JPL-Caltech / NASA
The glowing surface of Europa, Jupiter’s mysterious moon
A team of scientists has discovered that tiny grains of dust ejected from Earth’s atmosphere may have escaped the planet’s gravity, crossed interplanetary space and reached the icy surface of Europa, one of Jupiter’s moons.
In a new one, published last month in International Journal of Astrobiologyresearchers argue that dust particles from Earth, potentially carrying bacteria, may have reached the surface of this satellite in surprising quantities.
The work proposes a scenario of panspermia inversa. Instead of life from space arriving on Earth, the hypothesis suggests that terrestrial biological material may have traveled to another oceanic world in the Solar System.
According to , the study is based on the premise that particles with a diameter of around one micrometer could carry bacteria of a similar size, as long as, throughout the journey, they were not exposed to temperatures higher than approximately 27 °C.
According to the calculations presented, some dust grains released from the upper layers of the Earth’s atmosphere, approximately 150 kilometers altitudecould reach speeds sufficient to surpass Earth’s escape velocity.
Once released from the Earth’s gravitational field, these particles would be subject to the pressure of solar radiation, Jupiter’s gravity and the resistance of the interplanetary medium.
The model indicates, however, that only a very small fraction would survive the impact with Europa’s surface. To avoid destruction during collision with the ice, the grains would have to enter at an extremely low angle of about one degree to the surface.
Still, researchers estimate that about 300 million particles from Earth could reach Europa every second.
Over the course of approx. 3.5 billion years during which the total number of particles that could have reached this moon would amount to about 800,000 billion grains of dustaccording to the authors. This is such a large amount that it makes this hypothesis difficult to imagine.
Europa is covered by an ice crust, but beneath this layer lies a deep subsurface ocean, considered by scientists to be one of the most promising environments for the search for extraterrestrial life.
The study is also based on previous work that identified cracks in around 20% a 40% of the icy crust. These fractures would result from the heating caused by gravitational tides and the tensions generated by the influence of Jupiter.
According to the researchers, these fissures could act as access routes to deeper layers of ice and, eventually, to the underground ocean, before the bacteria become inactive due to the intense radiation reaching the surface. This process may take place over approximately 10 thousand years.
The presence of terrestrial particles in Europa’s subsurface ocean would therefore be plausible if there are biological and biochemical conditions compatible with their survival. The hypothesis reinforces scientific interest in this icy moon and makes Europa an even more fascinating target for astrobiology.
