Which came first? Earth or Water?

[beecee]

https://phys.org/news/2022-02-earth.html

Earth's water was around before Earth:

To understand how life emerged, scientists investigate the chemistry of carbon and water. In the case of water, they track the various forms, or isotopes, of its constituent hydrogen and oxygen atoms over the history of the universe, like a giant treasure hunt.

Researchers from the CNRS, Paris-Saclay University, the French Alternative Energies and Atomic Energy Commission (CEA), and the University of Pau and the Pays de l'Adour (UPPA), with support from the Muséum National d'Histoire Naturelle (MNHN), have followed the trail of the isotopic composition of water back to the start of the solar system, in the inner regions where Earth and the other terrestrial planets were formed.

more at link...................

 

the paper:

https://www.nature.com/articles/s41550-021-01595-7

Determination of the initial hydrogen isotopic composition of the solar system:

Abstract:

The initial isotopic composition of water in the Solar System is of paramount importance to understanding the origin of water on planetary bodies but remains unknown, despite numerous studies1,2,3,4,5. Here we use the isotopic composition of hydrogen in calcium–aluminium-rich inclusions (CAIs) from primitive meteorites, the oldest Solar System rocks, to establish the hydrogen isotopic composition of water at the onset of Solar System formation. We report the hydrogen isotopic composition of nominally anhydrous minerals from CAI fragments trapped in a once-melted host CAI. Primary minerals have extremely low D/H ratios, with δD values down to −850‰, recording the trapping of nebular hydrogen. Minerals rich in oxidised iron formed before the capture of the fragments record the existence of a nebular gas reservoir with an oxygen fugacity substantially above the solar value and a D/H ratio within 20% of that of the Earth’s oceans. Hydrogen isotopes also correlate with oxygen and nitrogen isotopes, indicating that planetary reservoirs of volatile elements formed within the first 2 × 105 years of the Solar System, during the main CAI formation epoch. We propose that the isotopic composition of inner Solar System water was established during the collapse of the protosolar cloud core owing to a massive admixture of interstellar water.

[Morto]

Does all water in the Solar System have the same origin? Isn't it mindblowing than Jupiter's moon Ganymede is expected to have more water than the Earth? 

[studiot]

 

On 2/3/2022 at 7:39 PM, beecee said:

planetary reservoirs

It should be noted that many crystalline substances incorporate 'water of crystallisation' in their crystal structure.

It is debatable whether this water can be counted as part of a 'reservoir' of available water.

Edited February 8, 2022 by studiot

[exchemist]

6 hours ago, Morto said:

Does all water in the Solar System have the same origin? Isn't it mindblowing than Jupiter's moon Ganymede is expected to have more water than the Earth? 

Depends how far back you go. The water would all have been present in the same cloud of gas and dust from which the solar system formed, and all the oxygen in it would have come, like all the other elements heavier than H, He and some Li, from stellar fusion in earlier generations of stars. So yes, it all has a common origin in that sense.

It's interesting about Ganymede's water, but maybe not hugely surprising, given that it is bigger by volume than Mercury and about half its mass. The vapour pressure of water in the cold of space that far from the sun is pretty low so, given its quite large gravity, not much would have evaporated into space. What is a bit curious is that it has quite a lot of other similarities to the Earth: a molten metallic core, creating a magnetic field, surrounded by a rocky (silicate) mantle and then an ocean of liquid water, all beneath an icy surface.  I see the internal ocean is even said to be salty. I'm not sure how that would arise, given the lack of the erosion cycle of the rocks that we have on Earth. 

 

[Morto]

On 2/8/2022 at 6:03 PM, exchemist said:

 I see the internal ocean is even said to be salty. I'm not sure how that would arise, given the lack of the erosion cycle of the rocks that we have on Earth. 

 

Does it matter if the water is salty or fresh? From the standpoint of finding some life forms? 

[exchemist]

13 hours ago, Morto said:

Does it matter if the water is salty or fresh? From the standpoint of finding some life forms? 

Perhaps not (though it probably does). However there are other standpoints besides the biological one. It interests me me from the standpoint of physical science.