The Geology Of Star Wars

Geology is strong in the successful Star Wars franchise, be it in the movies or behind the scenes.

Spectacular landscapes, like salt-plains in the Andes, an active volcano in Sicily, the dolo- and limestone peaks of the Dolomites, and the sand dunes of Tunisia act as a background for the struggles of our heroes against the dark side.

The famous lightsaber battle on Mustafar in the 2005 film Star Wars Episode III: Revenge of the Sith, was done by combining computer graphics with real footage of Mount Etna. The crew was filming in 2002 in Italy when just by chance Mount Etna erupted with spectacular lava fountains and flows, so they decided to film there.

In the movie, the fictional planet Mustafar displays a landscape covered entirely in dark rocks, igneous in origin as the many active lava flows and eruptions suggest. Likely the early Earth – some 4,5 billion years ago – was pretty much a lava planet, with a thin crust of basalt covering a fiery ocean of molten magma. Only later, when plate tectonics and erosion by water started, other rocks formed. Planets like Mars and Venus are still today covered mostly by basalt, even if it is not clear if there are active volcanoes to be found.

One of the most recent episodes of Star Wars, The Last Jedi (2017), features some spectacular landscapes, like the Salar de Uyuni, a dry salt-plain located in the Andes. In the movie, Crait is a small planet covered entirely with salty minerals. During a battle scene, it is shown that beneath the white crust of salt lays a red mineral. Halite, the mineralogical name for salt (NaCl), can become dark red/brown when exposed to radioactive radiation. Sylvite, a potassium chloride (KCl), has a reddish color that can become purple if exposed to radiation, but it is a rare mineral on Earth. Later our heroes escape through a cave filled with gigantic red crystals, likely crystallized over millions of years.

In the 2018 spin-off movie Solo: A Star Wars Story, scenes of a train heist on the planet Vandor-1 were filmed in the Dolomites, near the peaks of the Tofane, the Langkofel, Sella Pass and the Drei Zinnen. The base of those mountains are composed of the Cassian-Dolomit, the dolostone cores of former Triassic reefs. The relative plain summits – as seen in some scenes – are formed by erodible marl deposits of the Heiligkreuz- and Travenanzes-Formation, and the plane-bedded Hauptdolomit-Formation.

The fictional desert city of Mos Espa, the hometown of Anakin Skywalker, was built in 1997 for the movie Star Wars Episode I: The Phantom Menace and then abandoned in the Tunisian desert. Over the years it has become a tourist attraction. The dry climate preserves the buildings very well and the only menace for the site comes from the slowly moving barchan dunes, up to 6 meter high windblown accumulations of sand and gypsum grains. The set of Mos Espa, consisting of twenty buildings made of wood and plaster, was built on a flat, clay-rich pan and the city later expanded digitally in size, with dunes only barely visible in the background of some scenes.

However the prevailing wind, blowing from east to west, constantly moves the sand. The dunes are migrating with the wind eastwards, just in the direction of the remains of the abandoned site. Using the buildings as a fixed reference point in a quite featureless landscape, and comparing a series of satellite images from 2002 to 2009 and pictures taken by Star Wars fans over the years, researchers were able to calculate the migration rate of three larger dunes. With 4,8 to 15 meter per year, the dunes move with an average speed. The study notes that the dune located nearest to the film set slowed down in recent years, possibly influenced by changes in the wind pattern caused by the encountered obstacles. Even so, Mos Espa will be buried completely in estimated 80 years by the sand. The slow destruction of his home may also explain why Darth “Anakin” Vader doesn’t really like sand (as revealed in the 2002 film Star Wars Episode II: Attack of the Clones).

Geology, sort of, was also involved behind the scenes of Star Wars. Forty years ago the Death Star was blown up by the rebels in the 1977 sequel Star Wars: A New Hope. The computer animation for the simulated attack on the Moon-sized battle station was done using computers of the University of Illinois. At the time only a few computers were powerful enough to calculate the vector graphics as shown in the scene. Geologist Christopher Scotese had to share his spare computer time, used for simulations of how plate tectonics shapes Earth, with the special effects artists at work.

The Geology Of Jules Verne’s Journey To The Center of the Earth

Figure from the novel “Journey to the Center of the Earth” published by Jules Verne in 1864.

“Well gentlemen, at one point at least I agree … the materials of the geologists are not charts, chalk and chatter, but the earth itself. We should never know the truth until we are able to make that journey and see for ourselves.” 

from “Where Time Began,” a 1976 film based on Jules Verne’s novel Journey to the Center of the Earth.

Novelist Jules Verne was born on February 8, 1828, in the French city of Nantes. Today he is known as a pioneer of the science-fiction genre, imagining a submarine traveling twenty thousand leagues under the sea, a space projectile heading to the moon and a fantastic journey into the depths of our world. One hundred and fifty years after Verne’s visions, humans have walked on the moon, nuclear submarines can travel under the sea and we have started to explore the mysteries of the deep earth.

