A comprehensive technical companion to the novel, grounding its speculative elements in peer-reviewed science. This document covers propulsion physics, astrobiology, oceanography, xenobiology, resource economics, distributed intelligence, and the classification problem. Academic tone; accessible to educated lay readers.
The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is a plasma propulsion system invented by former NASA astronaut Franklin Chang-Díaz. The engine ionizes a neutral propellant gas (typically argon or xenon) to form a plasma, heats the plasma to extreme temperatures using ion cyclotron resonance heating (ICRH), and expels it through a magnetic nozzle to generate thrust.
Chang-Díaz, F. R. (2000). “The VASIMR Rocket.” Scientific American, 283(5), 90–97.
Chang-Díaz, F. R., et al. (2004). “The VASIMR Engine: Project Status and Recent Accomplishments.” 42nd AIAA Aerospace Sciences Meeting, AIAA-2004-0149. DOI: 10.2514/6.2004-149
The engine operates in two stages. In the first stage (helicon section), radio-frequency waves ionize the propellant gas. In the second stage (ICRH section), electromagnetic waves at the ion cyclotron frequency transfer energy perpendicular to the magnetic field, heating the plasma to temperatures exceeding 1 million K. The resulting high-temperature plasma is then directed aft through a magnetic nozzle — a diverging magnetic field topology that converts thermal energy to directed kinetic energy.
Longmier, B. W., et al. (2011). “Ambipolar Ion Acceleration in an Expanding Magnetic Nozzle.” Plasma Sources Science and Technology, 20(1), 015007. DOI: 10.1088/0963-0252/20/1/015007
The VX-200SS prototype, tested at Ad Astra’s Texas facility, demonstrated sustained operation at 200 kW input power with specific impulse (Isp) values ranging from approximately 2,000 to 5,000 seconds, depending on the thrust-to-Isp trade-off selected by the operator. At 5,000 seconds Isp, thrust is approximately 6 N — useful for station-keeping and slow orbit transfers, but inadequate for rapid interplanetary transit with crew aboard.
Squire, J. P., et al. (2014). “VASIMR VX-200SS Performance and Power Processing Unit Development.” 50th AIAA Joint Propulsion Conference, AIAA-2014-3531. DOI: 10.2514/6.2014-3531
The specific impulse of a rocket engine, measured in seconds, quantifies propellant efficiency. It relates directly to exhaust velocity via the equation:
$$v_e = I_{sp} \times g_0$$
where $g_0$ = 9.81 m/s². An engine with Isp = 5,000 s produces exhaust velocity of ~49 km/s. The novel’s VASIMR-X at 30,000 s Isp yields ~294 km/s — six times higher.
The Tsiolkovsky rocket equation governs the relationship between exhaust velocity, propellant mass, and achievable velocity change (delta-V):
$$\Delta v = v_e \ln\left(\frac{m_0}{m_f}\right)$$
For a Prometheus-class vessel (dry mass 1,200 tonnes, propellant mass 80 tonnes), the VASIMR-X delivers:
$$\Delta v = 294 \times \ln\left(\frac{1280}{1200}\right) \approx 19.2 \text{ km/s}$$
This is sufficient for a minimum-energy Mars transfer with substantial margin for course corrections. The 47-day transit time follows from continuous low-thrust trajectory optimization, which differs fundamentally from the Hohmann transfer orbits used by chemical rockets.
Stuhlinger, E. (1964). Ion Propulsion for Space Flight. McGraw-Hill. (Classic reference on electric propulsion trajectory mechanics.)
The VASIMR-X’s 40 MW electrical requirement per engine demands a power source far exceeding solar panels at Mars distance and beyond. The novel uses compact deuterium-tritium (D-T) fusion reactors, extrapolated from current research programs.
SPARC and ARC: MIT’s Plasma Science and Fusion Center, in partnership with Commonwealth Fusion Systems, developed the SPARC tokamak — a compact, high-field device using high-temperature superconducting (HTS) magnets made from rare-earth barium copper oxide (REBCO) tape. SPARC was designed to achieve Q > 2 (more fusion power out than heating power in), with the successor ARC reactor intended as a net-electricity-producing power plant.
Creely, A. J., et al. (2020). “Overview of the SPARC Tokamak.” Journal of Plasma Physics, 86(5), 865860502. DOI: 10.1017/S0022377820001257
Whyte, D. G., et al. (2016). “Smaller and Sooner: Exploiting High Magnetic Fields from New Superconducting Technologies for a More Attractive Fusion Energy Development Path.” Journal of Fusion Energy, 35(1), 41–53. DOI: 10.1007/s10894-015-0050-1
ITER: The International Thermonuclear Experimental Reactor, under construction in southern France, represents the conventional large-tokamak approach. ITER aims to produce 500 MW of fusion power from 50 MW of input heating — Q = 10. Its massive scale (23,000-tonne tokamak) illustrates why compact alternatives like SPARC/ARC are essential for space applications.
ITER Organization. (2018). “ITER Research Plan within the Staged Approach.” ITER Technical Report, ITR-18-003.
