Mairn

Mairn is the fourth planet from Sun in the Home system. It was the first planet to be colonized by humanity, who had dreamed of setting foot on this world since such an idea was first conceivable. Mairn has an average surface temperature of well below freezing, but a 0.42 atm carbon dioxide atmosphere allows the presence of liquid water on rare occasions. These Home-like conditions combined with metallic resources like silium in its upper crust made the world an ideal target for early colonization. The planet today hosts almost 100 cities with populations above 1 million, with a global vactrain system connecting them.

A litany of proposals to worldform Mairn have been put forth over the centuries, most of them involving the conversion of the planet’s carbon dioxide into oxygen to allow humans the opportunity to breathe its open air. Due to the required investment, none of these plans have made it past the proposal stage. The current plant species modified for life on its surface do convert CO2 into oxygen, but any significant change in oxygen percentage is expected to take several million years, due in large part to the planet’s rock absorbing most of the oxygen that finds its way into the air.

Surface Conditions

Despite what early dreamers had proposed, Mairn has no evidence of ever having hosted native life, though it was a notably wetter world in its past. The planet was thus a completely barren world of sand, rock, and ice for most of its geologic history.

The arrival of people reshaped the surface of the planet, as Mairn’s perfectly imperfect conditions presented an ideal challenge for early genetic engineers who wanted to modify organisms for survival in Mairn’s open wastelands. Some tests in the early Foundation Age were markedly successful, producing a species of aggressively fast-growing lichen that overgrew Mairn’s landscapes. These lichen were so successful that the Maircater Determination was drafted and ratified to ban such open testing in the future. A number of subsequent experiments, undertaken in accordance with the Determination, have produced a variety of more welcome plant species that now grow on the open surface of the planet. The vegetation is not green but rather dark shades of grey and purple, having been adapted to absorb all wavelengths of light in Mairn's more distant orbit. Some of these plant species are modified organisms from other worlds.