Dream on: Lunar pioneers reach for the stars

A BRANCH of science that has been languishing for decade will be revived. In the 1970s, the Moon was declared dry (by the Apollo missions, which landed on the equivalent of the Equator) and Mars declared dead (by the Viking landers).

People who wanted us to set up permanent bases on both those bodies were turned back from their grand plans, as others asked: why spend billions of dollars or pounds of public money to go to places which are so hostile, and useless?

In the past 18 months though, Mars has been declared to have had life (at least, scientists reckoned so) and now the Moon to have water.

Suddenly, space travel is back on the agenda. For not only does the Moon have water at its poles, but planetary geologists reckon there is water at Mars's poles too.

Water matters because humans need at least two litres a day to survive. However, carrying it out of the Earth's gravitational field is very expensive because it is heavy and can't be compressed: two litres of water will always take up two litres of space and weigh two kilograms. Raising that out of the Earth's gravity will cost pounds 14,000 in fuel. Providing enough for a permanent lunar colony would require regular supply ships and that makes a base on a dry Moon impractical.

But if there is water already there, everything changes. "When you're thinking of a permanent lunar base, this makes it possible," said Dr Ellen Stofan, a Nasa scientist who is planning studies for water on Mars.

Ice can be melted for drinking; and it can be electrolysed (using the free solar power) into oxygen for breathing, and hydrogen as a rocket fuel.

"It's terribly exciting in terms of potential, as a science base if nothing else." It would be a perfect site for astronomical observation: if you thought the Hubble Space Telescope produced impressive pictures, wait until there's a Moon Observatory.

But it's not the science value that people see. The Moon could be used as an assembly base for new rockets which would take off for more distant targets: initially Mars, but in time even further afield.

A low-gravity base would be an ideal staging post on the way to other planets. For instance, a Mars mission could send its rocket to the Moon partly-fuelled, or even partly-built; then you could finish building it in low gravity. "Anything that we don't have to lift out of the Earth's gravity is a saving," said Dr Stofan.

A further advantage is that if something goes wrong, it's easier to escape from the Moon than from a mission to Mars. "It's only three days away," explained Dr Stofan. "You can bail out more easily - it's a whole different thing if you're eight or nine months out."

How soon will it arrive, and how big will it be? That depends on how easy it is to build reliable shelters - safe from meteorites - and to mine the ice. Certainly, by the middle of the next century there will be something permanent there.

How much will it cost? Certainly, billions. "It will take an international effort," said Dr Stofan. "But I think that's the way everybody would want to do it." However, she doesn't see it supplanting the present efforts to build an International Space Station to replace the aging Mir. "The space station is the first step in working outside the Earth's atmosphere," said Dr Stofan. "But you have to do it slowly. We've never tried to build anything in space. People forget how complex it is: they see Star Trek on TV and think 'Oh, we're there already'. Really, it's much more complicated, and we have to do it one step at a time."