Wending Skies

The Empyrean

No man knows where Mankind came from. A realm bereft of ether is it said, one with but a single radiant - a sun - in the sky above. Where Mankind was looked on the birds flying in the sky and only dreamt of joining them. This, the Urmheimat, has been lost for hundreds of generations. The legends say that the tribes of Mankind swore themselves to a millennia of slavery to the Gods to escape the predations of the Darkstalkers and the Red-Eyes. When this time came to an end, they willingly continued to serve the gods, their interactions mediated by the ascended Greaters. Declaring a new calendar, Mankind embarked on the path of Civilization.

Mankind's home for over five thousand years, the Empyrean is the deep sky, the sea of clouds. Slowly circling the great Prime Radiant are the many Axial Worlds, each one a great orb of gas and ether. These planets are accompanied by entire hosts of smaller objects; moons, shells, rings, gas clouds and miniature radiants throwing their own light on their fellow travellers. It is on these lesser objects that Mankind and many others make their homes.

These smaller objects are only smaller in relative terms, with the largest moons true worlds unto themselves with their own miniature host of moonlets. Even those that do not rise to the level of planets still being several thousand km in diameter. Alongside them are the shells, continents set into the sky and equally as large albeit irregular and far flatter. Accompanying these are island, asteroids and comets, not to mention wandering seas and free-floating jungles.

Astrographic lexicon

• Dark Ether: The invisible 'stuff' that makes up the fundaments of the known universe. The actual nature of dark ether remains something of a natural mystery and it is only understood indirectly. Nonetheless its influence can be felt everywhere.
• The Void: Not all of space is full of ether and these vast bubbles of emptiness are known as voids/the void. While objects such as asteroids and comets can and regularly do wander through the void they are otherwise uninhabited - and uninhabitable.
• Radiants: Tiny outlets of pure energy, radiants emit unceasing amounts of heat and light into the cosmos from the Astra. Without them the skies would be cold and black.
• Axial Worlds: These are large bodies, often dozens if not hundreds of Gaian masses and typically swaddled in thick layers of gas and ether. They are so-named because other, smaller bodies circle them. Most axial worlds are also host to one or more radiants that illuminate their environs. While axial worlds themselves are almost inevitably uninhabitable (past perhaps cloud cities), their surrounding space is often well-populated.
• Rogue Worlds: Some axial worlds have, for whatever reason, no radiants near them. These tend to be of smaller size, though large rogues are not unknown. Drifting in the ether with just the twilight of distant radiants and reflected light to illuminate them they can be strange, exotic places and rarely owned by humans.
• Garden Worlds: The in-between axial worlds and small moons, garden worlds are so-called because they host natural - human-friendly - ecospheres. Some garden worlds are giant moons to axial worlds, while others drift alone with a local radiant to keep them pleasant. The term 'garden' is quite broad and even many icelocked or desert worlds are counted as such.
• Blasted Worlds: 'Blasted' worlds are those that are large enough to be garden worlds but have none of the habitability. Some are baked cinders by too-close radiants while others have fundamentally deadly atmospheres such as chlorine or etheric miasma.
• Moons: The smaller cousins to moon worlds, moons are mostly distinguished by size. More broadly and less scientifically, moons are those spheroid bodies that are not intrinsically human-habitable.
• Shells: Shells are large rocky masses broadly comparable in size to moons. The difference is that moons are spheroidal while shells are irregular but overall highly flattened, essentially continental plates set into space. Due to their flattened shape, shells normally have a 'light side' and a 'dark side', the former facing the local radiant while the latter commonly covered in ice and snow and in a state of perpetual chilly twilight. Shells also had planar gravity normal to their flat axis, contrasting to the spherical gravity of worlds.
• Asteroids: Tumbling, irregular rocks that can range down in size to literal gravel, asteroids are space junk - if sometimes valuable space junk. Mostly without any significant gravitational field they are often found in large drifts and provide home to all manner of deep-sky life from rockhoppers to space slugs to wyverns. Industrialized civilizations also find them convenient places to conduct mining or to place outposts for navigation, scientific or military purposes.
• Comets: The close cousins of asteroids, the main difference between the two is that comets are mostly made up of various ices. This in fact makes them an important - and thankfully common - resource, their ices mined to supply etheric clathrates to a busy galaxy. Like asteroids they are commonly home to various types of cosmofauna such as various species of skywhales. Conventionally, a large cluster of comets is called a 'drift' as compared to an asteroid 'field'.
• Clouds: The continual ebb and churn of ether and other cosmic gases results in an entire beastiary of deep-sky clouds. Some exist in nigh-perpetual storm belts while others are transient, coalescing and drifting across the cosmos before eventually dissipating.
• Nebulas: While luminifous ether is normally not harmful to life (in fact, it is often beneficial); it is understood that at a critical density it thickens greatly in process that is essentially self-sustaining. Known at this point as miasma, the high etheric density leads to the formation of all manner of exotic chemistry and to most living things (including humans) miasma is no more breathable than the effluent of an industrial plant. That said, there are entire orders of life that breathe miasma the way humans breathe air with some going between air and miasma in different stages of life. Misma can sometimes be found collected around shells or in drifting clouds but most grandly it can be found forming immense nebulae, even the smallest sufficient to entirely engulf an axial world.

