unexpected mineral found in Ryugu asteroid

Rare Mineral Found in Ryugu Asteroid Challenges Solar System Formation Theories

Hayabusa2 Mission Uncovers Crucial Clues from Ryugu

Pristine Samples and Their Importance

The untouched samples retrieved from asteroid Ryugu by the Hayabusa2 mission on 6 December 2020 have been crucial in refining our knowledge of primitive asteroids and solar system formation. Ryugu, a C-type asteroid, comprises rock akin to CI chondrite meteorites—rich in carbon and bearing clear signs of past aqueous alteration.

Discovery of an Unexpected Mineral in Ryugu

Identification of Djerfisherite

A team of researchers from Hiroshima University has identified the mineral djerfisherite—a potassium-bearing iron-nickel sulphide—within a grain from asteroid Ryugu. Its discovery is entirely unexpected, as such a mineral is not thought to form under the environmental conditions Ryugu is believed to have experienced.

The Journal Meteoritics & Planetary Science has published the team's findings.

Expert Insight from Dr. Masaaki Miyahara

"Ordinarily, djerfisherite is encountered in significantly reduced settings, such as those characteristic of enstatite chondrites. Its absence in CI chondrites and Ryugu material has been consistent—until now," explained Dr. Masaaki Miyahara, first and corresponding author and associate professor at Hiroshima University.

Challenging Current Understanding of Primitive Asteroids

Exotic Conditions or Early Solar System Transport?

"Its presence is akin to discovering a tropical seed embedded within Arctic ice—suggesting either a surprisingly exotic local condition or significant transport across vast distances in the early solar system."

Weathering Experiments and Analysis

Miyahara's research group had been conducting experiments to investigate how Ryugu grains respond to terrestrial weathering. During FE-TEM analysis, they identified djerfisherite in grain number 15 from sample plate C0105-042.

Implications for Solar System Formation Models

"The presence of djerfisherite within a Ryugu grain implies that substances with disparate origins might have mingled in the early solar system, or that Ryugu encountered previously undetected, chemically diverse environments. This discovery contests the assumption of Ryugu's compositional uniformity and raises intriguing questions regarding the complexity of primordial asteroids," explained Miyahara.

Thermal and Chemical History of Ryugu's Parent Body

Formation in the Outer Solar System

Ryugu originated from a larger celestial precursor, which came into being around 1.8 to 2.9 million years post-solar system formation. Scientists surmise this body took shape in the solar system's colder outer zones, rich in frozen water and carbon dioxide.

Radioactive Heating and Ice Melting

Within the parent body, the decay of radioactive isotopes produced heat that led to the melting of ice roughly 3 million years post-formation. During this period, temperatures are believed to have remained below 50°C.

Comparison with Enstatite Chondrites

Conversely, the parent bodies of enstatite chondrites, which exhibit the presence of djerfisherite, are believed to have originated closer to the Sun. Thermodynamic assessments indicate the mineral emerged from condensation within high-temperatures gases.

Experimental Confirmation

In addition, controlled hydrothermal experiments suggest that djerfisherite may from through chemical interactions between postassium-laden fluids and Fe-Ni sulphides at elevated temperatures exceeding 350 °C.

Hypotheses and Future Directions

Two Possible Origins for Djerfisherite in Ryugu

Two explanations were offered for the mineral's inclusion within the Ryugu grain: either it originated elsewhere and was introduced during the parent body's creation, or it formed locally as a result of thermal conditions exceeding 350°C.

Isotopic Analysis to Follow

Initial findings suggest that the hypothesis favouring intrinsic formation is the more probable explanation. Subsequent work will involve isotopic analysis of this and additional Ryugu grains to elucidate their provenance.

Toward a Deeper Understanding of Planetary Formation

Broader Scientific Goals

"Our ultimate objective is to piece together the early mixing events and thermal developments that influenced minor celestial bodies such as Ryugu, thereby enhancing our insight into planetary genesis and mterial movement within the nascent solar system," Miyahara remarks.

