The
next problem that remains to be tackled concerns the plants and how they would adapt to
the atmosphere. The oxygen and nitrogen levels in the atmosphere would be too low for many
plants, and if they were to be left in that condition, the planet would remain relatively
dry as the warmer temperatures would take centuries to melt Mars’ ice and deeply
buried permafrost. In the second phase of terraforming, the activation of the hydrosphere,
that the atmosphere is made breathable for advanced plants and primitive animals, and the
temperature is increased further.
The implementation of orbiting mirrors provides a potentially rapid method for hydrosphere activation. For example, if the 125 kilometer radius reflector were to concentrate its power on a smaller region, twenty seven terrawatts would be available to melt lakes. This enough to melt three trillion tons of water per year! This type of mirror could drive vast amounts of water out of the permafrost and into the nascent Martian ecosystem very quickly. In addition, activating the hydrosphere will destroy the oxidizing chemicals in the Martian regolith, thereby releasing some additional oxygen into the atmosphere in the process. Thus, while the engineering of such mirrors may be somewhat grandiose, the benefits to terraforming of being able to wield tens of terrawatts of power in a controllable way can hardly be overstated.