Space Apprentice, also known as Probationers (Russian: Стажёры, romanized: Stazhyory), is a science fiction novel by the Soviet writers Arkady and Boris Strugatsky.

Disappointed, Yuri wanders into a capitalist-run bar in which the owner/bartender is engaged in an ideological debate with a Russian communist.

The Earth (mostly-Russian) colonists there are battling an alien life form the giant slug (the Flying Martian Leech aka sora-tobu hiru).

Some colonists lament the lack of initiative that has descended over the colony in recent years, and Yurkovsky agrees.

The raid on slugs, which is carried out in part using the weapons brought by Yurkovsky, is reasonably successful, and the colonists cheer up.

On the way to the research space station Eunomia, the spaceship crew runs an emergency drill, and Yuri, while stressed and confused, holds up to the pressure.

The station was orbiting the Sun with parameters of 15 Eunomia, a very large asteroid that nearly completely disappeared after a few years of research.

Yurkovsky and Yuri witness a scheduled experiment on propagation of gravitational waves that are created by annihilating a chunk of the asteroid the size of Mount Everest.

The station is severely overcrowded, but the scientists gladly put up with the inconveniences such as food shortages or having to sleep in an elevator.

In the drive to maximize profits, the miners work more than six-hour-a-day despite health risks from the high levels of radiation in the mine.

After his arrival, Yurkovsky arrests the mine's director on multiple offences including smuggling liquor and prostitutes, with their possible subsequent killing.

He tells the workers to elect a replacement and reminds them that the mining license is given only temporarily and may be revoked at any time.

He says that these two men managed to deceive the rest of the crew so successfully because many people in communist society are not accustomed to others blatantly lying to them, and they are too proud to try to figure out the truth for themselves.

As they approach the rings, Yurkovsky notices an unusual (and seemingly artificial) rock formation and urges Krutikov to fly closer despite the danger of a meteorite collision.