Donald Delbert Clayton (March 18, 1935 – January 3, 2024) was an American astrophysicist whose most visible achievement was the prediction from nucleosynthesis theory that supernovae are intensely radioactive.

Not only did Clayton discover radioactive nucleosynthesis during explosive silicon burning in stars [2][3][4] 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.

He gathered support from influential astronomers and physicists for a new NASA budget item for a gamma-ray-observatory satellite,[7] achieving successful funding for Compton Gamma Ray Observatory.

Clayton was born on March 18, 1935, in a modest rented duplex on Walnut Street in Shenandoah, Iowa, while his parents were temporarily away from both family farms near Fontanelle seeking work during the Great Depression.

Becoming the first among his entire Iowa relations to seek post-high-school education, Clayton matriculated at Southern Methodist University and excelled in physics and mathematics, graduating summa cum laude in 1956.

At the urging of his SMU professors, he applied as a physics research student to California Institute of Technology (Caltech), which he attended bearing a National Science Foundation Predoctoral Fellowship.

Caltech afforded Clayton the chance to meet and later become a lifelong friend of Fred Hoyle, British cosmologist and creator of the theory of nucleosynthesis in stars.

A historic connection of Clayton's academic career to NASA's Apollo Program arose through establishment by Rice University of its Department of Space Science in 1963.

During the 1970s at Rice University Clayton guided Ph.D. theses of many research students who achieved renown, especially Stanford E. Woosley, William Michael Howard, H. C. Goldwire, Richard A.

During (1977–84) Clayton resided part-time annually at the Max Planck Institute for Nuclear Physics in Heidelberg as Humboldt Prize awardee, sponsored by Till Kirsten.

Clayton designated the crystalline component of interstellar dust that had condensed thermally from hot and cooling stellar gases by a new scientific name, stardust.

He and student Kurt Liffman computed a pathbreaking history of survival rates of refractory stardust in the interstellar medium after its ejection from stars;[37][38] and with student Mark D. Leising computed a propagation model of positron annihilation lines within nova explosions[39] and of the angular distribution of gamma ray lines from radioactive 26Al in the galaxy.

Feeling vindicated,[41] Clayton exulted in Nature "the human race holds solid samples of supernovae in its hands and studies them in terrestrial laboratories".

18  He began this academic segment (1989–present) by hiring three talented young astrophysicists [43] to vitalize joint research with the Compton Gamma Ray Observatory (launched in 1991 after several delays).

Its four instruments successfully detected gamma-ray lines identifying several of the radioactive nuclei that Clayton had predicted to be present in supernova remnants.

These workshops featured the excitement of new isotopic discoveries, and also helped participants focus their ideas for submission of abstracts to NASA's Lunar and Planetary Science Conference.

Following his retirement from academic duties in 2007, Clayton remained quite active in research problems involving condensation of dust within supernovae[47] and has also published a scientific autobiography, Catch a Falling Star.

Clayton's published refereed research papers prior to 2011 are listed at http://claytonstarcatcher.com/files/documents/JournalPub.pdf Clayton married three times: in 1954 in Dallas[48] to Mary Lou Keesee (deceased 1981, Houston) while they were students at SMU;[19]: 98–100  in 1972 in St. Blasien, Germany to a young German woman, Annette Hildebrand (divorced 1981, Houston);[19]: 300–301  in 1983 in the Rice University Chapel, finally to the former Nancy Eileen McBride[19]: 412–413  who was trained in art and in architecture and is today an artist.