Francesco (Frank) Asaro

Francesco (Frank) Asaro, 86, a Lawrence Berkeley National Laboratory (LBNL) senior scientist emeritus and nuclear chemist who helped devise the asteroid impact theory to explain the mass extinctions that wiped out the dinosaurs 65 million years ago, died in Redwood City, Calif., on June 10.

Born to avocado farmers in Escondido, Calif., Asaro attended the University of California, Berkeley, earning a B.S. in chemistry in 1948 and a Ph.D. in chemistry in 1953 under Isadore Perlman.

Asaro joined LBNL in 1950 to continue working with Perlman, who was also the head of the lab’s now-defunct Nuclear Chemistry Division. Together, they helped refine neutron activation analysis (NAA) into a technology precise enough to determine the origins of archaeological artifacts by measuring their chemical compositions.

For many years, Asaro was a scientist in LBNL’s Nuclear Chemistry Division, before working in its Environmental Energy Technologies Division.

He was part of the team that developed the mass extinction theory, which proposed that an asteroid’s impact hurled a cloud of dust into the atmosphere so thick that it obscured the sun, suppressed photosynthesis, and caused mass extinctions. For his part, Asaro contributed his great skill in measuring unusually high levels of iridium of extraterrestrial origin found in rocks from Earth’s Cretaceous-Paleogene boundary layer, which provided critical support for the theory.

Asaro spent much of his career applying NAA to archaeological studies. He demonstrated that Drake’s Plate, a metal plaque purportedly left by Sir Francis Drake when his ship dropped anchor at the California coast in 1579, was a fake. After his retirement from LBNL in 1991, Asaro continued to investigate a series of archaeological and historical challenges.

Asaro’s wife of 63 years, Lucille, predeceased him. He is survived by his son, Frank, and three daughters, Antonina, Catherine, and Marianna.