“Efforts made today and in the next decade will lay the foundation for an Earth Independent, sustained presence in deep space. Living and working in space require accepting risk and the journey is worth the risk.”

Nasa has divided the challenge of getting to Mars into three stages; Earth reliant, proving ground and Earth independent.

In the coming decades the space agency will continue to gather information from experiments aboard the International Space Station, so that crews can live in deep space without health problems from radiation and the effects of micro-gravity.

Currently the amount of time astronauts can spend in space is limited because of fears that space radiation causes cancer. Many crew members also need glasses after returning from space because the effects of micro-gravity causes pressure to build up in the optic nerve. There are also fears that astronauts could develop dementia or suffer fertility problems.

The first experiments away from the ISS will take place in cislunar space – the area of space around the Moon – before missions begin venturing further afield.

The final step will see human missions sent into Mars’ orbit or one of its moons, before crews eventually land on the Martian surface and set up colonies using modular architecture and 3-D printing.

“NASA is closer to sending American astronauts to Mars than at any point in our history,” said NASA Administrator Charles Bolden.

“Today, we are publishing additional details about our journey to Mars plan and how we are aligning all of our work in support of this goal. In the coming weeks, I look forward to continuing to discuss the details of our plan with members of Congress, as well as our commercial and our international and partners, many of whom will be attending the International Astronautical Congress next week.”

Nasa says it is also committed to designing ‘a new and powerful transportation’ system which will involve solar electric propulsion, using the Sun’s energy to take spacecraft deeper into space. Cargo ships will being shuttling supplies to Mars, months or even years before the first humans land.

It is hoping that the upcoming Asteroid Redirect Mission, which seeks to bring an asteroid into lunar orbit where it can be studied, will be using solar propulsion, and Mars scientists will be following its progress closesly.

“NASA’s strategy connects near-term activities and capability development to the journey to Mars and a future with a sustainable human presence in deep space,” said William Gerstenmaier, associate administrator for Human Exploration and Operations at NASA Headquarters.”

Probes and robotic rovers like Curiosity have already been on or around Mars for 40 years and Nasa will continue to send new landers in the coming decades to gather more information about the planet ahead of landing. Recent discoveries have shown that salt water which could sustain life is likely to be flowing on Mars. The remains of ancient lakes and river beds are also present.

The report concludes: “NASA and its partners are working on the solutions every day so we can answer some of humanity’s fundamental questions about life beyond Earth: Was Mars home to microbial life? Is it today? Could it be a safe home for humans one day? What can it teach us about life elsewhere in the cosmos or how life began on Earth? What can it teach us about Earth’s past, present and future?”

However Nasa may be beaten. The Mars One project, set up by a nonprofit organization based in the Netherlands has proposed to land the first humans on Mars and establish a permanent human colony there by 2027.