Journey to the Center of the Earth was published in 1864 and was immediately a critical success, and has remained in publication in both French and English to this day. In the opening chapters of the novel, the German Professor Otto Lidenbrock and his nephew Axel discover an ancient document, written by Snorri Sturluson. This (fictional) 16th-century alchemist described a journey into a large system of volcanic conduits, accessible from the crater of the Icelandic volcano Snæfellsjökull. So Lindenbrock and his nephew traveled to Iceland, employed a local guide, and following the document’s coded directions, entered the volcanic crater.

There, they descended through the sedimentary layers of the crust into its foundation. About 140 kilometers beneath the surface they discovered an underground sea occupying a cavern, roughly the size of Europe, hollowed in the granite of the lower crust. The travelers ventured upon the “Lidenbrock Sea”, as they name the newly discovered ocean, in a raft built out of the logs of “great palm-trees of species no longer existing” growing along the shores.

At sea, they witnessed a battle between Jurassic sea monsters and disembarked on an island with a geyser. Venturing inland they discovered living mastodons and primitive hominids. Verne’s bestseller was a product of rich imagination and research. He likely based his fictional travel account on the works of geologists like Alcide d’Orbigny, who classified rock strata by their fossil content, Elie de Beaumont, who worked on the origin of mountain ranges, and Charles Sainte-Claire Deville, who studied volcanoes.

Geological section, published by German geophysicist August Sieberg in 1914, showing the anatomy of a stratovolcano, with a main conduit, various lateral dikes and a large sill connected to the magma reservoir. In contrast to the sketch, the conduits for magma are in reality only a few meters wide.

An important source of inspiration to Verne were the books by the French scientist and writer Louis Figuier. In 1864 Figuier published La Terre avant le déluge, a popular science book discussing geology and paleontology. From Verne’s surviving correspondence with his publisher, we know that he started to work on his novel sometimes between January to August 1864. Some passages and scenes in Verne’s novel, like the battle between an ichthyosaur and a plesiosaur witnessed by the travelers, was likely inspired by an illustration in Figuier’s book. Verne’s imaginary forest growing along the “Lidenbrock Sea” was similar to the fossil forests of the Carboniferous period. The heat necessary to keep the forest alive comes from “the excessive heat of the globe. The Earth was still so hot in itself that its innate temperature dominated” as Figuier writes in his textbook. Before the discovery of radioactive decay, geologists believed that earth’s inner heat was the residual heat of its formation from a molten ball. Over time earth cooled down and a solid crust formed.

Verne’s explorers used the hollow volcanic conduit of Snæfellsjökull as a gateway to earth’s interior. Many geologists at the time believed that volcanic conduits, empty once the volcano erupted, connected a volcanic crater to magma chambers deep underground. Today we know that such conduits are far too small (and obstructed by solid rock) for humans to move through.

However, Verne was right when he described a chamber full of gigantic crystals found deep underground. For crystals to grow, they need the right conditions and a lot of time. In theory, there are no limits to how large a crystal can become, however, perfect conditions for crystal growth are rarely met. That said, such perfect conditions are found in the Cueva de los Cristales, located in the Naica Mine, Chihuahua, Mexico.

The mine of Naica was opened in 1828 to mine for lead, zinc and silver ore. In 1910 a natural cave was discovered, named later Cueva de las Espadas. The name derives from the three-foot long blade-like gypsum (calcium-sulfate) crystals covering the walls of the cave. However, what the miners discovered almost 90 years later, during the construction of a tunnel 0.2 mile below ground, is even more astounding. The Cueva de los Cristales hosts the most incredible crystals ever discovered, mirroring Verne’s fantastic description. Almost perfect conditions made it possible to grow gypsum crystals more than 10-meters in length and with an estimated weight of 40 to 50 tons.

The enormous gypsum crystals of Naica. Note person at bottom right for scale. Credit: Wikipedia/Alexander Van Driessche. CC BY 3.0. Van Driessche

Maybe Verne was right in even a more spectacular way. The largest crystal possible on earth could be indeed found at its center. Earth’s core is a solid ball of superhot iron and nickel alloy about 760 miles in diameter. Modern research suggests that it displays a crystalline structure. Unfortunately, at the moment, there is no way to be sure and visit this place as Verne imagined.

Geological Star Trek Review – “Arena”

Captain Kirk fights a Gorn in the 1967 TOS episode “Arena” – you can see Vasquez Rocks in the background.

Sulfur, niter (saltpeter) and carbon, as coal and as crystalline diamond, save Captain Kirk’s life in the 1967 TOS episode “Arena.”

When a remote outpost of the Federation is attacked by an unknown enemy, the Enterprise pursues the fleeing vessel, inadvertently entering a sector of space controlled by the Metrons, a race with powerful psychic powers. Kirk, transported by the Metrons to a desolate planetoid, is forced into a battle against the captain of the Gorn ship – a reptile-like creature protected by an almost indestructible armored skin.

The planetoid displays a rich geologic diversity. Kirk mentions finding ruby corundum. He uses niter (saltpeter), sulfur, and coal he finds to make gunpowder for use in a primitive cannon, and diamonds as projectiles (here – judging from the crystal shape – likely quartz was used as film prop). After injuring the Gorn, Kirk spares his life to the surprise of the Metrons.

