The Ark began as barely a blip on the jagged and tumultuous horizon. Dove negotiated his way gingerly across the frozen lake, his mind focused on getting inside and resting his cold and aching servos. He's been here before. It seems the most profound tragedy of his life that the world is round. In his mind he plays over the daydream of a flat world, extending forever in all direction, nothing but unending hills and valleys and oceans and forests, unrelenting newness everywhere. On a rational level he knows there are far corners and destinations he will never visit, but standing there, facing the Ark again after ten years, he feels acutely aware of the closed system of the world.
You can run as far as you like, the road will eventually take you back home. In school they told him the Universe was infinite, so sometimes he dreams of rockets instead.
We tried to cure the warming Earth. Our attempts did not have the results we anticipated. The huddled remainder of the human race waits out the Ice Age in a crumbling, decaying Ark. They sent out two messengers, Dove and Raven. No one ever heard from Raven again. Perhaps Raven found the one corner of the world not bent and rounded. Perhaps he found a rocket.
His direction was as sure as his programming. His life would resume in the way it had before the expeditions. He would carry on, as ever, repeating the same tasks, going forward blindly into the future.