Hal Clement made, alongside Clarke and Asimov, the triumvirate of “hard science” science-fiction writers; all three wrote during sci-fi’s “golden age” between 1940 and 1960, they all had science backgrounds, and all delighted in writing sci-fi that no matter how “out there”, was grounded in science (sometimes science yet-to-be-discovered) and the laws of physics.
Clement, who was a H.S.
physics chemistry (thanks LT! ) and astronomy teacher in his ‘regular’ life, particularly enjoyed creating worlds that were quite alien and quite plausible at once. he took pains to visualize and describe the worlds and inhabitants; he was a masterful world-builder.
one of Clement‘s most memorable world is Mesklin, the planet where Mission of Gravity is set; Mesklin is a planet of immense and varying gravity, it requires extreme adaptations by its inhabitants. one of these inhabitants, Barlennan, is the protagonist of Mission of Gravity. Barlennan is the captain of a trading expedition who comes across alien explorers and agrees to help them recuperate a scientific probe lost near one of Mesklin‘s poles.
Clement wrote “A Whirligig World”, an essay that explains the physics of Mesklin, and its inhabitants; it was first published in the magazine Astounding, and it was included in every subsequent edition of Mission of Gravity. it is a fine read on its own and a good introduction to the mechanics of world-building.