Mission of Gravity is a science fiction novel by American writer Hal Clement. The novel was serialized in Astounding Science Fiction magazine in April–July 1953. Its first hardcover book publication was in 1954, and it was first published as a paperback book in 1958. Along with the novel, many editions (and most recent editions) of the book also include "Whirligig World", an essay by Clement on creating the planet Mesklin that was first published in the June 1953 Astounding. Clement published three sequels to Mission of Gravity: a 1970 novel called Star Light, a 1973 short story called "Lecture Demonstration", and a 2000 short story, "Under". Mission of Gravity was nominated for a "Retro-Hugo" Award for the year 1954. Source: Wikipedia (en)