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Khorlu, Bronson's Star

This article originally appeared in Issue #007 of the PDF magazine, and was reprinted in the March/April 2022 issue.

Bronson’s Star system

Bronson’s Star is a K4v main-sequence star (“orange dwarf”) with five planets, an asteroid belt, and a small backwater colony. Despite its backwater location and low population, it is the subsector’s main source of the ultra-rare Second Stable Series “Ransdell Metals” used in high-temperature alloys and high-tech batteries.

Wend (X401000-0, Orbit 0) is a cratered Mercuriform rockball, tidally-locked, icecapped on its permanent dark side, usually lost in the sun’s glare.

Khorlu (D787671-6, Orbit 1-2) is the system main world, in a highly-eccentric orbit with extreme seasons; for of the year, its orbit takes it outside the liquid-water habitable zone. A population of around three million lives on-surface, primarily in five domed cities. Three small moons, Ocron (D100516-6), Lagon (XS003M8-6), and Itol (XS003M8-6), house a lunar highport/outpost and system defense facilities.

Bronson’s Belt (E000200-6, Orbit 3-4) is the system’s asteroid belt, sprawling well outside its nominal orbital region from the tidal pull of Gorfulu. Some sporadic Belter activity.

Gorfulu (LGG, 500 T-mass, Orbit 5) is the main gas giant in the system, with a magnificent ring system, six regular moons, and almost a hundred captured-asteroid irregular moons. Almost twice the mass of Jupiter, Gorfulu has too high a surface gravity and too strong a magnetosphere to be suitable for fuel skimming. Its gravity has swept clear the empty orbits between Bronson’s Belt and Strahl.

From Khorlu, Gorfulu appears as a brilliant yellow planet; close-up, the massive gas giant resembles “Saturn with smallpox”, with yellowish cloud bands peppered with white and pastel-colored storm systems, including at least a dozen “Great Red Spots”.

Strahl (SGG, 50 T-mass, Orbit 7), a small, pale blue gas giant with five moons, is the main fuel-skim site for the system. Almost the ideal mass for the purpose, Strahl’s surface gravity of gee allows even 1-G ships to skim and boost clear.

Strahl is barely visible in Khorlu’s night sky, appearing as a faint pale-blue star.

Danot (SGG, 20 T-mass, Orbit 8), a small gas giant with two moons, marks the edge of the system. Though its atmosphere is suitable for fuel-skimming, its surface gravity and location make it much less convenient for the purpose than Strahl. Beyond Danot lies only a moderate-density Kuyper Belt of small iceballs and comets.

Effectively a twin of Neptune, Danot is only visible from Khorlu through a telescope.

Khorlu (Bronson II) D787671-6 Ag, NI, Rich Eaglestone Trade Index 1

The system’s sparsely-settled main world is a medium-sized surface-habitable world, barely habitable due to its eccentric orbit. The extreme seasons (primarily harsh winters) are caused by the world’s orbit instead of axial tilt; Khorlu’s orbit takes it outside the habitable zone for of its year.

Planetary Geography

Most of Khorlu’s land area is concentrated in the Northern and Southern hemispheres, with an open “ring ocean” around its equator. Except for small outposts, all the population is concentrated in the Northern Hemisphere on one of the continents and a couple adjacent islands.

Surface Conditions/Sky Picture

Braked by suntide, the day is 30 hours long, with a year of around 125 local days. Climate in the settled area (one of the Northern Hemisphere continents) is extreme, temperate during Perihelion Summer and completely frozen over during Aphelion Winter. During Winter, all open water except the equatorial oceans freeze over, and even there ice crusts form overnight.

The first thing a visitor will notice is the sky color, which varies over the year. Most of the year, the sky is green, tinted by layers of aeroplankton in the upper atmosphere. Every late Autumn as the world cools, these floating plants sporate and die off in autumn rains of sticky green sludge called “Ublek”, fertilizing the lands, seeding the oceans, tainting the atmosphere, and leaving the sky a cloudless cold blue throughout Winter.

