Donald D. Clayton

American astrophysicist whose most visible achievement was the prediction from nucleosynthesis theory that supernovae are intensely radioactive. That earned Clayton the NASA Exceptional Scientific Achievement Medal (1992) for “theoretical astrophysics related to the formation of (chemical) elements in the explosions of stars and to the observable products of these explosions”. Supernovae thereafter became the most important stellar events in astronomy owing to their profoundly radioactive nature.

Not only did Clayton discover radioactive nucleosynthesis during explosive silicon burning in stars but he also predicted a new type of astronomy based on it, namely the associated gamma-ray line radiation emitted by matter ejected from supernovae. That paper was selected as one of the fifty most influential papers in astronomy during the twentieth century for the Centennial Volume of the American Astronomical Society.

He gathered support from influential astronomers and physicists for a new NASA budget item for a gamma-ray-observatory satellite, achieving successful funding for Compton Gamma Ray Observatory. With his focus on radioactive supernova gas Clayton discovered a new chemical pathway causing carbon dust to condense there by a process that is activated by the radioactivity.

Clayton authored four books for the public: (1) a novel, The Joshua Factor (1985), a parable of the origin of mankind utilizing the mystery of solar neutrinos; (2) a science autobiography, Catch a Falling Star; (3) a mid-career memoir The Dark Night Sky, of cultural interest owing to Clayton's conception of it in 1970 as layout for a movie with Italian filmmaker Roberto Rossellini about growing awareness during a cosmological life; and (4) Handbook of Isotopes in the Cosmos (Cambridge Univ. Press, 2003), describing in prose the nuclear origin of each isotope of our natural elements and important evidence supporting each nuclear origin.

Donald D.