In the pink

Oliver Morton introduces Duncan Steel to some Martians in Mapping Mars

Mapping Mars: Science, Imagination and the Birth of a World
by Oliver Morton
368pp, Fourth Estate, £18.99

Why do we call Mars the "Red Planet"? Scan the sky, and if it's bright enough to stimulate your retinal cones, the planet surely looks pink. We have landed probes on Mars. And what colour does the Martian sky appear in their cameras? That's right, pink. If Mars were a wine, we'd call it rosé. Look at the surface of Mars in detail, though, and it's red, largely due to its iron content. Rust, if you like.

This brings to mind the apocryphal story concerning corporate sponsorship for a manned Mars mission. The spacecraft is loaded with white paint, so that the astronauts can draw a long swirling line across the planet's face, and then add the words: Coca-Cola. An advertising hoarding to end them all.

Oliver Morton's book - longlisted this week for the Guardian first book award - is indeed concerned with drawing a line on Mars. Actually, lots of them: lines of latitude and longitude. How do you map another planet?

Fundamentally, Morton writes not so much about Mars, as Martians - but not little green men. In 1979 I went to the University of Colorado, to become a research student. I worked on a Nasa probe then in orbit around Venus. Mars was out of fashion with most of the US space hierarchy, but not with a group of my fellow students. Calling themselves the Mars Underground, they had a sign on their door which boldly stated: "The Martians are here, and they are Us."

What they meant was that the first Martians will be humans. One day men and women will live on Mars. That will come about by terraforming (making Earth-like) the planet. An earlier necessary achievement, though, is to explore and understand Mars. And the first step in that process is to map it.

This is being done by people, not by machines. One of my bugbears is reports that the Hubble Space Telescope has observed this, or the Galileo space probe has discovered that. This is called personification. People discover things, often helped by such inanimate if sophisticated tools. Lose sight of that, and you mislay a core characteristic of our species. So many science books are tedious because the authors ignore this, taking a mechanistic view, missing the fact that science is a human pursuit. Not for one moment could Morton be thus accused.

He writes about the men and women who have mapped Mars, albeit often from the comparative comfort of an office in Pasadena or Houston, rather than braving that planet's ferocious elements. Not that this applies to everyone: my friend Chris McKay dives under the ice in the frozen lakes of the Antarctic, studying the algal mats that eke out a living on the bottom, because he thinks that life may exist in similar habitats on Mars. Others risk their lives in New Mexico cave systems, or in the Gobi desert, for similar reasons.

The Martians involved are many and various. Not just scientists - and if you think scientists are boring, meet a few between these covers - but also sci-fi authors, and space artists, who have pictured Mars in their imaginations, showing what might be. Personalities there are aplenty, and Morton unveils their arguments, and prejudices.

This is science writing at its best. You don't need to have any great interest in astronomy to enjoy this book. If nothing else it will help you understand just what, despite their pitiful salaries, drives scientists to do what they do.

· Duncan Steel is working on a book about Earth's natural calendrical meridian