Planet with unusual metallo-organic xenosophonts

Image from Steve Bowers

Samael - Data Panel

PlanetSamael (Sitr'achra VI)
SystemHuycau - Sitr'achra Binary system
Radius5,239.116 km (0.821 Earth)
Mass2.960e+24 kg (0.496 Earth)
Mean density4,914.258 kg/m3 (0.891 Earth)
major axis0.889 A.U.
Orbital eccentricity0.091
Orbital period1.177 standard years
Rotation period17.721 hours
Axial tilt35.816
Mean surface gravity7.198 m/sec2 (0.734 g)
Sea level atmospheric pressure460,820.205 Pascals (4.548 atm)
Mean effective temperature126.806 K (-146.345C)
Mean surface temperature244.490 K (-28.660 C)
CivilisationMolybvitae polysapiens, commonly known as the Samaelians

From orbit, Samael appears to be a lightly-cratered terrestrial world streaked with wispy ammonia and carbon dioxide clouds, looking much like a slightly wetter version of a typical Arean-class planet. Its surface is easily seen at visible wavelengths, though outgoing infrared radiation is absorbed by the atmosphere. The single brownish-green ocean is surrounded by an extensive black border that becomes less dense with distance from the coast. Similar black regions outline the courses of rivers connecting mountains and inland lakes to the sea.


The Samaelian atmosphere extends from the surface to an altitude of 148.919 kilometers (the height at which aerodynamic effects on an entering spacecraft become significant). It consists primarily of carbon dioxide, ammonia, and nitrogen, with lesser amounts of water vapor, argon, carbon monoxide, and trace amounts of other gases. Circulation is quasi-geostrophic, typical of terrestrial worlds with relatively thin atmospheres, and is driven in zonal patterns as much by internal pressure gradients as by Coriolis forces. Two large Hadley cells, extending poleward from the equator to the Arctic and Antarctic Circles, and two polar cells blanketing the areas within those Circles, provide meridional circulation. Wind speeds vary by altitude, with those at the top of the atmosphere averaging 185.343 meters per second at the equator, while those at the surface average only 1.145 meters per second. With a mean scale height of 7.364 kilometers, the atmospheric density and pressure double or are halved with each 5.418 kilometer change in altitude. At the surface, Samael's mean sea level atmospheric pressure is 4.548 atmospheres (460.820 kiloPascals). The mean surface temperature of -28.660° Celsius (244.490 Kelvin) ranges from a low of - 77.642° Celsius (195.508 K) during polar high-pressure storms in winter to a high of -14.364° Celsius (258.786 K) near the center of large inland deserts in summer. Wind accounts for more than two-thirds of Samael's surface erosion. Snow is rare though not unknown in the polar regions (though rime may sometimes be found on the coastlines, usually accompanied by "salt pans" of white ammonium hydroxide crystals).


Samael's orbit around Sitr'achra lies well beyond the red dwarf's "habitable zone," the region of space in which liquid water can permanently exist on worlds with sufficiently thick atmospheres (Donbetyr is within such a zone around Huycau, as is Usiel around Sitr’achra). But Samael does, in fact, have liquid water covering nearly one-sixth of its surface. That this water is not frozen into ice is due to the large fraction of carbon dioxide in the atmosphere (68.889% by volume) and the presence of liquid ammonia (28.5%) in the water, which forms a eutectic mixture that resists the formation of ice crystals. Tides in the Samaelian seas, which are caused primarily by the gravitational attraction of Sitr'achra, are negligible and are typically overwhelmed by wind effects.

The Samaelian ocean, which cover 56,912,784.839 square kilometers of the surface, is relatively shallow; the lowest point lies at a depth of 4,370.518 meters. Ammonia rains, similar to those occurring in arid regions of many Gaian-type worlds, happen from time to time, forming the basis of Samael's hydrological cycle. Such rains are infrequent, however, due to the extremely slow rates of evaporation on and near the surface, and are mostly confined to regions bordering the shallow seas. Elsewhere, the planet is about as arid as the surface of Mars was before it was partially terraformed. It is believed that most, if not all, of the water in the Samaelian seas originated with cometary impacts early in the planet's history, before the world had cooled to its present temperatures. Some water may also have been brought to the surface via outgassing as the planet cooled, and in later undersea volcanic eruptions.


