Asteroid Discovery Suggests Widespread Liquid Water

A recent breakthrough in asteroid research by the Japanese Hayabusa spacecraft has profound implications for our understanding of liquid water’s potential presence within the solar system’s largest asteroid population. This discovery hinges on detecting minuscule salt particles in an asteroid sample, commonly known as sodium chloride or table salt. 

Although salt crystals may not typically pique the scientific imagination, these tiny mineral formations have captivated researchers at the University of Arizona Lunar and Planetary Laboratory.

The Clues in Salt Crystals

The intrigue surrounding these salt crystals arises from the fact that their formation is inherently linked to the existence of liquid water. Even more captivating is the asteroid’s identity; the sample was sourced from an S-type asteroid, a category historically considered devoid of hydrated or water-bearing minerals. 

This revelation significantly challenges prior assumptions about the dryness of a substantial portion of asteroids traversing our solar system.

Reshaping the Hypothesis

Published in Nature Astronomy, this finding revitalizes the notion that a significant portion, if not all, of Earth’s water, may have been delivered through asteroids during the tumultuous early days of our planet. 

Tom Zega, senior author of the study and a professor of planetary sciences at the UArizona Lunar and Planetary Laboratory, and Shaofan Che, the lead study author and a postdoctoral fellow at the Lunar and Planetary Laboratory, conducted a meticulous analysis of samples collected from the asteroid Itokawa during the 2005 Japanese Hayabusa mission, which were returned to Earth in 2010.

Proving the Origin

What makes this study groundbreaking is its ability to conclusively establish that the salt crystals originated from the asteroid’s parent body, eliminating any contamination concerns that had plagued previous research.

 According to Zega, these grains resemble common table salt when viewed under an electron microscope, displaying an unreal perfection in their square crystal structure.

A New Perspective on Ordinary Chondrites

The study highlights the sample’s classification as an ordinary chondrite, a type of extraterrestrial rock derived from S-type asteroids, which make up approximately 87% of meteorites collected on Earth. 

Interestingly, very few of these asteroids have been found to contain water-bearing minerals, contrary to the prevailing belief that ordinary chondrites were unlikely sources of water on Earth.

Water Delivery Hypothesis

This discovery has profound implications for theories concerning water delivery to early Earth. It aligns with the idea that water in the inner regions of the solar nebula, where Earth and other rocky planets formed, was scarce due to high temperatures. 

Thus, water must have been transported from the outer regions, most likely in ice via comets or certain types of asteroids like C-type asteroids.

A Tiny but Impactful Sample

The study focused on a minute dust particle, measuring about 150 micrometers in diameter, from which a tiny section about 5 microns wide was extracted for analysis, just enough to cover a single yeast cell. 

Various techniques were employed to eliminate potential sources of sodium chloride contamination, including human sweat, sample preparation processes, and exposure to laboratory moisture.

Strengthening the Hypothesis

Through meticulous comparisons and control experiments, the researchers established that the salt in the sample was indeed native to the asteroid Itokawa, offering compelling evidence of its presence from the solar system’s early days.

Zega highlighted the significance of asteroid impacts in delivering water to Earth, shedding new light on the concept that asteroids could have been much ‘wetter’ than previously assumed. 

The study of Itokawa, a peanut-shaped near-Earth asteroid, suggests that frozen water and hydrogen chloride could have accumulated there due to natural processes involving heat generation, likely originating from decay of radioactive elements and frequent meteorite bombardment.

The Promise of Water Chemistry

This discovery opens the door to exciting possibilities of water chemistry within asteroids, challenging conventional assumptions about these celestial bodies and their potential contributions to our understanding of Earth’s early history. 

Furthermore, evidence of alteration veins rich in sodium chloride within the sample supports the conclusion that water significantly shaped the asteroid’s history.

In conclusion, salt crystals in an asteroid sample may seem minor. Still, it has far-reaching implications for our understanding of the early solar system and the origins of water on Earth. 

This research offers a tantalizing glimpse into the hidden worlds of asteroids and the role they may have played in shaping our planet’s history.

Read the original article on Scitechdaily.

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