LUMINAIRE 0909 - The FTL communications link between Seyllin I and the Federation is located several kilometers beneath the surface of the barren mining world, stated engineers familiar with the planet. Four main subterranean cities linked by underground magrails hold the bulk of the planet's population, whose residents mostly support mining operations. Access points to the surface are limited due to extreme daytime surface temperatures, but robust thermal shielding methods allow for spaceport access and limited space elevator operations. Most of the power generation for the planet is conducted through geothermal or aneutronic fusion means, as some excavation sites have reached depths of more than 100 kilometers below the surface.
The economic value of Seyllin to the Federation is significant, accounting for a quarter of all raw ore production in the Thoulde Constellation, and making up a significant fraction of the Federation's supply of key heavy metals. It is unknown if the communications outage is associated with the earlier reported loss of the planet's Cassandra weather monitoring system.