Bigot, B. (2019). “ITER Assembly Phase: Progress toward First Plasma.” Nuclear Fusion, 59(11), 112001. DOI: 10.1088/1741-4326/ab0f84
The novel’s compact D-T reactors (30–50 tonnes, 100 MW thermal each) represent an extrapolation of the high-field compact tokamak concept. The mass and power density are aggressive but not physically impossible — they require advances in HTS magnet technology, tritium breeding blankets, and first-wall materials that are under active development.
The magnetic nozzle is the critical component linking the fusion plasma source to directed thrust. In a magnetic nozzle, the diverging magnetic field topology converts isotropic thermal energy (random particle motion) into directed axial kinetic energy (exhaust velocity). The physics is analogous to a de Laval nozzle in chemical rockets, but with magnetic fields replacing solid walls.
Ahedo, E., & Merino, M. (2010). “Two-Dimensional Supersonic Plasma Acceleration in a Magnetic Nozzle.” Physics of Plasmas, 17(7), 073501. DOI: 10.1063/1.3442736
Little, J. M., & Choueiri, E. Y. (2013). “Electron Cooling in a Magnetically Expanding Plasma.” Physical Review Letters, 117(22), 225003. DOI: 10.1103/PhysRevLett.117.225003
A key challenge in magnetic nozzle design is plasma detachment — the exhaust plasma must separate from the magnetic field lines at some downstream point, or it will curve back toward the spacecraft. Detachment mechanisms include resistive diffusion, electron demagnetization, and reconnection processes.
Merino, M., & Ahedo, E. (2016). “Magnetic Nozzle Plasma Exhaust Simulation for the VASIMR-like Magnetic Nozzle.” Plasma Sources Science and Technology, 25(4), 045012. DOI: 10.1088/0963-0252/25/4/045012
The novel’s single speculative propulsion element is a superconducting magnetic nozzle that maintains coherent plasma confinement at temperatures exceeding 10 million K — conditions approaching those in the core of the fusion reactor itself.
Current high-temperature superconductors (HTS), including REBCO and bismuth strontium calcium copper oxide (BSCCO), operate at temperatures below roughly 90 K (REBCO) in zero field and must be actively cooled. More critically, they suffer severe degradation under the 14.1 MeV neutron flux from D-T fusion reactions. Neutron irradiation creates defect cascades in the crystal lattice, degrading the critical current density.
Prokopec, R., et al. (2020). “Neutron Irradiation Effects on High-Temperature Superconductor Tapes for Fusion Applications.” Superconductor Science and Technology, 33(4), 044001. DOI: 10.1088/1361-6668/ab6ec4
The novel posits an advance in radiation-resistant superconducting materials — perhaps a nanostructured composite that self-heals lattice damage, or a fundamentally different superconducting mechanism operating at higher temperatures. This is the fiction. The nozzle degradation described in the worldbuilding bible (replacement every 18–24 months) acknowledges that even the fictional advance is imperfect — a deliberate choice to keep the technology feeling constrained and real.
A 100 MW thermal fusion reactor operating at ~40% conversion efficiency produces approximately 60 MW of waste heat per reactor. For a vessel with two reactors, total waste heat is on the order of 120 MW. In the vacuum of space, the only heat rejection mechanism is thermal radiation, governed by the Stefan-Boltzmann law:
$$P = \epsilon \sigma A T^4$$
At a radiator surface temperature of 600°C (873 K), with emissivity ε ≈ 0.9, the radiated power density is approximately 30 kW/m². Rejecting 120 MW therefore requires approximately 4,000 m² of radiator surface — consistent with the novel’s specifications. These radiators dominate the external profile of the vessel, a detail often omitted in science fiction but thermodynamically unavoidable.
Gilmore, D. G. (2002). Spacecraft Thermal Control Handbook: Fundamental Technologies. 2nd ed. AIAA. DOI: 10.2514/4.989117
Chemolithotrophy — the metabolic strategy of deriving energy from inorganic chemical reactions rather than sunlight or organic compounds — is well-established in terrestrial microbiology. Chemolithotrophic organisms oxidize reduced minerals (iron sulfides, hydrogen, ammonia, manganese) and use the released electrons to fix carbon and power cellular processes.
The paradigmatic example for the novel’s lithotrophs is Candidatus Desulforudis audaxviator, a sulfate-reducing bacterium discovered 2.8 km below the Earth’s surface in the Mponeng gold mine, South Africa. This organism forms a single-species ecosystem: it derives energy from the radiolysis of water by uranium decay, fixes nitrogen and carbon from inorganic sources, and has been isolated from the surface biosphere for millions of years.
Chivian, D., et al. (2008). “Environmental Genomics Reveals a Single-Species Ecosystem Deep within Earth.” Science, 322(5899), 275–278. DOI: 10.1126/science.1155495
Li, L., et al. (2006). “Sulfur and Carbon Isotope Geochemistry of the Deep Biosphere of the Witwatersrand Basin, South Africa.” Chemical Geology, 233(3–4), 312–334. DOI: 10.1016/j.chemgeo.2006.03.020
The deep subsurface biosphere on Earth is far more extensive than previously assumed. Magnabosco et al. estimated that subsurface microbial biomass constitutes 2–6% of all living biomass on Earth, distributed through kilometers of rock.
