How many planet classes are there?
The celestial objects recorded in the Colonial Administration's Registry of Debarkable Objects include not only planets but also dwarf planets, asteroids, moons, and comets: A debarkable object (DO) is defined as any non-human-made object in space on which a human spacecraft can come to rest and remain through the planet’s own gravity or through mechanical attachments. In plain English, a debarkable object is anything we can land a ship on.
The Colonial Administration categorizes these DOs based not on their astronomical status (planet/moon/asteroid/etc.) but on two factors: Their survivability (habitability) and their usefulness to human development and survival.
Habitability
Every DO is given a habitability rating which is based on a few key pieces of information about conditions on the surface: average temperature, extreme high and low temperatures, force of gravity, and composition of the atmosphere. This rating sorts the DOs into three classes: Habitable, Habitable with Modificiations (Habitable-M), and Uninhabitable.
Habitable DOs are celestial objects where humans can be expected to survive when left with basic supplies (food, water, shelter, medicine). Note that in this definition basic supplies does not include any form of climate control (heating elements, air conditioning systems . . . even fire). There are very few true (known) Habitable DOs in the galaxy, since the human organism is so temperature-sensitive; even our own planet of origin, Earth, might not be classified as a Habitable DO since in many regions the temperature (even before the Habitability Crisis) reached extremes that were fatal to humans without some form of climate control. This classification goes back to the earliest days of the Colonial Administration’s expansion from New Terra; in those days, the CA planted hundreds of seed colonies on various planets, some of them without guaranteed resupply for as many as 50 years. It was essential, for this reason, to tag for colonization only planets where the colonists would be able to survive without making any modifications to their environments, since the resources needed to perpetuate those environmental modifications might not be available in the long-term. Recently, there has been discussion of changing the rating system to create a sub-class of Habitable-M DOs where the only modifications required are basic climate control.
The modifications required for Habitable-M DOs, then, include a wide range of technological supports for human life: everything from heating devices to filter suits to protect against indigenous microbes to atmospheric bubbles of the kind often used to create temporary moon or asteroid colonies. The Colonial Administration has an internal system of codes to be used for describing the exact technological supports colonists on a particular DO would require; in informal communication, a Habitable-M DO may be described by indicating whether the modifications are required due to atmospheric composition (or lack thereof), temperature extremes, or other hazards. ”Other hazards” can be a controversial subgroup, as it includes local fauna; some people believe that fighting off predators is a natural human behavior and does not count as an extra modification. From a supply point of view, however, guns are a nonrenewable commodity, and for this reason, if a planet contains native fauna so aggressive that guns are needed to survive on its surface, then the Colonial Administration counts it as a Habitable-M DO. (Several planets originally classed Habitable were downgraded to Habitable-M when a resupply visit found all or most of the colonists dead due to the local fauna.)
Uninhabitable DOs are places where it is impossible for humans to survive for 144 hours even with technological supports. Generally, these are planets where the gravitational force or the atmospheric pressure is so great that humans would be crushed or completely incapacitated just by being on the surface. Planets with extreme temperatures (mostly extreme hot temperatures, since our current technology can cope with extreme cold, though not without significant energy costs) also fall into this category. As a recent article in the Journal of Astronomical Statistics noted, this category is continually shrinking as our technology develops to withstand more and more extreme planetary conditions.
Resources
The second part of the DO rating relates to the kind of resources available on the object. Because the Colonial Administration is concerned with promoting the survival and development of the human species, it categorizes all DOs according to the kind of natural resources they possess. The value attached to these resources is related to the materials needed by the Colonial Administration for development on New Terra and the other Inner Planets as well as for resupply of current colonies and expansion of the colonial project to new sites.
The three major resource groups are:
SR - standard resources (the 20 most abundant elements in the galaxy, which include iron, carbon, silicon, and sulfur)
VR - valuable resources (rare elements that are in high demand for industrial or technological purposes, such as copper, gold, plutonium, rhodium, etc.)
OR - organic resources (a more vague category, added later in the colonization process, which indicates that a DO has lifeforms that show potential to be used as a food source or in genetic engineering or that exhibit some scientifically interesting trait)
A number of sub-codes describe the specific resources within each broad category. Unlike habitability ratings, resource codes are often changed as new discoveries are made on a DO; in addition, resource codes may overlap, indicating that a particular planet, for example, has both valuable and organic resources.