Samael's lithosphere is divided into seventeen large tectonic plates that migrate very slowly across the surface. Despite its age and small size, the planet's interior is not yet totally inactive. Beneath Samael's relatively thin crust lies a thick and relatively cool mantle, a liquid outer and a solid iron inner core, all heated by pressure and the decay of radionuclides. The crust is composed mainly of reduced silicate compounds, graphite, and metals (similar in composition to Type CBa carbonaceous chondrites). Seismic activity has been recorded, though it is relatively infrequent and of a low average intensity. The surface is lightly cratered, though the eroded remains of some very large impact craters have been mapped from orbit. The surface topography consists of mountain ranges with narrow valleys near the tectonic plate boundaries, broad stony deserts in the continental interiors, and broad vegetation-covered plains near the coasts and along river banks and lake shores. The polar regions are generally cold and arid deserts, and are occasionally covered with thin transient dustings of carbon dioxide snow.


Samael formed about 6.016 billion years ago, and life appeared on its surface within two and one-half billion years after that. The planet is home to tens of thousands of recorded species, including the sophont Samaelians. Due to the alkalinity of the environment, as well as the low temperatures and strongly reducing atmosphere, carbon-based life forms were unable to become established (proteins are denatured and other complex carbon compounds are auto-catalyzed by molybdates into carbon dioxide), chance favored the emergence of self-replicating molecules composed of a variety of large, complex molybdenum ions. Unlike most transition metals, molybdenum is able to form single, double, triple, and quadruple bonds with a variety of other chemical elements. This versatility, combined with its ability to self-assemble into large and complex supra-molecular ions, makes molybdenum one of the few elements on Samael capable of forming life. Tungsten, another transition metal, is equally capable of forming such supramolecular ions, though it has not yet been observed to form Samaelian biomolecules; random chance appears the only reason for this disparity.

The high concentration of atmospheric ammonia (9.706% by volume), which strongly absorbs ultraviolet radiation, together with the planet's magnetic field, blocks nearly all harmful stellar radiation and permits life to thrive on land. All life discovered to date on Samael is based on inorganic molybdenum polyoxometallate redox chemistry. Generally, metabolism relies on reduction-oxidation reactions, primarily the [MoO4]2- <=> MoO3 reaction, though many others also occur. Photosynthesis has not been observed on Samael to date, though many organisms have evolved an ability to generate energy photovoltaically. Samael, like most "garden worlds," has a wide range of trophic niches, ranging from chemoautotrophic "plants" to heterotrophic forms which prey on "plants" and each other. About seventy percent of the nearly fifty thousand species catalogued to date are found on or near the surface of either land or sea. Of the remaining thirty percent, approximately one- third have adopted at least an occasional aerial lifestyle. Natural selection over the eons has produced an intelligent land-dwelling animal, which has gone on to create an advanced technical civilization.


All organisms on Samael can apparently trace their ancestry to single-celled plants that emerged on the shoreline or shallow margins of the ocean and spread into the remainder of the planet; all retain, to one degree or another, the photovoltaic abilities of their predecessors. Evolutionary adaptations, once developed on Samael, are retained across species after having proved useful, and seem only rarely discarded.

The most significant lifeform on this planet is the local xenosophont species, Molybvitae polysapiens, commonly known as the Samaelians; more details here. This species traces its ancestry back to a small, eight- legged and radially symmetrical creature that scuttled across the beach in search of prey about fifty million years ago. Over the eons that followed, two legs developed into arms and the symmetry changed from radial to bilateral as the organism grew in size and capabilities. The brain grew in size and complexity and, finally, about 150,000 years ago, the existing olfactory antennae gained the ability to conduct impulses between brains. This mutation spread throughout the population of otherwise anatomically-modern Samaelians as the survival value of the cooperative behaviors available to those with the mutation to out-compete those without. There are still a few remnant populations of Samaelians who lack this most recent mutation, mostly small groups living in isolated locations.


The base of the Samaelian marine ecosystem's food chain is occupied by small, multicelled organisms that float on the ocean surface. These "plants," [Lemboikhoz samaeli, the Samaelian boatman], each encased in a half-shell of transparent silicon dioxide to protect its molybdenum body from the highly alkaline seawater, are typically found in clusters of several dozen to hundreds of plants connected by intertwined leaves; these organisms collect sunlight to generate electrical voltages which power various chemical reactions on the surface of each leaf (the isocyanic acid-polyurethane reaction chief among them). To reproduce, spores encased in transparent silica spheres detach from the cluster to drift with the waves until they reach another sphere and join via silica tubules; genomic materials are exchanged between the spores, and a new plant emerges.

