Scientists Find Evidence of Flowing Water on Giant Asteroid

"Today, the near-Earth asteroid known as Ryugu is bone dry. But new research suggests that the half- mile space rock may have once been flowing with liquid water - and crucially, at a period in the solar system's history far later than when that would have been thought possible. The findings, published in a in the journal Nature, could add weight to the theory that soggy asteroids brought Earth its first stores of billions of years ago."

""This changes how we think about the long-term fate of water in asteroids," said study lead author Tsuyoshi Iizuka, an associate professor in the department of earth and planetary science at the University of Tokyo, in a statement about the work. "The water hung around for a long time and was not exhausted so quickly as thought.""

"When the Sun was still young, it was surrounded by a so-called protoplanetary disc of floating material that would eventually give birth to the planets. The leftovers became asteroids. And many c-type, or carbonaceous, asteroids like Ryugu formed past or near a certain boundary called the frost line, where temperatures were low enough for water to condense into tiny grains of ice."

"The work involved examining microscopic rock samples taken from the asteroid by the Japan Aerospace Exploration Agency (JAXA) probe Hayabusa2 in 2018 and 2019. In particular, the team measured the radioactive decay of the isotopes lutetium 176 and hafnium 176 to estimate the age of Ryugu - and it didn't add up, despite it normally being a reliable way of dating."

Microscopic rock samples returned by JAXA's Hayabusa2 mission show chemical and isotopic evidence that Ryugu once hosted liquid water well after the solar system's earliest epochs. Measurements of lutetium-176 and hafnium-176 decay used to estimate Ryugu's age produced inconsistent results, suggesting post-formation aqueous activity. Carbonaceous, c-type asteroids formed near the frost line where ice could condense, and retained subsurface water longer than expected despite vacuum-induced evaporation and freezing. Extended water retention on such asteroids increases the plausibility that wet asteroids delivered significant volumes of water to early Earth.

Read at Futurism