"Day on Acheron was dim twilight, night was darker than the farthest reaches of interstellar space, because not even stars shone through its dense atmosphere to soften the barren surface with twinkling light."
Aliens novelization, chapter 9

Acheron,[3] formerly known as LV-426, was one of three moons orbiting the gas giant Calpamos in the Zeta2 Reticuli system, 39 light years away from Earth. The moon was given its common name by the early human colonists who settled there. The main colonist base, Hadley's Hope, housed 158 people.[4]

Terrain and Climate[]


LV-426 seen from orbit.

Acheron has an equatorial diameter of just 1,200 km.[1][2] Despite its small size, the moon maintains a surface gravity equivalent to 0.86 of that on Earth,[5] indicating it is largely composed of incredibly dense materials. Its rotational period is about two hours.[6] Acheron's crust is made up of aluminum silicates, although there is evidence of magnesium silicate intrusion, manifested on the surface as basalt, rhyolite and microgranite lava flows.[5][7] Despite this evidence of past volcanic activity, as well as ongoing volcanic processes in the moon's core, the surface currently exhibits no discernible volcanism or tectonic activity. The moon's geological structure has led to the conclusion it is a recently captured body, entering Calpamos' orbit within the last 40 million years or so.[5] Indeed, the rings around Calpamos itself are thought to be the remnants of a previous satellite that was broken apart by the gravitational shift induced by Acheron's arrival.[5]

Acheron's indigenous atmosphere was described as "primordial", consisting mainly of nitrogen and carbon dioxide, with smaller quantities of oxygen, methane and ammonia, some of the latter existing in the frozen state.[8] It is constantly racked by strong winds, although the moon is too small for potentially dangerous storms to form.[9] Needless to say, Acheron under native conditions is inhospitable to human life.

Following the terraforming of Hadley's Hope, the atmosphere was breathable for humans, although it remained somewhat hostile with dim days and frequent storms.

Geographical features[]

The Ilium Range was a mountain range on the Acheron moon, located near to where USCSS Nostromo discovered an abandoned alien vessel in 2122.[10]

Flora and Fauna[]

"It's a rock. No indigenous life."
ECA representative regarding LV-426 (from Aliens)

Acheron has no indigenous life forms, and it is not the Xenomorph homeworld; the only Xenomorph samples on the moon were housed in the cargo bay of the derelict Engineer ship, which had crash-landed there an indeterminate period of time before.


Acheron is best known for the terraforming colony of Hadley's Hope, established on the moon in the mid-22nd century for the purpose of processing the moon's atmosphere to create a suitable environment for large-scale human habitation.


Early human interaction[]

Nostromo above LV-426

The Nostromo above LV-426.

LV-426 was first detected by Weyland Corp astronomers on May 14, 2039.[11] The moon was subsequently cataloged by a French deep-space probe.[5] It was assumed the moon was a low density Galilean ice ball with an ice crust over a silicate core due to Calpamos' (then named only IV) ring system.[5]

In 2090, business tycoon Sir Peter Weyland chose to fund Elizabeth Shaw's proposal to explore LV-223, another moon of Calpamos. He did so with a different agenda than Shaw's in mind; his real interest was in the neighboring LV-426, from which his company had recently detected a faint, almost imperceptible signal. The synthetic David was the only other member of Shaw's expedition to know about Weyland's interest in LV-426, with Weyland stating that no one else was to know about an additional mission to scout the moon until the time was right.[12]

The first comprehensive survey of LV-426 was not carried out until the 2130s, after the USCSS Nostromo set down on the moon in 2122.[5] The Nostromo was purportedly responding to a mysterious signal emanating from LV-426, per Weyland-Yutani protocol. In reality, the signal had previously been detected and decoded by Weyland-Yutani,[13] and Nostromo had been pre-selected to investigate, with the synthetic Ash surreptitiously placed aboard to ensure the safety of any lifeforms that were discovered. Though the Nostromo was damaged while landing on LV-426, a three-man exploration team -- consisting of Captain Dallas, First Officer Kane and navigator Lambert -- set out on a brief exploration of the moon's surface and discovered a derelict spacecraft that was the source of the signal. While exploring the derelict's interior, the crew came across the fossilized remains of an Engineer pilot and thousands of Xenomorph Eggs stored within the ship's cargo hull. Kane was subsequently impregnated by a Facehugger and was taken back to the Nostromo for treatment. The ship departed soon afterwards, but the Xenomorph implanted in Kane's chest later birthed in space, leading to the Nostromo's destruction. Following the loss of the Nostromo, the incident was covered up by the Weyland-Yutani personnel involved.[14]

It would be fifteen years before another ship visited LV-426, when the Nostromo's flight recorder was discovered by the crew of the USCSS Anesidora, captained by Henry Marlow. Hoping to use the recorder's flight data to locate and salvage the ship, they stumbled upon the derelict's beacon and landed on the moon's surface, eventually discovering the ship itself before realizing the Nostromo had found it first. Hoping it hadn't yet been claimed and adamant on ensuring nobody else would stumble across the derelict, Marlow found and deactivated the beacon. Soon after, the crew were forced to return to their ship when Marlow's wife, Catherine Foster, was attacked and impregnated by a Facehugger, much as Kane had been; this would lead to the Xenomorph outbreak on Sevastopol Station soon after.[15]

With the beacon deactivated and all of both crews -- save for Ellen Ripley of the Nostromo -- dead from both outbreaks, the moon faded back into obscurity; the derelict itself was not discovered during the moon's survey.

