Space Cadet

This is the seminal novel of a young man's education as a member of an elite, paternalistic non-military organization of leaders dedicated to preserving human civilization, the Solar Patrol, a provocative parallel to Heinlein's famous later novel, Starship Troopers (which is about the military).
Only the best and brightest, the strongest and the most courageous, ever manage to become Space Cadets, at the Space Academy. They are in training to be come part of the elite guard of the solar system, accepting missions others fear, taking risks no others dare, and upholding the peace of the solar system for the benefit of all.
But before Matt Dodson can earn his rightful place in the ranks, his mettle is to be tested in the most severe and extraordinary ways, ways that change him forever, from the midwestern American boy into a man of the Solar Patrol.
A young man reports for the final tests for appointment as a cadet in the Interplanetary Patrol, survives the tests, studies in the school ship, and goes on a regular Patrol vessel and encounters danger on Venus.