Some of these nebula contain shells inside their gaseous envelope, while others are bereft of anything larger than random rubble and ponds. The thick miasma of nebula tend to block light very effectively, and while they sometimes glow softly in various shades they can effectively shade entire radiants inside their dark whorls. Their high ether concentration also results in continuous lightning discharges and often unpredictable weather in the neighboring skies while inside the nebula proper the air - the miasma - is commonly stagnant. With all navigation methods save dead reckoning useless inside these opaque masses getting trapped inside one can be a death sentence.

Of course the ether and the miasma is equally valuable; it is a great source of gaseous ether in high concentration and all manner of industrially useful chemicals. An extremely short list would include Promethium R and Promethium S compound families, aerosolized Sakuradite, Merculite precursors, Polydichloric euthimal and Iotimoline particulates, not to mention more common etheric thiolins and hydrocarbons. Thus the edges of nebulae are often sites of extractive industries.

The largest nebulae often extend for quite significant distances, such as the Great Wall and the nearby Tiamat's Shroud, the Pillars of Creation and the Greater and Lesser Drakenwalds. A few are even haunted by weapons of ages past, with the aptly-named Gunpowder Nebula thick with millennia-old shock mines, their corroded metal shells still protecting a payload of metastable merculite.

A far more benign relative of the nebula are fogwalls. Benign, that is, until your ship smashes into a rock concealed inside the fluffy white mists. Consisting (mostly) of innocuous water clouds, fogwalls are readily distinguishable from nebula by their clean white color as opposed to various rich shades. Generally found at the intersection of multiple air masses, the main difference between a fogwall and a simple large cloudbank is that fogwalls are - within the bounds of seasonal variance - essentially permanent features. Like nebula, the shade side of fogwalls often creates significant mesoclimates with the most famous of this being Quahog Sound bordering the Nanket archipelago.

Concepts

FUEL

It is axiomatic that known space runs on ether and has for millennia. Ether in various forms permeates the universe and finds itself used in equally myriad ways, but the single most significant use today is as a fuel. In broad terms there are three conventional formats in which it is so used; ether clathrates, ether gas and ether geodes.

• Etheric Clathrates are cosmically common; 'burning ice' can be found across known space on ice moons, in glaciers or permafrost and permeating cometary drifts. If there is ice exposed to the cosmos, there is a good chance of there being ether clathrates somewhere. These ices - mostly but certainly not exclusively water ice - are naturally impregnated with ambient ether, the ices' molecular structure trapping the ether. The resulting clathrates are generally slightly less dense than natural ice and are stable to temperatures above freezing at which point they will begin to decompose into a far less convenient mixture of etherically-charged water, gas and miscellaneous secondary compounds nicknamed 'firedamp'. (This said, long-term storage is generally done with temperatures kept below the freezing point of water to minimize the emission of firedamp from nominally stable clathrates)

Originally clathrates were decomposed to separate out and collect the pure ether - a sometimes dangerous process - but roughly 1500 years ago a clever method of consuming them directly in the ice form was developed and what was originally a brilliant leap of engineering has long since became the common process. The ether is burned to provide energy and the water is exhausted as steam. The downside to all this is that etheric clathrates are never entirely pure. Various other materials come with them and these build up in the combustion chamber as 'fly gunk', an unpleasant and sometimes toxic mixture of burnt residues, mineral ash and etherically altered compounds. Thus the convenience of having fuel available almost anywhere that costs little more than the price of mining and shipping it must be set against the inconveniences of clathrate combustion engines.