Magnabosco, C., et al. (2018). “The Biomass and Biodiversity of the Continental Subsurface.” Nature Geoscience, 11(10), 707–717. DOI: 10.1038/s41561-018-0221-6
Other relevant chemolithotrophs include iron-oxidizing bacteria such as Acidithiobacillus ferrooxidans, which oxidize ferrous iron and pyrite in acidic mine drainage environments, and Geobacter species, which perform extracellular electron transfer — literally conducting electricity through protein nanowires extending from the cell surface.
Lovley, D. R. (2012). “Electromicrobiology.” Annual Review of Microbiology, 66, 391–409. DOI: 10.1146/annurev-micro-092611-150104
Reguera, G., et al. (2005). “Extracellular Electron Transfer via Microbial Nanowires.” Nature, 435(7045), 1098–1101. DOI: 10.1038/nature03661
Silicon carbide (SiC) is a compound of silicon and carbon occurring naturally as the mineral moissanite. It is extremely hard (9–9.5 on the Mohs scale), chemically stable, and possesses semiconductor properties that make it relevant to both biology and electronics.
SiC grains have been identified in Martian meteorites as presolar grains — interstellar material incorporated into the solar nebula before planet formation.
Moyano-Cambero, C. E., et al. (2017). “Petrographic and Geochemical Evidence for Multiphase Formation of Carbonates in the Martian Orthopyroxenite Allan Hills 84001.” Meteoritics & Planetary Science, 52(6), 1030–1047. DOI: 10.1111/maps.12851
The novel extrapolates from the presence of SiC in Martian materials to envision a biology that uses SiC crystalline lattices as both structural and conductive substrate. While no terrestrial organism uses SiC as a structural material, the concept draws on real silicon biochemistry research. Organosilicon chemistry has been demonstrated in engineered enzymes, and SiC’s semiconductor properties (wide band gap, high thermal conductivity) could theoretically support electrochemical signaling in a mineral matrix.
Kan, S. B. J., et al. (2016). “Directed Evolution of Cytochrome c for Carbon–Silicon Bond Formation: Bringing Silicon to Life.” Science, 354(6315), 1048–1051. DOI: 10.1126/science.aah6219
The presence of liquid water in the Martian subsurface is supported by orbital radar data. The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument aboard ESA’s Mars Express detected bright subsurface radar reflections beneath the south polar layered deposits, interpreted as a body of liquid water approximately 20 km across at a depth of 1.5 km.
Orosei, R., et al. (2018). “Radar Evidence of Subglacial Liquid Water on Mars.” Science, 361(6401), 490–493. DOI: 10.1126/science.aar7268
Subsequent analyses have debated whether the reflections could be explained by alternative materials (certain hydrated clays, metallic minerals), but additional radar detections of multiple bright reflections in the same region have strengthened the liquid water interpretation.
Lauro, S. E., et al. (2021). “Multiple Subglacial Water Bodies below the South Pole of Mars Unveiled by New MARSIS Data.” Nature Astronomy, 5, 63–70. DOI: 10.1038/s41550-020-1200-6
The Shallow Radar (SHARAD) instrument on NASA’s Mars Reconnaissance Orbiter has further mapped extensive subsurface ice deposits at mid-latitudes, confirming that water in various phases is abundant in the Martian subsurface.
Bramson, A. M., et al. (2015). “Widespread Excess Ice in Arcadia Planitia, Mars.” Geophysical Research Letters, 42(16), 6566–6574. DOI: 10.1002/2015GL064844
The novel’s lithotrophs communicate via electrochemical signals propagated through their crystal lattice. This draws on a rapidly growing body of research into bioelectrical signaling in organisms lacking nervous systems.
Plants transmit action potentials and variation potentials through their vascular systems in response to wounding, temperature changes, and light. These signals travel at 1–40 mm/s — comparable to the novel’s 0.1–10 m/s for lithotroph signals — and coordinate systemic physiological responses.
Fromm, J., & Lautner, S. (2007). “Electrical Signals and Their Physiological Significance in Plants.” Plant, Cell & Environment, 30(3), 249–257. DOI: 10.1111/j.1365-3040.2006.01614.x
Bacterial biofilms exhibit coordinated electrical signaling using ion channels, with potassium waves propagating through the biofilm to coordinate metabolic activity across thousands of cells.
Prindle, A., et al. (2015). “Ion Channels Enable Electrical Communication in Bacterial Communities.” Nature, 527(7576), 59–63. DOI: 10.1038/nature15709
More broadly, Levin and colleagues have demonstrated that bioelectrical patterns — voltage gradients across cell membranes — encode morphological information in developing organisms, effectively serving as a “bioelectric code” for pattern formation.
Levin, M. (2014). “Molecular Bioelectricity: How Endogenous Voltage Potentials Control Cell Behavior and Instruct Pattern Regulation In Vivo.” Molecular Biology of the Cell, 25(24), 3835–3850. DOI: 10.1091/mbc.e13-12-0708
The scientific case for a global liquid water ocean beneath Europa’s ice shell rests on multiple independent lines of evidence.
Magnetometry: The Galileo spacecraft’s magnetometer detected an induced magnetic dipole field at Europa, consistent with a globally distributed electrically conducting layer — most plausibly a saltwater ocean — responding to Jupiter’s time-varying magnetic field.
