Descent in the Outer Dark

When Janus stopped being just an orbital mechanics curiosity and became a genuine anomaly by broadcasting a signal, a flurry of probes was quickly launched, and Earth waited for the report. Janus was revealed not to be a moon at all. It was an alien artifact. 

It took some time to find out what sort of artifact. Even now, none of the experts are completely sure. Its creators and purpose remain obscure. What humanity learned was there was reward inside: the strange but sometimes useful artifacts of an unimaginably advanced civilization. And then there was something else. Death. It comes in hundreds of ways, at the hands of bizarre traps or random environmental shifts, but also at the hands of murderous alien beings or animals that reside inside the structure.

The Company runs the station serving Janus. Security is provided by a multinational group, but it was expedient to let a corporation run the actual operations. Plausible deniability. Contractors recruited from the desperate masses of a climate stressed and economically depressed Earth sign up to be minimally trained, fitted into battered, armored environmental suites and sent into the alien labyrinth inside, hoping to steal crumbs from the table of strange gods and get out of their realm alive. The statistics aren't good, but the stories of the few that survive to retire rich keep the volunteers coming.