Scientists uncover why carbon-rich space rocks rarely reach Earth

Scientists uncover why carbon-rich space rocks rarely reach Earth
by Simon Mansfield
Sydney, Australia (SPX) Apr 15, 2025
A comprehensive international study may finally explain why carbon-rich meteorites, which are thought to contain key ingredients for life, are so rarely found on Earth despite being common in space.

Scientists from Curtin University's School of Earth and Planetary Sciences, the International Centre for Radio Astronomy Research (ICRAR), the Paris Observatory, and several other institutions conducted the most wide-ranging investigation to date, analyzing nearly 8,500 meteoroid and meteorite events. The data was gathered from 19 fireball observation networks across 39 countries.

The research, published in Nature Astronomy, suggests that both the Sun and Earth's atmosphere act as selective filters that destroy fragile, carbonaceous space rocks before they can reach the planet's surface.

Dr Hadrien Devillepoix, co-author from Curtin's Space Science and Technology Centre and CIRA, said the study offers direct evidence that these carbon-rich meteoroids are highly susceptible to destruction well before atmospheric entry.

"We've long suspected weak, carbonaceous material doesn't survive atmospheric entry," Dr Devillepoix explained. "What this research shows is many of these meteoroids don't even make it that far: they break apart from being heated repeatedly as they pass close to the Sun."

Only those that avoid extreme solar exposure are likely to survive long enough to potentially enter Earth's atmosphere, the study found.

These carbonaceous meteorites are crucial to astrobiological research as they often carry water and organic compounds, including amino acids that may have played a role in the emergence of life on Earth.

Dr Patrick Shober of the Paris Observatory highlighted the broader implications: "Carbon-rich meteorites are some of the most chemically primitive materials we can study - they contain water, organic molecules and even amino acids. However, we have so few of them in our meteorite collections that we risk having an incomplete picture of what's actually out there in space and how the building blocks of life arrived on Earth."

The researchers also discovered that meteoroids formed through tidal disruptions - when asteroids are torn apart by gravitational encounters with planets - are especially fragile and rarely survive atmospheric entry.

Dr Shober noted this has significant ramifications for planetary science: "This finding could influence future asteroid missions, impact hazard assessments and even theories on how Earth got its water and organic compounds to allow life to begin."

Collaborating institutions included the Astronomical Institute of the Romanian Academy, the National Museum of Natural History, and Aix-Marseille University.

Research Report:Perihelion history and atmospheric survival as primary drivers of the Earth's meteorite record