Links on author, publisher, or year fetch more matching fiction.
- [novel] Donald Allen Wollheim's "The Secret of the Ninth Planet"; download: An interplanetary adventure to uncover what's behind "the theft of the solar system's light".
- Kris Neville's "Earth Alert!"; download; Imagination, February 1953: "What defense could she raise against mutant science--telepathy, invisibility, teleportation--especially since Earth was not aware of its danger!"
I haven't done the word count, but this appears to be nearly novel size. Or at least novella size.