Washington: A team of scientists including one of Indian-origin has discovered that microorganisms which crashed to Earth embedded in the fragments of distant planets might have been the sprouts of life on our planet.
Researchers from the Princeton University, the University of Arizona and the Centro de Astrobiologia (CAB) in Spain found that there is a high probability that life came to Earth - or spread from Earth to other planets - during the solar system's infancy when Earth and its planetary neighbours orbiting other stars would have been close enough to each other to exchange lots of solid material.
The findings provide the strongest support yet for 'lithopanspermia', the idea that basic life forms are distributed throughout the universe via meteorite-like planetary fragments cast forth by disruptions such as volcanic eruptions and collisions with other matter.
Eventually, another planetary system's gravity traps these roaming rocks, which can result in a mingling that transfers any living cargo.
Previous research on this possible phenomenon suggests that the speed with which solid matter hurtles through the cosmos makes the chances of being snagged by another object highly unlikely.
However the new research reconsidered lithopanspermia under a low-velocity process called weak transfer wherein solid materials meander out of the orbit of one large object into the orbit of another.
In this case, the researchers factored in velocities 50 times slower than previous estimates, or about 100 metres per second.
Using the star cluster in which the Sun was born as a model, the team conducted simulations showing that at these lower speeds the transfer of solid material from one star's planetary system to another could have been far more likely than previously thought, explained first author Edward Belbruno from Princeton in a statement.
The research suggested that of all the boulders cast off from our solar system and its closest neighbour, five to 12 out of 10,000 could have been captured by the other.
Earlier simulations had suggested chances as slim as one in a million.
Co-authors Amaya Moro-Martin, an astronomer at CAB and Renu Malhotra, a professor of planetary sciences at Arizona, noted that low velocities offer very high probabilities for the exchange of solid material via weak transfer, and also found that the timing of such an exchange could be compatible with the actual development of the solar system, as well as with the earliest known emergence of life on Earth.
The team found that the solar system and its nearest planetary-system neighbour could have swapped rocks at least 100 trillion times well before the sun struck out from its native star cluster.
The study was published in the journal Astrobiology and will be presented at the 2012 European Planetary Science Congress.