Why do meteorites that land on Earth not match their asteroid brethren in space?
Patrick Shober, postdoctoral fellow at the Paris Observatory and NASA’s Johnson Space Center, watches the skies for answers.
Faculty Bio:
Patrick Shober is a planetary scientist who investigates small solar-system bodies—from asteroids and comets to the spectacular fireballs their debris creates in Earth’s atmosphere. He earned his PhD at Curtin University in Perth, Australia, where he worked with the Desert Fireball Network to trace meteor paths and recover fresh meteorites. Recently starting a fellowship at NASA’s Johnson Space Center, his research combines orbital dynamics, lab analysis, and field recovery to better understand our solar system.
Transcript:
Beyond planets and moons, our solar system is strewn with leftover building blocks—asteroids. Every day, pieces of these asteroids hit the Earth and if the fragment is tough enough, it can survive a fiery plunge through our atmosphere and land as a meteorite—a space rock we can hold in our hands.
Yet asteroids don’t match meteorites in museums, and we don’t know why. Dark, water-bearing carbonaceous asteroids are abundant in space, but only four percent of recovered meteorites are this material. Why the mismatch?
To investigate, an international network of automated fireball cameras—nineteen arrays on five continents—watched the sky every clear night for decades. Each station films the whole sky, all night. When a bright shooting star—or fireball—flares, overlapping views capture its streak. We triangulate the path, predict where stones may fall, and—crucially—calculate the object’s orbit. Analyzing more than 8,500 such atmospheric impacts, we uncovered two natural filters that explain our mismatch.
Firstly, the rocks are getting baked too much when near the Sun. We find that carbonaceous debris is missing even before it reaches Earth. Repeated baking and freezing shatter the weakest, most porous, water-rich rocks into dust.
Secondly, we still have the atmosphere. Of the fragments that survive space, roughly only half are strong enough to survive all the way to the ground.
Every meteorite is a double survivor, branded by both filters. Continued monitoring of atmospheric impacts will refine this link, enabling meteorites to tell an ever clearer story of our solar system’s origins and evolution.
Read More:
[The Conversation] – Why the meteorites that hit Earth have less water than the asteroid bits brought back by space probes – a planetary scientist explains new research
[Nature Astronomy] – Perihelion history and atmospheric survival as primary drivers of the Earth’s meteorite record
