Earth may have helped produce alien life on several other planets, experts say.
Long before astronauts flew into the stars, it is believed that tiny bacteria were carried 150 km into orbit by high-speed vertical winds.
The microorganisms would have been trapped in space dust at hyperspeed and sent vast distances to alien worlds where they delivered life.
Life on Earth could have started by the same method with the arrival of organic matter from elsewhere, think the boffins.
A study by Professor Arjun Berera (corr), of the School of Physics and Astronomy at the University of Edinburgh, notes that the biosphere – the parts of the Earth where life is known – previously extended to a altitude of 77 km.
This was the highest point at which fungal spores were found.
But dust samples from outside the International Space Station – which orbits 400 km – were found to contain DNA from several types of bacteria similar to those found around the Barents Sea, where the Gulf Stream meets the frigid arctic. Studies suggest that this biological material was deposited on the ISS while it was in orbit rather than being transported into space by it or by visiting astronauts.
Professor Berera’s article says vertical winds can blow at speeds of up to 150 meters per second, especially during geomagnetic storms near the Earth’s poles.
His team calculated that small particles the size of bacteria could be thrown up to at least 120 km into the air by these winds and reach higher altitudes.
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About 150 km from space, the dust that hisses through Earth’s atmosphere has enough momentum to facilitate the planetary escape of biological particles.
The study indicates that this raises the possibility of a transfer of life to and from neighboring planets. Such events would be rare but over the millennia can have astrobiological significance.
The professor said: “All it takes is maybe a few biological particles to escape and maybe sow life. If a biological particle escapes from Earth and lands on something that was conducive to life, biology tends to develop quite easily.
“Even though the probability of an escape event to occur is quite low, such as once every 50 years, if you think about long geological timescales, many potential life transfer events could occur from of this mechanism. “
His study indicates that the process would be even easier on Mars where the gravity is lower and the atmosphere thinner.