TROJAN: Nefra Contact

The moon of Jupiter named Trojan was discovered in 2025, and explored by Earth astronauts shortly thereafter, as it appeared to represent a threat for an alien power. As United Nations Space Administration (UNSA) sets out to make international, perhaps interplanetary, claims over this alien phenomenon, they realize the moon is hollow, and harbors some sinister concern for the survival of Earth.
Two sets of explorers, one convicts sent from Nefra to set up gravitational transportation, the other astronauts from Earth, explore this new world, and interact in a way neither their respective powers had ever expected.
This could be the beginning of interplanetary piracy and war, or it could be the beginning of reunion; or it could be just the beginning of the end.