I'm trying to create the backstory for a world which has 2 planets populated with genetically modified humans, and 'normal' humans who live on space stations/domed habitats built on moons. I also need the ‘normal’ humans to be at war with one of the planets.
So far, I have come up with
• An extinction event is threatening the entire solar system, leading to a generational ship(s) being sent out, with the mission of continuing humanity should this event come to pass.
• In the decades leading up to the discovery of the event, small unmanned laser sail probes have been sent to exoplanets of interest maybe 4 – 10 light years away (a probe takes 12 to 30 years to get there, and data takes 4-10 years to get back, so over a period of 16 – 40 years exoplanet data has been collected). The probes send back detailed data regarding the atmosphere and soil of their target planet.
• System ‘X’ is of interest because there are 2 planets in the habitable zone, both with atmospheres (and oceans) that could be potentially be terraformed with technology currently being developed, which used genetically modified bacteria/algae to create a breathable atmosphere similar to Earth. However, one planet has 2G gravity, and one is saturated with a new compound that is dangerous to humans.
• The new compound could be theoretically be used as an extremely efficient fuel source (or some other important use). Because of this, they choose to send a generational ship to this system, and populate the planets with genetically modified humans, who will mine resources for the colony from the planets.
• Generational ship takes 300-350 years to arrive using a fusion drive to reach the system. Before launch, they send out small laser sail probes with terraforming ‘payload’ of bacteria/alga to create breathable atmosphere, which arrive faster, giving around 300 years for terraforming to occur.
• Once they arrive, the ship becomes the base for the first and largest space station of the ‘normal’ human colony - these humans have a monopoly on advanced technology.
Anyway, I feel that my backstory is overcomplicated, and also has the problem of why they would be interested in a new fuel if they already have a fusion drive or similar to get to the system in the first place. But, if it's not a fuel, there would have to be another reason that they would send a ship to somewhere with no planets that are suitable for 'normal' humans.
Just wondering if anyone had any ideas to simplify it – all I really need is a self-enclosed system with the 2 planets with genetically modified humans, and ‘normal’ humans on space stations, and for one of the planets to have a mystery compound poisonous to 'normal' humans (this is required by the story).