According to a new analysis, Earth’s water may have originated from materials found in the inner solar system at the time the planet developed, rather than from far-reaching comets or asteroids. According to the results, Earth may have always been muddy. Researchers from Nancy, France’s Centre de Recherches Petrographiques et Geochimiques (CRPG, CNRS/Universite de Lorraine), including one who is now a postdoctoral fellow at Washington University in St. Louis, discovered that a form of meteorite known as an enstatite chondrite contains enough hydrogen to deliver at least three times the amount of water contained in the Earth’s oceans, and probably much more.
Enstatite chondrites are made entirely of material from the inner solar system, i.e. the same stuff that originally made up the Earth. “Our findings suggest that the Earth’s building blocks may have played a significant role in the formation of the planet’s water,” said lead author Laurette Piani, a CPRG researcher. “Even though the temperatures were too high for water to condense, hydrogen-bearing material was present in the inner solar system at the time of the rocky planet formation.”
Since the Earth’s building blocks are always assumed to be dry, the results of this study are surprising. They come from the solar system’s inner reaches, where temperatures are too hot for water to condense and bind with other solids during planet creation. Water didn’t have to come from far away, according to the meteorites.
“For me, the most fascinating aspect of the discovery is that enstatite chondrites, which were thought to be almost ‘dry,’ contain an unusually high abundance of water,” said Lionel Vacher, a postdoctoral researcher in physics at Washington University in St. Louis.
While completing his PhD at Universite de Lorraine, Vacher prepared some of the enstatite chondrites in this study for water analysis. Vacher is studying the composition of water in other forms of meteorites at Washington University.
Enstatite chondrites are extremely rare, accounting for less than 2% of all known meteorites in collections. Their isotopic resemblance to Earth, however, makes them particularly appealing. Enstatite chondrites have oxygen, titanium, and calcium isotopes that are identical to those found on Earth, and this study found that their hydrogen and nitrogen isotopes are also similar. The abundances of an element’s isotopes are used as a distinctive signature to determine where the element originated in the analysis of extra-terrestrial materials.
“If enstatite chondrites were the building blocks of our world, as their identical isotopic compositions strongly imply, this finding suggests that these forms of chondrites supplied enough water to Earth to explain the origin of Earth’s water, which is incredible!” Vacher remarked.
The paper also suggests that enstatite chondrites may have provided a significant amount of atmospheric nitrogen, which is the most abundant part of the Earth’s atmosphere. “Only a few pristine enstatite chondrites remain,” Piani said, “those that have not been altered on their asteroid or on Earth.” “We carefully picked the enstatite chondrite meteorites for our analysis and used a special analytical method to avoid being influenced by the presence of terrestrial water.”
Researchers were able to precisely calculate the quality and composition of the small quantities of water in the meteorites by combining two analytical techniques: traditional mass spectrometry and secondary ion mass spectrometry (SIMS). “It was widely thought that these chondrites evolved near to the sun,” Piani said before this research. “As a result, enstatite chondrites were widely regarded as ‘dry,’ and this frequently reaffirmed belief has likely prevented any comprehensive hydrogen studies.”