There are almost 5.000 known mineral species, yet the vast majority of rocks are formed from combinations of a few common minerals, like feldspars, quartz, amphiboles, micas, olivine, garnet, calcite, and pyroxenes. We still know little about other worlds. Over 300 minerals have been identified in meteorites, 130 minerals were discovered so far on Mars and 80 on Earth’s Moon.

By convention, the names of terrestrial minerals (a crystalline combination of one or various elements) end with the suffix -ite, the denominations of elements with the suffix – ium, -um, -on, -gen, or -ine. This nomenclature is not always applied in Star Trek.


  • De FOURESTIER, J. (2005): The Mineralogy of Star Trek. Axis, Vol.1(3): 1-24

Geological Star Trek Review – “Encounter at Farpoint”

» Space: the final frontier. These are the voyages of the starship Enterprise. Its continuing mission: to explore strange new worlds. To seek out new life and new civilizations. To boldly go where no one has gone before! «

Encounter at Farpoint is the pilot episode of the American science-fiction television series Star Trek: The Next Generation (TNG), which premiered on September 28, 1987. In the 79 episodes of Star Trek: The Original Series almost 50 minerals are mentioned, and in TNG, successfully running from 1987 to 1994, also minerals play a role. 74 different mineral and mineral-like names are mentioned in the 178 produced episodes. Set almost 50 years after the original voyage of the first Enterprise, the new spaceship and new crew is again checking on mining colonies or retrieving minerals and ore from distant worlds.

The new captain of the Enterprise – Captain Jean-Luc Picard – has a passion for archaeological research, but also a general interest in the collection of natural curiosities. A large cross-section of an agate nodule and a malachite concretion are among the mineral specimens on display in the captain’s ready room on board the Enterprise.

Picard keeps also a small transparent crystal of unknown origin on his desk. He often plays with the crystal when he has to make an important decision, like seen in the episode Conspiracy, Where Silence Has Lease, Suddenly Human, A Matter of Time, The Masterpiece Society and more. His first officer, William T. Riker, also did so on occasion (Gambit, Part I).

Jean-Luc Picard’s favourite crystal 💎

In the first episode with the title Encounter at Farpoint the newest flagship of the United Federation of Planets, Starfleet’s USS Enterprise-D, travels to Deneb IV for its maiden voyage. Deneb IV (or Alpha Cygni IV) is a Class M planet according to the classification system adopted in the Star Trek universe. The classification system is based on size (gas giants or small, rocky worlds), composition (rock-metal core or gas), geological activity (inactive- active), atmosphere (from oxygen-rich to toxic) and comprises fourteen planet types. For example, planets suitable for humanoid life-forms, small, rocky worlds with some geological activity, and an oxygen-rich atmosphere, are classified as M after Minshara, the native name of Vulcan, homeworld of Commander Spock. Deneb IV is also tectonically active as the mention of geothermal energy suggests.

The natives of Deneb IV, the Bandi People, offer a highly advanced base on the planet’s surface – Farpoint Station – to be used by Starfleet. As the crew of the Enterprise visits the station, they soon discover that the entire building is actually an alien life-form, able to convert the geothermal energy into matter and structures of the station.

The transformation of energy into solid matter plays a role in the replicator units and holodeck – a highly evolved virtual reality engine – of the Enterprise. Even more important is the property of Radan to control the flux of energy. In the Star Trek universe, Radan is not only a rare and valued gemstone, but this mineral is used in its purest and crystalline form – dilithium – in the spaceship’s reactors. Curiously enough, quartz, one of the most common minerals on Earth, is almost never mentioned in Star Trek. Perhaps because quartz is often used as a prop for dilithium crystals in various episodes.

Spock & “Scotty” during the delicate operation replacing dilithium crystals in the reactor core, from the TOS- episode “Elaan of Troyius”. Real quartz crystals were used as props.

Its (supposedly) cubic crystal structure can somehow control the reaction between matter and antimatter, providing the energy for the warp-drive, making faster-than-light travel possible. This science-fiction property of the crystalline dilithium is loosely based on real science. Some crystals, such as calcite, can filter or distort certain wavelengths of light, a form of energy.

Dilithium crystal as featured in TNG as a part of the warp-core.


  • De FOURESTIER, J. (2005): The Mineralogy of Star Trek. Axis, Vol.1(3): 1-24
  • De FOURESTIER, J. (2016): The mineralogy of Star Trek: the next series. Axis, Vol.12(1): 1-24
  • De FOURESTIER, J. (2020): The mineralogy of Star Trek: Notitiae Novum. Axis, Vol.16(1): 1-25
  • NOOR, M.A.F. (2018): Live Long and Evolve – What Star Trek Can Teach Us about Evolution. Princeton University Press: 208
  • STEVENSON, D.S. (2018): Granite Skyscrapers – How Rocks Shaped Earth And Other Worlds. Springer: 386

Geological Movie Review – “Alien”

When the movie “Alien” was released in 1979, it quickly terrified audiences worldwide. Its unexpected mix of classic horror and science-fiction elements got at first mixed reviews, however, over the years Alien had come to be regarded as one of the best horror-science-fiction films ever made.”Alien” screenwriters Dan O’Bannon and Ronald Shusett based parts of their script on various older science-fiction movies and tales, like “At the Mountains of Madness”, a science-fiction/horror story published by American author H.P. Lovecraft in 1936. In the story, a team of scientists is hunted and killed by ancient creatures resembling fossil animals. Lovecraft apparently based this part of his story on the real discovery of fossil archaeocyathids in Antarctica made in 1920 by geologist William Thomas Gordon. Archaeocyathids are an extinct group of sponge-like creatures believed to be among the oldest animals ever to live on Earth.

