Terraforming

Terraforming is changing certain characteristics of a planet or other object such as an asteroid to make it more suitable for life, including atmospheric composition, soil, weather, and flora/fauna. It is usually preceded by some form of base or habitation on the planet. It is also a long-term process that can take millenia or tens of millenia. If the object is too far away from its home star, a stellification engine may be required.