Implacable aliens in the cosmos who must be fought. The problem of mutual relations and the solution, usually in the form of treaties or defensive alliances. This can be for common defense, cultural reasons, economic reasons, or by conquest. For whatever reason the indepenent human and/or alien worlds unite. The rise of contact and commerce between many human-colonized worlds or many worlds of alien intelligences that have come to trust and do business with one another. Nourse, THE MARTIAN WAY by Isaac Asimov, HIGHER EDUCATION by Pournelle and Sheffield, ISLANDS IN THE SKY, THE OTHER SIDE OF THE SKY by Arthur C. Note that the performance of available rocket engines will affect the rate of exploration.Įxamples: TALES OF KNOWN SPACE by Larry Niven, SPACE CADET, FARMER IN THE SKY, THE ROLLING STONES, THE MOON IS A HARSH MISTRESS, PODKAYNE OF MARS, BETWEEN PLANETS, 'Logic of Empire' by Robert Heinlein, SPACE DOCTOR by Lee Corey, HIGH JUSTICE, EXILES TO GLORY, 'Tinker' by Jerry Pournelle, LIFEBOAT aka DARK INFERNO by James White, SCAVENGERS IN SPACE by Alan E. Stories of the first colonies on such worlds, their problems internal and external, their conflicts with the parent world (maybe even a war of independence), interplanetary commerce, spaceship trade lanes, space pirates, asteroid mining, the weird wonders of the Outer Planets. Stories of the first efforts to set up terrestrial bases on the planets. Initial voyages to Luna and the planets of the solar system.

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