Most meteorites that reach Earth can be traced to three locations

An international team of scientists has completely transformed our understanding of meteorites and their origins.

The experts have successfully demonstrated that 70% of all known meteorite falls originate from just three young asteroid families.

The study was led by researchers from the CNRS, the European Southern Observatory (ESO, Europe), and Charles University (Czech Republic).

Mysterious origins of meteorites

Traditionally, meteorites have fueled our curiosity about the cosmos. They serve as tangible pieces of the universe that we can observe, analyze, and learn from without leaving our home planet.

The international research team concluded that of all known meteorite falls, the majority can be traced back to three young asteroid families – Karin, Koronis, and Massalia.

These families were born from collisions in the main asteroid belt about 5.8, 7.5, and roughly 40 million years ago. Most noteworthy among these families, the Massalia family has been identified as the source of 37% of known meteorites.

While it’s true that we have records of more than 70,000 meteorites, only 6% had been clearly identified by their composition. These “achondrites” are known to come from the Moon, Mars, or Vesta (one of the largest asteroids in the main belt).

The origin of the other 94% of meteorites, the majority of which are ordinary “chondrites,” had remained a puzzle.

Life cycle of asteroid families

But why are the three young asteroid families such prolific contributors to meteorite falls? The answer lies in the life cycle of asteroid families.

Young families are defined by an abundance of small fragments left over from collisions. This abundance, coupled with the fragments’ high mobility, increases the risk of collisions that can lead to escape from the belt, possibly hurtling towards Earth.

In contrast, asteroid families produced by older collisions are “depleted” sources of meteorites. Over time, the abundance of small fragments naturally erodes and eventually disappears, paving the way for new sources of meteorites from more recent collisions.

Breakthrough in meteorite origins

The monumental discovery was made possible by a telescopic survey of the composition of all the major asteroid families in the main belt, bolstered by state-of-the-art computer simulations.

This method was extended to all meteorite families, unveiling the primary sources of carbonaceous chondrites and achondrites, adding to those from the Moon, Mars, and Vesta.

Consequently, the origin of more than 90% of meteorites has now been identified – a significant leap in our understanding.

Broader implications of the research

This research has also enabled scientists to trace the origin of asteroids that are large enough to pose a threat to life on Earth.

For instance, it turns out that the asteroids Ryugu and Bennu – recently sampled by the Hayabusa2 (Japanese Aerospace Exploration Agency JAXA) and OSIRIS-REx (NASA) missions and studied in laboratories around the world – are derived from the same parent asteroid as the Polana family.

Even after this remarkable breakthrough, the origin of the remaining 10 percent of known meteorites remains uncharted. Undeterred, the team is already gearing up for their next mission – to characterize all young families formed less than 50 million years ago.

Significance of meteorite origins research

As we advance our comprehension of meteorite origins, the implications for both scientific inquiry and practical applications become increasingly compelling.

Future research prospects include a more detailed analysis of less-studied asteroid families, potentially identifying their contribution to the remaining 10% of uncharted meteorite origins.

The emphasis on innovative observational methods and computational models holds the promise of refining our understanding of the cosmic processes that govern the distribution and descent of meteorites.

These efforts are supported by ongoing and future space missions tasked with bringing back direct samples from asteroids.

Further research will improve our understanding of the meteorites themselves, as well as the formation and evolution of our solar system.

Intersection of space research

The knowledge gained from meteorite studies extends beyond academic curiosity, offering valuable applications in fields ranging from geology to planetary defense.

Understanding the composition and behavior of meteorites can help experts draw parallels with Earth’s geological history, providing clues to the early conditions and processes of our planet.

This research also helps to inform the development of planetary defense strategies, as the ability to predict and mitigate potential impacts from space debris is enhanced.

Moreover, meteorite-oriented discoveries fuel advancements in material science, potentially leading to the development of novel materials or understanding natural occurrences in extreme environments.

As our grasp of these cosmic visitors strengthens, we stand better equipped not only to unravel the mysteries of our own planet but also to anticipate and navigate the challenges of space exploration and habitation.

The study is published in the journal Astronomy and Astrophysics.

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