Unveiled Reasons Why the Richest Carbon Asters Often Miss Reaching Earth
In a groundbreaking study, a team of astronomers, including Patrick Shober from the Paris Observatory and Hadrien Devillepoix from Australia's Curtin Institute of Radio Astronomy, have shed light on why carbon-rich meteorites are underrepresented on Earth.
The research findings indicate that the diversity of carbon-rich rocks needs to be considered beyond the ones that reach our planet. The primary reason for this discrepancy lies in the fragility of carbon-rich asteroids, which are abundant in the solar system, both in the main belt and closer to Earth.
Thermal stress and fragmentation in space are the main culprits behind the breakup of these asteroids. Research shows that carbon-rich asteroids experience large temperature fluctuations when they approach the Sun. These fluctuations cause cracking and fragmentation in space itself, long before these bodies enter Earth's atmosphere. As a result, many fragile carbonaceous materials break apart into smaller, less carbon-rich fragments or dust that do not survive to become meteorites on the ground.
While it was previously thought Earth’s atmosphere destroys fragile carbonaceous meteorites during fiery entry, recent studies suggest atmospheric entry is not the primary cause of their scarcity. Instead, thermal fracturing in space dominates their destruction.
The intrinsic fragility of carbonaceous material also plays a role. Carbonaceous chondrites, which contain water and organic compounds, are often more friable, making them more susceptible to breakage both in space due to thermal cycling and during impact events, compared to more robust rocky or metallic meteorites.
Only the drier and more resistant fragments of carbonaceous asteroids tend to survive the journey through space and atmosphere and become meteorites found on Earth. This biasing terrestrial collections towards less carbon-rich material.
Carbon-rich meteorites, such as those studied by Shober, are some of the most chemically primitive materials we can study. They contain water, organic molecules, and even amino acids, offering a unique opportunity to study some of the oldest material in the solar system.
The research team analyzed nearly 8,000 meteoroid impacts and 540 potential falls from 19 different observation networks around the globe. Their findings suggest that many carbon asteroids break apart as they pass close to the Sun due to heating.
To get a proper assessment of the diversity of carbon-rich rocks, astronomers will have to consider those that couldn't survive the journey to Earth. The team's research focuses on the meteoroids created by tidal disruption events.
The discrepancy between the abundance of carbon asteroids in space and on Earth is due to them getting obliterated by the Sun and Earth's atmosphere. However, missions like Japan's Hayabusa2 and NASA's OSIRIS-REx have brought rocky material from distant carbon-rich asteroids to Earth for more extensive investigation.
Despite their rarity, carbon-rich meteorites on Earth still provide valuable insights into the building blocks of life and the solar system's history. The team's findings underscore the importance of studying these rare, yet crucial, celestial bodies.
The research paper on this topic has been published in Nature Astronomy. Devillepoix stated in a university release that they had long suspected weak, carbonaceous material does not survive atmospheric entry. The team's findings confirm this suspicion, offering a new perspective on the study of meteorites and the solar system as a whole.
- The findings of the study suggest that Earth’s atmosphere is not the primary cause for the scarcity of fragile carbonaceous meteorites; instead, thermal fracturing in space dominates their destruction.
- Carbonaceous chondrites, which contain water and organic compounds, are often more friable, making them more susceptible to breakage in space due to thermal cycling and during impact events.
- To get a proper assessment of the diversity of carbon-rich rocks, astronomers will have to consider those that couldn’t survive the journey to Earth, such as the meteoroids created by tidal disruption events.
- The research published in Nature Astronomy indicates that only the drier and more resistant fragments of carbonaceous asteroids tend to survive the journey through space and atmosphere to become meteorites found on Earth.
- The team’s findings emphasize the importance of studying carbon-rich meteorites, as they offer a unique opportunity to study some of the oldest material in the solar system, containing water, organic molecules, and even amino acids.
