012, will give the successful applicants a one-way trip to Mars in an attempt to colonise the planet.

Co-founder and CEO Bas Lansdorp said: "The large cut in candidates is an important step towards finding out who has the right stuff to go to Mars. These aspiring Martians provide the world with a glimpse into who the modern day explorers will be."

The number of successful applicants is split 50/50 between men and women from all around the globe. Mars One says that 39 are from the Americas, 31 from Europe, 16 from Asia, seven from Africa, and seven from Oceania.

Eventually around 40 people will be sent to Mars on a permanent basis. The finalists will train for seven years and Mars One will begin sending out four at a time from 2024.

The space settlers will inhabit living units of 50sqm per person. Inflatable components will provide bedrooms, working areas, living rooms and a plant production unit, which will allow settlers to grow vegetables.

While Mars One says returning to Earth is not completely out of the question, once settled, the astronauts will not be able to come back as their bodies will have adjusted to Mars's 38% gravitational field.

If they did come back to Earth, they would not be able to adjust to the higher gravity because of a change in their physiology, including a reduction in bone density, muscle strength and circulatory system capacity.