The Asura Planet was a planet with an extremely vile and nasty environment. Although the atmosphere was normal and could allow humans to survive on it, the temperature here was very extreme. During the night, the temperature would plunge to below 100 degrees celsius and during the day, the temperature would rise up to near 80 degrees celsius. It would either be so cold that one would be frozen or so hot that one would be baked. This was simply a place akin to hell. It basically wasn't suitable for humans to stay here.
Hence, this place became a forbidden zone where death criminals were sent to. If the criminals on death row wished to live on, they had to modify the environment, allowing it to become a life planet suitable for humans to survive in.
Although the process was very slow, using death criminals could be considered a type of recycling wasn't it?