Kivelson, M. G., et al. (2000). “Galileo Magnetometer Measurements: A Stronger Case for a Subsurface Ocean at Europa.” Science, 289(5483), 1340–1343. DOI: 10.1126/science.289.5483.1340
Surface geology: Europa’s surface displays a suite of features — double ridges, cycloidal fractures, chaos regions, and lenticulae — that are best explained by the presence of a subsurface ocean and periodic tidal deformation of the ice shell.
Pappalardo, R. T., et al. (1999). “Does Europa Have a Subsurface Ocean? Evaluation of the Geological Evidence.” Journal of Geophysical Research: Planets, 104(E10), 24015–24055. DOI: 10.1029/1998JE000628
Hubble observations: Water vapor plumes were tentatively detected erupting from Europa’s south polar region, consistent with cryovolcanic activity drawing on a subsurface liquid reservoir.
Roth, L., et al. (2014). “Transient Water Vapor at Europa’s South Pole.” Science, 343(6167), 171–174. DOI: 10.1126/science.1247051
Sparks, W. B., et al. (2016). “Probing for Evidence of Plumes on Europa with HST/STIS.” The Astrophysical Journal, 829(2), 121. DOI: 10.3847/0004-637X/829/2/121
The thickness of Europa’s ice shell is a critical parameter for both scientific models and the novel’s engineering (the Throat must penetrate the full ice column). Estimates range widely depending on methodology.
Conductive ice shell models, which assume heat transport purely by thermal conduction through solid ice, yield thicknesses of 15–30 km. Convective models — in which solid-state convection occurs within the warmer, ductile lower portion of the ice shell — permit thinner conductive lids (perhaps 3–5 km) overlying a thicker convecting layer (10–20 km total).
Billings, S. E., & Kattenhorn, S. A. (2005). “The Great Thickness Debate: Ice Shell Thickness Models for Europa and Comparisons with Estimates Based on Flexure at Ridges.” Icarus, 177(2), 397–412. DOI: 10.1016/j.icarus.2005.03.013
Nimmo, F., & Manga, M. (2009). “Geodynamics of Europa’s Icy Shell.” Europa, University of Arizona Press, 381–404.
The novel adopts a 15–25 km range, consistent with the thinner end of conductive models and the total thickness of convective models. This is a defensible choice that makes the engineering of the Throat extremely challenging but not physically impossible.
Europa’s internal heat — the energy source that maintains its ocean in liquid state — derives primarily from tidal dissipation. Jupiter’s enormous gravitational field, combined with the orbital resonance with Io and Ganymede (the Laplace resonance), forces Europa into a slightly eccentric orbit. The resulting time-varying tidal stresses flex Europa’s interior, converting orbital energy into heat through viscous dissipation.
Hussmann, H., Spohn, T., & Wieczerkowski, K. (2002). “Thermal Equilibrium of the Interior of Europa and Implications for an Ocean.” Icarus, 156(1), 143–151. DOI: 10.1006/icar.2001.6776
Tobie, G., Choblet, G., & Sotin, C. (2003). “Tidally Heated Convection: Constraints on Europa’s Ice Shell Thickness.” Journal of Geophysical Research: Planets, 108(E11), 5124. DOI: 10.1029/2003JE002099
The total tidal heat flux at Europa is estimated at 20–200 mW/m², with most models favoring values around 30–80 mW/m². This is comparable to Earth’s average geothermal heat flux (~90 mW/m²) and sufficient to maintain a liquid ocean and potentially drive hydrothermal circulation at the rocky seafloor.
If Europa possesses a rocky silicate seafloor in contact with liquid water, and if tidal heating extends into the silicate mantle, then hydrothermal circulation is expected. Water percolating through hot rock undergoes serpentinization reactions — the hydration of ultramafic minerals (olivine, pyroxene) — which produce molecular hydrogen, methane, and alkaline fluids.
Vance, S. D., et al. (2016). “Geophysical Investigations of Habitability in Ice-Covered Ocean Worlds.” Journal of Geophysical Research: Planets, 121(8), 1378–1399. DOI: 10.1002/2016JE005081
On Earth, serpentinization-driven hydrothermal systems support chemosynthetic ecosystems at sites such as the Lost City hydrothermal field, where alkaline fluids (pH 9–11) rich in hydrogen and methane sustain microbial communities independently of photosynthesis.
Kelley, D. S., et al. (2005). “A Serpentinite-Hosted Ecosystem: The Lost City Hydrothermal Field.” Science, 307(5714), 1428–1434. DOI: 10.1126/science.1102556
The novel’s Europan ecosystems are modeled on these terrestrial analogs: chemosynthetic primary producers at hydrothermal vents supporting a complex food web culminating in the cephalopoid Europans.
NASA’s Europa Clipper mission, launched in October 2024, is designed to perform detailed reconnaissance of Europa through approximately 50 close flybys. Its instrument suite includes ice-penetrating radar (REASON), a magnetometer, mass spectrometers (MASPEX, SUDA), thermal imaging (E-THEMIS), and high-resolution cameras.
