Changing a planet to be more like Earth.
To inhabit Mars, we would need first to create an atmosphere. Currently, the Carbon dioxide level is at 95.97% which is not so good for any living organism. It can take thousands of years to terraform an entire planet. To make the air on Mars breathable, humans used a combination of different techniques.
1. Solar Mirrors heat the Planet
2. Crash large icy comets into the surface to thicken the atmosphere
3. Large terraforming factories produce atmospheric gases
4. Terraforming factories continues for hundreds of years
5. Plants are planted in habitable areas to help produce oxygen
6. Terraforming is complete
2000 B.E.S.*- Ancient astronomers on Earth discover Mars
1997- First rover lands on Mars, The Pathfinder
2040- First human subterranean colony is established
2300- Humans build above ground domes to live on the surface
2800- The first plants take root outside of the colony
2900- Air is breathable in areas near the terraforming towers
2950- There are large areas of breathable air around the major cities