Earthfall

This alternate version of Space: 1999 has the moon being knocked into an alternate dimension, speeding away from Earth. Twenty years later, the Alphans have become their own culture, with their own history. Excavation on the moon reveals a spaceship half a million years old, filled with mummies of being so close to humans that a deadly disease is passed on to the Alphans. While battling they disease, they are learning how the alien starship drive works and attempting to employ it for themselves, but their experiments trap the moon in the event horizon of a black hole. They manage to escape—barely—and suddenly find themselves back in orbit around Earth. But is this devastated planet really Earth?