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Early Earth haze may have contributed to formation and sustenance of life
Washington | November 07, 2006 12:14:59 PM IST
A new study by scientists at the University of Colorado, Boulder, shows that hazy skies on early Earth could have provided a substantial source of organic material useful for emerging life on the planet. For their study published in the proceedings for the National Academy of Sciences, the researchers measured organic particles produced from the kind of atmospheric gases thought to be present on early Earth. The laboratory experiment modelled conditions measured by the Huygens probe on Saturn's moon, Titan, last year during the NASA-European Space Agency's Cassini mission. Margaret Tolbert, one of the study authors, says that they mimicked hazy skies of Saturn's moon, Titan, by exposing methane gas to an ultraviolet lamp, and then added carbon dioxide gas to the mix to see if conditions that were probably present on early Earth would produce a similar organic haze. "It turns out that organic haze can form over a wide range of methane and carbon dioxide concentrations. This means that hazy conditions could have been present for many millions or even a billion years on Earth while life was evolving," she said. Study co-author Melissa Trainer said that the atmospheric chemistry of Titan might hold valuable clues to understanding the climate on Earth when life was just forming, as it is an unusual solar system moon that has an atmosphere made of organic aerosol particles, which are formed through photochemical processes when sunlight reacts with methane gas. She said that a similar haze hanging over Earth early in its history could have supplied more than 100 million tons of organic material to the planet's surface each year. "As these particles settled out of the skies, they would have provided a global source of food for living organisms," said Trainer. Tolbert said that previous studies on the understanding of early life on Earth were focused on extreme environments like hydrothermal vents, where energy and nutrients are plentiful. But the new study shows that such a high-energy food source could have been produced globally early in Earth's history, possibly expanding the habitable domain for early life. The study also shows that besides serving as a source of organic material, a haze layer over Earth could have shielded living organisms from harmful UV rays and helped to regulate the planet's climate. "It's exciting to see that the early Earth experiments produced so much organic matter. An organic haze produced this way on early Earth could have contributed to the formation and sustenance of life," said Carl Pilcher, director of NASA's Astrobiology Institute, headquartered at NASA Ames. (ANI)
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