An Astounding Discovery from the Hayabusa2 Mission

In a groundbreaking revelation, pristine samples collected from asteroid Ryugu by the Hayabusa2 mission have opened new doors to our understanding of the early Solar System. Launched in 2014 and returning on December 6, 2020, these samples have unveiled secrets about primitive asteroids that were once shrouded in mystery.

Enter Djerfisherite: A Surprising Visitor

Researchers at Hiroshima University have made a remarkable discovery—djerfisherite, a rare potassium-containing iron-nickel sulfide mineral, was found in a grain from Ryugu. This unexpected find poses intriguing questions, as djerfisherite typically forms under conditions vastly different from those believed to be present on Ryugu.

As Masaaki Miyahara, the lead researcher, aptly puts it, "Finding djerfisherite in a Ryugu grain is akin to discovering a tropical seed encased in Arctic ice—either suggesting unexpected local conditions or long-range transportation in the cosmos."

The Quest for Understanding

The discovery surfaced during experiments aimed at examining terrestrial weathering effects on Ryugu grains. While employing advanced field-emission transmission electron microscopy, the team stumbled upon djerfisherite within their samples, specifically the number 15 grain from C0105-042.

Miyahara explains that this mineral’s presence hints that materials with profound differences in formation histories may have mingled early in the Solar System's evolution. This revelation challenges the long-held belief that Ryugu is a uniform entity and brings forth new layers of complexity regarding primitive asteroids.

Ryugu’s Cosmic Origins

Asteroid Ryugu is part of a larger parent body that formed between 1.8 to 2.9 million years after the Solar System's inception. Thought to originate in the outer regions of the Solar System, Ryugu's parent body housed icy water and carbon dioxide, which melted under the heat of radioactive decay around 3 million years post-formation.

Unlike enstatite chondrites—which are believed to derive from the inner Solar System and known for containing djerfisherite—the conditions and thermodynamic processes that allowed for djerfisherite's formation differ significantly.

Two Compelling Theories About Djerfisherite’s Origin

Miyahara’s team has proposed two intriguing hypotheses regarding djerfisherite's unusual presence: either it arrived from an external source during the early phases of Ryugu’s formation, or it formed under elevated temperatures on Ryugu itself, exceeding 350°C.

Initial evidence leans towards the second hypothesis, suggesting the mineral may have formed intrinsically within Ryugu. The continued study of isotopes in Ryugu grains will offer further insights into their origins.

The Road Ahead: Unlocking the Secrets of the Early Solar System

As the study proceeds, researchers aim to reconstruct the early mixing processes and thermal histories that shaped small celestial bodies like Ryugu, enhancing our understanding of planetary formation and material movement in the cosmos.

This extraordinary find not only reshapes our views but also poses new questions, driving the quest for knowledge about the Solar System’s past and the complexity of its primitive asteroids.