Howell, S. M., & Pappalardo, R. T. (2020). “NASA’s Europa Clipper — A Mission to a Potentially Habitable Ocean World.” Nature Communications, 11, 1311. DOI: 10.1038/s41467-020-15160-9
Phillips, C. B., & Pappalardo, R. T. (2014). “Europa Clipper Mission Concept: Exploring Jupiter’s Ocean Moon.” Eos, Transactions American Geophysical Union, 95(20), 165–167. DOI: 10.1002/2014EO200002
The mission’s objectives include confirming the ocean’s existence and characterizing its salinity, determining ice shell thickness and structure, assessing the potential for current geological activity, and searching for biosignatures in any plume material. The novel’s timeline places KAIC’s operations decades after Clipper’s findings have confirmed the ocean and provided detailed characterization of the ice shell — making Clipper the scientific foundation upon which the colonial enterprise is built.
Europa’s ocean is expected to differ significantly from Earth’s sodium chloride-dominated seas. Spectroscopic observations of Europa’s surface identify magnesium sulfate (MgSO₄) as a dominant salt, along with sulfuric acid hydrate and possibly sodium and potassium chlorides.
McCord, T. B., et al. (1998). “Salts on Europa’s Surface Detected by Galileo’s Near-Infrared Mapping Spectrometer.” Science, 280(5367), 1242–1245. DOI: 10.1126/science.280.5367.1242
Zolotov, M. Y., & Shock, E. L. (2001). “Composition and Stability of Salts on the Surface of Europa and Their Oceanic Origin.” Journal of Geophysical Research: Planets, 106(E12), 32815–32827. DOI: 10.1029/2000JE001413
This MgSO₄-dominant chemistry has implications for ocean pH, density stratification, and biological compatibility. The novel incorporates this detail: the Europans’ biochemistry is adapted to sulfate-rich water, and their hemocyanin-analog oxygen carrier functions in a different ionic environment than terrestrial hemocyanin.
The novel’s Europans are cephalopoid — convergent with terrestrial cephalopods in body plan and cognitive sophistication. This design choice is grounded in the remarkable intelligence demonstrated by octopuses, cuttlefish, and squid on Earth.
Godfrey-Smith, P. (2016). Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness. Farrar, Straus and Giroux.
Octopuses possess approximately 500 million neurons (comparable to a dog), two-thirds of which are distributed in their arms rather than concentrated in a central brain. They exhibit tool use, observational learning, play behavior, individual personality variation, and problem-solving involving multiple sequential steps.
Mather, J. A., & Anderson, R. C. (1999). “Exploration, Play, and Habituation in Octopuses (Octopus dofleini).” Journal of Comparative Psychology, 113(3), 333–338. DOI: 10.1037/0735-7036.113.3.333
Finn, J. K., Tregenza, T., & Norman, M. D. (2009). “Defensive Tool Use in a Coconut-Carrying Octopus.” Current Biology, 19(23), R1069–R1070. DOI: 10.1016/j.cub.2009.10.052
Cephalopod intelligence evolved along a completely independent lineage from vertebrate intelligence. The last common ancestor of cephalopods and vertebrates was a simple bilateral organism in the Cambrian period, over 500 million years ago. This represents the most compelling case of convergent evolution of complex cognition on Earth.
Hochner, B. (2012). “An Embodied View of Octopus Neurobiology.” Current Biology, 22(20), R887–R892. DOI: 10.1016/j.cub.2012.09.001
The concept of convergent evolution — the independent evolution of similar features in unrelated lineages — is a cornerstone of the novel’s biological plausibility. If intelligence evolved independently in cephalopods and vertebrates on Earth (in the same ocean, under the same physics), it is reasonable to hypothesize that similar selection pressures in Europa’s ocean could produce analogous cognitive complexity.
Conway Morris, S. (2003). Life’s Solution: Inevitable Humans in a Lonely Universe. Cambridge University Press.
McGhee, G. R. (2011). Convergent Evolution: Limited Forms Most Beautiful. MIT Press.
The key environmental drivers favoring intelligence in Europa’s ocean mirror those in Earth’s: a three-dimensional fluid medium rewarding spatial reasoning, predator-prey dynamics selecting for behavioral flexibility, and social structures selecting for communication and cooperation.
In the absence of sunlight, bioluminescence becomes the dominant visual channel in the deep ocean. On Earth, approximately 76% of deep-sea organisms produce bioluminescence, used for predation, defense, communication, and mate attraction.
Widder, E. A. (2010). “Bioluminescence in the Ocean: Origins of Biological, Chemical, and Ecological Diversity.” Science, 328(5979), 704–708. DOI: 10.1126/science.1174269
Haddock, S. H. D., Moline, M. A., & Case, J. F. (2010). “Bioluminescence in the Sea.” Annual Review of Marine Science, 2, 443–493. DOI: 10.1146/annurev-marine-120308-081028
The novel’s Europans have evolved bioluminescent chromatophore organs covering their entire mantle surface — an elaboration of the chromatophore system observed in terrestrial cuttlefish and squid. On Earth, cuttlefish (Sepia spp.) can produce complex, rapidly changing color and texture patterns across their skin for camouflage, signaling, and communication.
