Supramundane habitats supported by gas pressure
Image from Steve Bowers
Purcell currently has two complete layers of habitable environment suspended inside its atmosphere

Purcell - the Osmin System - Data Panel

StarOsmin, TYC 6305-2141-1
Type G1V
Luminosity 0.55 x Sol
Distance from Sol 121 ly
Mass 0.846
Constellation Sagittarius
Planet 1Purcell.
Type AmmoNeptunian GeliJotunnian HydrogeoBarian
Semi-major axis = 4.99 AU, Orbital period = 12.1 years, Eccentricity = 0.045, Mass = 19.59 x Earth, Radius = 4.9 x Earth
Planet 2Siochan.
Type CryoNeptunian GeliJotunnian HydrogeoBarian
Semi-major axis = 8.21 AU, Orbital period = 25.56 years, Eccentricity = 0.06, Mass = 14.11 x Earth, Radius = 4.1 x Earth
The Osmin system was first reached in 2188 AT during the first Expansion era, by the Sagittarius Beachhead Undertaking. This system has only two neptunian type planets and a number of planetoids in an inner belt. The moons of Purcell and Siochan were the location of most of the earliest habitats, but by the Second Federation Era the atmosphere of Purcell was host to an increasing number of bubblehabs. During this period the majority of the independent habitats in this system were aligned with the Mutual Progress Association; a significant fraction of the population were provolved baboons, and their Metal Monkey companions.

During the Version War this system was attacked in 4498 by a Negentropist fleet from Rho1 Sagittarii. The system itself was not militarised at this time, so the inhabitants were largely defenseless; most of the conflict centered around the stargate in distant orbit around the star, and the wormhole stations were damaged with many casualties.

Negentropist forces occupied the planetary system, and commandeered many of the planetoids in the local belt for logistical resources. However the stargate archai in the Osmin system refused to submit to the Negentropist assault, and closed the traversable throat of the gate. This meant the Negentropists could no longer use this link as means to attack other systems, but it also denied the use of this connection to the MPA. In 4512 the Negentropist Fleet (now considerably larger) left the system to target several nearby systems which had been subject to MPA counterattacks. The Purcell system remained under occupation by a remnant Revisionist occupation force until the end of the War.

The Purcell BubbleShell and Hominism

During the ComEmp period the numerous bubblehabs in the atmosphere of Purcell began to align themselves into a single circumplanetary strip. Not all of these habs were occupied yet, but they linked together in 5121 for mutual support and stability. Gradually the number of habitats increased, under the encouragement of the transapient Raed (an ex-Metal Monkey), until they formed a continuous interconnected shell supported entirely by gas pressure. This was acheived in 7669. During this period a large fraction of the population (both Talking Baboon and Metal Monkey) adopted the religion or cult known as Hominism. Hominism is the belief that Human Beings are inherently worthy of respect, more worthy in many ways that their own mindchildren such as vecs and provolves, because it was humans who were responsible for the creation of both sophont robots and sophont animals.

The Hominists on Purcell, and on several other worlds, developed a distinctive way of paying respect to humanity; most of them opted for transformative medical morphism, changing their body-type into human form. Both provolves and vecs, and several other clades of the inhabitants of this system, changed themselves into idealised humans. These neo-humans occupied the extensive surface of the bubble shell within Purcell, fifty kilometres below the cold surface clouds of ammonia and illuminated by floating sun-clouds.

Despite their human appearance, the Hominists still retained many of the behavioral characteristics of their original phyle, and often formed cultures that were significantly different from normal human examples. The baboon-humans lived in large wandering troops, often ranging over large areas of the Purcell shellworld; and the vec-humans preferred to live in clean, well-organised cities with predictable and constrained patterns of behaviour.

Shellworld supported by gas pressure
Image from Steve Bowers
Currently Purcell has two concentric layers of continuous habitable surface supported by gas pressure.
In 9008 a second, deeper shell was constructed under the first; this layer has an atmospheric pressure much greater than that of the first shell, and the inhabitants are significantly different to those on the Top shell. The atmosphere in this undershell is mostly helium, with a breathable amount of oxygen, but the density of the air mandates that locomotion is more difficult. The trend for Hominism has receded significantly since that date, and many sophonts on this world are modified so they can thrive on both levels.

In the Current Era a third layer, with an even more extreme environment, has been commenced, but it is many centuries from completion at present.
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Development Notes
Text by Steve Bowers
Initially published on 21 June 2021.