Dinem is a cool D-Class world and the fifth planet in the Vamana system. The planet was very similar to Mars before terraforming. It even had similar temperatures, with a average temperature of -60 °C. Before terraforming, its atmosphere also contained bits of sulfur dioxide and sulfuric acid which gave the planet beige colored sand dunes similar to the Sahara Desert on Earth.
The surface of Dinem is composed of salt flats, sandy basins, sand dunes, and rocky mountains. The only difference is that there doesn't seem to be any signs of previous water, unlike Mars before terraforming. This means that the planet never had, and probably never will, have any water on it's surface. There are also few craters, due to it's atmosphere thicker than Earth's with a pressure of 1.11 atm that keeps meteors from hitting the surface.
TerraformingIn the 43rd century, a probe discovered the Vamana system and it's planets. A few months later, colonists settled on a few of these planets. Most settled on Frigus. Some, being the very distant descendants of those who first landed on the red planet, looked at Dinem and saw how similar it was to Mars before terraforming. They set up a colony there, near a white salt flat bubble near the north pole. Terraforming the planet was a hard process. It required the colonists to remove the large amount of carbon dioxide from the air, along with the toxic sulfur dioxide and acid.
The colonists began by planting a large variety of engineered plants adapted to the cold near the equator in order to take advantage of the long hours of sunlight. The plants flourished in the CO2 rich atmosphere.However, the small amount of sulfur in the atmosphere began to affect the plants in an unusual way. The amount of sulfur in the atmosphere was just enough that the plants absorbed it and grew 50% larger than predicted and their leaves turned a vibrant lime color. A band of green-yellow life appeared on the planet's equator.
The atmosphere began to warm, reaching -60 °C, By the year 4309, they had successfully removed nearly all the sulfur from the planet's atmosphere, and dropped the carbon dioxide to 42 percent. At that point, they had gotten to a point were if they removed anymore carbon dioxide, the planet would lose some of it's greenhouse effect, and the temperatures would start to drop again.
In order to combat this, the colonists constructed giant mirrors in orbit around the planet and turned them towards the planets polar regions. The reflected light caused the polar ice caps to melt. Water started to pool near the poles, and then finally was able to flow down onto the planet and make lakes, rivers, and very small seas. Melting the poles also lowered the albedo of the planet, speeding up the warming process. By that time, the average surface temperatures reached above 0 °C. Cities started to pop up around the planet.