The next is the gravity, around 10% below a standard gee. Then the yellow (greenish yellow in Summer) shift in colors from the sun, distinctly orange, half again normal size in the green sky of Summer, shrinking down to a little under “normal” size in the blue sky of Winter. The orange sun shares the sky with three moons, two barely large enough to show a disc.

Native Life

Life Score 4 (microbes and simple vegetation), mostly in the seas and sky (aeroplankton), reproducing asexually through spores. The two most noticeable forms of multicellular vegetation are the aeroplankton and “stalkers”.

Aeroplankton are colonies of tiny plants that float in the upper atmosphere, held aloft by hydrogen in “gasbag” cells. They are annuals, growing on the ground and blooming atop the thawing oceans in early spring, floating into the air (and tinting the sky green) from secreted hydrogen during mid-to-late Spring, then sporating/dying off and falling as Ublek – green sludgy rain – as Winter freezes the world. During the skyfall in early winter, the atmosphere becomes Tainted; the dead aeroplankton are slightly toxic until winter snowfall and spring thaws wash the toxicity away. The aeroplankton also changes Khorlu’s appearance over the course of the year:

Aphelion Winter: Khorlu appears as a conventional “semi-snowball” world, with large polar icecaps, land white with snow and mountain glaciers, and coastal oceans frozen over with visible pack ice in the deep oceans.

Spring: As the planet thaws, aeroplankton blooms in the equatorial oceans, changing their color from blue to green; as Spring progresses, the atmosphere fills with a green haze, obscuring the surface. This haze begins around the Equator, but is soon carried over the planet in green swirls of “superclouds”.

Perihelion Summer: With surface features all-but-hidden beneath a green haze of aeroplankton, Khorlu resembles a slow-spinning gas giant, a featureless green speckled with swirling clouds and “ghosts” of surface features.

Autumn: As the planet cools, the aeroplankton dies off and falls out of the atmosphere, starting at the poles and moving towards the Equator. By mid-Autumn, Khorlu has taken on a unique appearance; an irregular equatorial belt of Summer green, poles of Winter icecaps, and two belts of “normal”-appearing surface in-between.

“Stalkers” are the largest of Khorlu’s land vegetation, the size of trees but appearing more like giant asparagus stalks. No leaves, just photosynthetic cells covering the entire surface of the tall serrated stem. Roughly analogous to bamboo, but grow from the tops instead of the bases. These plants go dormant during Aphelion Winter, secreting alcohol-based antifreeze sap; any break or cut in the surface smells of alcohol, as do all forested areas. New stalks sprout from underground rhizome-roots every Spring thaw. These plants provide the only “lumber” on-world, more like bamboo than true wood; logging is in the form of clear-cutting forests in a rotating pattern, as last year’s clear-cuts resprout the following Spring.

Cautions and Hazards

The main hazards all have to do with the eccentric orbit and extreme seasons.

During Perihelion Summer, the main hazard is sunburn; though K-class stars don’t put out as much UV as hotter stars, Khorlu doesn’t have as strong an ozone layer.

During Autumn, as the world swings away from its sun, the Ublek falls begin as the nights go below freezing; the dead aeroplankton are slightly toxic, tainting the atmosphere. This hazard lasts for around 10-15 days until the temperature drops further and snow buries the organic residue for Aphelion Winter. Ublek-fall begins near the poles, then over the next few days moves towards the Equator.

The first sign of Ublek-fall in a region is a cold snap of two or three days duration; then the Autumn rain turns bright green and thick. The first few rains provide warning; by the time the rain turns green enough to become toxic, filter masks must be worn when not under cover (such as under the city domes).

