Callisto is the fourth Galilean moon of Jupiter. Various nations and corporations conduct mining operations on the moon, and in 2158 a Chinese team discovered a large subterranean sea teeming with previously undocumented life.[1] Chris Hooper worked in one of the mines on Callisto for around a year before being posted to the DSMO Marion.



  1. Tim Lebbon. Alien: Out of the Shadows, p. 11 (2014), Titan Books.