The Moon
History
Pre X8
High above Earth, it's nearest celestial, lies the Moon. Poets waxed philosophically about it for ages before humankind finally stepped foot on it in the 20th century.
After the initial landing on the Moon, Humans gave relatively little more thought to it for years. It wasn't until after the Eurasia colony fell that they began to consider the Moon as a possible location to live. Though they couldn't do much until Earth had been cleaned up after the colony disaster. Once Earth was more hospitable they began to consider options for space again. They eventually settled on orbital elevators to reduce the cost needed (compared with using shuttles).
They eventually built a large central location to use to deliver goods to and to house those living there so they could establish a larger colony.
Post X8
After the events of the Jacob's Elevator incident, the Moon was closed off for a period of time while researchers combed through everything to ensure it was safe for everyone else to return. They recovered the wreckage of both Sigma and Lumine. Eventually it was cleared for use again and construction continued.
AR2 spoilers
AR2 spoilers
Though it was later revealed that Lumine had survived. He faked his death by attacking Axl (prompting X and Zero to attack and destroy his body) though he had transformed into a smaller purple cable like form prior to his body being destroyed (which is what he had used to attack Axl). He waited until X, Axl and Zero were gone before returning to his proper form. Once work crews showed up he then grabbed a worker and replaced them to return to Earth in relative peace… So he could come up with another plan.