The Next Fifty Years by John Brockman

Author:John Brockman
Language: eng
Format: epub
Tags: Fiction
ISBN: 9780307429070
Publisher: Knopf Doubleday Publishing Group
Published: 2009-04-01T16:00:00+00:00

PAUL DAVIES

Was There a Second Genesis?

“THAT MARS IS INHABITED by beings of one sort or other is as certain as it is uncertain what those beings may be.” With these dramatic words, the American astronomer Percival Lowell informed the world about a network of canals he thought existed on the Red Planet. Lowell conjectured that Mars was a dying, drying planet, whose inhabitants built channels to bring melt water from the polar caps to the arid equatorial regions. He produced elaborate maps to support his theory.

That was in 1906, when the idea of life on Mars seemed entirely plausible. H. G. Wells brilliantly exploited this belief in his highly successful book The War of the Worlds, written in 1898. Many astronomers at least paid lip service to the possibility that Mars might harbor some form of life. Then in the 1960s the Mariner space probes sent to Mars failed to reveal any sign of the much discussed canals. In 1976 two NASA spacecraft landed on Mars and found a desolate, lifeless terrain. They scooped up dirt and analyzed it for microbes and traces of organic compounds. Nothing was found. The Red Planet seemed to be a freeze-dried desert bathed in lethal ultraviolet rays. In short, Mars looked dead—very dead.

Recently, however, opinion has begun to shift. Maybe we were too hasty in writing off Mars as an abode for life. The early photographs of the surface from the Mariner series showed dried-up river channels, while the much more detailed pictures from the Mars Global Surveyor orbiter, obtained in the last few years, reveal what look like floodplains, dried-up lake beds, and even the hint of an ancient ocean. Evidently Mars was once warm and wet, and not unlike our own planet. Could life have flourished there in the remote past? Might it still be clinging on today in some obscure niche?

There is a good chance we shall learn the answers to these questions in the next fifty years. The nascent subject of astrobiology looks set to advance dramatically over the coming decades, and research projects such as NASA’s Origins Program promise to make the technology available for us to seek out life beyond Earth and address the age-old question: Are we alone? As the one planet (besides Earth) in our solar system accessible to human exploration, Mars will receive special attention. Motivation to go there is strong. It could be our only chance of studying a second genesis, another location in the universe where life has emerged from nonlife.

Where exactly must we look for life on Mars? Its surface is forbiddingly hostile to any form of familiar life, for which liquid water is essential. There is abundant water ice at the poles, but the temperature is far too low for it to melt. Even if it did, the liquid would rapidly evaporate, because the atmospheric pressure on Mars is less than 1 percent of that on Earth. In the past, Mars must have had a much thicker atmosphere, laden with greenhouse

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