The Japan Aerospace Exploration Agency (JAXA), Hayabusa2 mission brought back uncontaminated primitive asteroid samples. An extensive analysis of 16 particles taken from Ryugu revealed many clues to the processes that occurred before, during, and after the solar system’s formation. Some of these processes are still shaping the surface of today’s asteroids.
The isotopic and elemental data showed that Ryugu contained the most primitive presolar nebular material (an ancient disk containing gas and dust around what would become the sun). Some organic materials could have been inherited from the solar systems. Amino acids were among the organic materials that were identified. These are the building blocks for all the proteins found in living organisms on Earth. Uncontaminated samples of asteroid material have been found to contain protein-forming amino acids. This suggests that Ryugu and other asteroids may have provided the raw materials needed for the origin of all life.
Ryugu samples also provided chemical and physical evidence that Ryugu was created from an icy body (at least 10 km in size) in the outer solar system. This body had experienced aqueous alteration (complex chemical reactions involving water). The icy body was broken into a fragment resembling a comet (about 2 km long). Sublimation of ice allowed the fragment to become today’s dry porous asteroid. Space weathering, which involves the bombardment of an asteroid with particles from the sun or distant stars, modified the surface materials such as organic matter to give them distinct albedo (reflective qualities), which is how the asteroid appears today.
The material left behind after the formation and orbiting of the sun’s planets are called comets or asteroids. These bodies could have formed initially in a large disk of gas and dirt (protosolar nebular) around the sun (protosun). This would allow them to preserve clues about the Solar system’s processes.
The protosolar nebular would have spun fastest towards its center, which would have concentrated most of the material in this area. The protosun’s temperature was then increased as some of the material began to fall onto its surface. The protosun’s higher temperature would have resulted in greater radiation output. This could have led to photoevaporation (energy evaporation from light) within the inner solar system.
The extensive geochemical analysis of Ryugu samples revealed that there were primitive organic materials, despite the effects of space weathering, which alters and destroys the information within Organic Matter. Ryugu particles contained amino acids similar to those found in the proteins of all living organisms on Earth. Ryugu particles are important because they have not been exposed to Earth’s biosphere like meteorites. Their detection, therefore, proves that Ryugu could have formed at least some of Earth’s building blocks.
Hydrothermal activity is a hypothesis about the origin of life. This requires sources of amino acids. Meteorites and asteroids such as Ryugu are strong candidates because they have an abundance of amino acids. Also, such material could have been easily delivered to the Earth’s surface. The Ryugu samples’ isotopic compositions suggest that Ryugu-like materials could have provided Earth with water, an essential resource for the origin and maintenance of life.
The study’s findings provide valuable insights into the processes that affected the earliest asteroid ever sampled by humans. These insights are already changing our understanding of events before and during the solar system. Future research on Ryugu samples will improve our understanding of the solar system.
