On the surface, the red planet’s freeze-dried world of rocks, ice, and dust looks like an unlikely place to plant a garden.
But rocks and minerals found by the Mars rovers show it must once have had warmer, habitable living conditions.
Now, using photo-realistic CGI visualizations, we’ll make a science fiction dream of Mars - a world of trees, rivers, and blue skies - a plausible future, bringing it to life after three-and-a-half billion years in a deep freeze.
The first and most important step in making Mars habitable is to warm it up, raising the average temperature 35 to 55 degrees Fahrenheit. (Average Mars temperature is about -81 degrees Fahrenheit.)
Bold concepts on how to warm up Mars range from detonating hydrogen bombs and guiding space rocks on a collision course with Mars to setting up little factories on the planet whose intent is to produce greenhouse gases.
Much of the new Mars would be an icy world, like summer above the Arctic Circle, with atmospheric pressure equivalent to a mountain twice the height of Mt. Everest.
The next step is turning Mars green and producing a breathable atmosphere, which will be a much longer and more difficult process.
Lichen and moss, which thrive on carbon dioxide, will be the first imports of plant life from Earth, perhaps 50 to 100 years after warming begins. They build soil, create more nutrients and pave the way for grass and woody shrubs.
Once established, Martian forests will spread on their own, improving the soil and the atmosphere, creating a livable world for more than just plants.
It could take 100,000 years for trees to transform an icy blue Mars with a carbon dioxide atmosphere into a warm, green planet with enough oxygen for humans to breathe.
A fully terraformed Mars may never be as warm and wet as Earth because it’s too small and too far from the sun. Low elevations where the atmosphere is thicker and regions near the equator will be the warmest.