When the Earth came into being, it was too hot for water. But where did she come from then? Two new studies reveal how Jupiter played a role.
Humanity exists because there was a real explosion. And more than once. During the birth hours of the solar system, dust particles first formed small pieces, and then large asteroids. Massive bodies constantly merged with each other and melted into a new body. In the end, only a few planetary debris remained, which gradually cleared their way around the sun. This is how the Earth appeared 4.5 billion years ago.
This theory of the origin of the Earth is a scientific compromise. Only he does not answer all the questions. Where did water come from on the blue planet? After all, researchers are unanimous in the opinion that when the Earth formed, it was too hot for water molecules. There are several theories about its origins.
Two relevant studies at once promote one of the newest theories, according to which Jupiter played a leading role. Water and other liquid substances were brought to Earth not in the way they thought about it earlier, at a later stage with the help of comets and asteroids, but already at the first stage of the planet's emergence.
In the beginning there was a heat
When the cosmic bombardment took place, the temperature inside the solar system was so high that water only existed in the form of gas. But the young, unformed planets could not accept this gas. Instead, a strong solar wind carried it into the depths of space. Only later did the vital chemical compound H20 return from the outer, cold solar system. When? And How?
Research by scientists Mario Fischer-Gödde and Thorsten Kleine from the University of Münster indicates that the strange motion of the planet Jupiter during the solar system's first million years brought water back to Earth. These data contradict the widespread theory, according to which water ended up on Earth only in the last phase of the Earth's origin 4.4-3.9 billion years ago with the help of meteorites and asteroids. Their main argument is the rare element Ruthenium.
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The material has special properties. It gravitates towards iron, siderophilic, as the researchers say, and therefore, in the early stages of the planet's emergence, for the most part sank to the core, which contains iron. But ruthenium is also found in the layers of the Earth's crust and mantle. Ideal for Fischer-Gedde and Kleine, because by doing so they know what to tell about the recent history of the Earth.
Wandering Jupiter
Terrestrial ruthenium has a specific composition. It is composed of atoms with different numbers of neutrons, isotopes, and thus possesses a kind of chemical fingerprint that the team could compare to ruthenium from young meteorites.
Depending on the origin of the meteorites, which are remnants of the young solar system, the composition of their ruthenium also differs. Comets containing water from the outer solar system have a different fingerprint than dry meteorites from the inner solar system. The origin of the mantle from the last stage of the emergence of the Earth can be explained by this.
The results of the Fischer-Gedde study indicate that the mantle comes from meteorites from the enstatite chondrite family. Water-rich objects from the outer solar system do not appear to have collapsed.
“Since we can rule out that the water arrived on Earth with the meteorites, it happened just before that,” says Torsten Kleine. His research substantiates the “Big Pivot” model, which was established only a few years ago.
In accordance with this model, young Jupiter drifted towards the inner solar system due to the effect of the planet's gas envelope. When Saturn later emerged, it was pulled outward again into today's orbit. While the gas giant pushed rocky material towards the Sun on its way back, it threw meteorites and water from the outer solar system towards Earth. “This brought a lot of water-containing meteors to Earth at some point in time,” says Kleine. And this happened rather early in the history of the Earth.
Waterless meteorites shaped the Earth
Another study by Nicholas Daufas from the University of Chicago supported the researchers in their theory. The American researcher also turned to the idea of ruthenium and applied it to several elements simultaneously. All of them appear both on Earth and in meteorites. Unlike German scientists, he did not test his assumptions on real cosmic elements, but developed on the basis of available research a mathematical model about the origin of terrestrial material. According to it, the Earth emerged in two phases. At the first stage, the building material was formed by some water-rich meteorites from the outer solar system - about one-tenth of the then Earth's mass - and water-free enstatite chondrites. At the second stage, there were no more water-rich meteorites; only enstatite chondrites were sent to Earth.
No data on comets
The problem is that all scientists studied only meteorites, that is, celestial bodies that fell to Earth. “We assume that the ratio of isotopes of ruthenium is less consistent with the ratio with the Earth, the further from the Sun comets appear,” says Kleine. "Thus, we exclude external celestial bodies as carriers of water at the last stage of the emergence of the Earth." If, contrary to expectations, there are comets outside the solar system that have the same isotopes of ruthenium as Earth, this model will no longer function.
What is missing to solve the mystery about the source of earth's water is reliable data about such celestial bodies. They can be provided from comet expeditions. Since the European Space Agency's Rosetta mission has yet to provide enough data, researchers are betting on future projects. However, an official decision on such a mission has not yet been made.
Tobias Landwehr