A planet with a reclusive cybercosm in the Tiwa system.


Sonthaya (Ross 128 b)- Data Panel

Parent starStar: Tiwa (Ross 128)
Spectral type: M4V (Red dwarf)
Mass: 3.341E29 kg (0.168 x Sol)
Radius: 136844 km (0.197 x Sol)
Luminosity: 0.00362 x Sol (bolometric)
Temperature: 3192 Kelvin
Age: 9.45 billion years
Distance from Sol: 9.8 ly (Current Era)
PlanetSonthaya in the Current Era
Orbital characteristics:
- Semi-major axis: 7,420,000 km (0.050 AU)
- Period: 9.866 days
- Eccentricity: 0.036
- Inclination: 0.2°
Physical characteristics:
- Type: Vesperian Hephaestian.
- Mass: 8.062E24 kg
- Radius: 6,928.7 km
- Density: 5,787 kg/m^3
- Gravitational acceleration: 11.209 m/s2 (1.143 g)
- Rotation period: Tidally-locked
- Albedo: 0.27
- Average surface temperature: 283 K
- Surface pressure: 1.1 kPa
- Composition: 95% CO2, 3% CO, 1% Ar, 1% other
Satellites: none
Other Worlds in this systemArun, Titanian (Diameter 4910km): Rattikan, LithicGelidian, 2008km
Population DemographicsPopulation: The cybercosm's population is estimated to be in the hundreds of billions, dwarfing the surface population.
Population breakdown (surface):
S0: 680,000
Sophont AIs: 410,000
- Vecs: 330,000
- Uploads: 50,000
- Aioids: 30,000
- Others: 700
Bionts: 270,000
- Tweaks: 130,000
- Neogens: 110,000
- Others: 30,000
S1: 1 (Garuda)


Sonthaya is a planet in the Ross 128 system, also known as the Tiwa system. It is a tidally-locked Hephaestian world slightly larger than Earth. This volcano-ridden temperate terrestrial planet was never terraformed. Instead, it was gradually transformed into a full-fledged botworld, divided into zones by various different mechanomes.

Sonthaya was the destination of a Southeast Asian colony mission that was launched in 502 AT. When they arrived in 617 AT, the colonists found that this inhospitable world was already partly covered by a range of diverse mechosystems, built by autonomous probes and von Neumann systems which had arrived in the decades before the crewed craft. A beamrider ship, the Karl Schroeder, arrived in 642 AT and established a colony in the local Kuiper Belt, eventually establishing a functioning cycler route a few centuries later.

Because of its geologically active status and the semi-feral mechosystems, the planet was seen as a poor target for terraformation. Most of the newly-arrived colonists chose to upload their mindstates and live in isolated virtual worlds instead. These virtual worlds were gradually integrated into the evolving mechosystems, becoming increasingly complex and exotic as time passed. A number of colonists who declined to upload themselves left the system in 1185 AT, aboard the colony ship Mingkwan, which reached Gliese 783 in 1317 AT to found the conservative world of Lok Mai.

The large colony ship Utnapishtim-6 that reached Ross-128 in 1220 AT was a speculative venture of the Star Pilgrim Corporation, which sent colonizing missions to many systems during the Early Federation period.

Most of this new wave of colonists opted to inhabit the small, colder outer worlds of Arun and Rattikan, or build space habitats to their own custom designs. A small number of colonists employed genetic engineering to adapt to the hazardous environment of Sonthaya, becoming radically tweaked or completely neogenic bionts.

During this period, Ross-128 became a member of the Eridanus League, joining just as the League was becoming increasingly disunited.

Sonthayan Mechosystem
Image from ATMLVE
A wire-tree in the Golden Mechosystem on Sonthaya, one of the most hazardous of the local mechanomes.

Due to subjective long-term isolation, the reclusive Sonthayan cybercosm cultures have become estranged from mainstream Terragen society while most of the vecs and genetically-modified bionts who inhabit the surface have adopted Lo Tek lifestyles. As a result, few newcomers choose to settle here in favor of the other worlds and habitats in the system.

The planet's mechosystem balance is maintained by an S1 animin, known as Garuda by the locals, although the entity does not use this name itself, or indeed any name at all.
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Development Notes
Text by The Astronomer
additional material by Steve Bowers
Initially published on 08 August 2019.