Researchers in Japan have found salt minerals on the asteroid Ryugu. This discovery hints that liquid water may have existed on its larger parent body long ago. The results come from samples collected by Japan’s Hayabusa2 mission, and they could change our understanding of water’s history in the solar system.
The team from Kyoto University examined tiny grains of sodium carbonate, halite (rock salt), and sodium sulfates from the asteroid’s material. These salts typically form where there is liquid water, signaling that Ryugu’s parent body may have held water billions of years ago, likely before it froze or evaporated.
Planetary scientist Toru Matsumoto explains that these salt crystals give insight into how and when water disappeared from that ancient body. This supports the idea that Ryugu could have been part of a larger object that once had hot water or interacted with watery environments.
This finding is significant because it connects with discoveries on other celestial bodies believed to hold vast subsurface oceans. For instance, salty deposits might also exist on:
- Ceres, the largest asteroid in the belt between Mars and Jupiter.
- Europa and Ganymede, two of Jupiter’s moons that have icy surfaces covering liquid water.
- Enceladus, Saturn’s moon, known for its water-rich geysers.
These places are considered promising candidates for extraterrestrial life as they might provide stable environments for liquid water. The discovery on Ryugu strengthens the idea that water was common in the early solar system and might still be hidden away in pockets across various worlds.
The Hayabusa2 spacecraft launched in 2014 and reached Ryugu in 2018. It collected over five grams of material and returned to Earth in 2020. Scientists have been carefully studying these samples to learn more about how our solar system evolved and how planets formed.
Finding salt minerals adds to earlier discoveries from Ryugu, which included organic molecules and carbon-rich compounds. These elements are vital for understanding the building blocks of life.
This discovery also raises interesting questions about how Earth’s early oceans formed. Some scientists think that water-rich asteroids and comets may have bombarded young Earth, bringing with them the necessary components for oceans and possibly even the origins of life.
By studying Ryugu’s minerals, scientists can compare them with Earth’s oldest rocks and meteorites. This comparison could clarify how Earth’s water cycle began. If the mineral compositions match, it would support the idea that Earth’s seas have extraterrestrial roots.
The success of Hayabusa2 has set the stage for more asteroid sample-return missions, such as:
- NASA’s OSIRIS-REx, which brought back material from asteroid Bennu.
- JAXA’s MMX mission, targeting Phobos, one of Mars’ moons.
- ESA’s Hera mission, which will study the impact of NASA’s DART on an asteroid.
These missions aim to deepen our understanding of asteroids, which are critical to understanding how planets formed and how water might be distributed in the cosmos. The more we learn, the closer we get to answering the big question: How did life begin in the universe?
Salt minerals on Ryugu are a vital piece of the puzzle regarding our solar system’s history. As scientists continue to study these asteroid samples, they may uncover more about water, life, and how planets come together.
With new missions planned to explore more celestial bodies, researchers are on the path to discovering how the essential ingredients for life spread across the solar system—and maybe even beyond.