Hanlon, R. T., & Messenger, J. B. (2018). Cephalopod Behaviour. 2nd ed. Cambridge University Press.
The Europans’ chromatic communication channel — carrying emotional, social, and cultural information through bioluminescent display patterns — extrapolates from documented cephalopod visual signaling on Earth. Male cuttlefish perform elaborate chromatic courtship displays, and some species have been documented displaying different patterns on different sides of their body simultaneously (signaling attraction to a female on one side while displaying aggressive coloration toward rival males on the other).
Brown, C., Garwood, M. P., & Williamson, J. E. (2012). “It Pays to Cheat: Tactical Deception in a Cephalopod Social Signalling System.” Biology Letters, 8(5), 729–732. DOI: 10.1098/rsbl.2012.0435
The novel’s extension — a chromatophore system capable of encoding complex narrative information (oral histories, artistic performance, ritual) — is speculative but follows logically from the observed communication bandwidth of terrestrial cephalopod chromatophore systems, given hundreds of thousands of additional years of evolutionary refinement in a social species.
The Europans’ sonar channel — carrying precise, symbolic, grammatical information via click trains — draws on dolphin and whale echolocation and communication systems.
Au, W. W. L. (1993). The Sonar of Dolphins. Springer-Verlag.
Janik, V. M. (2014). “Cetacean Vocal Learning and Communication.” Current Opinion in Neurobiology, 28, 60–65. DOI: 10.1016/j.conb.2014.06.010
Dolphins produce broadband clicks for echolocation and narrowband tonal signals (whistles) for communication. Sperm whales use patterned click sequences (codas) that vary between social groups and may encode identity and social information. The novel combines echolocation and communication click trains into a single, complex sonar language system.
The novel’s submersibles use magnetohydrodynamic (MHD) drives — a real propulsion technology that accelerates a conducting fluid (such as saltwater) by passing it through crossed electric and magnetic fields. MHD drives have no moving parts, produce minimal acoustic signature, and are ideal for operations in an ocean where sonar-dependent organisms are sensitive to noise.
Lin, T. F., Gilbert, J. B., & Roy, G. D. (1991). “Analyses of Magnetohydrodynamic Propulsion with Seawater for Submarine Vehicles.” Journal of Propulsion and Power, 7(6), 1081–1083. DOI: 10.2514/3.23426
The Japanese experimental vessel Yamato 1 demonstrated seawater MHD propulsion in 1992, achieving speeds of approximately 8 knots. While terrestrial MHD drives are limited by the relatively low conductivity of seawater, Europa’s MgSO₄-enriched ocean may offer higher ionic conductivity, improving MHD efficiency.
Rare-earth elements (REEs) — the lanthanides plus scandium and yttrium — are critical to modern technology. Neodymium magnets power electric vehicle motors and wind turbines. Cerium is essential for catalytic converters and glass polishing. Lanthanum is used in battery electrodes and optical lenses.
On Earth, REE deposits are associated with carbonatite intrusions, ion-adsorption clays (particularly in southern China), and placer deposits. China’s dominance of the global REE supply chain (~60% of production, ~85% of processing) creates strategic vulnerability for other nations.
Haxel, G. B., Hedrick, J. B., & Orris, G. J. (2002). “Rare Earth Elements — Critical Resources for High Technology.” USGS Fact Sheet 087-02. U.S. Geological Survey.
Humphries, M. (2013). “Rare Earth Elements: The Global Supply Chain.” Congressional Research Service Report R41347.
Mars’s basaltic volcanic composition, extensive weathering history, and impact-basin geology (particularly Hellas Planitia) provide plausible mechanisms for REE concentration. Basaltic magmatism can concentrate incompatible elements (including REEs) in residual melts, and impact events can redistribute and concentrate mineral deposits.
Platinum-group metals (PGMs — platinum, palladium, rhodium, iridium, osmium, ruthenium) are among the rarest elements in Earth’s crust and are concentrated primarily in layered mafic-ultramafic intrusions (such as South Africa’s Bushveld Complex) and in placer deposits.
Hydrothermal systems can mobilize and concentrate PGMs through chloride and bisulfide complexation in hot, reducing fluids. On Earth, elevated PGM concentrations have been documented in active and fossil hydrothermal systems.
Pašava, J. (1993). “Anoxic Sediments — An Important Environment for PGE: An Overview.” Ore Geology Reviews, 8(5), 425–445. DOI: 10.1016/0169-1368(93)90037-Y
Holwell, D. A., & McDonald, I. (2010). “A Review of the Behaviour of Platinum Group Elements within Natural Magmatic Sulfide Ore Systems.” Platinum Metals Review, 54(1), 26–36. DOI: 10.1595/147106709X480913
The novel’s premise — that Europa’s hydrothermal systems have concentrated PGMs in seafloor sediments at levels far exceeding terrestrial deposits — is plausible given the long duration of hydrothermal activity (potentially billions of years), the lack of biological scavenging until Europan life evolved, and the enrichment of the primordial rocky mantle in siderophile elements.
The economic viability of extraterrestrial resource extraction has been the subject of serious academic and commercial analysis. Studies by Sonter and later by Andrews et al. developed frameworks for evaluating asteroid mining economics, considering launch costs, transit times, extraction efficiency, and return-on-investment timescales.
