A seed ship is a class of vessel sent out by humanity in the closing years of the Gauna invasion of the Solar System. Seed ships were massive, measuring kilometers long and tasked with a single mission: the continued survival of the human race.Unlike smaller vessels like the Mizuki or the Gardes, a Seed Ship is designed to last for an undetermined amount of time. Seed ships carried colonists away from the besieged Earth and out into the stars. Hundreds of Seed Ships were created in the twilight years of humanity, and those Seed Ships were sent out in different directions to avoid the Gauna threat.
So far, we know of two Seed Ships: Sidonia and Aposimz. Aposimz is the only other Seed Ship named in the series, while Sidonia is the only Seed Ship given anything more than the most cursory details. As the ships flew away from earth, they rapidly spread apart, gradually losing contact due to transmission delays and course changes that made it impossible to tell where to target messages. At the time of last contact, Aposimz was already so far away that the final message took over 150 years to reach Sidonia.
We can assume certain general characteristics of each Seed Ship:
- Self-sustainability, allowing a crew and colony of hundreds of thousands to survive for dozens or hundreds of years between star systems.
- Self-defense, including Mass Driver Cannons.
- Sub-light capabilities. Humanity had not (at least at the time of the Seed Ship launches) mastered faster than light travel.
Seed Ships came in all shapes and sizes, from cone-like shapes to more traditional starship designs.