Hans Rudolf Giger, Swiss surrealist artist, architect and industrial designer, was hired to create all forms of the Alien featuring in the film, from the egg to the adult. Giger created various versions of the alien life-cycle, like a gigantic egg nest, replaced in the final movie with an egg silo inside a derelict spaceship. The eggs were directly inspired by female reproductive organs, slightly modified to avoid censorship. The facehugger, a parasite attaching to the head of its victim to incubate an embryo, is based on the bones and muscles of a human hand and male genitalia, its springlike tail was added to emphasize its quick movements. The parasitic life-form was an idea of Ronald Shusett. Shusett suggested that one of the crew members be implanted with an alien parasite to explain how the alien life-form, discovered at first as an egg in a derelict alien spaceship, came on board of the mining spacecraft Nostromo. The parasite bursts from the chest of its victim and soon the crew has to deal with the fast-growing life-form hiding in the air vents of the spaceship. The design of the chestburster and the full-grown xenomorph (alien-shaped thing) is based on Giger’s “Necronom IV“, an artwork created in 1976. The surrealist drawing shows a female figure composed of different parts of insects, parts of vertebrates and even fossils. Giger used the fossils of 300 million-year-old crinoids, commonly called sea lilies, on display in the Aathal dinosaur museum as a source of inspiration.

A petrified crinoid. Similar fossils inspired the creature featured in the successful “Alien” saga.

The earliest known crinoids date back to the Ordovician (some 450 million years ago). Their remains are very common in the fossil record, forming rocks like limestone or dolostone. The skin of echinoderms, including sea cucumbers, sea urchins, crinoids, brittle stars and starfish, is covered with tiny ossicles made of calcium carbonate forming a protective, yet flexible, outer shell. In a similar way, Giger’s Alien is protected by a silicon-based external skeleton. This outer shell is also very useful to contain the acid blood of the creature. Concept artist Ron Cobb added the acid blood as a defense mechanism, making it impossible to kill the Alien without damage to the crew or the spaceship.

In the sequel “Aliens” a team of space marines enters an Alien hive, the walls resembling Goethite, Grube Eisekaute, Bad Marienberg, Germany.

The life-cycle of the Alien from egg to queen (as introduced in the sequel) resembles the life-cycle of real animals, the Ichneumonidae. The Ichneumonidae is a wasp family preying on insects. An adult female wasp will lay her eggs within a host through a process known as ovipositing. The eggs will grow and develop into larvae, which will feed on their host from the inside-out. Somewhere along the way the host will actually die or be kept in a state very near death until, finally, the little wasp spins a cocoon around and-or within its host, eventually emerging as an adult wasp. A horrified Charles Darwin famously mentions in a letter sent in 1860 to his friend, the botanist Asa Gray, the parasitoid wasp:

» I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within the living bodies of caterpillars… «

In their natural environment, these wasps play important roles in regulating the populations of their insect hosts, and have been used in agricultural crops to control caterpillar pests. Dolichogenidae xenomorph is a parasitoid wasp species named in 2018 after the xenomorph, as “the wasp is also black and shiny like the Alien.”

The graphic representation of the “perfect organism” earned the visual effects team of “Alien” a well-deserved Academy Award.

Geological Star Trek Review – “Amok Time”

In September 2018 astronomers announced the discovery of an exoplanet with 8.47 times Earth’s mass and twice Earth’s radius in the 40-Eridani star system, nearly 17 light years away from Earth.

In the Star Trek universe, Eridani is the star system where the planet Vulcan is located, the homeworld of Commander Spock.

In the episode “Amok Time”, first aired on September 15, 1967, the Enterprise visits the planet for the first time. As it orbits its sun on a very narrow orbit, surface temperatures are very high. The atmosphere is very thin, barely breathable, and non-Vulcans have a hard time adapting to the harsh environment. According to Star Trek lore, the desert-planet Vulcan orbits its sun together with the planet T´Khut, a geologically very active lava-planet.

The classification of planets in the Star Trek universe is based on size (gas giants or small, rocky worlds), composition (rock-metal core or gas), geological activity (inactive- active) and atmosphere (from oxygen-rich to toxic). For example, small, rocky worlds with some geological activity and an oxygen-rich atmosphere making them suitable for humanoid life-forms are classified as M after Minshara, the native name of Vulcan.

“Amok Time” (1967).

In the movie “Star Trek 2”, released in 1982, the star 40-Eridani-A is mentioned as Vulcan’s sun. In 1991, Gene Roddenberry, creator of Star Trek, published a brief article together with astrophysicists Baliunas, Donahue and Nassiopoulos, arguing that the constellation of Eridani would be the most fitting place for Spock’s homeworld.