Sonter, M. J. (1997). “The Technical and Economic Feasibility of Mining the Near-Earth Asteroids.” Acta Astronautica, 41(4–10), 637–647. DOI: 10.1016/S0094-5765(98)00087-3
Andrews, D. G., et al. (2015). “Defining a Successful Commercial Asteroid Mining Program.” Acta Astronautica, 108, 106–118. DOI: 10.1016/j.actaastro.2014.10.034
The novel’s economics acknowledge that interplanetary mining is marginally viable even with fusion-powered transport. The critical factor is that VASIMR-X propulsion reduces transportation costs by orders of magnitude compared to chemical rockets, while terrestrial resource depletion and geopolitical supply-chain risks inflate the value of extraterrestrial sources. This is consistent with economic analyses showing that space mining becomes competitive when launch costs fall below approximately $1,000/kg to LEO and when terrestrial supply constraints raise commodity prices.
The novel’s lithotroph intelligence — a distributed network with no central brain that nonetheless exhibits cognitive behavior — draws heavily on research into Physarum polycephalum, a slime mold that solves computational problems without neurons.
In the landmark experiment by Nakagaki et al., Physarum was placed in a maze with food sources at two points. The slime mold explored the maze, then progressively retracted its tendrils until only the shortest path between food sources remained — effectively solving the maze.
Nakagaki, T., Yamada, H., & Tóth, Á. (2000). “Maze-Solving by an Amoeboid Organism.” Nature, 407(6803), 470. DOI: 10.1038/35035159
Subsequent studies demonstrated that Physarum could replicate the topology of the Tokyo rail network when food sources were placed at positions corresponding to major cities, and that it could find near-optimal solutions to the traveling salesman problem.
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Mycorrhizal fungal networks — the “Wood Wide Web” — connect trees in forests through underground hyphal networks, facilitating the transfer of carbon, nitrogen, phosphorus, water, and signaling molecules between individuals.
Simard, S. W., Perry, D. A., Jones, M. D., Myrold, D. D., Durall, D. M., & Molina, R. (1997). “Net Transfer of Carbon between Ectomycorrhizal Tree Species in the Field.” Nature, 388(6642), 579–582. DOI: 10.1038/41557
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The fungal network functions as a distributed resource-allocation system. Hub trees (“mother trees”) connected to many partners can preferentially route resources to kin seedlings, and chemical alarm signals transmitted through the network can trigger defensive responses in neighboring trees that have not yet been attacked.
Babikova, Z., et al. (2013). “Underground Signals Carried through Common Mycelial Networks Warn Neighbouring Plants of Aphid Attack.” Ecology Letters, 16(7), 835–843. DOI: 10.1111/ele.12115
The synthesis of these phenomena — chemolithotrophic metabolism, crystalline conductive substrates, distributed computation, and bioelectrical signaling — forms the scientific foundation for the novel’s lithotrophs.
The concept of non-neural intelligence has gained traction in theoretical biology. Baluška and Levin have argued that intelligence is not a property of neurons per se, but of any system capable of processing information, storing memory, and adapting behavior — criteria that cellular networks, biofilms, and even chemical systems can satisfy in principle.
Baluška, F., & Levin, M. (2016). “On Having No Head: Cognition throughout Biological Systems.” Frontiers in Psychology, 7, 902. DOI: 10.3389/fpsyg.2016.00902
Lyon, P. (2015). “The Cognitive Cell: Bacterial Behavior Reconsidered.” Frontiers in Microbiology, 6, 264. DOI: 10.3389/fmicb.2015.00264
The lithotrophs represent an extreme extrapolation of this principle: a mineral-biological network that has accumulated computational complexity over geological timescales. The novel’s estimate of ~10¹⁴ operations per second (comparable to a mammalian brain) distributed across hundreds of kilometers is speculative but dimensionally consistent with the information-processing capacity of large-scale biological networks.
There is no universally accepted scientific definition of life. NASA’s working definition — “a self-sustaining chemical system capable of Darwinian evolution” — is widely used in astrobiology but has known limitations. It excludes individual organisms (which do not evolve), mules and other sterile hybrids, and potentially artificial life systems. It may also include self-replicating chemical systems that most biologists would not consider alive.
Joyce, G. F. (1994). “Foreword.” Origins of Life and Evolution of the Biosphere, 24(5), xi–xii. (Source of the NASA working definition.)
Benner, S. A. (2010). “Defining Life.” Astrobiology, 10(10), 1021–1030. DOI: 10.1089/ast.2010.0524
Cleland, C. E., & Chyba, C. F. (2002). “Defining ‘Life’.” Origins of Life and Evolution of the Biosphere, 32(4), 387–393. DOI: 10.1023/A:1020503324273
The novel exploits this definitional ambiguity. The lithotroph network does not reproduce in the conventional sense (individual filaments grow, but the network as a whole does not divide or produce offspring). Whether it satisfies “Darwinian evolution” depends on whether the network’s adaptive responses to environmental change qualify as evolution or merely as phenotypic plasticity. The classification committee’s decision to categorize the lithotrophs as geological formations rather than life forms exploits a genuine gap in biological ontology.
