Persistent cosmic deposition
An international research team has demonstrated that Earth has been receiving particles from an ancient kilonova for more than 100 million years. The conclusion stems from measurements of rare isotopes embedded in a slowly accumulating ferromanganese crust retrieved from the Pacific Ocean floor.
Analytical approach
The crust, which records millennia of metal‑oxide deposition, contains traces of plutonium‑244, an isotope produced exclusively in highly energetic events such as kilonovae. High‑resolution mass spectrometry allowed the scientists to quantify its concentration and reconstruct its temporal profile.
Implications for cosmic chemistry
The findings suggest that the ejecta of a single kilonova explosion can be incorporated into Earth’s atmosphere over geological timescales. This steady “plutonium rain” provides new insight into the distribution of heavy elements across the solar system and the role of catastrophic events in Earth’s chemical evolution.
Future work
Published in Nature Astronomy, the study calls for additional deep‑sea sampling across various ocean basins to map the global extent of kilonova remnants. Continued monitoring may also reveal whether comparable deposition processes are ongoing today.