Scientists have found liquid water trapped in crystals within rock samples returned from the asteroid Ryugu about 300 million kilometers (186 million miles) from Earth.
Samples from the asteroid were found to contain a variety of minerals, including calcium- and aluminum-rich particles, magnetic minerals such as lodestone, as well as carbonated water containing salts and organic matter.
The samples were returned to Earth for analysis by the Japan Aerospace Exploration Agency (JAXA) Hayabusa2 mission in 2020.
The findings, published in the journal Sciences on Friday, will offer more evidence to support the theory that life, or the precursor molecules of life, on Earth could have originated in space.
“Liquid water trapped in crystals was found in the sample. The water remained in micron-sized vacancies,” JAXA said in a statement.
In the study, scientists analyzed 17 samples from Ryugu that measured between 1 and 8 mm and found an iron sulfide pyrrhotite crystal that contained carbonated water.
The researchers suggested that the parent space rock from which asteroid Ryugu descended was born in the darkness of a cloud of stellar gas located far from the reach of sunlight.
In this main body, they said there would be variations in the water-to-rock ratio between the surface and the interior, with rocks deeper underground holding more water.
Simulations carried out by the scientists suggested that Ryugu’s main body amassed about 2 million years after the formation of the Solar System and then heated up to about 50°C over the next 3 million years, resulting in chemical reactions. between the water and the rock.
Samples from the asteroid were found to contain some material near the surface of the main body before its destruction by impact and some from the interior of the main space rock.
The scientists compared the hardness of the samples to that of volcanic igneous rocks on Earth, making them soft and allowing them to be cut easily with a blade.
The researchers found a diverse set of minerals in these rock fragments, the differences of which, they said, can be explained by the different conditions for chemical reactions with water.
The scientists said the hydrated minerals, including silicates and carbonate compounds discovered in the asteroid sample, likely formed when raw materials from the main body reacted with water and carbon dioxide inside the giant space rock. .
Based on the state and stability of some of these minerals, the researchers said the water temperature in some parts of the bedrock could have been around 25C.
Other studies have also suggested that the magnetite iron ores in the Ryugu samples formed “surprisingly low” temperatures of less than 40 °C.
The new analysis also revealed that “coral crystals” grew from Ryugu’s liquid water.
Based on these findings, the researchers said an environment “similar to Earth’s oceans” existed in Ryugu’s interior, adding that such water-bearing asteroids are more widely distributed in the Solar System than non-water objects.