Within a few days, Ublek-fall is at its peak, falling even from clear skies; unmixed with rain, it is a sticky green sludge that gathers everywhere until the cold Autumn rains wash it away into watercourses, lakes, and eventually the oceans. This is the time of maximum inhalation hazard, as the sky changes color from green to a normal deep blue.

Ublek is most toxic when inhaled as an aerosol (such as spray or mist). The toxicity manifests as a severe allergic reaction with symptoms similar to an asthma attack; the severity varies from person to person and according to the amount inhaled.

Inhaled, Ublek-spray or mist causes 1 point of damage per hour plus a chance of a severe allergic reaction. When first exposed, roll 2D against Endurance. If End+, take 2D damage from anaphylactic shock. (Ephedrine injector will stop the reaction; Endurance recovers 1 point/hour.) If continuous exposure, check no more than once every hour.

Ublek is only toxic when inhaled or ingested. It has no other effects, and can easily be washed off.

As Aphelion Winter sets in, snow buries the remaining Ublek. There is still a danger of residual toxicity in lakes, rivers, and oceans, or when digging into the snow. In the last case, the danger sign is when you hit a layer of green snow. (Never mind the yellow snow, don’t eat green snow.) This secondary hazard ends only when the Spring rains wash away the residue.

Though not as toxic as when inhaled, Ublek residue is still toxic when ingested (as in drinking “green water”); the toxicity manifests as GI symptoms of varying severity, usually nausea, vomiting, and diarrhea as the body tries to flush out the toxin.

When ingested, roll 2D against Endurance. If End+, take 1D damage (starting with Endurance) from GI symptoms plus 3D minutes incapacitated while the body purges itself. If End-, temporary DM –4 on all actions from mild stomach cramps.

During Aphelion Winter, freezing and exposure are a constant danger outside of the Five Cities; the cities are domed and geothermally-heated and rural settlements are insulated and heated. Outside the temperature never climbs above freezing – and dips even lower at night – until the Spring thaw breaks the spell of snow and ice and the sky once more turns green. If you are stranded outside during Aphelion Winter without proper shelter or Arctic survival gear, you will die.

Population and History

Khorlu appears to have been in the process of being colonized when the Long Night went down; the original colonization project was in the process of building four or five large settlements under huge geodesic dome arrays when the project apparently went bust. Abandoned in mid-construction, the domed cities were left as-is through the Long Night; no one knows if any of the original colonists were left behind on-world. When the current colonists first settled (completing the unfinished domed cities), there was no sign of any existing inhabitants.

Around forty years ago, a consortium of several nonconformist groups (some of them refugees from nearby worlds’ political upheavals) staked out Khorlu for settlement, completing the domed cities and settling in. Within a generation, friction between the two main factions in the cities of Hendron and Midian (with additional friction between two Midianite factions) split whatever unity the colony may have had. Since then, the Four (now Five) Cities have been effectively independent in a very loose association.

The result of this final wave of colonization, Khorlu’s current population is fairly-generic light-skinned humans, varying slightly among the Five Cities. The people of Hendron and Ransdell are of a more “European” ethnic type, those of Midian a medium-skinned “Asian” type, and the isolated religious colonists of Eberville are yet a different ethnic type, a generic medium-skinned people. The people of Talon are a mixture of those of Hendron and Midian, and outside the Five Cities you can find any combination or mixture of the above.

Politically, Khorlu is a loose federation of five city-states, each named for their founders, each built in a domed-over crater for climate-controlled protection from the harsh winters. All except Talon have an almost fairy-tale appearance under their dome, with a central crater lake rimmed by terraced buildings, bridged over by further arcological structures.

Eberville (population 200,000 Gov D with elements of A, Law 9) – A small religious colony that has little to do with the others or offworlders. Not hostile so much as standoffish. The sect that named and settled Eberville was a last-minute addition to the colonization project.

Hendron (population 600,000, Gov 2, Law 1) – Second largest city, home to one of the two D-ports on-surface. Most easygoing and hospitable of the Five Cities, major rival of Midian with a completely-opposite political philosophy and social climate.

