The near-Earth asteroid Ryugu garnered attention as the Hayabusa2 mission retrieved and brought back valuable samples. These samples provide profound insights into the solar system, particularly in understanding how asteroids may have contributed to Earth's organic molecules.
A recent study, titled "Microstructural and chemical features of impact melts on Ryugu particle surfaces: Records of interplanetary dust hit on asteroid Ryugu" published in Science Advances led by Megumi Matsumoto from Tohoku University delved into Ryugu samples, revealing compelling evidence of cometary organic matter transported to the near-Earth region.
A sample (ID: C0149) of asteroid (162173) Ryugu in the transport container (see [1]), exhibited at Sagamihara City Museum.
'Cometary Organic Matter' Found in Ryugu Samples
Ryugu, an asteroid situated near Earth and devoid of a protective atmosphere, exposes its surface directly to the harsh conditions of space. The ongoing bombardment by small interplanetary dust particles prompts continuous alterations in the asteroid's composition. In a recent investigation led by Megumi Matsumoto and her team, a notable revelation emerged as they scrutinized samples obtained from Ryugu.
The researchers detected tiny features on the sample surfaces, identified as 'melt splashes,' varying in size from 5 to 20 micrometers. These splashes resulted from the impact of micrometeoroids, comprising cometary dust, showcasing the dynamic interplay between Ryugu and extraterrestrial materials.
According to Matsumoto, advanced 3D CT imaging and meticulous chemical analyses uncovered that these melt splashes primarily comprised silicate glasses featuring voids and small inclusions of spherical iron sulfides.
The chemical compositions of the melt splashes indicated a fusion between Ryugu's hydrous silicates and cometary dust. The mixing and subsequent melting of these materials during impact-induced heating led to the creation of the observed melt splashes. The voids within the splashes corresponded to the release of water vapor from Ryugu's hydrous silicates, captured within the solidified structures during rapid cooling.
Further scrutiny of the melt splashes brought to light the existence of small carbonaceous materials exhibiting nano-pores and iron sulfide inclusions. Interestingly, these carbonaceous materials bore textural similarities to primitive organic matter found in cometary dust, despite lacking nitrogen and oxygen.
Matsumoto suggested that the carbonaceous materials might have originated from cometary organic matter, undergoing the evaporation of volatiles, such as nitrogen and oxygen, during the impact-induced heating process.
READ ALSO: Oxygen Isotopic Signatures in Asteroid Ryugu Samples Reveal the Space Rock's Birth Place
Cometary Matter Transport and Life's Building Blocks
The significance of the discovery extends beyond Ryugu, suggesting the potential transport of cometary matter, possibly containing life's building blocks, from the outer solar system to near Earth.
Matsumoto emphasized that these organic materials could be the tiny seeds of life delivered from space to Earth. The research team is committed to continuing their examination of Ryugu samples, aiming to uncover more melt splashes and enhance our understanding of the influx of primitive space materials to Earth.
This finding resonates with ongoing NASA research, where scientists are thoroughly analyzing samples from the asteroid Bennu collected by the OSIRIS-REx spacecraft.
In an October announcement, NASA claimed to have found the "building blocks of life on Earth" in preliminary samples obtained from outside the spacecraft's collection instrument. While there is still much work ahead before conclusively attributing life on Earth to organic matter from space, these recent results have ignited justified excitement in the scientific community.
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