A work that has “coherence” presents ideas that are logically arranged to help the reader better understand the text.
Coherence in a text is essential to provide the reader a smooth reading experience. A text is coherent when certain characteristics are met: topics are related and follow a logical order, vocabulary is easy to read and straightforward, grammar structures add cohesion and clarity, literary resources are correctly used (example: parallelism).
If for whatever reason we are forced to leave Earth there are no other hospitable planets we could live on. By making mars more like Earth we could eventually relocate to mars.