Earth's water was here all the time

[Pinball1970]

The origin of hydrogen, and, by extension, water, on Earth has been highly debated, with many believing that the necessary hydrogen was delivered by asteroids from outer space during Earth's first approximately 100 million years. But these new findings contradict this, suggesting instead that Earth had the hydrogen it needed to create water from when it first formed.
A team from Oxford using a rare type of meteorite, an enstatite chondrite, which has a composition analogous to that of the early Earth (4.55 billion years ago), have found a source of hydrogen which would have been critical for the formation of water molecules.

They demonstrated that the hydrogen present in this material was intrinsic, and not from contamination. This suggests that the material which our planet was built from was far richer in hydrogen than previously thought.

The findings, which support the theory that the formation of habitable conditions on Earth did not rely on asteroids hitting Earth, have been published in the journal Icarus..

The origin of hydrogen, and, by extension, water, on Earth has been highly debated, with many believing that the necessary hydrogen was delivered by asteroids from outer space during Earth's first approximately 100 million years. But these new findings contradict this, suggesting instead that Earth had the hydrogen it needed to create water from when it first formed.

Article here https://phys.org/news/2025-04-scientists-evidence-theories-earth.html

Paper here https://www.sciencedirect.com/science/article/pii/S0019103525001356?via=ihub

 

[C C]

Since sufficiently intact or hydrated carbonaceous chondrites seldom reach Earth (article below), this study helps remedy that shortcoming -- in terms of the view that bodies composed of their material were the primary source of Earth's water.

Though I suppose supporters of the "icy asteroid impacts" hypothesis would contend that billions of years ago even the smaller pre-meteors had not become as degraded as they are now. And of course, many asteroids are robust enough for their inner mass to be shielded from the alternating stresses, as well as better survive the descent through Earth's atmosphere.

There are other rival explanations for the origin of Earth's water, too. Including the impact that formed the Moon, and an already existing proposal that Earth acquired water during its early accretion or formation phase.

Why the meteorites that hit Earth have less water than the [virgin] asteroid bits brought back by space probes
https://theconversation.com/why-the...netary-scientist-explains-new-research-252456

KEY POINTS:

• Observations and sample-return missions show us that space rocks tend to be rich in water, carbon and organic compounds. Yet most meteorites that have made it to Earth are not. Why?
• Astronomers long thought the space rock’s journey through our atmosphere filtered out these materials. But a new study published April 14, 2025, found something else.
• The temperature changes from space rocks traveling back and forth near the sun formed cracks in the rocks. So space rocks lose much of their carbon material before they even make it to Earth.

EXCERPTS: Surprisingly, we found that many asteroid pieces don’t even make it to Earth. Something starts removing the weak stuff while the fragment is still in space. The carbonaceous material, which isn’t very durable, likely gets broken down through heat stress when its orbit takes it close to the Sun.

[...] This process effectively fragments and removes weak, hydrated boulders from the population of objects near the Earth. Anything left over after this thermal cracking then has to survive the atmosphere.

[...] For decades, scientists have presumed that Earth’s atmosphere alone explains the scarcity of carbonaceous meteorites, but our work indicates that much of the removal occurs beforehand in space.
_

 

[exchemist]

The origin of hydrogen, and, by extension, water, on Earth has been highly debated, with many believing that the necessary hydrogen was delivered by asteroids from outer space during Earth's first approximately 100 million years. But these new findings contradict this, suggesting instead that Earth had the hydrogen it needed to create water from when it first formed.
A team from Oxford using a rare type of meteorite, an enstatite chondrite, which has a composition analogous to that of the early Earth (4.55 billion years ago), have found a source of hydrogen which would have been critical for the formation of water molecules.

They demonstrated that the hydrogen present in this material was intrinsic, and not from contamination. This suggests that the material which our planet was built from was far richer in hydrogen than previously thought.

The findings, which support the theory that the formation of habitable conditions on Earth did not rely on asteroids hitting Earth, have been published in the journal Icarus..

The origin of hydrogen, and, by extension, water, on Earth has been highly debated, with many believing that the necessary hydrogen was delivered by asteroids from outer space during Earth's first approximately 100 million years. But these new findings contradict this, suggesting instead that Earth had the hydrogen it needed to create water from when it first formed.

Article here https://phys.org/news/2025-04-scientists-evidence-theories-earth.html

Paper here https://www.sciencedirect.com/science/article/pii/S0019103525001356?via=ihub

Very interesting. Conventionally, water molecules are thought too light to have been present at the temperatures of the inner part of the protoplanetary disc. But these researchers seem to think H was present, bound to S as H2S etc and dissolved in the minerals of the forming earth. Presumably later reactions oxidised these sulphur species, giving rise to water. I as intrigued by the comment about isotopic evidence that H was present from the start., contrary to the later cometary accretion hypothesis. I wonder what that is about.

 

[sculptor]

Very interesting. Conventionally, water molecules are thought too light to have been present at the temperatures of the inner part of the protoplanetary disc. But these researchers seem to think H was present, bound to S as H2S etc and dissolved in the minerals of the forming earth. Presumably later reactions oxidised these sulphur species, giving rise to water. I as intrigued by the comment about isotopic evidence that H was present from the start., contrary to the later cometary accretion hypothesis. I wonder what that is about.

Was O also here from the start?

 

[exchemist]

Was O also here from the start?

Bound in silicate minerals.

 

[sculptor]

Bound in silicate minerals.

It is commonly said--posted--printed that the primary producers produce Oxygen. It seems most likely that those claims are just a sloppy use of the language? Whereas, it seems more likely that plants just change the chemistry?

 

[exchemist]

It is commonly said--posted--printed that the primary producers produce Oxygen. It seems most likely that those claims are just a sloppy use of the language? Whereas, it seems more likely that plants just change the chemistry?

They generate free oxygen from CO2 and water, by means of photosynthesis. That is a photochemical reaction, or series of reactions. Nobody sensible says they create oxygen out of nothing.