Examination of a tiny meteorite fragment from a 2008 Earth impact has uncovered evidence of a massive parent body, comparable in size to the dwarf planet Ceres.
In 2008, the four-meter-wide asteroid 2008 TC3, weighing about nine tons, entered Earth's atmosphere and exploded over Sudan, scattering 600 meteorites totaling roughly 10 kilograms. Scientists at the Southwest Research Institute in Texas recovered a 50-milligram fragment (AhS 202) from one of these. After polishing, they analyzed its composition using an infrared microscope. Findings are detailed in Nature Astronomy.
Spectral analysis revealed minerals including amphibole, which forms only under specific temperatures, pressures, and prolonged exposure to water. This marks the first detection of such a mineral in a meteorite of this type.
These conditions are impossible on small solar system bodies, indicating formation in a massive object that later fragmented. Researchers estimate its diameter at 640 to 1,800 kilometers, drawing comparisons to Ceres (950 km), the main asteroid belt's largest body and smallest dwarf planet.
“Carbonaceous chondrite meteorites capture early solar system geological activity, offering clues to their parent bodies' histories,” says lead author Vicky Hamilton. “Some show low-temperature, low-pressure water exposure; others indicate heating without water. Intermediate water-present metamorphism has been rare—until now.”
This meteorite's composition is striking yet potentially not unique. Asteroids Ryugu (Hayabusa2) and Bennu (OSIRIS-REx) show signs of extended water interaction. Samples from both missions—Hayabusa2's just this month—will soon allow direct comparisons.