The 40-Eridani system is a triple star system, with Eridani-A as the primary star accompanied by a red and a white dwarf star, named respectively Eridani-B and Eridani-C. Only Eridani-A is stable enough to host a hypothetical habitable planet. Eridani-B emits too much dangerous radiation and Eridani-C is prone to flares, sudden eruptions of energy and matter. As Eridani-A is smaller than our Sun, also the habitable zone where a planet could exist with liquid water is narrower. Unlike the fictional planet Vulcan, the real exoplanet seems to be a Super-Earth or a small gas giant. According to the published preliminary results, the planet orbits its star in just 39 to 40 Earth days, within the inner limit of the habitable zone.

Geology of strange, new worlds plays also a role in Vulcan society.

In the 1996 movie “Star Trek: First Contact” the geological survey ship T’Plana Hath approaches our solar system in the year 2063. Attracted by the Phoenix warp test – the first faster-than-light flight in human history – the Vulcan ship lands on Earth, making the first peaceful contact with humanity in Bozeman, Montana.

The first contact between humans and extraterrestrial geologists.

However, in the later Enterprise (2001–2005) episode “Carbon Creek” another survey ship crash-lands on 1950s Earth somewhere in Pennsylvania. Following the “First Directive”, the Vulcans keep their true alien identity a secret and work as geologists in the local coal industry.

In a parallel timeline, the first contact ends with the humans killing the Vulcan geologists and claiming the technologically advanced survey ship for humanity. This mirror universe, where the Federation is replaced by an evil Terran Empire, is first seen in the 1967 episode “Mirror, Mirror.” During negotiations for mining dilithium on the Halkan homeworld, a magnetic storm causes a transporter malfunction, sending Kirk, McCoy, Scotty, and Uhura to the parallel Enterprise.

Famously Commander Spock is the science officer aboard the Enterprise, including some notions of geology.

“Obsession” (1967).

In the episode “The Apple”, Spock immediately notes the lush vegetation of the planet Gamma Trianguli VI. He correctly deduces that soil-nutrients (and therefore geology) play a role in supporting this peculiar paradise-like ecosystem. With his sharp geological eye, Spock identifies also hornblende and quartz in a collected rock.

Interesting. Extremely low specific gravity, some uraninite, hornblende, quartz. Fragile, good cleavage. An analysis should prove interesting.

Hornblende, Moos in Passeier, South Tyrol.
“You must be one with the rock” from the episode “By Any Other Name” (1968).

Geological Star Trek Review – “The Enemy Within”

During a minerals-gathering mission on planet Alpha 177 by the crew of the Enterprise, a transporter accident creates an evil duplicate of Captain Kirk.

In the episode the malfunction is explained by the interference of a yellow ore, collected on the alien planet’s surface, with the transporter’s circuits. The ore is not identified in the episode, but seems to consist of some alien mineral.

In many episodes of Star Trek the crew of the Enterprise visits mining colonies or is on a mission to search for valuable minerals and crystals. There exists even a geological tricorder, designed for analyzing rock samples and comparing them to the records memorized in the mineralogical database of the federation. By convention, the names of terrestrial minerals end with the suffix “-ite”, the denominations of elements with the suffix “- ium”, “-um”, “-on”, “-gen” or “-ine”. Unfortunately it seems that this nomenclature is not always applied with the necessary scientific scrutiny in the 23th century.

There are around 5,000 to 7,000 minerals known on Earth, but we still know little about the mineralogy of other worlds. Over 300 minerals have been identified in meteorites so far. Meteorites display a mineral composition different to most rocks found on Earth. The most common type are stony meteorites, consisting of silicate minerals like olivine, pyroxene and traces of iron-nickel alloys. Just 1% of meteorites are pure silicate rocks. The smell of some fragments resembles asphalt or solvents, evidence for 4.6 billion years old carbon-compounds preserved inside the rock. 4 to 5% of all space debris is represented by iron meteorites, consisting of an almost pure iron-nickel alloy with eventually embedded small crystals of silicate minerals.

Around 130 minerals were discovered on Mars and 80 to 100 on the Earth’s Moon. Most are also found on Earth, however, as some of those minerals were formed under conditions that don’t exist on Earth, such as low gravity or the complete absence of liquid water, some are indeed unknown, alien minerals.

There are about 15,300 possible ways to combine all known elements, so there may be even more alien minerals out there.

The mineralogy of an exoplanet depends on its chemical composition. By analyzing the light of a star, it is possible to identify the chemical composition of distant star systems. As the star and the planets form from the same accretion disk, knowing the chemical composition of the star can provide also some information on the chemical composition of the planets orbiting the star.

The exoplanet 55 Cancri -e is roughly twice Earth’s radius, but has just eight times its mass. Its specific density is too low if compared to Earth. Earth is composed mostly of iron, oxygen, magnesium and silicon, with some sulfur, nickel, calcium and aluminum added to the mix. Observing the composition of the 55 Cancri-e’s host star, astronomers discovered a high concentration of carbon and oxygen. It’s likely that most minerals on 55 Cancri-e are based on a combination of the two elements, forming minerals with a low specific density. Surprisingly enough, carbon minerals are quite rare on Earth. Just fifty have been identified on Earth, and most are associated with life, forming from decaying organic biomass. It seems that on Earth, life “hijacked” carbon and carbon-minerals formed by pure inorganic processes (like diamonds) are uncommon.

