Tiny speck of asteroid dust could solve mystery of where water comes from

Scientists might soon have an answer for where the Earth’s water came from.

Researchers at the University of Arizona have uncovered evidence suggesting that tiny salt grains discovered on an asteroid sample brought back to Earth by the Japanese Hayabusa spacecraft could hold the key to unravelling the origins of Earth’s water.

The study focused on a dust particle obtained from asteroid Itokawa, an S-type asteroid measuring approximately 1,100 feet in diameter and completing a rotation every 12 hours.

Analysis of this particle revealed the presence of tiny salt grains composed of sodium chloride, the same compound that constitutes table salt.

The revelation of salt grains on Itokawa is significant as it suggests that the space rock may have once been enveloped in liquid water.

Sodium chloride is a highly soluble compound, readily dissolving in water. If Itokawa had experienced a watery environment, the salt grains would have dissolved within it.

However, the fact that these grains remain intact on the asteroid’s surface strongly suggests that the water present had evaporated, leaving behind the salt residue.

The researchers propose that the water on Itokawa potentially originated from comets or C-type asteroids.

These celestial bodies, which likely resided farther out in the universe, migrated inward and eventually impacted a young Earth, delivering their watery cargo in the process.

‘The most likely scenario is that comets or C-type asteroids brought water to Earth. The salt grains on Itokawa provide strong evidence that liquid water was once present on this type of asteroid,’ said Shaofan Che, the study’s lead author.

Previous studies of Itokawa suggest that the water in the dust was produced by ‘space weathering’.

Beyond its implications for Earth’s water, the discovery of salt grains on Itokawa suggests the potential existence of water on other celestial bodies within our solar system.

This opens up the possibility of future missions targeting these asteroids to extract water, thereby harnessing it as a valuable resource for spacefaring endeavors.

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