Human beings are to go back to the Moon within the next 15 years and this time they will stay, according to ambitious plans to establish a lunar base announced by Nasa.

The first manned mission to Earth’s satellite in two generations will blast off by 2020 to start work on an outpost that eventually will be occupied permanently, the US space agency said.

At first, crews of four will make week-long runs to the Moon, before larger missions make progressively longer trips to build up living modules and power plants. The goal is to establish a full-time human presence by 2024, with astronauts spending six-month tours at the lunar base.

The station will operate chiefly as a science laboratory preparing for manned missions to Mars, developing and testing survival technology and serving as a staging post for flights to the Red Planet. Scott Horowitz, the associate administrator for exploration systems at Nasa, said: “With such an outpost, Nasa can learn to use the Moon’s natural resources to live off the land, make preparations for a journey to Mars, conduct a wide range of scientific investigations and encourage international participation.”

The plan to return astronauts to the Moon for the first time since Gene Cernan and Harrison Schmitt left aboard Apollo 17 in December 1972 was announced by President Bush two years ago.

Nasa has decided now that this should involve a permanent base after canvassing the opinions of more than 1,000 scientists from 14 countries, including Britain, and is open to the idea of making the outpost an international project.

Nasa officials said that the scheme would have to be accomplished within the agency’s existing budget, though they would not be drawn on how much it would cost. The hope is that funds made available by the retirement of the space shuttle fleet in 2010 and the completion of the International Space Station could be diverted to the lunar base, and that other nations will also invest.

It is certain to be very expensive, with a total cost running into hundreds of billions of pounds. Last year, Nasa said that the cost of planning an initial return to the Moon would exceed $100 billion (£51 billion).

Michael Griffin, the agency’s administrator, has likened the project to the exploration of Antarctica during the last century. The first explorers, such as Amundsen, Scott and Shackleton, went there only for short missions, and the continent was then largely ignored for decades after their accomplishments. It was only in the second half of the century that scientists returned to establish research stations.

Appropriately, the most likely location for the lunar base is the Moon’s south pole, which is among the more hospitable places for human habitation and one of the most interesting for scientists to study.

Both poles are under consideration because they have more moderate temperatures and receive more sunlight than the equatorial regions visited by the Apollo missions. The sunlight is particularly important as a base would have to rely on solar power, at least in its early years before nuclear power could be used.

One attractive site is the Shackleton Crater, close to the south pole, which is almost permanently sunlit. It is also thought to hold deposits of oxygen and hydrogen, which could be extracted to provide the station with resources that would not then have to be ferried from Earth.

Shana Dale, the Nasa deputy administrator, highlighted the Shackleton Crater as a promising option. “It’s exciting. We don’t know as much about the polar regions.”

Before astronauts make the trip, Nasa will first explore the Moon further with robotic missions to scout suitable landing sites. The Lunar Reconnaissance Orbiter is scheduled to be launched in 2008 to survey the lunar surface, and robotic landers are planned for 2010 and beyond.

Human crews would then fly to and from the Moon using the Orion exploration vehicle that will succeed the space shuttle. This will be launched by Nasa’s new Ares rockets.

A suitable lunar lander, however, has yet to be designed. It is likely to be a hybrid craft, capable of landing and acting as the first habitation module for the permanent base.

Some scientists, however, have questioned whether a lunar base is the best use of Nasa’s resources. “There’s a great temptation to jump on the bandwagon completely as some people say the train’s leaving the station and we’ve got to be on it,” Dan Lester, of the University of Texas, told the website Space.com. “We are saying that might be a little naive.”

Lunar goals

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