Vespene gas

Vespene gas was a hydrocarbon compound and the most plentiful high-performance fuel in the galaxy, one of the two foundational resources of the Koprulu sector alongside minerals. Usually green and often found in geysers, it was prized by terrans for its unusually high potential energy rating, consumed raw by the zerg as nourishment, and used by the protoss as a catalyst for their psi-driven machines. Its abundance in the sector was one of the chief reasons human colonists were able to survive and prosper far from Earth. (StarCraft (manual); StarCraft Field Manual)

Discovery and properties#

According to Doran Routhe, a scientist of the United Powers League, planetary systems beyond the Solar System might hold new resources to benefit a resource-depleted Earth. Although the terran colonists who left Earth traveled far beyond their intended destination, Routhe's theory proved correct, for the Koprulu sector held resources not found on Earth, vespene gas among them. (StarCraft (manual))

Vespene was usually green, though contamination could alter its color, and silver deposits had been observed. It was highly prized by terrans for its unusually high potential energy rating, serving as fuel for high-performance engines, energy reactors, and simple vehicles in much the way fossil fuels had served Earth. It was most often found in geysers, but deposits also occurred in asteroid fields and could be extracted directly from a planet's crust with greater difficulty, and crystallized vespene appeared alongside mineral fragments inside asteroids. The gas's electromagnetic returns allowed geo-survey units to locate deposits. Purity was highly valued, and hydrogen sulfide was a particularly dangerous impurity, giving contaminated vespene a yellowish tinge and rendering the mixture explosive. (StarCraft (manual); StarCraft: I, Mengsk; StarCraft: Shadow of the Xel'Naga; StarCraft: Frontline Volume 1; StarCraft II: Wings of Liberty; StarCraft: The Dark Templar Saga: Firstborn)

Use by the three races#

Vespene was used by all three of the sector's major races. The terrans relied on it most directly as a fuel. The zerg had adapted to consume raw vespene as nourishment, drawing on its high caloric capacity to drive their greatly accelerated metabolisms, with raw exposure enhancing the physical capabilities of the ultralisk and increasing the aggressiveness of the roach. The protoss, by contrast, used vespene as a catalyst for their psi-driven machines. (StarCraft (manual); StarCraft: Brood War (manual); StarCraft II: Legacy of the Void)

Vespene formations slowly regrew over time on worlds such as Antiga Prime, a renewal that contributed greatly to the ability of terrans to survive in the sector. Yet while a geyser effectively held an unlimited supply, beyond a certain point it would collapse, leaving only trace amounts behind. (Backwoods (StarCraft Compendium map of the month); StarCraft (manual))

Strategic role#

Vespene was strategically vital enough to shape the wars of the sector. During the era of the Terran Dominion, a Geological Procurement Services division was charged with finding and exploiting vespene geysers for the Dominion war effort. The resource also played a direct part in the opening of the Guild Wars: at the Noranda Glacier refinery on Onuru Sigma in 2485, the vespene had been contaminated with hydrogen sulfide, making it explosive, and the Kel-Morian Combine ambush of Confederate forces there helped touch off the wider conflict. The gas's volatility made vespene stores a persistent hazard on any battlefield where it was stored or harvested. (StarCraft Field Manual; StarCraft: I, Mengsk; StarCraft: Shadow of the Xel'Naga)