Rip Foster Rides the Gray Planet - Harold L. Goodwin

"Foster, Lieutenant, R. I. P.," blared the voice horn, and five minutes later Rip Foster was off into space on an assignment more exciting than any he had ever imagined. He could hardly believe his ears. Could a green young Planeteer, just through his training, possibly carry out orders like these? Sunny space, what a trick it would be! From the moment Rip boards the space ship Scorpius there is a thrill a minute. He and his nine daring Planeteers must cope with the merciless hazing of the spacemen commanding the ship, and they must outwit the desperate Connies, who threaten to plunge all of space into war. There are a thousand dangers to be faced in high vacuum—and all of this while carrying out an assignment that will take every reader's breath away. - Summary by Original book cover