A study led by the Southwest Research Institute proposes a new explanation for the composition of meteorites, published on July 8, 2026, in Science Advances. The research aims to solve the mystery of how millimeter-sized, spherical mineral grains became concentrated within the parent bodies of the most common meteorites, known as chondrites.
Understanding Chondritic Asteroids and Meteorites
Chondritic asteroids are ancient celestial bodies that orbit the sun, while chondrite meteorites are rocky fragments that fall to Earth. Both types of bodies contain primitive materials. Chondrite meteorites consist mainly of chondrules, which are tiny, once-molten droplets of rock, embedded in a fine-grained matrix. “While several mechanisms may have created the chondrules themselves, I have always been surprised by how homogeneous the chondritic asteroids seem to be,” said Hal Levison, the first author of the study. “We were looking for a process that corrals these small droplets into asteroid-sized bodies.”
The Role of Giant Impacts in Meteorite Formation
The research indicates that the answer to the chondrite mystery may lie in the chaotic final stages of terrestrial planet formation, during which planetary embryos—moon- to Mars-sized bodies—frequently collide. Using numerical simulations, the team investigated giant-impact scenarios that generate sheets of molten and solid ejecta. “This circum-embryo disk orbits a growing protoplanetary embryo, accumulating into larger bodies and forming asteroid-sized satellites,” Levison explained. This process is similar to how Mars's moons, Phobos and Deimos, were formed.
Escaped Satellites and Their Significance
The study finds that some of these satellites can be dynamically liberated from their orbits around the planetary embryo, leading them to establish independent orbits around the sun. These escaped satellites become the parent bodies of chondritic asteroids, which are the source of the chondrite meteorites found on Earth. “As such, chondritic asteroids are not leftover random rubble from the solar nebula,” said Kevin Walsh, the third author. “They are escaped satellites—former moons-in-the-making—that carry within them a detailed record of the violent processes that built the terrestrial planets,” added Rogerio Deienno, the second author of the work.
- Publication date: July 8, 2026
- Published in: Science Advances
- First author: Hal Levison
- Key concepts: impact cratering, meteorites, accretion, asteroids, solar system
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