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terrestrial-life-ryugu-asteroid-contamination-discovery

Surprising Discovery: Terrestrial Life Found on Ryugu Asteroid Sample Despite Rigorous Contamination Measures

Introduction: The Panspermia Hypothesis and Its Implications

The panspermia hypothesis suggests that life could withstand transfer between planetary bodies, serving as a potential secondary pathway for life to arise on various planets within a solar system. Discovering alien life in meteorites or on asteroids would have far-reaching implications for how we comprehend the origins and dissemination of life across the universe.

Microbial Traces in Meteorites: An Ongoing Debate

The Possibility of Extraterrestrial Life in Meteorites

The discovery of microorganisms in chondritic meteorites has long sparked discussions regarding the possibility of extraterrestrial life reaching Earth, potentially even serving as the origin of life here. Although research has generally concluded that these microbial traces are terrestrial contaminants, the theory that they may be extraterrestrial travelers persists.

The Imperial College London Study: Findings from Ryugu

 Researchers' Discovery of Microorganisms on Asteroid Sample

A team of researchers from Imperial College London has found that a sample returned from asteroid Ryugu was quickly colonized by terrestrial microorganisms, despite rigorous contamination control protocols.

Methodology: Rigorous Contamination Control

In the article 'Rapid colonization of a Space-Returned Ryugu Sample by Terrestrial Microorganisms,' published in Meteoritics & Planetary  Science, researchers analyzed sample A0180, a tiny (1x0.8 mm) particle obtained from asteroid 162173 Ryugu by the JAXA Hayabusa 2 mission.

Upon arrival on Earth, the sample was housed in a hermetically sealed chamber and opened in nitrogen within a class 10,000 clean room to ensure no contamination occurred. Particles were isolated using sterilized tools and stored in nitrogen-filled, airtight containers. The sample was then subjected to Nano-X-ray computed tomography and embedded in an epoxy resin block for scanning electron microscopy analysis.

Discovery of Microbial Colonization

The sample's surface exhibited rods and filaments of organic material, interpreted as filamentous microorganisms. These structures displayed size and morphological variations consistent with known terrestrial microbes. Over time, changes in filament abundance were observed, suggesting the cyclical growth and decline of a prokaryotic population with a 5.2-day generation time.

Statistical Analysis: Contamination or Extraterrestrial Origins?

Evidence for Terrestrial Contamination

Statistical analysis suggests that the microorganisms were introduced through terrestrial contamination during sample preparation rather than originating from the asteroid itself.

The study revealed that terrestrial organisms rapidly colonized the extraterrestrial material, despite stringent contamination controls.

Recommendations for Future Sample-Return Missions

Researchers advocate for stricter protocols in future sample-return missions to preserve sample integrity and prevent microbial contamination.

Challenges in Obtaining Uncontaminated Samples

Earth's Microbial Life and Its Pervasiveness

A significant challenge in obtaining uncontaminated samples is that all collection tools are sourced from a planet teeming with microbial life.

NASA strives to prevent the transfer of Earth microbes to Mars by constructing probes and landers in controlled cleanroom environments. However, this has proven to be an immense challenge, as some microbial species found in these clean rooms resist disinfection and even utilize cleaning agents as nutrients.

The Evolutionary Unity of Life

Earth's microbial life is so pervasive that every resource is utilized, and every niche is occupied. This phenomenon reflects the evolutionary unity of life, with all organisms descending from a common origin rather than multiple independent origins.

Genomic evidence sup ports this notion. The absence of new, independent origins of life on Earth may be attributed to the com plete occu pation of ecological niches. In a system dominated by evolved organisms competing for survival, any newly emerged life form would likely be outcompeted and quickly eliminated.

The Study's Impact on the Panspermia Hypothesis

A Revitalization of the Panspermia Hypothesis

The study revitalizes aspects of the panspermia hypothesis by confirming that extraterrestrial organic material can provide metabolic energy to Earth-based organisms, underscoring the adaptability of microbes to non-terrestrial environments.

Implications for Future Exploration

The results indicate that despite advanced contamination control measures, cleanrooms cannot completely exclude microorganisms, suggesting that Earth microbes have likely been introduced to the Moon and Mars.

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