Life from Earth may have been carried to moons of Jupiter and Saturn on rocks that blasted off our planet, scientists say.
The notion that life might travel on rocks knocked off a world's surface is known as lithopanspermia.
Researchers say if these meteoroids encase hardy enough organisms, they could seed life on another planet or moon.
Although lithopanspermia might seem far-fetched, a number of
meteorite discoveries suggest it might at least be possible,
'Astrobiology Magazine' reported.
Rachel Worth, an astrophysicist at Pennsylvania State
University and study lead author and her colleagues analysed where
batches of several thousand rocks travelled once ejected off both Earth
and Mars.
"We ended up simulating over 100,000 individual fragments," Worth said.
While most of these meteoroids slammed back into their home
planet, a great many rocks also were either swallowed by the Sun or left
the solar system entirely.
Researchers calculated that over the course of 3.5 billion
years, about 200 million meteoroids large enough to potentially shield
life from the rigours of space were blasted off Earth.
Roughly 800 million such rocks were ejected off Mars during the same period.
Scientists calculated about 83,000 meteoroids from Earth and
320,000 from Mars could have struck Jupiter after travelling 10 million
years or less.
Also, roughly 14,000 from Earth should have hit Saturn in that time, and no more than 20,000 from Mars.
Since the moons of those giant worlds are relatively close to
their planets, many of them might get peppered by these meteoroids as
well.
Researchers calculated that Saturn's moons Titan and Enceladus
and Jupiter's moons Io, Europa, Ganymede and Callisto should each have
received between one and 10 impacts both from Earth and from Mars.
These findings suggest the possibility of transfer of life from
the inner solar system to the outer moons, although very rare,
currently cannot be ruled out.
However, researchers cautioned they are not saying "that life has made it to any of these moons, just that it could.
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