Signs of Ancient Water found on Ryugu
Located within the inner asteroid belt between Earth and Mars, Asteroid Ryugu has long fascinated astronomers and scientists due to its intriguing characteristics. With a diameter of approximately one kilometer, Ryugu orbits the Sun at an average distance of about 300 million kilometers from Earth, deriving its name from a Japanese folktale’s underwater palace.
In December 2014, the Japan Aerospace Exploration Agency initiated the Hayabusa2 mission, embarking on a profound quest to explore the asteroid Ryugu and the ancient secrets within our solar system. However, navigating through the cosmos presented myriad challenges for Hayabusa2, such as precision maneuvers, and adaptation to interstellar conditions, that required meticulous planning.
After a six-year voyage spanning over 3 billion kilometers, Hayabusa2 finally reached Ryugu in June 2018. The mission’s primary goal was to procure pristine samples from this ancient cosmic wanderer, offering insights into our solar system’s origins.
Throughout its exploration, Hayabusa2 carefully surveyed Ryugu, revealing a rugged landscape and its unique features. Using its cutting-edge technology, the spacecraft deployed rovers and a lander to study the asteroid’s surface.
With great accuracy, Hayabusa2 collected samples from Ryugu’s surface. Using its alluring technique, the spacecraft fired a projectile into the asteroid, capturing debris ejected by the impact. This resulted in the acquisition of invaluable samples from the asteroid’s interior.
The Discovery
In December 2020, Hayabusa2 made its successful return to Earth, carrying precious samples — fragments from Ryugu. Weighing in at more than 5 grams, these samples provide a pristine glimpse into the asteroid’s ancient history. The most crucial aspect of this is that it is untouched by the contaminants of the earth’s atmosphere.
Analyses of Ryugu’s samples indicated mineralogical and chemical diversity, exhibiting similarities to Cl Chondrites — undifferentiated stony meteorites containing chondrules (small, spherical particles found in meteorites, believed to be among the oldest materials formed in the early solar system), representing some of the oldest materials in the solar system. This resemblance to Cl chondrites, coupled with variable chromium isotopic compositions has sparked various discussions among researchers.
Moreover, this mission unveiled carbon-rich components that contribute to Ryugu’s low albedo (reflectivity of a surface or object, specifically how much light it reflects). This combined with factors like grain size and porosity, suggests the asteroid’s carbon-rich nature, shedding light on its formation and evolution.
However, while most elements are similarly distributed across Ryugu and its carbonaceous siblings, scientists have previously found the distribution of chromium doesn’t follow the same pattern. This one element varies in concentration more widely over Ryugu’s surface than in other studied examples of the same type of asteroid.
To understand why, a large team led by Tetsuya Yokoyama (Tokyo Institute of Technology) zeroed in on this element.
“Both of the chromium and titanium isotope ratios for Ryugu are different from those of Earth and any type of meteorite, except for the Ivuna-type(meteorites of a rare subgroup of carbonaceous chondrites) carbonaceous chondrite,” Yokoyama says. The result suggests that wherever Ryugu and other Ivuna-type chondrites come from, it’s different from the origin of other meteorites — “possibly from the outer solar system,” he adds. “This finding reinforces our previous conclusion that Ryugu and carbonaceous chondrites share a common heritage.”
It’s even possible that carbonaceous chondrites, which are among the most water-rich asteroids, helped deliver water to early Earth.
Water and Organic Molecules
One of the most groundbreaking findings from the Ryugu samples is the identification of ancient water and organic molecules. Studies have revealed the presence of extraterrestrial amino acids, indicating the asteroid’s connection to water in the past and breaking out discussions on the distribution of life’s building blocks in our solar system.
The distribution of elements within Ryugu’s samples, particularly the variations in chromium isotopes, hints at a wet past, fostering discussions about water’s role and the asteroid’s possible origins from the outer solar system.
Conclusion
In conclusion, Hayabusa2’s expedition to Ryugu significantly advanced our understanding of space origins. By delving into celestial bodies like Ryugu, scientists gained crucial insights into our solar system’s formation, paving the way for potential resource utilization in space exploration
