Dinosaur-killer asteroid chemical makeup revealed
Asteroids (and the smaller meteoroids that break off of them) come in three major varieties, each with their own chemical and mineral makeup: metallic, stony and chondritic. In the new study, Goderis and his colleagues, including the study’s lead author, Dr. Mario Fischer-Gödde of the University of Cologne in Germany, examined the chemical composition of the thin clay layer to unlock the asteroid’s secrets.
The researchers sampled 66 million-year-old rocks from Denmark, Italy and Spain and isolated the parts containing the metal ruthenium. (Like iridium, ruthenium is more abundant in space rocks than in Earth’s crust.) The team also analyzed ruthenium from other asteroid impact sites and meteorites. The chemical makeup of the ruthenium from 66 million years ago matched the chemical makeup of the ruthenium present in a certain kind of chondritic meteorite, the scientists found.
“We noticed that there’s a perfect overlap with carbonaceous chondrite signatures,” Goderis said. Therefore, the asteroid that killed the dinosaurs was probably a carbonaceous chondrite, an ancient space rock that often contains water, clay and organic (carbon-bearing) compounds.
While carbonaceous chondrites make up the majority of rocks in space, only about 5% of the meteorites that fall to Earth belong to this category. “There is quite some diversity in carbonaceous chondrites, and some of them can smell,” Goderis said. But in the inferno, when the Chicxulub impactor landed, Goderis said, “you probably wouldn’t have had the time for a good sniff.”
