Japan Space Agency: Liquid water found in rock samples from asteroid Ryugu

The Japan Institute of Astronomical Sciences (JAXA) announced that after preliminary cataloging, eight teams conducted a preliminary analysis of rock samples from the "Ryugu" brought back by Hayabusa 2. The Stone Analysis team at Stony Materials has now published their latest findings in the international journal Science.

A team of researchers including JAXA and Tohoku University in Japan analyzed rock samples from Ryugu and found that they contained liquid water. This water is "sealed" in pyrrhotite crystals composed of iron and sulfur, and the water contains salt and carbon. Although some previous studies have suggested that the "Dragon Palace" rock sample may contain water, this is the first time that liquid water has been found directly.

Highlights of the study's findings include:

• The Ryugu samples that have undergone a large-scale reaction with liquid water contain particles (such as Ca- and Al-rich inclusions) formed in a high-temperature environment (>1000 °C). These high-temperature particles are thought to have formed near the sun and then migrated to -200°C in the solar system layer, which together with various substances constitute the core origin of Ryugu (Ryugu Matrix). This suggests that there was a massive mixing of matter inside and outside the solar system at the birth of the solar system.

• The magnetic field information left in the samples suggested that the Ryugu parent body was likely born in a nebula gas far away from the sun and impenetrable to sunlight. The mineral composition shows that the asteroid was born about 2 million years after the formation of the solar system and is about 100 kilometers in diameter. This matrix was later destroyed, thus becoming the current Dragon Palace.

• The Ryugu Matrix formed in the low-temperature region below -200°C, where water and carbon dioxide exist in the form of ice.

• The liquid water in the sample was found to be trapped in the crystals. This water, which once existed in the Ryugu mother, is carbonated water that contains salt and organic matter.

• Crystals shaped like coral reefs are derived from the liquid water that exists inside Ryugu.

• In Ryugu Matrix, the ratio of water to rock varies between the surface and the interior, with rocks deep underground containing more water.

• The hardness, heat transfer, and magnetic properties of the samples were measured. The results showed that Ryugu's samples were soft enough to be cut with a knife. It also contains a large number of small magnets, which means it's a natural hard drive that records past magnetic fields.

• The computer-simulated the process from the birth of the Ryugu mother body to its impact destruction. This is the first time in the world that measurements of the hardness and temperature of actual asteroid samples have been incorporated into simulations of asteroid formation and evolution, providing a more precise picture of asteroid evolution.

• The simulation results show that the Ryugu parent body accumulated about 2 million years after the formation of the solar system, heated up to about 50°C in the next 3 million years, and experienced a chemical reaction between water and rock; the diameter of the impactor that destroyed the Ryugu parent body It is about 100 kilometers long, and its size is only about 10 kilometers at most; the current dragon palace mother body is about 10 kilometers in diameter. Today's Ryugu is composed of material from areas far from the impact point.