Habitability Gradient
When considering worlds for potential colonization, the Republic has created a standard two-factor classification system known as the habitability gradient. This alphanumeric value is vitally important for those who seek to settle on or exploit new worlds, as it directly impacts both the private sector and governmental support they are likely to receive for their efforts.
The first factor is alphabetic and evaluates the celestial body’s ability to support life on a scale from A to D. For planets, this includes whether it falls within its star’s habitable range. The criteria are altered slightly for moons and other satellites, but the general objective remains the same.
Planets classified as A are capable of supporting Umbrians comfortably. Class B planets are still habitable, but overall less friendly and forgiving. Class C planets require protective equipment to inhabit and are not inherently capable of supporting Umbrian populations.
Class D planets are completely hostile to Umbrian life, either too hot or too cold. These can only be colonized through the use of fully sealed habitations, and are deadly when exposed to the elements.
The second factor takes into account other factors which may make the planet difficult for normal Umbrian existence. This scale runs from four to one, with four being most habitable and one representing significant challenges to Umbrian habitation. This factor represents such features as atmospheric composition, atmospheric pressure, gravity, protection from solar and cosmic radiation, environmental toxicity, and even aggressive or hostile microbial life, flora or fauna.
Class Four planets are extremely receptive to both Umbrians themselves and planet and animal species which may be selectively introduced to provide food for a budding colony. Class Three planets are less friendly and may require significant modification to plants in order for them to thrive on the planet.
Class Two planets feature elements where prolonged occupation may lead to health problems without some form of technological compensation. This class includes planets where gravity or atmospheric pressure is too high or too low for Umbrians, or where the atmospheric composition isn’t sufficiently oxygenated.
The final class, Class One, is actively hostile to colonial development. These worlds’ atmospheres or environments may be toxic to Umbrians, or they may contain aggressive or predatory plants and animals or virulent microbial life.
Together, these two factors represent the overall habitable utility a planet, dwarf planet or moon, with planets rated as A4 representing the most comfortable and D1 representing lifeless bodies whose value lies only in their raw materials.