Scientists Identify Mysterious Asteroid as Source of Unusual Cosmic Dust on Earth

Every year, thousands of tons of cosmic dust in the form of tiny micrometeorites fall onto Earth, originating from asteroids and comets. A new study published in "Science Advances" reveals that a significant portion of this dust comes from an unknown asteroid, previously unrecognized in terrestrial meteorite collections. Researchers discovered unique particles, named SCumPo, characterized by high sulfur content and abundant olivine, lacking magnetite, a common mineral in cosmic dust, indicating a carbon-rich environment that prevented iron oxidation.

These particles also exhibit heavy oxygen isotope ratios, suggesting the parent asteroid was influenced by water with an unusual oxygen composition. Simulations of their atmospheric entry show they arrived at very high speeds, implying their source is a near-Earth asteroid rather than the distant asteroid belt between Mars and Jupiter. Matthias Van Ginneken, a cosmochemist at the University of Kent and lead author, noted that while this asteroid might already be cataloged among over 40,000 known near-Earth objects, confirming its identity requires direct sampling, a challenging endeavor.

The discovery highlights the untapped potential of micrometeorite research, which remains in its infancy. Only a small fraction of cosmic dust collections have been studied, and other unknown sources may be hidden in Antarctic and global dust samples. Researchers estimate that up to 10% of micrometeorites collected could originate from this enigmatic asteroid, which has been continuously depositing dust on Earth for over a million years.