Geological Star Trek Review – “The Devil in the Dark”

The 1967 Star Trek episode “The Devil in the Dark” was written in just three days by screenwriter Gene L. Coon. Despite the rushed production, this first season episode is almost always included in every “best of” list. Trekkies value the story and message, as Kirk finds a peaceful solution to a conflict with an unknown life-form, but also love some remarkable classic scenes and lines, including “Pain! Pain! Pain!” and “I’m a doctor, not a bricklayer!” This episode holds also a special place in many geologist’s hearts as it features a lot of geo-babble.

It is one of the rare episodes starting not on board of the Enterprise, but in the mines of Janus VI. According to federation classification Janus VI is a type-E rocky planet with an iron core, similar in size to Earth but just 1.3 billion years old and apparently without atmosphere or life on the surface. It’s rich in minerals and elements, like gold, uranium, platinum, cerium and the fictional pergium. Mining an extraterrestrial world is still fiction, but science shows that it may be profitable. Asteroids are rich in platinum, iridium, palladium and gold. One hundred tons of rock from an asteroid might today be worth more than 9,000 dollars, compared to just 60 dollars worth the same amount of terrestrial rocks. Estimated 5,000 to ten millions of asteroids can be found near Earth and companies are already dreaming of future prospecting and mining spaceflights. Mining asteroids would not necessarily benefit Earth, as bringing the ore to Earth would be costly, but might benefit nearby colonies, outposts or industrial complexes. In “Devil in the Dark” it is mentioned that “dozen planets depend on you for pergium.” Pergium is somehow needed for common power generators (but apparently outdated, as Chief Engineer Scotty hasn’t seen such a thing in over twenty years), providing energy not only for the colony on Janus VI but other worlds.

The mining colony in the episode was successfully operating for over fifty years but after the miners opened up a new level deep within the planet suddenly a monster started to attack and kill people. The Enterprise sends Kirk, Spock and McCoy for help. Spock during a meeting with the chief engineer Vanderberg, the administrative head of the mine, notes a strange sample in the office:

“It’s a silicon nodule. There are a millions of them are down there. No commercial value.”

“But a geological oddity, to say the least. Pure silicon?”

“A few trace elements. Look, we didn’t call you here so you could collect rocks.”

Later Spock and Kirk are able to injure the supposed monster and recover what seems to be living tissue, however, a close inspection reveals the tissue to be “fibrous asbestos, a mineral.” Asbestos is indeed a silicate mineral, which is found as aggregates of thin fibrous crystals on Earth.

Byssolithe, a type of silicate, forms fibrous crystals.

After this discovery Spock speculates that the supposed monster is an alien life-form, not based on carbon compounds as on Earth, but on silicon. The strange silicon nodules destroyed by the clueless miners are eggs and the creature was just defending her children. After Spock joins with the mind of the creature a peaceful agreement is found between the miners and the alien. The miners will not hurt or kill the creatures and the creatures will allow the miners to use their tunnels to mine the deeper pergium-rich layers of the planet (and so become rich). The Horta, as this alien is named in the series, use a sort of hot acid to melt their tunnels in the solid rocks.

The silicon-based life-form as depicted in Star Trek is surprisingly scientifically accurate. In life as we know it only ten elements play a mayor role. Carbon is one of the most important elements, followed by oxygen, nitrogen, hydrogen, potassium, calcium, magnesium, iron, phosphorus and sulfur. Carbon is common in the universe but relatively rare on Earth. Strangely silicon is quite common in Earth’s rock, but plays only an insignificant role in biological processes. Some microorganisms, like radiolarians and diatoms, use silaffins and silica-hydrogels to build their tiny shells. Siliceous sponges use silicon to support their body by constructing a framework composed of tiny needles of silicon dioxide. However, all those organisms use silicon only to build their skeleton, not in their living tissue or metabolism.

Carbon, despite its relative rarity on Earth, has some important advantages for life on Earth. It can form stable and complex macromolecules within the range of terrestrial temperatures. Living bacteria are found on Earth in 240°F hot springs and on frozen rocks of Antarctica, thriving at -60°F . Atomic bounds between carbon-carbon, carbon-oxygen and carbon-hydrogen atoms are strong and the formed molecules are soluble and stable in water. Water is so important for carbon-based life as it´s a perfect environment for molecules to react with each other, resulting in a life-sustaining metabolism. Silicon, like carbon, can form stable bounds with itself and other elements like carbon, nitrogen, phosphorus, oxygen, sulfur and many metals. Such silanes can form sheets, chains, tubes and even complex three-dimensional frameworks. In theory silanes could be combined to form organelles of a living cell and even reactive molecules sustaining an alternative metabolism.

