Where Did Earth's Water Come From? Primitive Asteroids May Have Brought H20 to Our Planet

Where Did Earth's Water Come From? Primitive Asteroids May Have Brought H20 to Our Planet
(Photo: Wikimedia Commons/NASA/JPL-Caltech)

A group of ancient space rocks could be the ones responsible for the presence of water on Earth. Researchers say the Erigone family of asteroids may have brought H20 to our planet.

Where Did Earth's Water Come From?

Astronomers trying to piece together the history of these tiny space rocks that are thought to have once transported water to Earth are seeing a glimpse into the past thanks to a family of primitive asteroids.

Eight asteroid families retain their primordial chemistry. The pristine samples are of great interest to astronomers because their primitive compositions may provide information about the solar system's environment during the formation of the parent asteroids of these families.

In other words, they might enable us to see into the past solar system's mysteries. To document the chemical makeup of these asteroid families, planetary scientist Noemí Pinilla-Alonso of the University of Central Florida has been co-leading a project called the Primitive Asteroid Spectroscopic Survey (PRIMASS).

Brittany Harvison, a Ph.D. student of Pinilla-Alonso, finished the work by analyzing infrared data of the Erigone family of primitive asteroids, the last asteroid family examined for the PRIMASS project. Cosmologically speaking, the Erigone family is relatively young, and the collision that gave rise to it is estimated to have happened only 130 million years ago.

According to Harvison in a statement, there are theories that some of the Earth's water may have come from early solar system asteroids. Understanding how these primitive asteroids were brought into Earth's orbit forms a significant part of these ideas. Therefore, investigating ancient asteroids in the solar system may shed light on what happened all those years ago.

The Erigone family has been a major target for astronomers due to its extreme hydration. Coincidentally, the asteroid 52246 Donaldjohanson will be the first stop for NASA's Lucy space mission, destined for Jupiter's Trojan asteroids. This C-type asteroid, named after an American paleoanthropologist, is a member of the Erigone family, so when Lucy passes by on April 20, 2025, scientists can examine it up close.

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Why Did Venus Dry Out?

While astronomers are still searching for water sources on Earth, another study may have found why Venus lost water and dried out. According to the researchers, it could be due to a chemical reaction called HCO+ dissociative recombination.

Previous theories suggested that Venus lost its water through a process known as hydrodynamic outflow, which describes how gas departs from a planet's atmosphere.

However, this mechanism could not have removed enough water for Venus to become as dry as it is now. Conversely, water would be lost twice as quickly due to HCO+ dissociative recombination as hydrodynamic outflow suggested. This mechanism would also account for any discrepancies in data from previous Venus spacecraft instruments.

The researchers found that this mechanism nearly doubles the Venus H escape rate, the quantity of current volcanic water outgassing and impactor infall required to maintain a steady-state atmospheric water abundance. Additionally, they assert that these higher loss rates resolve long-standing issues by simultaneously explaining Venusian water's observed abundance and isotope ratio and enabling faster desiccation in the wake of postulated late ocean scenarios.

However, the researchers said further study is needed to confirm if HCO+ dissociative recombination is the cause of Venus's water loss.