September 24, 2012
More Evidence That Life Was Delivered By Space Rocks
Lee Rannals for redOrbit.com — Your Universe Online
Astronomers have provided more evidence that life was delivered to Earth through collisions with objects like asteroids.Researchers presented a paper at the European Planetary Sciences Congress on Tuesday, showing microorganisms that crashed to Earth might have been what sparked life.
The astronomers report under certain conditions there is a high probability that life came to Earth during the Solar System's infancy when Earth would have been close enough to planetary neighbors to exchange solid material.
The findings provide the strongest evidence that life forms are distributed throughout the Universe through meteorite-like planetary fragments cast by disruptions like volcanic eruptions and collisions with asteroids.
Previous research suggested that the speed at which objects hurtle through space made the chance of them being captured by another planet very small.
This new research suggests that a process called weak transfer greatly increases the odds that this process could have taken place. The study is based on principles of weak transfer developed by mathematician Edward Belbruno.
"Our work says the opposite of most previous work," Belbruno said in a statement. “It says that lithopanspermia might have been very likely, and it may be the first paper to demonstrate that. If this mechanism is true, it has implications for life in the universe as a whole. This could have happened anywhere."
The astronomer said that low velocities offer high probabilities for the exchange of solid material through weak transfer, and also found that the timing of these exchanges should be compatible with the actual development of the Solar System.
The team reports that the Solar System, and its nearest planetary-system neighbor could have swapped rocks at least 100 trillion times before the Sun jumped out from its native star cluster.
The evidence also shows that basic life forms could date from the Sun's birth cluster days.
"The conclusion from our work," Amaya Moro-MartÃn, who also worked on the project, said in a statement, "is that the weak transfer mechanism makes lithopanspermia a viable hypothesis because it would have allowed large quantities of solid material to be exchanged between planetary systems, and involves timescales that could potentially allow the survival of microorganisms embedded in large boulders."
The research shows that the exchange of material between different planetary systems is likely, but it stops short when the solid matter is captured by the second planetary system.
"The study of the probability of landing on a terrestrial planet is work that we now know is worth doing because large quantities of solid material originating from the first planetary system may be trapped by the second planetary system, waiting to land on a terrestrial planet," Moro-MartÃn said in a statement. "Our study does not prove lithopanspermia actually took place, but it indicates that it is an open possibility."