Moon

Luna, known commonly as the Moon, is the Earth's only continuous natural satellite.

Background
Fueled by a collapsing Earth ecosystem and degenerating society, Luna was first colonized in 1997, with the foundation of the Euro Space Agency (ESA) colony Tycho, Luna has since become colonized with various permanent bases, founded and maintained by allied nations of the ESA. With the existence of gravity and ability to soft-land machinery, along with heat drills to form glass-like tunnels, Luna was far easier to colonize than open space. Buried ice was mined for air and water, plants were brought in to create viable ecosystems, and the Tycho mass driver was modularly dropped and reassembled to construct and later utilize to catapult raw materials towards the Crystal Palace construction at the time. While the original bases were simple pressure domes and workshacks planted by Orbital Transfer Vehicles (OTV), by 2020, they expanded via nuclear and solar laser drill-created subterranean tunnel networks. Water is mined through lunar ice, and recycled heavily, while air comes through underground hydroponic gardens lit by large surface shutters.

Luna is mined heavily for raw materials utilized in orbital colony constructions at the LaGrange points. Three mass drivers allow a stream of Lunar material in Earth orbit. A Lunar "day" takes approximately 2 Earth weeks.

Major Cities
Two permanent cities exist on Luna: Tycho and Copernicus, both controlled by the ESA. Tycho, with a population of 18,000 by 2025, controls two mass drivers, able to boost Lunar rocks and ores to the O'Neill One Habitat constructions. Copernicus, with a population of 12,000, controls a single mass driver.

As both cities were constructed underground, their construction required blasting and nuclear-powered heat smelters to form park-like caverns, eventually being topped with smelted lunar sand pressure domes to provide air and recycling.

Tycho
Tycho is the largest of the two cities on Luna, originally only supposed to be a small base for orbital transportation and resources, it grew over time into a small bustling city. It maintains two mass drivers used to boost the Lunar rock and ore out to the L-5 constructions. In 2008, during the First Orbit War, the colony was responsible for the destruction of Colorado Springs, dropping a two-ton rock on the city.

Copernicus
The second largest city on Luna, Copernicus is a smaller city than Tycho, but not by much. Much of the area is dedicated to mining for resources, however that doesn't stop them from living comfortable lives. Due to only having one mass driver and being smaller in general, the people here are more friendly and out-going.