The question of sentience — subjective experience, or “what it is like” to be a particular organism — is even more fraught. The philosophical “hard problem of consciousness” (Chalmers, 1995) remains unresolved, and no empirical test can definitively establish or rule out sentience in a non-communicative system.
Chalmers, D. J. (1995). “Facing Up to the Problem of Consciousness.” Journal of Consciousness Studies, 2(3), 200–219.
In practice, sentience is inferred from behavioral indicators: flexible problem-solving, learning, communication complexity, self-recognition, and apparent emotional states. The Cambridge Declaration on Consciousness (2012) affirmed that non-human animals, including mammals, birds, and cephalopods, possess the neurological substrates that generate consciousness — but this declaration relied on neuroanatomical analogy to human brains, a criterion that categorically excludes organisms with non-neural information processing.
Low, P., et al. (2012). “The Cambridge Declaration on Consciousness.” Francis Crick Memorial Conference, Cambridge, UK.
The novel’s lithotrophs present the hardest case: a system that exhibits behavioral indicators of intelligence (symbolic representation, novel problem-solving, coordinated adaptive responses) but lacks any neuroanatomical analog. Mark’s argument for their sentience relies on functional criteria (what the system does), while the classification committee relies on structural criteria (what the system is made of). Both approaches have legitimate scientific support. The committee’s structural argument mirrors the historical tendency to deny intelligence to organisms that do not resemble the observer.
The novel’s legal mechanism — the UN Deep Space Resources Compact, which grants exploitation rights to the entity that classifies an alien world as “non-inhabited” — deliberately parallels the Doctrine of Discovery, the legal framework that European colonial powers used to claim sovereignty over territories occupied by indigenous peoples.
The Doctrine originated in a series of 15th-century papal bulls (particularly Inter Caetera, 1493) and was codified in international law through cases such as Johnson v. M’Intosh (1823), in which the U.S. Supreme Court held that indigenous peoples had rights of occupancy but not sovereignty, because European “discovery” conferred superior title.
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The critical parallel is structural: in both the historical Doctrine of Discovery and the novel’s DSRC, the entity doing the claiming also controls the classification of the inhabitants. The question “are these beings persons?” is answered by the people who benefit from the answer being “no.” The novel does not allegorize — it transposes the identical legal mechanism to a new context and examines whether the outcome differs when the “inhabitants” are genuinely non-humanoid.
The novel’s DSRC Article 7 creates a binary classification system: sentient (Category A, protected) or non-sentient (Category B, exploitable). This mirrors real challenges in animal welfare law, environmental law, and emerging discussions about AI rights.
The European Union’s Treaty of Lisbon (2007) recognizes animals as “sentient beings” and requires member states to “pay full regard to the welfare requirements of animals” — but provides no mechanism for determining which animals qualify and which do not. In practice, the line is drawn by taxonomic fiat (vertebrates are generally protected; invertebrates, with the recent exception of cephalopods in UK law, generally are not).
Birch, J. (2017). “Animal Sentience and the Precautionary Principle.” Animal Sentience, 2(16), 1. DOI: 10.51291/2377-7478.1200
The Animal Welfare (Sentience) Act 2022 (UK) extended sentience protections to decapod crustaceans and cephalopods, based on a systematic review of behavioral and neurophysiological evidence. The review’s methodology — assessing indicators such as nociception, learning, anxiety-like behavior, and play — represents the most rigorous attempt to date at empirical sentience evaluation.
Birch, J., et al. (2021). “Review of the Evidence of Sentience in Cephalopod Molluscs and Decapod Crustaceans.” LSE Consulting Report for the UK Government.
The novel’s classification committee could have applied similar criteria to the lithotrophs and Europans. That they did not — that they chose structural over functional criteria — is the moral crux of the story.
The scientific content of A Conquest of Two Worlds can be divided into three categories:
Established science: Europa’s subsurface ocean, tidal heating, hydrothermal vent ecosystems, chemolithotrophy, cephalopod intelligence, bioluminescence, distributed biological computation, MHD propulsion, VASIMR technology, rare-earth and platinum-group metal geology, and the definitional problems surrounding life and sentience.
Plausible extrapolation: Compact fusion reactors at the power density required for spacecraft, silicon carbide as a biological substrate on Mars, the concentration levels of PGMs in Europan hydrothermal systems, the economic viability of interplanetary mining, and the cognitive capacity of a large-scale distributed mineral-biological network.
Fiction: The superconducting magnetic nozzle operating at fusion temperatures (the single speculative technological leap), the existence of the lithotroph and Europan civilizations themselves (consistent with known science but not predicted by it), and the specific cultural, social, and technological characteristics of those civilizations.
The novel’s scientific fidelity serves its thematic purpose. The story argues that the exploitation of alien life is not a failure of technology or knowledge but a failure of classification — a deliberate choice to define the Other as less than a person. By grounding every element except one in real, peer-reviewed science, the novel denies its readers the comfort of distance. This is not a fantasy about impossible aliens in an impossible universe. It is a thought experiment about real physics, real biology, real economics, and real legal history — applied to organisms that are fictional only in the narrow sense that we have not yet discovered them.
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