Science that moves in a religious way

Despite evidence that the red planet is a poisonous desert, James Lovelock writes, finding life on Mars remains for many scientists a Holy Grail.

In the 1930s, Electric Lane in Brixton, south London, had two intriguing establishments: Young's eel and pie shop where, in full view on a wooden slab, live eels were cut up into short, still wriggling pieces; and next door a secondhand bookshop that sold American pulp magazines. I would stop there on my way back from school and purchase, for a few pence, old issues of Astounding Stories , my favourite science-fiction magazine. I liked stories and brief novels that followed on from H. G. Wells; these sparked my adolescent imagination without seeming scientifically impossible. Journeys to Mars were prominent among them and assumed a fertile planet with an advanced civilisation.

I did not know it then, but the experience of those two shops caused me to spend much of my life as a scientist thinking about the meaning of life and how to find it on places like Mars. Therefore, I was delighted to be asked to review Laurence Bergreen's splendid book The Quest for Mars .

He writes with great distinction and skilfully reports the excitement, the disappointments and the future hopes of Martian expeditions by robot spacecraft and eventually even by astronauts. These amazing voyages during the last 30 years of the 20th century show us how wrong we were to think that there was life on Mars. With clear pictures and factual science they showed that Mars is utterly barren, indeed worse than that: the surface of Mars is poisonous and a desert more alien than we ever imagined. Dead Mars is utterly different from our own live Earth and to me these discoveries are as important to understanding life and the Earth as those that Darwin gathered during the voyage of the Beagle . Most scientists disagree and see the discovery of life on Mars, now or in the past, as their true goal. Good reporter that he is, Bergreen acknowledges the majority opinion by his revealing subtitle "The Nasa scientists and their search for life beyond Earth". I think it most unlikely that there is life anywhere in the solar system other than here on Earth, but I share with most scientists the thought that on some of the myriad planets likely to exist in the universe, life like ours is probable.

This book is easy to read but hard to put down. It is remarkably free of technical obscurities and will please a wide range of readers, from professional scientists to those still at school. The book moved me on two levels: first as an account of the human and political side of American space science and all the conflicting forces that move it and, second, as an exhibition where scientists can display their exquisitely crafted instruments and their views of the discoveries made using them.

It is a humane, yet wholly objective account of a scientific endeavour and tells a thrilling story with conviction. I know, because I was a consultant to the scientists and engineers who designed the experiments and made the spacecraft at the Jet Propulsion Laboratory, in the 1960s and 1970s. Little seems to have changed other than the individuals involved, and JPL is still a lively world. Exciting yes, but in the background there exists a cliff-hanging fear of failure that lasts from the start of a project to its embodiment in a spacecraft, the launch, and the flight across the solar system to Mars and planet fall. I am amazed to find that the constructive aggro over the shared ownership of the JPL between Nasa, a government department and Caltech, a university, still endures. So typical is the remark of a young scientist of the Pathfinder mission to Mars who says of Nasa civil servants: "They are like rusty old guns, they don't work and they can't be fired." Yet from that tension came such stunning successes as the Viking mission, whose two spacecraft, expected to work for 30 days on Mars, actually still functioned five years after landing there.

The book reveals how in spite of its proud agnosticism science quite often moves in a religious way. The belief in the presence of life on Mars held by many scientists is almost an article of faith and no amount of contrary evidence seems to shake it. Everyone in the book seems to repeat as a mantra that without water there can be no life and whenever water is found or suspected they assume the presence of life. The converse -that without life a terrestrial planet like Earth or Mars cannot retain water - is never mentioned or considered. It is burgeoning life that keeps our planet moist, and life's absence is one reason why Mars is dry.