That said, silicon shows a very strong affinity to oxygen and hydrogen. On Earth the tissue of a silicon-based life-form would slowly react with the oxygen of the air and the hydrogen in the water, corroding and killing the creature. Doctor McCoy even mentions this fact in the episode. However, Spock notes that the creature comes from within the planet, where suitable conditions for silicon-based life might exist.

Silicon-life would need an oxygen-free atmosphere, an environment with no water and an alternative liquid for its metabolism. Possible alternative solvents that may work include liquid methane and ethane, but also sulfuric and hydrocyanic acid.  The acid could explain the (fictional) ability of the Horta to “digest rock” and to “tunnel” so quickly “for nourishment” through the planet. As such compounds are unstable at higher temperatures, the silicon-based life-form would best thrive in a very cold environment.

Could such life really exist? Unfortunately we don’t know for sure and the Horta is never again mentioned in the original series. Maybe this question will be answered by future generations, when humanity encounters life, but not as we know it. How will we react? In “The Devil in the Dark,” the first response was fear and hate, in the end overcome by knowledge and emphaty – a message in the best tradition of Star Trek.

Geological Star Trek Review – “The Man Trap”

“Captain’s log, Stardate 1513.1. Our position, orbiting planet M-113. On board the Enterprise, Mister Spock temporarily in command. On the planet the ruins of an ancient and long-dead civilisation. Ship’s surgeon McCoy and myself are now beaming down to the planet’s surface. Our mission, routine medical examination of archaeologist Robert Crater and his wife Nancy. Routine but for the fact that Nancy Crater is that one woman in Doctor McCoy’s past.”

“The Man Trap” was the first episode ever aired of Star Trek – The Original Series (TOS) on September 8, 1966, even if it was the sixth episode produced. The National Broadcasting Company rejected the original pilot as they wanted an episode featuring a monster in space to get the public’s interest in the new science-fiction series.

In the episode, Captain Kirk and his crew visit the alien planet M-113 to check on an archaeological expedition. The planet’s surface appears at first lifeless. However, ruins seen in the background testify that a long lost civilization once existed here. The planet was also home to a multitude of creatures according to the sculptures and designs left in the architecture that scatters the surface of the now barren world. There remains some plant life, hardy drybrush, and poisonous plants.

The archaeological outpost on the planet M-113 is infiltrated by a mysterious shape-shifting creature that requires salt – the sodium-chloride mineral halite – to survive and is willing to obtain it by any means necessary. Crewman Darnell is the first victim of the “salt-vampire” and also the first “red-shirt” (wearing a blue shirt) to be killed in TOS.

The origin of the salt-vampire remains unknown and it is also never explained if the creature is somehow related to the ancient megalith builders. This poses an intriguing question. Without the ruins, would a hypothetical exo-scientist, as seen in the episode, be able to infer the existence of a former alien civilization?

Earth is the only planet we know for sure can host a technologically advanced civilization, however, buildings and cities are surprisingly short-lived. Even modern iron and concrete resist weathering for just some decades to centuries. Monuments build from sedimentary rocks, like the pyramids, may last some thousand years in dry environments. Reliefs in massive rocks, like Mount Rushmore carved into Harney-Peak granite, may remain recognizable for some hundred-thousand years.

Even if our technological wonders won’t survive millions of years into the future, other traces may remain. In just a few centuries, we have modified more than 70 percent of Earth’s land surface. Humans today move ten times more sediments than all natural processes combined, like landslides or rivers. Since the year 1500 more than three-hundred species of large vertebrates went extinct and many argue that we are witnessing the beginning of a mass extinction event. Earth will need millions of years to recover and replace the lost species.

Since the industrial revolution in the 19th century, humans have modified the concentration and flux of carbon and nitrogen in Earth’s atmosphere. New artificial materials, like plastic, are polluting the environment. Future geologists may find rare traces like “technofossils” – anomalous minerals or unnatural materials like plastiglomerate in the geological record. It is unknown how long such artificial materials will survive in the geological record. If buried in sediments, like plastic fragments on the bottom of the sea, maybe some million years. Eventually, heat, pressure and time will break the molecules apart and erase any direct evidence for humanity’s former presence on Earth.

Chemical signatures preserved in sedimentary rocks, caused by the changes in abundance of certain elements, like carbon (resulting from burning fossil fuels), nitrogen (used as fertilizer to feed seven billion people), radioactive or rare earth elements (used in modern technology), may still be detectable after billion of years. However, there are natural processes that may mimic such anomalous concentrations. The famous Oklo-reactor, a two billion years old uranium ore deposit that experienced a slow nuclear fission, was likely not built by an ancient civilization but formed by microbial activity.

Even climate change alone will not be sure evidence of a technologically advanced civilization. In the past, there were geological epochs with higher concentrations of carbon dioxide. 55 million years ago, during the Paleocene–Eocene Thermal Maximum, over some thousands of years a massive flux of greenhouse gases from the ocean into the atmosphere occurred and Earth’s global temperature rose by 8°C in response. However, the speed humans are changing the climate is unprecedented in the history of the Earth.

