Saturday, 13 June 2009

New mechanism may double a planet's lifespan
Washington : A team of scientists from the California Institute of Technology (Caltech) has come up with a mechanism that doubles the future lifespan of the biosphere of a planet, while also increasing the chance that advanced life will be found elsewhere in the universe.
As the sun has matured over the
past 4.5 billion years, it has become both brighter and hotter, increasing the amount of solar radiation received by Earth, along with surface temperatures.
Earth has coped by reducing the amount of carbon dioxide in the atmosphere, thus reducing the warming effect.
According to Joseph L. Kirschvink, the Nico and Marilyn Van Wingen Professor of Geobiology at Caltech, the problem is that “we’re nearing the point where there’s not enough carbon dioxide left to regulate temperatures following the same procedures.”
Kirschvink and his collaborators Yuk L. Yung, a Caltech professor of planetary science, and graduate students King-Fai Li and Kaveh Pahlevan, say that the solution is to reduce substantially the total pressure of the atmosphere itself, by removing massive amounts of molecular nitrogen, the largely nonreactive gas that makes up about 78 percent of the atmosphere.
This would regulate the surface temperatures and allow carbon dioxide to remain in the atmosphere, to support life, and could tack an additional 1.3 billion years onto Earth’s expected lifespan.
Increasing the lifespan of our biosphere, from roughly 1 billion to 2.3 billion years, has intriguing implications for the search for life elsewhere in the universe.
The length of the existence of advanced life is a variable in the Drake equation, astronomer Frank Drake’s famous formula for estimating the number of intelligent extraterrestrial civilizations in the galaxy.
Doubling the duration of Earth’s biosphere effectively doubles the odds that intelligent life will be found elsewhere in the galaxy.
“It didn’t take very long to produce life on the planet, but it takes a very long time to develop advanced life,” said Yung.
On Earth, this process took four billion years.
“Adding an additional billion years gives us more time to develop, and more time to encounter advanced civilizations, whose own existence might be prolonged by this mechanism. It gives us a chance to meet,” said Yung.

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