One variant on clathrates that finds localized use is etheric fats. These can be harvested from skywhales and other deep-sky beasts and while requiring some specific features to be used can generally be considered interchangeable with etheric clathrates in all important regards.

• Ether Gas has been used for millennia; originally used by magi to power their spellcraft, it was adopted as an energy-dense fuel for engines as mass-produced machinery supplemented and eventually mostly replaced magic. The terminology of 'gas' is heritage as these high-purity fuels come in not just gaseous but also liquid form. Ironically despite its association today with aviation and other high-performance roles, ether gas was used as a fuel long before etheric clathrates were. The main advantage of ether gas stems from its purity and energy density. Various formulations exist of binder and additive compounds (such as the Mastery-standard AERO-C, military Zip or more recent AP-9) but broadly speaking all these premixes exist to stabilize ether and make it safer and more convenient to handle while not materially affecting its energetic qualities. From a performance perspective, etheric gas is clearly the superior option.

The purity of etheric gas comes with its own downsides however. By far the most significant is that in most cases it is naturally unavailable in desired quality and must be refined out of natural feedstock. Various sources (including etheric clathrates) can be used, but on the industrial scale it demands significant infrastructure. The intrinsic nature of the local impurities also matters and while etheric gas can be extracted from many sources, only some are truly worthwhile to do so. Others result in dirty mixtures full of difficult to remove impurities. (fly gunk, in effect) High purity etheric gas is also a feedstock for myriad industrial processes and many states only have enough for their domestic manufacturing purposes and tightly limit the use of etheric gas as fuel to the most critical sectors. Others import millions of tons monthly.

• Etheric Geodes are the final common source of energy. These are made of ether that due to specific conditions has crystalized into a solid mass. Different colors are caused by even extremely small percentage impurities. Long recognized as incomparable sources of energy, geodes have historically been prized by magi for the greatest workings. Their first major technological use was the enormous Oklo geode-catalyzed radiothermal pile-reactors used in Freeman battlemoons. Crude but long-lived (even now, most of two millennia since their construction, several of their ancient heat-piles still provide energy) they were replaced by much smaller and less cumbersome geode-power technologies. Pure-geode power systems required more regular refueling - on the order of years - but for that period still gave nearly unlimited energy reserves while not being exceptionally large. The main limitation to geode power is the rarity of geodes. In practice, natural geodes are normally milled into appropriately-sized prisms or cylinders and then assembled into fuel assemblies.

Rules for fuel systems
Fundamental rule: 'Ether' represents ether gas; unless a ship has one of the following features it is assumed to use standard ether gas power and all rules apply as normal.

-0 Clathrate Fired - Clathrate fired engines have been ubiquitous since almost the dawn of the Great Empires of Man and they remain so. A long-understood and very mature technology their main advantage is that a fuel source is never far. So long as a clathrate-fired ship is within operational range of a fleet base it does not cost Ether to move, battle or other normal operations. Conversely, ships with clathrate fuel may not undertake underway refueling and thus must operation out of fleet bases and require simple albeit regular maintenance to discharge their reaction chambers. They also suffer a certain loss of stealth as they tend to generate large but harmless trails of steam-ice clouds in their wake. The clever use of clathrate bunkers does provide a small increase to survivability thanks to the use of icerooms as additional ballistic protection. Clathrate-fired ships still require annual ether upkeep representing the various fluids, gases and manufactured products that consume refined ether.

+1 Geode Core - With the appealing benefit of essentially unlimited cruising range, geode powerplants are a potent albeit uncommon power source. A ship with a geode core does not pay upkeep for transit, battle, etc, but must pay its annual ether upkeep in geodes - once initialized the geode cascade reaction will consume all the fuel in the core and thus fuel assemblies are built to be easily replaced on an annual basis. The innate sustained power also allows for optimization of engines for higher cruising speeds, giving geode cored ships a +25% speed increase. Geode power has no specific downsides past the cost of both the reactor and the fuel, though the ship will need to return home for an annual refueling, a process that is generally unfeasible in the field.