Ransdell (population 500,000, Gov 1) – Third largest city and Khorlu’s hook into the interstellar economy, with a mining-based economy in partnership with several offworld corporations. Ransdell sits in the midst of a “fossil” impact basin containing the subsector’s only known deposits of unique natural Second Stable Series metals, valuable for high-temperature alloys and high-tech electric batteries. Ransdell has a dedicated E-port for shipping metals offworld, administered by one of its partner corps.

Midian (population 800,000, Gov B with elements of 3 & 9, Law 9) – Largest city and nominal capital, a bureaucratic oligarchy with high law level. The Midianites fancy themselves the dominant city-state and planetary government; in practice, they have effective control only over their valley. Major rival of Hendron; the governments of the two cities do not like each other, and have a low-grade “Cold War” underway.

Talon (population 300,000, Gov 2, Law 3) – Newest of the Five Cities, founded by exiles/expats from Midian and still under construction. Unlike the other four cities, Talon is composed of a sprawl of small domes in various stages of completion instead of a single large dome-over-crater. Pretty much a boomtown with a “frontier” atmosphere.

Of the Five Cities, Hendron, Ransdell, and Midian all cluster within 300km of each other; Eberville is around 500km distant from the three, and Talon is along the coast some 1000km away. All five cities have a “halo” of smaller settlements and rural holdings, and are connected by a series of roads passable even in the dead of Aphelion Winter.

Like its destination, the road to Talon is still under construction. Only about a third of the road is passable, aided by a Winter shortcut – an ice-road plowed and marked over frozen ocean separating Talon from the main inhabited landmass. This ice-road shortens the distance to Talon by half, but is only useable when the oceans freeze over during Aphelion Winter, about 1/3 of the year. (Ice Road Truckers, anyone?)

The remaining population (some 600,000, about the same as in Hendron) is scattered all over in various homesteads, farmsteads, and small rural holdings (similar to those in Andre Norton’s Postmarked the Stars), dug in along the roads connecting the Five Cities. These farmsteads provide most of the agriculture leading to the Ag world classification. All agriculture on-world concentrates into Perihelion Summer, less than half the year. Between Ublek-fall Autumn and Spring Thaw the farmsteads hunker down for the freezing Aphelion Winter. During this time the only agriculture is specialty items grown under the city domes.

The Five Cities are all-electric, using geothermal power. Ransdell metals are used in high-efficiency batteries which power most everything on-world, including the in-town “runabouts” and long-haul cars, buses, and trucks. Local battery technology is the main exception to the Tech Level of 6, being more like Tech 10-12. Rural holdings without city power feeds often use some form of solar power.


Khorlu’s entire offworld economy and hook into interstellar trade is the mining and exporting of Ransdell Metals. Strip-mined from meteoric deposits around the city of Ransdell, these ultra-rare Second Stable Series metals are vital in the manufacture of high-temperature alloys and high-tech batteries.

The mining industry is owned and operated by the City of Ransdell in partnership with various Midianite, Hendronese, and offworld corporations, and is very straightforward. The Ransdell Metal ore is taken from various open-pit mines in the highly-eroded impact basin around Ransdell, refined in vast smelters on the outskirts of the city itself, and shipped offworld through Ransdell’s E port. Being meteoric, the ore comes out of the ground pre-refined and requires only minimal smelting to separate out and alloy the various Ransdell Metals in the optimal combinations for offworld use. Details of the smelting and alloying operations are jealously-guarded Trade Secrets.


All five cities maintain their own small starports; Hendron’s and Midian’s are both Class-D, while the other three are Class-E. An additional Class D highport is located on Ocron, the largest moon. All five surface ports have aero-shuttle service between them, mostly by charter.

