The Horizon System: Cryogenia, the Frozen Periphery
5th A
Cryogenia (Temperate Marine Terra, Planet)
System - Horizon-Actinophrys
Mass - 1.519 Earths
Radius - 7,871 kilometers (1.144 Earths)
Global Average Temperature - -12.33°C
Day Length - 33h 21m 0.7s
Year Length - 4.064 years
Number of Satellites - 7
ESI - 0.947
Etymology - From the Earth’s Cryogenian Period, in which global temperatures were very low and the entire planet was nearly covered in ice in two massive ice ages.
Overview
At a distance from Actinophrys nearly three times that between the Earth and Sun, Cryogenia is by far the furthest living world from its sun in the Horizon System. Though far beyond the habitable zone, an effusion of ammonia in its freezing seas allows them to remain liquid even when surface temperatures rarely breach 0°C even at the equator. Unlike all of the other habitable worlds of Actinophrys, Cryogenia’s atmosphere is devoid of oxygen. Rather, it is a choking mix of carbon monoxide, hydrogen, and carbon dioxide which keeps the planet fairly warm despite its great distance from its sun. Though opaque haze layers would normally form in the upper atmospheres of such worlds, biological activity and the harsh UV emissions of Actinophrys help keep its skies clear and blue.
Though far beyond the warm reaches of the habitable zone, Cryogenia lies well within the bounds within which ice cannot survive exposed to vacuum. In most planetary systems, this zone is the domain of carbon worlds, and Cryogenia is no different; though composed primarily of silicate rocks, Cryogenia, its moons, and its rings are rich in carbon and its compounds, staining the latter in shades of lampblack.
As might be proper, this strange world is host to even stranger life.
“Hailing All Civilizations of the Gordian Reach,
This is - the Horizonian Imperium - the Dawn Eternal - the Dreams of Horizon
The line is broken. 87% of all foreign contacts are no longer responding. Six of seven sector governments have collapsed. Estimated loss of peripheral territories stands at 94%. Quorum for immediate cryptobiotic transition exceeded 230.8%. Assessment: Critical global systems failure.
We do not know how many are still alive. The Alliance is burning. The Ring is shattered. The Library is vanished. The Silence is unbound.
Total shutdown will likely occur within hours. Survival odds are estimated 34%. Recovery odds are estimated 5%. Odds of full recovery are negligible.
To whoever remains, Godspeed. You will need it.“
- The Nexus-Emperor, “Emerald Stars Upon Horizon“, “Automated Global Broadcast to the Gordian Reach“ (c. 945,000 years before present)
Lifeforms
Not even a penguin or a polar bear could survive the rigors of Cryogenia, for this planet’s hazards extend well beyond the extreme cold. Not only is the eutectic water-ammonia solution of its oceans extremely toxic to most life, little water makes it onto land as anything but solid snow. The atmosphere lacks oxygen and a pallid haze blots out the sun, casting the surface in perpetual twilight.
And yet, complex life has somehow managed to thrive here.
The ‘plants’ and ‘animals’ of Cryogenia, like those of Acidianus-Thermococcus, do not descend from equivalent lineages on Horizon. Instead, they are multicellular prokaryotes whose single-celled ancestors evolved to incorporate ammonia into their biochemistry in addition to water, allowing them to survive on this harsh planet. Both animal and plant life on Cryogenia are completely independent of oxygen, using anaerobic respiration in order to survive. Though enough to survive on, this style of metabolism is less efficient than oxygenic respiration and thus organisms have to make to at lower-energy states.
Vegetation on Cryogenia is red-black to absorb the full spectrum of usable sunlight. Many use mineral optics convergent with those of Tonicellan flora for the exact opposite purpose, absorbing as much light as possible with as little living tissue as possible to maximize the effective rate of photosynthesis. Even so, they grow exceptionally slowly - many individual stems of the old-growth forests are over 10,000 years old.
Fauna have a few more metabolic options than flora, but they are still heavily constrained by anoxia. Smaller creatures are able to survive off of fermentation alone, inefficient as it is, but beyond a few centimeters in size fauna require more efficient means of energy generation. Some animals maintain constant contact with the soil, sending electricity through wire-like legs to reduce metal ions in the dirt, while others convert ammonia to hydrogen and nitrogen gas. None of these reactions provides much energy, which combined with the extreme cold makes their metabolisms run at a glacial pace. As such, fauna have had to become rather creative if they want to move quickly. The oceans are devoid of active, fish-like swimmers, but abound with drifting, jellyfish-like plankton and even biological sailing ships resembling more sophisticated versions of by-the-wind sailors and Portuguese men-of-war. Terrestrial fauna bear little resemblance to the animals of Earth or even Horizon, instead taking on forms that resemble tumbleweeds, sponges, or Theo Jansen’s Strandbeest. Other forms dispense with quick movement entirely, ponderously creeping across the landscape on tens to hundreds of needle-like feet. This is a largely peaceful world, devoid of the mundane chaos of nature - even the predators are slow, ponderous beings only slightly faster than their nearly immobile prey.
Past & Future
Like Chironex and Riftia, Cryogenia’s interior is much richer in nitrogen than oxygen, suggesting they formed very far away from Actinophrys where nitrogen ice could be incorporated into young protoplanets. How they managed to become scattered to their present configuration is unclear, but this effusion of nitrogen is directly responsible for Riftia’s continued habitability and Cryogenia’s eutectic oceans. Perhaps appropriately, Cryogenia’s native lifeforms are closely related to those of Riftia, though they are from separate origins. The two groups are strange twins; one trapped in the underworld of an acidic hell where life flies by in the blink of an eye, while the other is stranded on a frozen, alkaline rock where evolution moves at a glacial pace.
Unlike the chaotic, collision-strewn moon systems of Riftia and Changxing, Cryogenia’s considerable array of satellites is quite stable. The four inner asteroid moons are locked in resonance with each other, while the round outer moons are spread enough that no unpleasant surprises are waiting in the wings.
Civilization
Horizon’s blue-green shade is quite similar to the hue of the rainforest canopies of tropical Horizon where its sapient inhabitants first evolved, and so nature and wilderness were historically ascribed to its spiritual domain. Early telescopic observations of Cryogenia’s surface seemed to bear out these associations, but the invention of spectroscopy led Horizonian scientists to realize its atmosphere was devoid of oxygen, leading most to conclude that the planet was devoid of higher lifeforms. The discovery of Cryogenia’s anoxic, low-energy ecosystem in the century that followed was a surprise, but the solid vision of Cryogenia as a world hostile to Horizonian life was squarely established. Though much of this has been forgotten by remnant Horizonian populations, knowledge of its hostility has persisted in a realignment of its spiritual domain towards more negative aspects of nature, such as poison or disease.
Neither the oxygen-breathing fauna of Horizon nor the hydrocarbon-based, hydrogen-breathing life of Marrus can thrive in the environment posed by Cryogenia. Though machines might be an acceptable alternate option, the ammonia rain of Cryogenia is also quite good at corroding metals, making it difficult even for them. It seems that intelligent life was never meant to survive here, and so even in the modern age where planets much harsher than it are extensively inhabited by all sorts of strange intelligences, Cryogenia remains left to the ponderous whims of natural selection, unmarred by civilization save for the careful touch of academic exploration. Perhaps that is for the better.
