On September 12, 2019, 2:49 p.m. summer time, a small celestial body with a diameter of around two meters hits the earth’s atmosphere from space and races across the sky of northern Germany as a clearly visible ball of fire. The next day, Erik Due-Hansen found a black, charred stone on the lawn of his front yard in the Weiche district of Flensburg.
The small meteorite fragment, which weighs only 24.5 grams, holds a great secret: it contains the oldest traces of liquid water on earth to date. This is the conclusion reached by Addi Bischoff from the University of Münster, Mario Trieloff from the University of Heidelberg and 39 colleagues in the journal “Geochimica et Cosmochimica Acta” who examined the cosmic bolide.
Tiny mineral grains in the meteorite testify that liquid water had already formed three million years after the formation of the first solid celestial bodies in our solar system. 4.565 billion years ago, gigantic gas planets like Jupiter had only just formed in the still young solar system, rock planets like Earth, Mars and Venus followed many millions of years later.
The space around the young sun was still full of gas and dust, which gradually agglomerated into ever larger structures. “According to our model calculations, one of these young celestial bodies had a diameter of perhaps a hundred kilometers, a small fragment of which landed on earth in 2019 in Flensburg as a meteorite,” says the physicist and geochemist Trieloff about the origin of the front garden find.
The sun wasn’t alone then. Hundreds and thousands of other stars were formed in their cosmic neighborhood, “including giant stars that burn their fuel very quickly and age much faster than our sun,” says Trieloff.
Isotope residues give an indication of the age of the meteorite
Shortly before their end, these star giants produced many heavy elements, such as the radioactive isotopes manganese-53 and aluminum-26, and hurled them into our solar system, where it was stored in the rock of the gradually forming planets, right next to the “earthly one “Manganese-55 isotope.
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Since manganese-53 decays with a half-life of 3.7 million years, nothing is left of this isotope for a long time. In contrast, the resulting chromium-53 is stable and still completely present. Using the proportions of the isotopes, Trieloff’s team was able to determine the age of the Flensburg meteorite: just 4.565 billion years. “This means that the Flensburg meteorite contains the oldest carbonate rocks that have been found in such celestial bodies so far,” says Trieloff.
But the researchers discovered even more: “When we determined the composition of the oxygen and carbon isotopes in the tiny carbonate particles of the Flensburg meteorite extremely precisely with the Heidelberg ion probe, we found clear indications that the carbonates had precipitated from hot water are, ”says Trieloff.
Meteorite allows conclusions to be drawn about water
The energy for this heating of the water came from the aluminum-26 that was supplied by the dying giant stars in the vicinity of the young solar system. This isotope decays with a half-life of 720,000 years. This releases energy that is hardly dissipated by the rock and therefore accumulates as heat inside.
“According to our calculations, this process provides enough energy to heat water to temperatures of 100 to 200 degrees Celsius, at which the carbonates formed,” explains Trieloff. The researchers have thus found the oldest evidence of liquid water in the solar system. Apparently it has “rained” on earth with meteorites for billions of years – one of the prerequisites for life.