Hendron and Midian are both Class-D ports (minimal maintenance and fueling facilities), scaled around a maximum ship size of 2000-dton Type TI Frontier Transports. Between the two, traffic is usually a couple small (200-600 dton) ships a week.

Ransdell’s attached port, though only Class-E (no repair or fueling facilities), is the largest of the five, able to handle 6000-dton bulk freighters for the Ransdell Metal trade and minimal other traffic. Ransdell normally sees a large (2000-6000 dton) freighter once or twice a month.

Eberville and Talon are also Class-E ports, but can only take ships of under 1000 dtons. Most of their traffic is aero-shuttle service from the other cities, usually by charter.

Ocron provides the Class D Highport facilities for unstreamlined ships with on-call shuttle service to Hendron and Midian.
Other than Ransdell Metal exports (averaging a couple thousand dtons/month), traffic is fairly minimal, with an Eaglestone Trade Index of 1 – less than 50 passengers and 500 dtons of freight per week.

Except for the abovementioned Ransdell Metal shipments, offworld traffic normally routes through either Hendron or Midian, and the rivalry between the two ports (as between the two cities) is fierce, including extralegal “dirty tricks” to make sure the Free Traders use their city’s port and not the other. Given the choice, most offworld crews prefer Hendron’s easygoing attitude and low Law Level to the Midianite bureaucracy and high Law Level; most of the “dirty tricks” steering in traffic are Midianite.

The only local insystem patrol and rescue craft are small craft from the D ports.

Local Folk Belief: The Old Ones

A widespread folk belief is that of “The Old Ones”, a hidden population of quasi-fey folk left over from before the Long Night. Depending on who is telling the story, The Old Ones are either descendants of the vanished original colonists deliberately hiding from the new settlers – or their ghosts.

Filling a niche similar to Irish Faeries or Icelandic Huldefolk, The Old Ones are credited in folklore with causing disappearances or deaths in Aphelion Winter, rescuing or covertly helping settlers in trouble in the wilderness, appearing to give warnings in the manner of a Vanishing Hitchhiker variant, or performing various acts of petty thievery and mischief in backwoods settlements – never anywhere where the tales can be fact-checked.

Belief in The Old Ones varies from place to place, but the farther away you are from one of the domed cities, the stronger the belief and more numerous the stories and legends.

Tech Level Anomalies

Though officially Tech Level 6 (World War Two technology), imported high-tech is fairly common, especially in Ransdell. Midian and Hendron also have their share of imported high-tech. Midian’s is firmly in the hands of the ruling oligarchy; Hendron’s is a bit more evenly distributed.

The higher the tech level of imported technology, the more difficult it is to maintain; TL6 can maintain mechanical and basic electrical systems, but not the solid-state electronics that become universal at TL8 and above. Because of this, most imported “high-tech” is still relatively low, around TL8-9. Anything TL10 and above requires dedicated offworld maintenance and spares – yet another strain for a sparsely-populated Nonindustrial world.

The other main exception is electric (not electronic) and battery technology, which thanks to Ransdell metals is more like TL 10-12. These high-tech batteries are locally maintained.

Armed Forces

Each city-state maintains its own militia force, equipped to Tech Level 6 with some offworld higher-tech. Hendron’s and Midian’s militias are brigade-sized, Ransdell’s regiment-sized, and Eberville’s and Talon’s are reinforced battalion-sized. All are equipped for arctic conditions, including the ubiquitous “snowcrawler” APCs powered by Ransdell batteries. Given the political situation, there have been skirmishes between the Hendronese and Midianite forces, and Ransdell has had to take up arms on occasion to protect their mining/export economy.

System defenses are under the authority of a joint Hendron/Midian/Ransdell command, and consist of missile bases both on Khorlu’s surface and on all three moons. A couple armed gigs (“poor man’s fighters”) are available, as are a dozen or so non-combat Small Craft. So far, System Defense Command has been relatively free of the friction between the two largest of the Five Cities.

