Hal Clement dominates a specific hard-sf niche. He designs worlds. Now, you might have doubts about a book-long planetology lecture, thinly disguised as a novel. Clement made it work, for his audience, better than Forward, who followed in his footsteps, ever made it work for his own. Clement's written a number of entertaining books, but three in particular, from the fifties and sixties, stand out:
Mission of Gravity (***). The planet Mesklin is unique: Its enormous size and rapid rotation have combined to produce a planet whose surface gravity is three times that of Earth at the equator -- and increases to seven-hundred times that of Earth at the poles. When an exceedingly expensive unmanned probe fails, the team researching the planet contacts a native trader (at the equator, naturally), and persuades him to retrieve the probe. For his own reasons, he agrees. What would conditions be like on a world where all falls are fatal falls and missile weapons are a good way to get holes in your feet? In a way, Mission of Gravity is a novel-length science lecture superimposed upon a storyline, but it works. If you read one book by Clement, read this one.
Close to Critical (***). Once again there's a story of humans interacting with the natives of an unusual planet, but once again the real star of the book is the planet itself. In this case it's the planet Tenebra, a high-gravity planet with a surface temperature of close to four hundred degrees (fahrenheit, presumably), a pressure of eight hundred atmospheres, and a somewhat corrosive atmosphere. (This is a planet where talking about the weather is not idle chit-chat.) The leisurely study of this planet, however, becomes rushed when two children are accidentally stranded on it.
Cycle of Fire (***) follows the usual pattern, only this time the planet on which the obligatory crash takes place is not, in itself, unusual. Except that its orbit, which is unusual, is about to enter the phase in which the entire biosphere burns to a crisp. Which calls for some unusual adaptations, especially for an intelligent species.
Dani Zweig firstname.lastname@example.org
The inability of snakes to count is actually a refusal, on their part, to appreciate the Cardinal Number system. -- "Actual Facts"