Greening of a Planet

What is our future in space? The answer goes a long ways to telling what the rest of our future will be and how we should prepare for it. Many stories about space travel speak of dreams of our omnipotence, but seem unrealistic. The basic principles of science and human sociology seem universal, but tell a different tale. Where do they lead? A spaceship with settlers arrives at a distant solar system. Their ship is loaded with supplies. Still without a world that can replace those supplies, the settlers are without hope or a future. Alien microbes would be too dangerous for them to land on anything but a sterile planet, but that has many challenges of its own. Will they be able to build a settlement that can survive in the long term? A story approximately every century shows the society developing for a little over 2100 years.