Space Apprentice, also known as Probationers (Russian: Стажёры, romanized: Stazhyory), is a science fiction novel by Soviet-Russian writers Arkady and Boris Strugatsky, originally published in 1962. It is set in the Noon Universe following The Land of Crimson Clouds and "Destination Amalthea", hundreds of years before the other Noon novels.This is the Strugatsky brothers' final hard science fiction novel, and it gives reasons why they decided to move into social science fiction instead. Source: Wikipedia (en)