Space rocks could have spawned life on Earth

New research presents more evidence for lithopanspermia theory


Credit: NASA, ESA and Jesús Maíz Apellániz (Instituto de Astrofísica de Andalucía)

The Sun may have spent its early years in a young star cluster like Pismis 24.

How did life begin on Earth? It’s a question that scientists and philosophers have asked for thousands of years. But new research by an international team suggests that the first traces of life could have arrived from outer space, hitchhiking on fragments of rock from distant planets.

The team, made up of scientists from Princeton University, the University of Arizona and the Centro de Astrobiología (CAB) in Spain, believe microorganisms could have travelled to Earth some time during the early Solar System, when our planet and its neighbours were close enough to exchange material.

These findings are based on the theory of lithopanspermia, the idea that basic life forms were scattered across the Universe on planetary fragments from things like volcanic eruptions and collisions with asteroids, and that eventually these rocks were captured by another object’s gravity.

This controversial theory had been shunned in the past after research suggested that the speed at which these fragments travel through space made the likelihood of them being trapped by the gravity of another planet very small.

But in a series of new computer simulations of the star cluster our Sun was born in, it appears that these fragments could have actually been moving far slower than previously thought, gradually leaving the orbit of one object and entering into the orbit of another. Edward Belbruno first demonstrated this process, known as weak transfer, in 1991, when he was able to guide the Hiten probe to the Moon using only small amounts of fuel.

Furthermore, evidence from rocks on Earth dating back to the Sun's early years, suggests our planet contained surface water, vital in sustaining life, during a period when the speeds of objects travelling between the Sun and its closest neighbours were small enough to allow weak transfer to take place.

This new research has huge implications for life in the Universe, as lithopanspermia could have been replicated on other Earth-like planets, where life could flourish.


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