Prometheus is a titanoid-class world in the Proxima Centauri star system, and the homeworld of the Prometheans. It is a frigid world with a liquid solvent cycle of ammonia-suspended hydrocarbons, which pool in the ancient craters on the surface. Prometheus hosts a thriving biosphere of partially silicon-based organisms, among them a sophont species capable of interstellar spaceflight.

Humans' first manned surface mission to Prometheus was the Arete Mission in 12080-12086 UME, which had no direct successors.


Prometheus is ringed by a pair of low mountain ranges, originating not from tectonic activity -of which there is very little on Prometheus- but ancient impact events. Scattered across the surface are the remains of ancient impact craters, the largest and deepest of which have become the basins of ammonia-hydrocarbon seas. Apart from the unique geographic structure and geological composition of this planet, it possesses a variety of rather typical geographic and biomic features such as plains, pocket forests, tundras, and all the components of a global watershed.

Fauna & Flora

Prometheus is home to the Promethigenid group of organisms, which are primarily characterized by their mixed carbon-silicon biochemical basis and heavy reliance on sound and infrared senses. These include bioluminescent autotrophs, pack-hunting aerial predators, and a single sophont species: the Prometheans.

Prometheus (SHEO-I image)
Prometheus, as seen by SHEO-I.


Location under
Proxima Centauri
Included Organizations
Location 4.25 ly from Sol

Orbital Characteristics

Semi-major axis 0.64 AU
Semi-minor axis 0.60 AU
Orbital period 539.76 days
Rotation period 11.5 hours
Natural satellites 4

Planetary Characteristics

Class small frigid titanoid (TI)
Radius 3512.3 km (0.55 x REarth)
Surface area 1.55e+8 km2
Volume 1.81e+11 km3
Mass 6.34e+23 kg (0.11 x MEarth)
Gravity 3.5 m/s2
Atmospheric pressure 1.4 atm
Atmosphere composition
  • 93% N2
  • 4.5% CH4
  • 2.5% other gases
Average temperature -183.6°C

Biosphere Information

Life Semi-organic multicellular (marine, terrestrial)
Native sophonts Prometheans
Tech level 12
Population 3.4 billion


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