244Pu has recently been discovered in deep-sea deposits spanning the past 10
Myr, a period that includes two 60Fe pulses from nearby supernovae. 244Pu is
among the heaviest r-process products, and we consider whether it was created
in the supernovae, which is disfavored by nucleosynthesis simulations, or in an
earlier kilonova event that seeded 244Pu in the nearby interstellar medium that
was subsequently swept up by the supernova debris. We discuss how these
possibilities can be probed by measuring 244Pu and other r-process
radioisotopes such as 129I and 182Hf, both in lunar regolith samples returned
to Earth by missions such as Chang'e and Artemis, and in deep-sea deposits.Comment: Extensive rewrite of v1 with added emphasis of lunar sample return
missions, including Artemis and Chang'e. 11 pages, 4 figures, 2 tabl
