For more than two decades, scientists have wondered whether extraterrestrial life can flourish deep beneath the ice crusts that can boast of moons in our outer Solar system. Space missions like Galileo to Jupiter and Cassini to Saturn has stumbled upon evidence that some of the moons hide the global oceans, heated by the gravity of giant planets in orbits which they rotate. And researchers at the ocean, located much closer to home, found a vibrant community living in the dark around geological objects on the ocean floor.
Combine those two facts and can easily imagine an alien seas teeming with germs. But a new study looks deeper into the rock, and suggests that these worlds can be dead inside, not only biologically but also geologically.
“We wondered what it would be like if you were on a submarine and can fly over the surface of the ocean floor on Europa (Jupiter’s moon),” says lead author Paul Byrne, a planetary geologist from the University of North Carolina.
It is on the seabed astrobiologists hoping to find heated and full of minerals sea water spewing into the ocean, like the hydrothermal vents and black the den on the Ground. In our oceans, these elements support the bustling community of microbes that can eat formed in the place of chemicals, where the constant churning of hot stones and sea water. If such structures are found in the ocean of alien worlds, the prospect of finding life on planets far from the Sun, will become closer to reality.
“I was hoping that we will be able to describe how should look like a chain of volcanoes, which will be similar to fault zones — and suddenly came to the conclusion: well, it looks like they won’t be there,” says Byrne.
Before coming to this conclusion, scientists are focusing on the breed itself and determined what force it would take to break the stone in two ways, which we know on Earth: the usual faults that occur when a rock breaks and cracks that occur when rocks are compressed, requiring more power. The more power is required for the destruction of the breed, the less geologic activity occurs, and therefore less interactions between fresh rocks and the alien water, which in theory could support life.
Byrne and his colleagues focused on four ocean worlds: satellites of Jupiter, Europe and Ganymede and Saturn — Enceladus and Titan. For each of these worlds has been calculated strength of the rocks. While there are many questions about these satellites that we are not yet able to answer, it turns out that the calculations of the strength of the breed, which are usually made on the Ground for the extraction of minerals, is fine.
These calculations are based on the thickness of the cold, hard layer of rock that lies on top of a warm and soft layer, which can not be broken. Help analogy. “Imagine a Mars bar or Milky Way chocolate for caramel,” says Byrne. “Glaze can be considered as a brittle hard layer”. Than it is thicker, the harder it is to break.
The researchers then added the other quantities such as the gravity body at a predetermined depth, the weight of water and ice on the rocky surface of the moon. Even when they included a range of likely values for the unknown input estimates for each of the moon fit into one range.
Byrne said that these initial results, which he represented at the conference, suggest that the rock is so durable that all of these satellites does not reach enough power to regularly crumble. The case in the vast weight of water and ice, lying on the rock. The breed is strong, because even in the absence of strong gravity it is a lot of water.
Each moon, which was studied by the team showed different calculated toughness of the breed, but the results were not particularly promising for a possible aliens or geological presentations. “In Europe, it seems, are hard to make some kind of crack or fault, but on Titan and Ganymede nothing was happening,” says Byrne.
The strength of the breed of Enceladus is not so high, because the moon is much smaller than the other three, and thus the whole water and ice on its rocky surface will be less. And the rocky core is more porous. If these pores will line up, they can bring the water to a depth. Maybe Enceladus is the most promising companion all of these.
In addition, the Enceladus water and stone do interact — we saw the plumes spewing into space, in which Cassini found organic compounds.