Doesn’t stand the test of time. It’s repetitive, disrespectful and unimaginative science fiction from the not so golden age of SF.
As mentioned in other reviews, the conception resembles a series of Star Trek episodes. Each episode, a mixed crew is send to another planet to explore the habitat.
Things start going south with Russell’s definition of a mixed crew. Whites because they are good at technology. Blacks because they don’t get space nausea. Martians (!) because they use very little air, are fairly immune to cosmic ray-burn and with their tentacles are formidable fighters. No women. I could live with this as a representation of the time the book was written.
But this definition is a foreshadowing of Russell’s narrow-minded imagination. Each planet visitation follows the same structure of exploration, making first contact, getting attacked, finding ways to fight back and finally abscond back to Earth. A banal plot repeated four times and the author’s ideas for the different alien lifeforms can’t rescue this wreck of a spaceship.
One note: I read the German translation which probably is an abridged version of the book.