Combining various observations, like the rate of changes preserved in the geological record, the presence of anomalous materials, a spike of certain chemical elements and the extinction of species, future alien geologists visiting Earth may realize that a civilization, technologically advanced enough to influence the entire planet, once existed here. Will they find a thin layer of boundary clay, suggesting a sudden catastrophe ending this civilization? Was it a gradual demise following environmental problems? Or did the civilization survive still for thousands of years by adapting or changing its behavior in time? In the stratigraphic record time can be compressed and even future geologist may not be able to clearly distinguish between a sudden event, lasting just some centuries, or a prolonged era of a hundred-thousand years.

Galaxy Science Fiction, June 1951.


  • SCHMIDT, G.A. & FRANK, A. (2019): The Silurian hypothesis: would it be possible to detect an industrial civilization in the geological record? International Journal of Astrobiology. Volume 18, Issue 2: 142-150

Geological Star Trek Review – “Where No Man Has Gone Before”

“Enterprise Log: Captain James Kirk commanding. We are leaving that vast cloud of stars and planets which we call our galaxy. Behind us: Earth, Mars, Venus, even our sun are specks of dust. A question: what is out there in the black void beyond? Until now our mission has been that of space law regulation, contact with Earth colonies and investigation of alien life. But now, a new task; a probe out into where no man has gone before.”

Opening narration by Captain Kirk in the original cut of the pilot of the series.

“Where No Man Has Gone Before” was the second pilot produced for Star Trek The Original Series, as the first pilot “The Cage” was rejected at first by TV executives, and actually the third episode ever broadcast. Actor Leonard Nimoy was recast as Mister Spock, but it is the very first time William Shatner plays Captain James R. Kirk.

The spaceship Enterprise is patrolling the outer barrier of the galaxy, when a distress signal from the spaceship Valiant, lost over two centuries before, is received. Following the signal, they soon encounter an energy field. As they try to fly into the field, impulses of unknown energy hit some members of the crew, apparently causing some sort of accelerated evolution. Both Kirk’s friend and helmsman Gary Mitchell and ship’s psychiatrist Dr. Elizabeth Dehner quickly develop god-like psychic powers, threatening to destroy the Enterprise. As there is no way to control Mitchell, Kirk decides to leave him stranded on the nearby planet Delta Vega, a planet similar to Earth except its slightly smaller size, with an automated lithium cracking station operating there.

The matte painting of the “lithium cracking station” on Delta Vega.

Mining an extraterrestrial world is still fiction today, but science shows that it may be profitable in the future. Asteroids are rich in rare elements like platinum, iridium, palladium, and gold. One hundred tons of rock from an asteroid might today be worth more than 9.000 dollars, compared to just 60 dollars worth the same amount of terrestrial rocks. An estimated 5.000 to 10 million asteroids can be found near Earth’s orbit and companies are already dreaming of future prospecting missions and mining spaceflights. Mining asteroids would not necessarily benefit Earth, as bringing the ore to Earth would be extremely costly, but might benefit nearby colonies, outposts, or industrial complexes in space.

The mentioned lithium, a real element, will in later episodes be replaced with the fictional dilithium. In the Star Trek universe, this mineral is not only a rare and valued gemstone known also as Radan, but it is used in matter-antimatter reactors powering spaceships. Its (supposedly) cubic crystal structure can somehow transform energy and control the flow of antimatter. This science-fiction property of the crystalline dilithium may seem far-fetched, but some real crystals – such as calcite – can filter or distort certain wavelengths of light, a form of energy.

Meanwhile, Mitchell escapes from his prison in the cracking station. Dr. Dehner is able to distract and injure Mitchell but is killed during the fight. Kirk must face the injured and weakened, but still dangerous Mitchell. After a hand-to-hand battle in the mountains and a ripped shirt, Kirk uses a phaser rifle to trigger a rockslide killing Mitchell and saving his ship.

The set of the barren and rocky landscape used to show the planet’s surface was recycled from the rejected original pilot. Desert planets like Delta Vega are among the most visited by the Enterprise crew, a plot device to limit needed film sets and costs. In 79 episodes of Star Trek TOS, the Enterprise explores the geology of many planets, sometimes inhabited by humanoids or by alien lifeforms. The classification of planets in the Star Trek universe is based on size (gas giants or small, rocky worlds), composition (rock-metal core or gas), geological activity (inactive- active), atmosphere (from oxygen-rich to toxic) and comprises fourteen planet types. For example, planets suitable for humanoid lifeforms, small, rocky worlds with some geological activity and an oxygen-rich atmosphere, are classified as M after Minshara, the native name of Vulcan, homeworld of Commander Spock.

The first episode of Star Trek aired September 8, 1966, three years before the first manned Moon landing. Virtually nothing was known about the geology of other worlds. Yet the authors of Star Trek display a lot of imagination in creating exotic worlds and got many things right. In later episodes the Enterprise will explore ice worlds and lava planets. Small ice moons are very common in our solar system and the Jupiter moon Io is geologically very active, with its surface covered in sulfuric lava.


  • NOOR, M.A.F. (2018): Live Long and Evolve – What Star Trek Can Teach Us about Evolution. Princeton University Press: 208
  • STEVENSON, D.S. (2018): Granite Skyscrapers – How Rocks Shaped Earth And Other Worlds. Springer: 386