Around 466 million years ago, Earth was bombarded by a massive swarm of space rocks that collided violently with our planet. This may have been the result of a large asteroid breaking apart into smaller fragments while traveling in orbit between Mars and Jupiter. The family of asteroids known as Massalia, a group of asteroids that share similar orbits, is likely the main cause of this massive impact. In fact, this asteroid family dominates nearly 40% of all meteorites that have fallen on Earth, with two other asteroid families named as sources for most Earth-related meteorites.
Thousands of meteorites have been recovered from Earth after a fiery journey through space. Now, new research is able to trace the origins of the majority of these falling space rocks, indicating that three young asteroid families are responsible for over 70% of meteorites on Earth. This discovery was detailed in three studies published in Nature and Astronomy & Astrophysics, and the new findings can help scientists uncover secrets of the early solar system.
The three asteroid families, Karin, Koronis, and Massalia, formed through collisions in the main asteroid belt, specifically around 5.8 million years ago, 7.5 million years ago, and 40 million years ago. While this may seem like a long time to our human minds, it is relatively recent compared to the age of the solar system (around 4.5 billion years).
Michael Marsset, a researcher at the European Southern Observatory and lead author of one of the research papers, told Gizmodo: “Recent impact events that occurred in the asteroid belt completely dominate the flow of material to our planet.” “You might think that the flow of meteorites should be a mix of all the compositional layers we observe in the asteroid belt, but it’s not at all, as three asteroids that recently split apart dominate it.” Marsset and his colleagues use the word “flow” to refer to the movement of meteorites from space to Earth.
Marsset explains that he wanted to trace the origin of meteorites to resolve the contradiction between space rocks on Earth and those observed in the asteroid belt. So far, researchers have been able to trace the origin of only about 6% of meteorites, primarily from the Moon, Mars, and one of the largest asteroids in the asteroid belt, Vesta. But the source of the remaining rocks remained a mystery.
By using telescopic surveys of all major asteroid families in the main asteroid belt, along with computer simulations of the collisional and dynamic evolution of these main families, scientists behind the recent discovery were able to uncover the primary source of most other meteorites. Based on the chemical composition of the meteorites, researchers traced them back to the original body from which they separated before landing on Earth.
Pierre Vernazza, a researcher at the French National Center for Scientific Research, said: “Such major collisions don’t happen every day, but every 30 to 50 million years seems to be a correct recurrence, even with three major impacts over the past eight million years or so.” The researcher and lead author of one of the studies told Gizmodo.
While the results are surprising, there may be a reason why young asteroid families dominate the flow of meteoric material to Earth. Younger asteroid families tend to retain many smaller-sized fragments left behind by collisions that caused their breakup. These fragments face a greater risk of colliding with each other, potentially pushing some smaller debris towards Earth. Marsset said, “Collisions within these families are still active.” “That’s why they dominate meteorite production.”
Meteorites are small rocky clues to the secrets of the solar system that end up on Earth. Scientists can learn a lot from studying meteorites, allowing them to take a rare look at the early years of Earth and neighboring planets.
Marsset said: “Meteorites retain a lot of information about our early planetary disk in their current composition.” “By linking these meteorites that we can study in detail with specific families in the asteroid belt, we can reconstruct the original compositional and thermal gradient of our early planetary disk. And that’s ultimately the goal of this kind of study. This is what we want to learn.”
In addition to tracing the origin of these space rocks, a close study of meteorites can reveal insights into the chaotic beginnings of our celestial neighbors and what happened millions of years before our arrival.
