Johndale Solem origin of the shape of rubble-pile asteroids. His analytic theory of the breakup of comets by planetary tidal forces resulted in his calculation of the diameter and density of the parent comet of Shoemaker-Levy 9 as it was before breaking up in the tidal field of Jupiter in 1994 (1994a). Solem's research on interplanetary travel culminated in his MEDUSA concept, a nuclear explosive propelled spacecraft for interplanetary space travel (1994b). Gregory Matloff said this was "a surprising [propulsion] concept which might greatly reduce spacecraft mass." The concept inspired research and elaboration by the aerospace community. At the behest of NASA's
The Elves and the Shoemaker cartoon short "Holiday for Shoestrings". In the "Due South" episode, "The Deal", Det. Ray Vecchio vaguely recollects this story when discussing a poor cobbler with his partner, Constable Fraser. In "", a spinoff miniseries of the Vertigo comic-book series "Fables", the shoemaker appears as an employee in Cinderella's shoe store, while the elves are the builders and suppliers of the store's inventory. "Muppet Classic Theater" had a version where a shoemaker (played by Kermit the Frog) faces ruin until his livelihood is saved by a group of philanthropic entertainers (played by The Elvises) who, naturally, make only blue suede shoes.