Oxygenating and Greening the Planet
The much-needed ingredient still missing for humans and animals is oxygen. As the atmosphere develops, the composition of the air can be tailored to suit human needs.
Scientists have developed a solar-powered machine that extracts pure oxygen from carbon dioxide found in the thin Martian atmosphere. The Mars In-Situ Propellant Production Precursor prototype is important, not only because it converts the carbon dioxide to oxygen. But also because NASA could use the technology to fuel a returning flight from Mars to Earth. The plan is to mix the oxygen with rocket fuel to create combustion that will launch a vehicle off Mars.
On Earth, plants make the majority of the oxygen supply. On Mars there's a chicken-and-egg problem: the planet needs photosynthetic plants to make oxygen from carbon dioxide, but the climate must be warm enough and the soil conditions must be inviting to growth. In order for plants to thrive, scientists need to begin lower on the evolutionary ladder. They need to introduce ammonia-producing microbes into the Martian soil that will convert nitrogen from the atmosphere into the soil for larger plants like grasses and mosses to grow. The bad news is that scientists estimate that this could take hundreds of years. Once the soil is ready, scientists can introduce simple plant life.
Building a global functioning atmosphere for human habitation will require the development of a complex ecosystem that may very well require large stretches of forests and high biodiversity. Scientists imagine a planet with forests that will one day replace the artificial means of oxygenation.