Starjammer is rules for Pathfinder in space—different, by the way, than Paizo’s soon-to-be Starfinder game. Starjammer includes new player races, class archetypes, feats, and spells. There are rules for customizing spaceships, using skills with advanced technology, classifying planets, and adjudicating environmental hazards. The equipment section features such items as magnetic shields, misfortune lanterns, hardsuits, dwarven steam suits, and star marine armor.
The Starjammer Core Rules ebook is 238 pages published by d20pfsrd.com and available via DriveThruRPG for $15.