Late Jupiter

The Galilean Moons of Jupiter were the next location humans for their terraforming project after the success seen on Mars. Ganymede and Callisto proved to be ideal locations and after only a decade after terraforming began, did people start to populate the moons. A few short years later, deep inside a cave on Callisto, a mysterious ship of unknown origin was discovered. No living being was found inside, as well as no remains. Soon another was found by a research station on the volcanic moon of Io. Estimated to be over a thousand years old and yet, remarkably, the on board computers functioned nearly perfectly. Even more remarkable, the two ships' computers were still able to communicate to each other. A wondrous discovery that some are willing to kill for.