The Expanse: Explaining The Protomolecule

Thomas Jane as Miller in The Expanse

Syfy's interplanetary space adventure The Expanse has been a critical success and showed great improvement in its second season. As such, it's perhaps not surprising that a third season has been commissioned, and with the narrative nicely heating up and reaching into territories of space that both characters and viewers are unfamiliar with, fans can surely expect some answers to the show's many mysteries to be forthcoming.

At the center of the show's enigmatic core is the Protomolecule. This story element has been present since the series premiere and although the cast continue to slowly learn more and more about it, the Protomolecule is still very much an unknown quantity heading into The Expanse's season 2 finale. Plenty of questions remain: where exactly does the Protomolecule come from? What is it capable of? Is it sentient? Season 3 will likely delve deeper into these questions but recent episodes have also revealed plenty of fresh information regarding this bizarre blue substance.

Readers of James S.A. Corey's original book series may already have the jump on what the Protomolecule will herald for Earth and the residents of its galaxy but the TV adaptation won't necessarily stay completely faithful to the source material. Picking through the series' highly involved and often complex narrative, what have we learned about the Protomolecule so far and what may be inferred from this information for the show's future?


Julie Mao before she gets infected on The Expanse

The first appearance of the Protomolecule -- in Earth's galaxy at least -- came on Phoebe Station. Although Thomas Jane's Joe Miller initially theorized that a bio-weapon had been developed on Phoebe, this is only partially true. This Protomolecule was already on Phoebe when humans discovered it and was then taken under the ownership of Earth-born, mega-rich businessman Jules-Pierre Mao. Mao took control of the Protomolecule samples and began to research and develop it -- primarily, it seems, for use as a weapon. He later attempted to transport the Protomolecule on the Anubis ship, although those samples became compromised, leading to the destruction of the entire crew and the infection of Mao's daughter Julie, who was a prisoner on board at the time.

Mao then orchestrated several high-profile experiments to test the extent of the Protomolecule's abilities. The first shown on-screen is the incident at Eros, where his scientific team intentionally unleashed the substance on the station's population and monitored the subsequent effects. The second large-scale demonstration came at Ganymede where a Protomolecule Hybrid (we'll get to those later) was released upon soldiers of both Earth and Mars to devastating results. Although both of these planets have been involved with Mao's Protomolecule development at various stages, the businessman is loyal to neither and seems happy to play them against each other for his own gain.

Mao intends to sell the weaponized Protomolecule to the highest bidder, while the crew of the Rocinante are seeking to destroy it and expose the conspiracy. Crew member Naomi has, however, secretly preserved a sample in space in the hopes of creating a vaccine for those infected.


Protomolecule Hybrid in The Expanse

The Protomolecule's modus operandi seems to be to find human hosts, infect them and then absorb their physical body along with their consciousness. In its raw form, the Protomolecule is considered to be a highly toxic substance and is mostly viral in nature, particularly as a liquid, but it is not an airborne contaminant. Exposure to the material will result in the host showing severe degeneration and as depicted with Julie Mao, slowly dying from something not unlike radiation poisoning. Jules-Pierre Mao can control the spread of the Protomolecule to some degree, as shown on Eros where the Protomolecule was used to methodically infect the entire station.

Apparently, the effect is somewhat different in certain children. On Ganymede Station, experiments were being undertaken exposing youngsters with immune defects to the Protomolecule and with some scientific meddling, the group was able to create part human, part Protomolecule Hybrids that possess superior strength and are able to venture into space without a breathing apparatus. Such a creature was unleashed upon the station itself and single-handedly took out two groups of well-trained marines from both Earth and Mars.

Though both the Eros and Ganymede field tests yielded interesting results, they also proved the Protomolecule to ultimately be uncontrollable. Eros becoming a self-propelled asteroid and the Hybrid nearly sparking a war between Earth and Mars were both unintended consequences that Mao and his scientists never foresaw or intended.

The Protomolecule has thus far shown itself to be quite robust and resistant to many forms of destruction, although complete incineration via fire or missiles seems to do the trick. Crashing into a planet, however, isn't quite as successful, as it was revealed in 'The Weeping Somnambulist' that the location on Venus upon which Eros landed is now crawling with Protomolecule activity, as the element survived both breaking the planet's atmosphere and the resulting crash.

One weakness the Protomolecule does seem to suffer from, however, is a need for power -- most notably electricity -- to fully function. Julie found that nearby electrical appliances strengthened the substance's hold on her and when the Rocinante crew explored the Anubis ship, the Protomolecule only started acting up once they reignited the ship's engines.


Thomas Jane as Miller and Florence Faivre as Julie in The Expanse

Although the Protomolecule is being treated as a 'thing' by the likes of Jules-Pierre Mao, several scenes in The Expanse have heavily suggested that the material is sentient in its own right and this may be at least partially due to its penchant for absorbing humans. The incident on Eros saw the Protomolecule feed on around 100,000 people and this resulted in the substance taking over the entire station and driving it through space. Radio signals from the dead station were also transmitting on various noises and voices -- something Miller heard in person when he explored the infested Eros.

Crucially, the Protomolecule managed to generate a sentient version of Julie Mao who acted as the controller when the station began moving. Miller speculated that the manifestation of Julie meant that when the Protomolecule infests a human being, the human is capable of infesting it in return and imprinting its own personality and desires onto it, suggesting the substance is perhaps designed to be a tool of creation. To this end, the Protomolecule is seen to be constantly evolving and could even be in possession of its own will to survive. Dresden, chief scientist of the Protomolecule project does state, however, that the substance is "evidence" of extraterrestrial life beyond the solar system, rather than life itself.

The Future

Daniel Cash as Dresden in The Expanse

Maybe the foremost question surrounding the Protomolecule is how exactly it found itself on Phoebe Station. "Alien" seems to be a taboo word in The Expanse but the show heavily suggests that the substance was placed on Phoebe by something or someone from another system, rather than originating there naturally. Unquestionably, the series seems to be heading further into more extra-terrestrial territory, and although it remains to be seen whether the Protomolecule was introduced to our universe as a weapon, a gift, or an experiment, contact with new life seems inevitable at some point.

Before The Expanse reaches that stage however, it appears as if the show will dive fully into the creation of the Protomolecule Hybrids. The title of the season 2 finale, 'Caliban's War' refers to Project Caliban -- the code name for the experiment to infect children with low immune systems with Protomolecule -- and the final shot of the penultimate installment saw one of the creatures stowed away with on the protagonists' ship. It was also confirmed by one of the project's scientists that there are multiple Hybrids on the loose, although their allegiance remains unclear at this stage. Whatever happens in The Expanse, you can be sure the Protomolecule will be at the heart of it, as will its mysterious creators.

The Expanse season 2 concludes with 'Caliban's War' April 19 on Syfy.

Next: The Expanse: TV Show Factions Explained

What Happens to Justice League 2 & 3 if WB Releases the Snyder Cut?

More in SR Originals