RED PLANET <i> by Robert Heinlein (Del Rey: $3.95) </i>

Although his sprawling “Stranger in a Strange Land” became one of the icons of the ‘60s counterculture, Robert Heinlein did his best writing in the juvenile novels he produced during the late ‘40s and early ‘50s. Crisply paced, neatly plotted and peopled with agreeable characters, “Red Planet” (also “Tunnel in the Sky,” “Starman Jones,” “Farmer in the Sky” and “Time for the Stars”) still can entertain readers, while such “adult” works as “Glory Road” and “Farnham’s Freehold” have been consigned to the shelves reserved for pretentious bores.

A pronounced conservatism runs through Heinlein’s work, and he manages to transplant old-fashioned Midwestern values to other planets and centuries. Near the end of “Red Planet,” at a town meeting on Mars, the colorful, wise Doc declares, “Any man old enough to fight is a man and must be treated as such--and any girl old enough to cook and tend babies is an adult, too.”