The International Space Station is the centre of attention for human spaceflight for the near future. But what comes next?

A whole universe waiting to be discovered

There's a whole universe waiting out there to be discovered: the astronauts who fly on board the Space Station's 400-km high orbit are really just dipping their toes into the limitless of ocean of space. Already, ESA and other space agencies are involved in careful long-term planning that might see humans travelling further out into our Solar System.

Where to begin? If space is an ocean, then the Moon is our nearest island. The last time it saw human visitors was in December 1972, when the final American Apollo astronauts returned from a mission to the lunar highlands. But space scientists have not been ignoring the Moon for the last thirty years. Instead, a series of space probes in the 1990s have sent back information that could make future human missions both easier and more useful.

Artist's view of a lunar base

The most exciting possibility is that water may exist on the Moon's airless and apparently bone-dry surface, frozen in the permanent shadows of deep craters near the Moon's poles. The water is probably left over from comet impacts millions of years ago – which makes it scientifically very interesting. Comets are made from the original material that formed the Solar System almost five billion years ago. It would be nice to find a sample of the stuff almost in our own backyard.

That water could also make a lunar base possible. Astronauts could use solar power to convert it into oxygen and even rocket fuel. At the very least, lunar water would greatly reduce the need to ferry water supplies from Earth.