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Earth and other planets got their first water from an unexpected source

Ever wonder how our seemingly dry, fireball Earth got its first water during the early days of our planet? Well, some recent findings might just quench your thirst for knowledge.

Thanks to the age data obtained from certain meteorite classes, we now have fresh insights into the birth of water-rich cosmic bodies in the primordial solar system.

These mini astronomical structures, or planetesimals as they’re scientifically known, played the role of a cosmic delivery service, continually bringing in materials for planet construction – including our own Earth, which initially had little water to begin with.

Enter Professor Dr. Mario Trieloff, the director of the Klaus Tschira Laboratory for Cosmochemistry at Heidelberg University’s Institute of Earth Sciences.

He explains, “These small bodies did not just supply the building materials for the planets.” They are, in reality, the very source of Earth’s water, Trieloff adds.

Putting the puzzle pieces together

These planetesimals themselves emerged at cooler temperatures in the outer solar system, where ice existed as solid-state water.

This is in stark contrast to other celestial bodies that formed earlier in the solar system’s history, which were too hot and too close to the sun to harbor ice.

The early-forming bodies experienced intense thermal conditions, preventing the accumulation or retention of volatile substances such as water.

By meticulously analyzing age data and utilizing sophisticated computational models, an international research team, including distinguished earth scientists from Heidelberg University, was able to trace the thermal evolution of the parent bodies of these planetesimals.

Isotopes and Earth’s first water

Their research involved examining isotopic compositions and conducting simulations to understand the heat dynamics and material composition of these early solar system objects.

The team discovered that some planetesimals formed extremely rapidly, in less than two million years. These swift-forming bodies experienced such intense heating that they melted completely, thereby losing all their volatile elements, including water.

The rapid heating was likely due to the decay of short-lived radioactive isotopes, which released substantial amounts of heat.

A second group of planetesimals, as revealed in the current study, formed later at cooler temperatures in the outer reaches of the solar system.

These planetesimals benefited from the lower thermal environment, which allowed them to preserve their water content.

This water was trapped within crystalline structures, enabling these bodies to retain their volatile elements despite forming at later stages of the solar system’s development.

For Earth’s first water, size does matter

Scientists found that the ability of planetesimals to form continually, even during the later phases of the solar system, was due to several delaying effects.

These delaying effects were crucial in allowing the building blocks of planets to persist over extended periods.

Essentially, they observed that frequent collisions between dust agglomerates – the raw materials for planetesimals – obstructed the rapid growth of small planets.

These agglomerates, made up of tiny particles, would collide and stick together, but the chaotic environment of the early solar system caused these formations to frequently break apart.

This constant cycle of collision and fragmentation slowed the formation process, enabling planetesimals to continue forming over much longer timescales.

Dr. Wladimir Neumann, who led the research conducted at several institutions including Heidelberg University, highlighted the crucial role of certain celestial bodies in Earth’s formation.

He explained, “Thanks to these smaller, water-rich planets or their fragments in the form of asteroids or meteorites, Earth was able to avoid becoming a bone-dry, life-hostile planet during its growth process.”

The study suggests that these water-bearing objects were instrumental in shaping our planet into a habitable world, contributing significantly to its water content during its early stages of development.

Not just Earth’s story

Could it be that Earth’s story of acquiring water is not unique? Since the birth of planetesimals in extrasolar planetary systems operates on the same physical laws as our solar system, the research team postulates that there could be Earth-like planets elsewhere in the cosmos.

According to Professor Trieloff, if these planets have also received water from smaller bodies over their evolutionary journey, they could potentially fulfil the prerequisites for the origin of life.

Could this be the beginning of a new understanding of life’s possibilities in the universe? Only time will tell. Despite this being still a theory, it does make us appreciate our water sources a bit more, doesn’t it?

After all, life, as we know it, owes a lot to these small, fascinating planetesimals. Isn’t it amazing where a little cosmic dust can lead us?

The full study was published in the journal Scientific Reports.


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