Was Earth’s Water Always Here? Unexpected Meteorite Composition Provides Origin Evidence

Ocean Stars

The Earth is the only planet known to have liquid water on its surface, a fundamental characteristic when it comes to explaining the emergence of life. However, was this water always present in the rocks that made up our planet? Alternatively, was it delivered later by asteroids and comets that bombarded the Earth? Or did the Earth’s water originate from a combination of both sources?

In the journal Science, scientists from the Centre de Recherches Pétrographiques et Géochimiques in Nancy (CNRS/Université de Lorraine) contribute to this debate by showing that most of the water present on the Earth today has probably been there right from the very beginning. And yet the Earth was formed in a region of the Solar System where temperatures were too high for water to condense and clump together with other solids as ice, long supporting the hypothesis of a late addition of water.

Sahara 97096 Meteorite

An approximately 10-centimeter long piece of the Sahara 97096 meteorite, one of the enstatite chondrites studied. Water concentrations of around 0.5% by mass were measured in it, and part of the hydrogen was found to be located in the chondrules (the white spheres visible in the photograph). Sample belonging to the French National Museum of Natural History (Paris). Credit: © Christine Fieni / Laurette Piani

However, the amount of water present in the rocks that made up the Earth had never been accurately estimated. The scientists focused on meteorites with a composition similar to that of the Earth, called enstatite chondrites[1], and more specifically on a small number of these that underwent little heating over the course of their lifetime and thus still exhibit a primitive composition. Using two complementary techniques, they measured their content in hydrogen and determined precisely where part of this was located.

Their results show that the Earth’s primitive rocks probably contained enough water to provide at least three times the amount of water in the Earth’s oceans, and possibly much more.

In addition, the hydrogen in these meteorites has the same isotopic composition[2] as that of the water stored in the Earth’s mantle, while the isotopic composition of the oceans is consistent with a mixture containing 95% of water from the enstatite chondrites and a mere 5% of water delivered by comets or water-rich asteroids. The Earth therefore appears to have obtained the overwhelming majority of its water from its constituent materials.

Notes

[1] These are very rare, making up less than 2% of meteorites. Although thirteen were brought together for this study, some of them had been altered, and only eleven of them were considered to have their original water content.

[2] A molecule of water is made up of two hydrogen atoms and one oxygen atom. Like many chemical elements, hydrogen can exist in several different forms called isotopes, which differ in their mass.

For more on this research, read:

Reference: “Earth’s water may have been inherited from material similar to enstatite chondrite meteorites” by Laurette Piani, Yves Marrocchi, Thomas Rigaudier, Lionel G. Vacher, Dorian Thomassin and Bernard Marty, 28 August 2020, Science.
DOI: 10.1126/science.aba1948

4 Comments on "Was Earth’s Water Always Here? Unexpected Meteorite Composition Provides Origin Evidence"

  1. Outgassing of water seems so much easier to accept than any extraterrestrial origin. The deuterium isotopic data support it. The unexpected meteorite data add to the conclusion. Outgassing also seems likely to be true for Mars.

  2. Torbjörn Larsson | September 14, 2020 at 5:35 am | Reply

    The key part of the paper, for me, is that it is the first time enstatites are robustly identified as major Earth mantle component, earlier papers put their origin zone further in towards the Sun. This plays well with new planetary formation scenarios where planets typically forms within a million years, and a local dust hail contributes with the majority of mantle material after a hefty protoplanetary core has accreted.

    The water from enstatites also plays well with the modern view of gas giant migration before planets were fully formed – so they could settle into nice orbits before the disk was gone – and an exponential decreasing impact bombardment with rare earth elements and a smidgen of volatiles added. (E.g. likely no “late bombardment” spike.)

  3. More mega $ grant sponsored bs – ie = they do not know, nor can they – nor will they.

    However they’ve gotta come up with something that might sound credible no matter how actually absurd – along with atoms + DNA invented themselves from…?

    • Torbjörn Larsson | September 15, 2020 at 11:22 am | Reply

      More bs comment, gish galloping – as the suggested creationism superstition tend to do irrelevancies and giving no basis for such inflammatory, non-constructive criticism.

      Nothing in nature outside of animal tool use ‘invent’ itself, it is all natural processes. If you are asking what DNA evolved from, the core genetic and metabolic machinery has long shown that it evolved from RNA. It even resulted in multiple Nobel Prizes:

      – “The Nobel Prize in Chemistry 1989 was awarded jointly to Sidney Altman and Thomas R. Cech “for their discovery of catalytic properties of RNA.”

      Altman’s acceptance speech text on Nobelprize org is titled: “The RNA World”

      – “The Nobel Prize in Chemistry 2009 was awarded jointly to Venkatraman Ramakrishnan, Thomas A. Steitz and Ada E. Yonath “for studies of the structure and function of the ribosome.””

      In the colophon to the scientific information paper on the Nobelprize org site we see the revolutionary, evolutionary significance of the prize winners works:

      “In the beginning it was generally believed that ribosomal protein carried out the
      ribosome’s catalytic actions. Then it was believed that ribosomal RNA was the catalyst. Now, we know that peptide bond formation on the bacterial ribosome and perhaps on the ribosomes from all organisms is catalyzed by ribosomal RNA as well as ribosomal protein and also by the 2’-OH group of the peptidyl-tRNA substrate in the P site (Figure 7). This catalytic triad of ribosomal RNA, ribosomal protein and tRNA substrate may reflect a more complex starting point for the route to the present protein dominated world than a pure RNA world.”

      [The ubiquity of ribosomal RNA was already used to identify different organism populations – I have done so myself – and has in the decade since never failed to do so.]

      But if you are a creationist, how come that all life – with no exception – makes phylogenetic trees from shared ancestors? The likelihood for evolution based only on that against creationism or other suggestions of several origins is an astounding 10^2000+ against the superstition (due to tree combinatorial statistics). It is the best evidenced fact we have in all of science, and it is also one that anyone can check in a few minutes with free data, software and tutorials on genome sites like NCBI. You can sit your whole life and test evolution ata clip of a tree every half hour, when you get up to speed. It is not like this is a hidden fact – we can see evolution in each others faces (showing variation, and having evolved by selection to be uniquely identifiable).

      [And that is beside the fact that the observation in cosmology of average flat space over sufficiently large volumes show that nature is without creationist magic as its total energy is zero and its large scale expansion is spontaneous – there are no ‘gods’ having put in any form of action into it – and has always and will always be such.]

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