The search for life on Mars is a quest for a Holy Grail; scientists are human and some of them need to believe in something more exciting than scientific objectivity. Many take as their legend the science fiction of Star Trek , the saga of galactic imperialism. The dull reality of a solar system, which apart from the Earth is devoid of life, is no recipe for a new episode of this astrobiological soap opera. Nasa is obliged to look for life on Mars; it would greatly prefer intelligent life but at a pinch bacteria will do. At best, it will only find ancient dead bacteria and even this is better than no signs of life at all. The wonderful thing about science is that in the end the truth prevails, so it does not matter too much why we go to Mars so long as we do.

Space scientists and engineers invest a sizeable portion of their lifespan preparing and executing one of the robot missions to Mars. About half of them fail and there is bitter disappointment when years of dedicated work crash from the peak of excitement at a flawed planet fall. The hero of this book is Jim Garvin, a planetary geologist, whom we meet first on the volcanic islet of Surtsey off Iceland. He is a member of a team that uses the Mars Global Surveyor spacecraft as if it were a spy satellite gazing down from near-space at the landscape of Mars. The spacecraft carries an exquisitely sensitive camera, a laser altimeter to measure small changes in Martian altitude, a magnetometer that discovered that Mars once had a magnetic field like the Earth, and a gravity meter. Garvin appears throughout the book to explain and reveal his thoughts about the mission and to give his personal views on its stunning success. But there is also the poignantly ignominious failure of the Mars Climate Orbiter due to a misunderstanding of metric and imperial units of force, an error almost as silly as arriving late at an airport having assumed it was 20 kilometres not miles away. It lost a spacecraft costing $100 million and several lifetimes of wasted effort. Then there was the Mars Polar Lander that did everything right except survive on landing. Bergreen wonderfully sketches Carl Sagan, the charismatic figure who was a good scientist but who lived in a world of fantasy about life on Mars. He died in 1996 but his persuasive influence still seems to haunt the corridors of Nasa. His enthusiasm helped to launch those wonderfully engineered Viking spacecraft that went to Mars in 1975 but forced them to make the search for life their only important goal. As I read, I could imagine him still arguing that somewhere on Mars was an oasis rich with life.

Carl was a good friend, though we often disagreed, and I was disappointed to read that the Viking project scientist, Gerry Soffen, attributes to him the idea of finding life on Mars and other places through the presence of disequilibria. In other words, the idea of using life's tendency to change the chemistry and physics of a planet and so make it recognisably different from a dead planet. Were he still alive, Sagan would be the first to admit he did not think of this, but read it in a report I wrote for Nasa in April 1964, and which subsequently appeared as a Nature paper; he even argued against it. The fact is important because the search for atmospheric disequilibria is a promising way to detect life on planets outside the solar system and Nasa will have to use it if and when we have the telescopes able to see Earth-like extra-solar planets. It was also the thinking that led to Gaia theory and "earth system science".

Understanding the Earth is by far our most pressing need, but it would be wrong to think on this account that Nasa's exploration of Mars is a waste of time and money. Just as the print you read stands out against the white background of paper, so we need the contrast of a dead planet to understand the living planet we now inhabit. Medical science grew in understanding by examining dead bodies and we should look on Mars as an awful example of what happens when a planet either never had life, or lost it. I wish that Nasa would consider a proper understanding of Mars as a planet to be of equal importance as the search for life.

I treasure this book for the intensity of its detail. I learnt from it that the more powerful rockets were reserved for the CIA's spy satellites. Space science, like most of science, is inextricably linked with war. The Apollo mission would have never happened but for the tension between the Soviet Union and the United States. Throughout history, war and science have been in bed together and were fecund. Archimedes's catapults successfully defended Syracuse in 215 BC; later the British admiralty asked Newton to help them improve their gunnery and he did; Darwin's voyage was on a naval ship and Ernst Mach worked with the Austro-Hungarian army. It is easy to forget that the rockets that lifted our instruments into space were first built for military cargoes.

Perhaps some day when a manned expedition at last lands on Mars, among them will be an astronaut who is as good a storyteller as Bergreen and will tell the story as it really is. We need tales of epic journeys to lift our spirits in the darker years to come.

James Lovelock is an independent scientist who recently published his autobiography, Homage to Gaia .