Froin (world)

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Froin/Five Sisters (Spinward Marches 0539)
Milieu 1116
StarportC Routine: No Construction, Major Repair, Unrefined fuel
Size5 Medium (8,000 km, 0.40g - 0.57g)
Atmosphere3 Vacuum (very thin)
Hydrographics5 Wet World 50%
Population2 Low (600)
Government2 Participating Democracy
Law5 Moderate Law (no concealable weapons)
Tech Level9 Early Stellar (fusion)
See also UWP
System Details
Primary M2 V M7 V
Worlds 12
Gas Giants 1
Planetoid Belts 0
Cultural Details
Government Participating democracy
Law Level Moderate
Cultural Extension 1137
Army Size (BEs) 0
Economic Details
Technology Level 9
Economic Extension
Labor1Low (60)
Infrastructure1 Extremely limited
Importance Extension -1
Resource Units 4
GWP (BCr) 0
World Trade Number 2.5
Trade Volume (MCr/year) 0
Starport Details
Classification Class-C
Port Size 0
Building Capacity (Tons) 0
Port employees 0
Port passengers (annual) 0

Froin supports a population of fewer than 10,000 sophonts. This world has the Imperial Research Station Zeta for the Sector. It is a member of Third Imperium in the Five Sisters Subsector of Spinward Marches Sector and in the Domain of Deneb. Froin, as a member world of the Third Imperium, holds the estate of an Imperial knight, a member of the Imperial Nobility charged with overseeing the world.

Froin System
Five Sisters/Spinward Marches 0539
Position Distance Name UWP
Primary 'Oin' 'M2 V'
1 0.4 AU Gloin Gas Giant
1 3   * Gloin I' Y300000-0
2 6   * Gloin II' Y300000-0
3 8   * Gloin III' Y300000-0
4 19   * Froin' C535225-9
5 35   * Gloin V' Y400000-0
2 102 AU Aoin M7 V

Astrography & Planetology[edit]

Froin is a member of the Spinward Main. Froin is a member of the Collace Arm.

The Froin system is characterized by its old central red dwarf, its single gas giant, and orbiting smaller red dwarf companion star, Aoin. System age is roughly 9 billion years.

Binary Solar System[edit]

Froin Binary Star System
Star Name Hierarchy Category Mass (Sol) Temp (K) Luminosity (Sol)

M2 V

Primary Main Sequence 0.4258 2400 - 3300 0.027
Unit Diameter Min Distance Hab Zone Jump Shadow M-Drive Limit
AU 0.0044 0.01358 0.13 - 0.21 0.44 4.4
Orbit #  *  * 0 1 6
Star Name Hierarchy Category Mass (Sol) Temp (K) Luminosity (Sol)

M7 V

Secondary Main Sequence 0.273 1900 - 2700 0.004
Unit Diameter Min Distance Hab Zone Jump Shadow M-Drive Limit
AU 0.0026 0.00525 0.05 - 0.08 0.26 2.6
Orbit #  *  *  * 0 5

World Data[edit]

Froin is a world commonly referred to as being on the ass-end of space. It is a cold, dim world with no real neighbors and few visitors. While there is a settlement focused on mining the ores uncovered by the the meteor strike that created the smaller crater, some 90% of the population is employed at the Crater Downport. The main activity here is to serve the rare enterprising or foolish trader that made it out this far.

System Overview[edit]

Main Contents Stars Orbital Distances (AU)
* Central star * Primary Oin, M2 V * Inner limit 0.10 * Companion Binary, Aoin
* 1 terrestrial moon * Temperature (K) 3500 * Inner life 0.850 * Temperature (K) 2820
* * Luminosity (sols) 10.6 * Outer life 1.45 Luminosity (sols) 17.0
* Large Gas giant * Mass (sols) 0.45 * Snow line 0.39 Mass (sols) .28
* * Radius (AU) 0.002 * Outer limit 48.0 Radius 0.0016
* * Stable life 20+ billion yrs --


Orbit SubOrbit Name Diameter Density Gravity Rotation Revolution e World Type
0.4 -- Gloin 133300 2.5 4.68 18.4h 62.05d 0.00 Gas Giant
0.4 3 Gloin I 4.5 4.5 0.02 tl 1.7d 0.04 Terrestrial
0.4 6 Gloin II 5.3 4.6 0.02 tl 4.25d 0.02 Terrestrial
0.4 8 Gloin III 4.3 5 0.02 tl 6.5d 0.01 Terrestrial
0.4 19 Froin 3120 4.9 0.43 tl 14d 0.00 Terrestrial
0.4 8 Gloin V 4.5 4.3 0.02 tl -- 0.02 Terrestrial


  • Orbit is in AU or planetary radii for satellites
  • Diam = diameter in miles (X 1.609 for km)
  • Dens = average density in g/cc
  • Grav = 'surface' gravity in G's
  • Rot/Rev = rotation or revolution period in hours (h), days (d), or years (y) ; tl = tide-locked
  • e = orbital eccentricity
  • Type = G:Space/FI classification


A large gas giant with a relatively sparse family of moons, orbiting a dim red star. If there were any other planets within this system, they no longer exist. Of its satellites, only one of the five is habitable, Froin. The remainder are small dead rocks, which hold navigational beacons. Currently, the beacons on Gloin I and II are not functional.

