According to a study published on June 16 in the journal Science, the theory that rocky planets like Earth and Mars accumulate volatile elements such as hydrogen, carbon, oxygen, nitrogen, and noble gases during their formation may be overturned.
Professor Sujoy Mukhopadyay and Dr. Sandrine Péron from the Department of Earth and Planetary Sciences at the University of California, Davis (UC Davis, USA) stated that the previous fundamental assumption about planet formation was that planets initially gathered these volatiles from the young Solar Nebula.
Chassigny meteorite, a valuable extraterrestrial object that fell in France. (Photo: PHYS)
This theory applies to other star systems as well. Young planets are often molten rocky spheres, which allows volatiles to easily dissolve into the magma ocean, subsequently forming atmospheres through degassing processes. The reservoir of volatiles continues to be enriched by chondritic meteorite impacts on the planet later on.
According to PHYS, scientists also expect that the volatile elements found on Earth and Mars will reflect the composition of the Solar Nebula, particularly through the isotopic ratios of noble gases, especially krypton. Mars is of particular interest because it formed quickly, solidifying just 4 million years after the birth of the Solar System, while Earth took 50-100 million years.
However, the Chassigny meteorite, which fell in the northeastern region of France in 1815, changed everything. Using modern krypton isotopic measurements, scientists from the Rare Gas Laboratory at UC Davis have been able to infer the origins of the elements in the rock.
Surprisingly, the krypton isotopes correspond with those from chondritic meteorites, rather than from the Solar Nebula. The meteorite indicates that the interior composition of Mars is entirely composed of krypton from chondritic meteorites, while the Martian atmosphere contains elements originating from the Solar Nebula.
This also suggests that the Martian atmosphere could not have formed entirely through outgassing from the mantle as previously thought. Additionally, this discovery indicates that Mars had completed its fundamental developmental stages before the Solar Nebula was dissipated by radiation from the Sun, implying that the planet must have been cold immediately after its formation.
With the surprising similarities between Mars and Earth, this leads to the suspicion that Earth’s formation may not be as we imagined: the early history of Earth needs further research and potentially a rewrite.
