Water and the Search for Life on Mars

"Why explore Mars? The simple answer is, we're going to Mars to search for life. We're following the water because on Earth where you find liquid water, organic material, and energy, you find life." u find life"

Ed Weiler, NASA's Associate Administrator for Space Science

Ear where you find liquid water,

A century ago, the world was enthralled by Percival Lowell's vision of a Mars criss-crossed with the canals of a dying civilization distributing water from the polar caps. Later, Mars was thought to have been cold, dead and dry for eons, but striking new evidence suggests the planet was relatively warm and wet in geologically recent times, and that even now there are reserves of water frozen beneath the planet's surface.

Today, robot spacecraft maneuver across the Martian surface while others orbit overhead seeking evidence of water, ice, and landing sites for further exploration. In recent years, the very possibilities for life have dramatically expanded as discoveries by biologists and oceanographers have revealed bizarre life forms where none would have been expected. And as the growing evidence that water flowed on Mars becomes indisputable, more spacecraft are soon to follow.

This highly absorbing book relates how NASA and ESA have sought evidence of life on Mars. 'Follow the water' with noted science writer David Harland as he assembles and weighs the evidence in this timely and compelling book. It contains what you need to know behind today's, and possibly tomorrow's, headlines, including details of the Mariner, Viking, and Pathfinder missions and evolving theories of Martian geology and climate. It explains how the search accelerates with the Mars Orbiter and Mars Exploration Rovers Spirit and Opportunity. Harland sets this within the broader perspective of the likely nature of life on Mars as compared to primitive life on Earth. Finally, he analyzes the implications of there beinglife on both planets. Join the scientific adventure of a lifetime in this well-researched and thoroughly engrossing true account.

Résumé

Mars has long been believed to have been cold, dead and dry for aeons, but there is now striking new proof that not only was Mars a relatively warm and wet place in geologically recent times, but that even today there are vast reserves of water frozen beneath the planet's surface. As well as casting fascinating new insights into Mars' past, this discovery is also forcing a complete rethink about the mechanisms of global planetary change and the possibility that there is microbial life on Mars.

David Harland considers the issue of life on Mars in parallel with the origin of life on Earth. At the time the Viking instruments were designed, it was thought that all terrestrial life ultimately derived its energy from sunlight, and that the earliest form of life was the cyanobacteria with chlorophyll for photosynthesis. It was assumed the same would be the case on Mars and that microbial life would be on or near the surface that the Vikings had sampled.

In parallel with these NASA projects, the European Space Agency developed the Mars Express remote-sensing orbiter, which has detected traces of methane that may have been released by microbes. If microbial life is found on Mars, will it be based on DNA? Will this indicate that life developed independently? Or that it has characteristics in common with the most ancient forms of terrestrial life? If life is found on two planets in the same planetary system, this would favour the panspermia hypothesis. And if martian life is radically different, then in light of the discovery of planetary systems around other stars, this would, as remarked by Philip Morrison of MIT, "transform life from the status of a miracle to that of a statistic". These are all questions that the exploration of Mars for life are aimed to answer.

Contenu
Peering at Mars.- A close look.- The Vikings.- What is life?.- A multiplicity of missions.- The water dilemma.- Spirit.- Opportunity.- Future prospects.