Froin (Mainworld Data)[edit]

  • Mass : 0.43 earth
  • Apparent day length : Tidally locked
  • Axial Tilt : 0.0 degrees
  • Atmospheric pressure : 0.05 atm (very thin)
  • Atmospheric composition : nitrogen 72%, carbon dioxide 26%, others 2%
  • Hydrographics : 50%, polar glaciers
  • Albedo : 0.35
  • Greenhouse effect : N/A
  • Average surface temperature (G:Space) : 195 K (Frozen)
  • Weather factor : N/A (Earth=10, so less stable)
  • Life : no animals, max IQ 0 (no primate/cetacean equivalents);

Other units are as per the World table, above.


Froin is an old rock with a fair amount of metals, mostly radioactive endpoint elements. The core is still warm due to gravitational stretching from its giant neighbor. There is a large icepack around each of the polar regions. 2 large, interlinked craters are evident on the “spinward” side of Froin. The main settlement is located in the smaller crater, Crater Deep; the downport is located in the center of the second crater, Crater Shallow. The downport Crater is approximately 50mi (80km) in diameter and 8mi deep at center. A 2-track pressurized transit system connects the starport/town to the settlement.

A crater impact that carved a semicircular zone into the edge of the southern icepack houses a Imperial Research Area known as Research Station Zeta with its own staff. Crater Zeta is 20 miles across,

History & Background (Dossier)[edit]

Froin was a ball of low grade rock with no resources and nothing to attract major settlement. First discovered by the Darrians in the pre-Maghiz period, who accorded it no importance. it was equally ignored by the Third Imperium during their expansion into District 267 in the 400s

This isolation eventually attracted the Ministry of Science's attention, when it was looking for a world to build the Spinward Marches' Research Station Zeta.


Froin is a small world that runs itself as a democracy; everyone who has spent at least 200 days on the surface over the last standard year who registers to vote at least 10 days before an electoral event is a legal voter.

There is an elected President, Vice-President, a unicameral Board of Laws (32 members) and a Judicial Court of Law. 3 Common Courts handle most cases; appeals and special cases are heard by the Judicial Court. The Vice-President administrates the meetings of the Board of Laws, and may break ties.


Population 600 sophonts

The Shallow Downport and the Shallow Startown make up the bulk of employment and trade opportunities . Employment is offered in all areas of administration, engineering, gravitics, jump-tech, material working, robotics, etc. Lower tech trades are also present: Chandlers, freight workers, warehousing, longshoremen, animal handlers, etc. In addition, several technical and trade schools are present here.

The planetary post office is also present here.

The Settlement in the Crater Deep is focused on mining metal ores, refining them, and transporting them to the starport.

There are advanced communications networks in place with triple redundancy throughout the Craters. Only wireless communications exist with Research Station Zeta; that and a hard overland trek to the security checkpoint.

Froin's primary export are metals, primarily lead, depleted uranium, and bismuth.


Local culture is disjointed, with many disparate sub-cultures based on common origins, species, and interests. Many races have arrived here over the years. Imperial humans are the majority, but Darrians, Sword Worlders, a Vargr pack, and a Mewey trading enclave also make their home here. No known Zhodani live on Froin.

Structures tend to be mostly underground, connected by tunnels or pressurized tubes over the surface. Public transit is commonly available, but dirty and generally in a barely functional state. Family abodes tend to be grouped in Inverts, which are a series of chambers cut into the rock off of a central shaft, in a manner somewhat like an inverted skyscraper of other worlds. Family and sub-cultural structure are strong in the Settlement. Schools are grouped by Invert and Invert-hex.

Sports are a central theme in the overall culture, and fuel stories, politics and occasional riots. Various sports are popular across the sub-cultures, and form a major bonds across otherwise different groups. There are 3 major arenas in the Crater Shallow Startown, and 2 in the Crater Deep Settlement. Smaller gyms and arenas exist.

Education is provided to age of 18, focusing on trade-based education and starship-repair professions. A small university exists in the startown, called Hope University.

Marriage customs vary by subcultural standards, but generally follow Imperium norms. Marriages are generally considered a religious custom, and accompanied by relatively large celebrations. Local government will register any marriage recognized by any clergy, but clergy-recognition is required. Couples are the norm, though some plural marriages exist, including at least one group marriage which is a sub-culture unto its own.

Burial customs also vary by subcultural standards, but are ruled by economics. Simple burial under a meter of frozen soil on the open surface is most common. Other groups excavate catacombs; these can span multiple levels for hundreds of meters. Burial customs typically involve wrapping the deceased with fabric inscribed with messages and adorned with small items.. The deceased is then frozen solid for burial.


But the world underwent a major expansion after the Collapse. While not as important as Iderati or Emape, about twenty percent of all the Mortal Coil's traffic passes through its huge port. Most ships that pass through are low jump independents that are making an interface from the Coil along the lower Spin Main into Plankwell on their way to Collace or Forine. About ninety percent of the population is employed at the starport at this point. The port becomes the fourth largest in Five Sisters, and unsupervised automation became a necessity out of the huge traffic load and the overworked staff.

References & Contributors (Sources)[edit]

This list of sources was used by the Traveller Wiki Editorial Team and individual contributors to compose this article. Copyrighted material is used under license from Far Future Enterprises or by permission of the author. The page history lists all of the contributions.