The role of primary producers of terrestrial biomass on Samael is assumed by a class of life forms that is more similar to fungi than to plants. In fact, these fungoids are nearly identical to animal life, in terms of basic biochemistry, but differ in that they rely on minerals for food and are relatively incapable of rapid movement. These fungus-like organisms spread broad, low-lying black "leaves" on and near the surface above intersections of their intricately interwoven subterranean root networks. These grow by slowly extending tendrils outward in search of usable mineral deposits they can use to sustain life. If a tendril senses a mineral concentration on the surface, such as the remains of a dead animal, it will breach the surface to burrow into the tissues of the dead animal. When a tendril locates a source of food, it gradually thickens as other parts of the plant migrate along the length of the tendril to reduce the distance the nourishment must travel; the radius to which this root grows is dependent on the amount of available food. When a part of the fungus is consumed or its food source is depleted, the remainder simply grows to replace the lost portions as new sources of nutrients are encountered. Movement is restricted to the soil, as burrowing through rock, while possible, is simply too energy-intensive to be practical (the by-product of the plant's feeding tends, over time, to produce more soil from the unusable rock matrices from which food has been chemically extracted). In optimal conditions, these plants can spread at a rate of up to 19,417 hectares per local year (about 16,497.026 hectares per standard year).


Marine animal life can be divided into two main groups: those that protect themselves from the alkaline environment by being encased within a protective shell of silica dioxide, and those that circulate an internally-produced acidic solution between their outer layers to neutralize the ammonia-rich water and minimize damage to their tissues. Of the first type, a notable example is the "driftnet floater" a colonial organism that drifts just beneath the ocean's surface. Like the L. samaeli plants described above, the driftnet floater generates energy from available sunlight, which it then uses to generate hydrogen for buoyancy from the surrounding liquid medium through electrolysis. Additionally, the animal feeds on small plants and animals that become ensnared in silicon dioxide "nets" surrounding its spherical shell. These nets, when full, are retracted into the floater's central cavity, the liquid is pumped out and the veils are bathed in an acidic solution to neutralize their contents, which are then digested by specialized colony members into a liquid form that is then distributed throughout the colony. The second group, whose members include the more active marine dwellers, include the Megachasma samaeli, a large filter feeder that constantly swims through the upper reaches of the oceans, and the three-tailed scourge. The scourge is armored along nearly its two-meter length by jagged silicon dioxide shells, which are used to protect the organism from other predators and also serves as a weapon against both prey and other predators. Those parts of the eel-like scourge not covered by these sharp growths circulate a hydrochloric acid solution between its inner and outer layers of skin.

The planet's low gravity and thick atmosphere combine to make active flight both very easy (one square meter of wing area can support a total body mass of more than 49 kilograms) and energy-efficient (active flight requires a minimum expenditure of about 0.795 kilocalories per kilometer per kilogram). As a consequence, many of the estimated thirty percent of species that do not live beneath the surface of the seas or the ground have taken to the air. Though very large flying organisms are certainly possible on Samael, the largest recorded to date is the eight-meter-long "worldflyer" (Fulladikosmo samaeli), an aerial filter-feeder that, relying on internally-generated hydrogen gas for lift as well as active flight using its flipper-like wings for propulsion, spends all of its time soaring through the dense lower atmosphere gathering suspended windblown dust in its two-meter-wide maw.

Other airborne life forms, such as the four-meter-long "blimp jelly" (Tristicomedentus samaeli), which drags its dozen pairs of tentacles along the ground as it floats a few meters above the surface looking for food, are "floaters," relying on internally-generated hydrogen gas for lift. Still others, like the ellipse-shaped "sky-ray" (Mantavolans samaeli), with its two and one-half meter wingspan, employ a strategy of actively "swimming" through the air as it and the other members of its hunting flock of up to ten individuals search for prey, which can include, on occasion, solitary Samaelians. Unlike the more passive "blimp jelly," which relies primarily on its senses of touch and taste to find food, the "sky-ray" uses its keen eyesight to find and attack its victims.

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Development Notes
Text by Radtech497
Initially published on 30 January 2013.