14 DAY TRIAL // According to the conclusions of a new study published in the December 6 online issue of the esteemed scientific journal Astrobiology, the inner planets in our solar systems – Earth and Mars especially – may have contaminated the gas giants Jupiter and Saturn with life.
The research group behind the work admits that the possibility of this having happened is relatively remote, but argues that it cannot be ignored out of hand. The investigation was focused on a field of science called lithopanspermia, which holds that life may travel through space on asteroids and comets.
Lithopanspermia is part of a larger theoretical framework called panspermia, which suggests that life can be spread through the Universe in numerous ways. Basically, what the new study suggests is that life on early Mars and Earth may have been scattered through space after comet or asteroid collisions.
When such impacts occur, large chunks of a planet's crust can be ejected into space. A series of studies underlying panspermia has proven that microorganisms can endure the conditions of such an ejection, as well as spending prolonged periods of time in space. The latest researches suggest that the organisms can also survive atmospheric reentry on another world.
The Astrobiology study indicates that discovering life on Saturn, Jupiter, or some of their moons, should be regarded skeptically, in the sense that those organisms may share a common root with life here on Earth. Experts have already established that Earth and Mars exchanged materials many times.
More than 100 pieces of Mars have been detected on Earth to date. It is possible that materials from our planet or Mars never reached Jupiter – the closest gas giant to the Red Planet – but astronomers cannot say that for sure, Astrobiology Magazine reports.
“There have been previous simulations looking at transfer between Earth and Mars, but we wanted to scale the simulations up in the hopes of seeing transfer to Jupiter and Saturn,” says Rachel Worth, who is an astrophysicist at the Pennsylvania State University, and the lead author of the new research.
“We ended up simulating over 100,000 individual fragments” of rocks ejected from Earth and Mars following impacts,” she adds. While most of these materials ended up falling back on their planets of origins, being engulfed by the Sun, or leaving the solar system, some made their way to other worlds.
Of these rocks, most eventually landed on planets closer to the Sun. For example, most Martian rocks landed on Earth and Venus, while most Earth rocks landed on Venus and Mercury. However, a very small percent of these rocks made their way to planets located farther away from the Sun.
The group established via this model that more than 200 million meteorites large enough to encase Earth-based lifeforms were ejected into space over the last 3.5 billion years. About 83,000 of these rocks hit Jupiter, while 14,000 hit Saturn. For Mars, these figures are 324,000 and 20,000, respectively.
“When planning missions to search for life on [Jupiter's moon] Europa or other moons, scientists will have to think about whether they can distinguish between life that is or is not related to that on Earth,” the Penn State researcher explains.
This research is not meant to suggest that “life has made it to any of these moons, just that it could. To know for certain that this kind of transfer has happened, we would need to actually identify an Earth or Mars rock on one of the moons in question,” Worth says.
“We tried to make our estimates as realistic as we could, but they are still estimates, and we can never know for sure what will be discovered in the future that might change our assumptions,” she concludes.