NASA Finds Primordial Water in 12 Kuiper Belt Dust Grains Beyond 30 AU
Updated
Updated · ScienceAlert · Nov 12
NASA Finds Primordial Water in 12 Kuiper Belt Dust Grains Beyond 30 AU
3 articles · Updated · ScienceAlert · Nov 12
Summary
Twelve dust grains collected from Earth's stratosphere preserve evidence of ancient water with an oxygen-isotope signature unlike inner Solar System material, pointing to a separate primordial reservoir beyond Neptune.
Track densities about 100 times higher than expected for asteroid-belt or Jupiter-family comet dust indicate the 10-to-30-micrometer grains likely drifted inward from the Kuiper Belt.
Clay minerals including saponite and serpentine show liquid water once altered the grains' parent bodies, likely when radioactive decay or collisions briefly melted interior ice billions of years ago.
The heavy-oxygen-rich signature supports models in which Saturn and the ice giants blocked outer material from mixing inward, preserving a distinct water reservoir at the Solar System's edge.
The finding, published in Science Advances, suggests some of the roughly 5,200 metric tons of cosmic dust reaching Earth each year may carry relatively pristine records of early Solar System chemistry.