I seem to have trouble hitting 'enter' on reviews of Heinlein novels, but who cares, cause there's only two types of Heinlein novels: Weird as hell, and totally awesome.

This is the second, with lots of smart 1950s space science about interplanetary travel with flying saucer drives, some really fascinating aliens, brave and capable characters (including a girl. Yay Peewee!). You just have to love how Kip and Peewee never give up, even when kidnapped by horrible bug-eyed monsters, running out of air on the Moon, freezing on Pluto, or representing all of humanity in a mortal trial before the intergalactic UN.