As is typical for orange/red dwarf systems, the hundred-diameter safe Jump limit is determined by the sun, corresponding to Orbit 2. Khorlu’s eccentric orbit carries it inward to Orbit 1 for Perihelion Summer and out to Orbit 2 for Aphelion Winter, causing great variations in minimum Jump distance.

In Summer when Khorlu is at perihelion, safe Jump distance is its maximum of .3 AU (45,000,000km) outsystem, corresponding to “close neighbor world” distance. This helps system defenses, as any attacker Jumping in must boost for 18 to 36 hours to reach Khorlu; even a “Dump-and-Jump” with 6-G missiles would give some 15 hours early warning.

In Winter, Khorlu arcs clear of its sun’s hundred-diameter limit; at this time, the safe Jump distance is at its minimum, the standard for a Size 7 world.

Between these two extremes, the safe Jump distance varies depending on the time of year, from the maximum of Perihelion Summer and the minimum of Aphelion Winter.

The Moons: Ocron, Lagon, and Itol

The three cities with starport facilities (Hendron, Midian, and Ransdell) maintain a joint highport/outpost on the largest moon of Ocron; this outpost has a population of less than 10,000 and maintains the fuel-skimming operations from Strahl’s atmosphere. This highport/outpost is a warren of domes and dugouts surrounding a small D-class port used mostly for refueling and fuel lighter basing, all in Ocron’s 0.1g.

The only facilities on Lagon and Itol are System Defense Command missile bases; both these moons are Redzoned to civilian traffic.

Bronson’s Belt (asteroid belt)

A handful of Belters operate in the sprawling asteroid belt of the system, searching for asteroids with the same Triple-S metals as Ransdell. So far, nobody’s found any.

Belters are sponsored by or involved with Midian, Hendron, and Talon; the only support facilities in the Belt are a couple non-starship “motherships” and domed outposts on a couple of the larger asteroids, totaling a few hundred permanent/long-term population.

Adventure Nuggets

The two cities of Hendron and Midian are bitter rivals, competing for interstellar traffic and the mineral/industrial wealth of Ransdell. Though too small to launch actual warfare, both have a miniature “Cold War” underway that could easily suck in visiting player-characters. Even if the rivalry doesn’t blow up into actual shooting skirmishes, espionage and intrigue are always underway.

This even extends to competition between Hendron’s and Midian’s D-class starports to attract traffic (such as player-character ships.)

Player-characters could also get mixed up in corporate espionage (up to and including “wet work”) around the trade secrets involved in Ransdell Metal production. The valuable industrial-metal shipments could also become targets of tradewar theft or piracy.

The Road to Talon is still under construction, without the amenities of the other main roads. A Talon run in the dead of Aphelion Winter can all too easily turn into a survival situation.

Much of Khorlu is unexplored, and much of the original colonization project remains a mystery lost during the Long Night. Maybe there is something to all those stories of The Old Ones…

And even a “conventional” adventure during Autumn or Aphelion Winter could be complicated by the toxic presence of Ublek. (Tip: Better to Eat Yellow Snow than Green.)

And if there’s even a rumor of a Ransdell Metal strike outside of Ransdell – in either Khorlu’s wilderness or Bronson’s Belt – all bets are off and Jokers are wild.

Designer’s Notes

Khorlu is loosely patterned after Bronson Beta from the 1933 novel After Worlds Collide (sequel to When Worlds Collide) by Philip Wylie & Edwin Balmer. System nomenclature was taken from the geography and characters in the novel.

Ublek was also taken from the novel, in the sense of a green sky from upper-atmosphere aeroplankton. The toxicity was added during Travellerization. Yes, it was named after the substance in the Dr Seuss story Bartholomew and the Oobleck. (“It’s not like rain, it’s not like snow; Oobleck, Oobleck, Oobleck, Oh!”) On Khorlu, the colonists probably named it after the fictional substance, similar to Pandoran Unobtanium.