A moon in the Balor system of the Caleston Rift, Caleston is the largest satellite of the gas giant Cernunnos.
Caleston is wracked with volcanism due to tidal stresses from Cernunnos. Because of the weak solar output, plant-like life on Caleston isn’t carbon-based and photosynthetic; instead it’s silicon-based and thermosynthetic, requiring heat to power its chemical reactions. These organisms flourish in volcanic vents, as well as during solar flares, when Balor can double or triple in luminosity.
Ancient asteroid strikes deposited major lodes of element zero within the molten sulfur mantle of Caleston. Eldfell-Ashland Energy’s mining operations made it the largest source of starship drive core material in the Attican Traverse, which threatened Caleston’s native biodiversity with industrial waste. The fragile domed cities established here in fact handled one of the largest element zero mining operations in the entire galaxy, supplying most of the Systems Alliance fleet’s drive cores.
Caleston isn't an Alliance holding, though. It's one of those planet states that function as independent near-Terminus nations, much like Noveria. Not truly in Citadel Space, nor recognising it as an authority over them, but not truly Terminus. An in-between world, playing both sides to survive.
During the Reaper War, the Reapers drove off Caleston’s protective fleet and threatened to puncture domes to force the population into submission. However, despite the suffering of the war, the survivors actually prospered in its aftermath. EAE’s self-reliance policy kept it and most of its holdings safe from the chaos of the relay damage, and Caleston was no exception. With almost every service that the relays’ temporary inoperability could have possibly threatened already installed into the local infrastructure, Caleston's residents were not left wanting. This put Eldfell-Ashland into a very advantageous position, and the corporation arguably runs the whole planet now.
A couple of years after the war, Caleston and the Systems Alliance released a joint statement confirming that the Syneu-Arcturus Treaty of 2184 would be honoured by both parties. The Treaty gives the Systems Alliance right of passage to the Caleston Rift in return for protection against military and pirate threats. In the latest agreement, the Alliance agreed to purchase the majority of its element zero and fuel needs from the Caleston trade republic in return for favourable bulk prices and supply routes to isolated worlds in the region, such as Ontarom.
Less than two years later, Caleston found itself at war with the Republic of Vies. This in turn led into the Systems Alliance-Vies War of 2190.