Eisenberg Viability System

The Eisenberg Viability System is a scale of measurement to determine a planet's viability for human life. It was developed by Dr. James Eisenberg of the Alpha-Blue Abstracts and Concepts Group made it as a simple marker utilizing extensive analyzation of a world's natural resources, weather patterns, flora, fauna and other essential variables in calculating a composite score for the world.

Class-A
Class-A worlds were the most Earth-like, capable to supporting vast populations and allowing for sustained life over an indefinite period of time, barring natural catastrophes. Worlds such as Eden, Avalon, New Manchester, Arcadia, Reimes, and Mercia are but a few examples of the dozens of Class-A worlds known to man.

Slight deviations are acceptable such as a slightly more hostile fauna population or increased weather conditions, although such deviations are listed in the Colonization Index for review.

Class-B
Class-B worlds are Earth-like worlds but require colonists to be prepared to actively defend themselves, either from the elements or the natural fauna, there are active variables at work that can easily kill an unprepared colonist on a Class-B world. Caution is advised, but once settlements and general defense forces are established, such worlds become more or less conventional places to live upon.

Worlds such as Achre, Mars or Europa are indicated as Class-B worlds.

Class-C
Class-C worlds life-supporting worlds are tremendously difficult to live upon and are only recommended to those who have thoroughly researched said world and its dangers. Class-C worlds are classified as such for consistent, unrelenting danger. While habitation is possible, it is only recommended in short amounts of time or within extremely secure locations reinforced either by highly resistant buildings or an active military presence, depending on the threat.

Worlds such as Ignis Natus, Glacies Petram, or Monstro Pelagus are prime examples of such worlds.

Class-D
Worlds that are not life-supporting but have the potential for rapid terraforming to occur. Such examples include Europa and Mars.

Class-X
Class-X worlds contain the vast majority of known celestial bodies, dictating that no life can exist upon it without full artificial assistance.