The protomolecule is an infectious agent of extra-terrestrial origin first discovered on Phoebe by the Martian Congressional Republic in 0 XTE. It has the ability to radically alter infected life forms and utilize their biomass in various ways.

Not a life-form in itself, the protomolecule is described by Antony Dresden as "a set of free-floating instructions designed to adapt to and guide other replicating systems". It is able to maintain its primary structure in a wide variety of conditions, and it has an affinity for carbon and silicon structures, but is likely anaerobic and will not degrade upon exposure to oxygen.[Citation needed] It can use ionizing radiation as an energy source, and its growth can speed up considerably if exposed to high doses.

Extrasolar origins Edit

It was initially believed by Protogen's scientists that Phoebe was intended as a weapon. The Investigator informs James Holden, however, that it functions as an advanced terraforming platform. It was created by extra-terrestrials around two billion years in the past, and launched in a Bracewell probe at a trajectory towards the Earth, which had only developed primitive life at the time. It was, however, captured by Saturn's gravity, where it became a satellite, and settled there as one of its moons.

At some point between its launch and the present day, the civilization that launched the protomolecule was attacked and seemingly destroyed by an as-yet-unidentified aggressor.

Humanity discovers the ProtomoleculeEdit

Protogen's ExperimentsEdit

Main article: Discovery on Phoebe

In 0 XTEMars landed on the ice moon Phoebe to survey it for ice mining. When core samples from the moon were investigated, however, silicate samples were found, and the Martian government approached Protogen as a cosponsor of a long-term research facility. Protogen discovered the alien agent, dubbed it the protomolecule, and began experimenting with it. Protogen killed off all other members of the Station on Phoebe to hide their discovery. The samples of the Protomolecule were placed in a safe onboard the Anubis to be taken to another location. On the way the Anubis would board the Scopuli and take prisoners to infect. This would get out of control however, when the entire crew and prisoners became infected by protomolecule. Only Julie Mao would survive taking a shuttle Anubis 1A to Eros. Julie however had also been infected and died from the protomolecule in a hotel on Eros. Protogen would find her body and retrieve the sample.

On ErosEdit

Main article: Protogen experiment on Eros

Having found the lost sample of the Protomolecule in the body of Julie Mao, Protogen was able to use it to infect the population of Eros as a controlled experiment to study. This was to see how the protomolecule would behave on a large scale with Eros having a population of 100,000. Upon the infection beginning signals were sent to Thoth Station where it was studied.

Osiris Station experimentsEdit

The Osiris Station was a sister facility along with Thoth Station where smaller protomolecule research was done[1].

Project CalibanEdit

Closeup of HPH in Roci cargo bay-enhanced


Main article: Project Caliban

Project Caliban was a Protogen experiment to use the Protomolecule to create a human-protomolecule Hybrids for use as supersoldier weapons. The Ganymede incident took place eighteen months after the Eros Incident in 11XTE[2]. This was the first weapons test of the Hybrids, and the programe continued until the end of Io Campaign when the project was ended and Protogen was seized and shut down.

Eros incident Edit

Main article: Eros Incident

In 9 XTE, the first major outbreak of the protomolecule, known as the Eros incident, took place. It was a controlled infection of the entire population of Eros, numbering one and a half million humans. With this amount of biomass, it was revealed that the protomolecule had the ability to create a hive mind of sorts, which integrated itself with the computer systems of Eros station.

Activity on Venus Edit

Following the descent of Eros Station to the surface of Venus in 9 XTE, the protomolecule began rapidly reshaping the planet. Observers throughout the Sol system observed these changes with great interest, but, despite the wealth of data, the objectives of the alien organism remained obscure.

The military science vessel Arboghast was tasked with observing Venus from orbit and relaying instrumental data to the UN. Eight months into her mission, the Arboghast received or emitted a brief radiation pulse of unknown nature and origin that interfered with all observing telescopes in the non-visible spectrum. Immediately following this, the entire vessel was disassembled into its structural components, down to the level of screws and bolts, methodically and with no discernible mechanism of action. The crew of 572 personnel were lost to vacuum exposure.

On Venus and beyond, the protomolecule hive mind displayed an ability for instantaneous communication, with events involving the substance anywhere in the system (mainly the activation or destruction of human-protomolecule hybrids) triggering a response from Venus' surface.

Ring Edit


the Sol gate is complete

In 12 XTE, the protomolecule launched a massive complex of structures just outside the orbit of Uranus and built a thousand-kilometer-wide object known as the Ring. This is the final stage of the protomolecule life cycle: to convert itself into a wormhole leading to the slow zone and Ring station.

The Stolen samplesEdit

Following the attack by the Free Navy on Tycho Station, the last known sample of the protomolecule is believed to be in the hands of the Free Navy. However, after the Free Navy Conflict, the whereabouts of the sample are unknown. In actuality the samples had been stolen by the Laconian Empire and taken to Laconia.

The Laconian system was kept secluded from the rest of the Interstellar human community over the next thirty years and using these new Protomolecule samples along with the discovered Ring Builder Empire shipyard Laconia Station developed new technologies.

The Protomolecule's life cycle Edit

Infection Edit

The protomolecule can infect other life forms on contact (it is anaerobic, and cannot be transmitted through the air).[Citation needed] While supposedly designed for use on simple, single-celled organisms, it is effective on multi-cellular life as well. In humans, it spreads internally and starts altering its host through a process that may take several weeks, during which the host hibernates, but which can be significantly sped up via exposure to ionizing radiation.

Spread Edit

After awakening from hibernation, the host becomes disoriented and feverish, with symptoms similar to a hemorrhagic fever. Shortly after, a brown fluid begins leaking out of its orifices. Human hosts at this stage are nicknamed "vomit zombies" because of their tendency to stagger around, spewing the brown fluid, which is highly infectious to other creatures.

Alteration Edit

The protomolecule will eventually begin to alter its host in a variety of ways, most frequently melding the biomass of multiple hosts and repurposing specific organs to carry out new functions.[Citation needed] Changes beyond this point seem to be highly variable and unpredictable, but recognizable features that might be incorporated in the resulting structures are black filaments, brown slime and blue luminescence.

Hive mind Edit

The protomolecule's original construction appears tuned for simple unicellular life, though able to operate with a wide variety of hosts including advanced, intelligent multi-cellular organisms. Given enough biomass from several intelligent hosts, the protomolecule is able to create a hive mind. In the only known instance of this occurring, an initial victim (Julie Mao) was used as a "seed" or template for the nascent consciousness, which then guided the utilization of all subsequent biomass.

It is unclear whether normal functioning with an active connection to its creators would result in a host gaining some measure of control over the development and behavior of the resulting structures as Julie did.

Media Edit

Eros infection
  • infected Eros
  • infected Eros
  • infected Eros
  • The Protomolecule rises from Venus

For TV viewers

External links Edit

For TV viewers


  1. The Expanse Novella: The Vital Abyss
  2. The Expanse Novel: Caliban's War, chapter 1: Bobbie
    Eighteen months before, there hadn't been sides.… Then Eros,…
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