Terraforming and colonization[]

LV-426 was later selected for terraforming and human colonization. This process began with the establishment of the colony of Hadley's Hope in 2157[16], with the construction of a nearby Atmosphere Processing Plant commencing two years later.[17] The early inhabitants of Hadley's Hope christened the moon Acheron,[3] after one of the rivers that wound through the netherworld (translated as "River of Pain") in ancient Greek mythology.[18]

Despite this human habitation, the colonists remained unaware of the derelict due to a combination of the moon's thick, debris-laden atmosphere shielding it from both visual and satellite detection and the Ilium mountain range blocking it from the colony's ground scanners.[19] It wasn't until twenty years later that Russ and Anne Jorden, Weyland-Yutani prospectors and residents of the colony, investigated the derelict on company orders after its location was deduced from the testimony of Ripley, who had just been rescued from deep space. Russ was subsequently impregnated by a Facehugger during his investigation of the ship, resulting in a full-scale outbreak in the colony. A Queen established a Hive in the Atmosphere Processing Plant, and the Xenomorphs killed or impregnated nearly all of the colonists.

A select few inhabitants managed to escape the incident: two disparate groups of colonists fled in two separate ships. One group escaped aboard the cargo freighter Onager and sought refuge on the nearby LV-223, ironically the same moon where the USCSS Prometheus disappeared in 2093, while a small group of four led by Captain Brackett of Acheron's resident Colonial Marine contingent safely escaped the system in a shuttle.[18] Rebecca Jorden, daughter of Russ and Anne, was the only colonist left alive at Hadley's Hope, managing to evade the Xenomorphs for an extended period of time thanks to her resourcefulness and familiarity with the colony's ventilation network.

A short while after the outbreak, a unit of Colonial Marines was dispatched aboard the USS Sulaco to investigate the loss of contact with the colony, accompanied by Ripley. After several battles with the Xenomorphs that resulted in the deaths of most of the Marines, the creatures' Hive was destroyed when the Atmosphere Processing Plant's reactor exploded. Only Ripley, Rebecca, Corporal Dwayne Hicks and the synthetic Bishop escaped Acheron. Unknown to them, the Hadley's Hope Queen had stowed away on board Sulaco, but was subsequently ejected into space by Ripley through an airlock.

Exploration by Weyland-Yutani[]

Despite the explosion on the moon, several Xenomorphs had survived in the ruins of Hadley's Hope, and a second Queen soon emerged. The Queen and her brood were discovered by a Weyland-Yutani team led by Michael Bishop, which had set up the Origin Facility around the derelict to study the Xenomorphs. A second group of Marines, hailing from the USS Sephora, subsequently landed on LV-426 and engaged both the Weyland-Yutani forces and the Xenomorphs. The research facility was overrun, although several personnel, including all the surviving Colonial Marines, managed to escape aboard a Weyland-Yutani starship.

In the early 23rd century, the derelict's telemetry was traced from LV-426 to LV-1201, where Weyland-Yutani set up a new research facility to study the Xenomorphs.

Behind the scenes[]


In Alien, LV-426 is not named and is simply referred to as a "planetoid" or "ball". In Aliens, the name LV-426 is given at the inquest aboard Gateway Station and subsequently throughout the film. The novelization of the film additionally states that the moon is also known as Acheron.[3] Director James Cameron also gives the name Acheron in a behind the scenes interview on the production of Aliens, after the river that, in Greek mythology, is described as the "stream of woe", a branch of the river Styx, and which forms the border of Hell in Dante's Inferno. Greek history and mythology are a recurring point of reference in the Alien franchise; other notable examples include the comics Aliens: Rogue and Aliens: Dead Orbit (which contain numerous references), the ships Archimedes and Anesidora, the novels Alien: River of Pain and Alien: Into Charybdis, and references to the Titan Prometheus in both Prometheus Tech and the film Prometheus.

Cameron suggests that the moon may have earned the name Acheron from an early colonist with a literary interest and a sense of irony.[20] On the timeline of the official viral website for Weyland Corp, as part of the promotion for the film Prometheus, the moon's name appears as officially "Acheron LV-426", bringing both of the established names together. The moon was originally going to appear in Prometheus, but ultimately the moon LV-223 was used instead.

The name Acheron is reused in the novelization of Alien3, although it was repeatedly misspelled as "Archeron" in early editions. LV-426 is mentioned again in the musings of Dr. Mason Wren in the novelization of Alien Resurrection, in which the researcher reflects that the loss of the derelict was a great setback. Unlike earlier novels, the moon is once more referred to as LV-426. While never overtly stated in any source, it seems likely that LV-426 is the moon's technical designation, while Acheron is a more common name.


  • The Ilium Range mentioned in Aliens is named for the Latin Ilia (one side of the pelvic bone, groin). The mountain range therefore prophetically symbolises the pelvic shape of the derelict spacecraft (as well as the phallic shape of the Xenomorph cranium).
  • In Alien, the film's original screenplay and its accompanying novelization, LV-426's diameter is said to be only 1,200 km.[1] For a moon so small to have a surface gravity of 0.86 G, it would have to be unfeasibly dense, and its surface would also be visibly curved when standing on it (which it clearly is not in the film). The Colonial Marines Technical Manual later changed the moon's size to a more realistic 12,201 km diameter, however, the Weyland-Yutani Report later reverted this to the original size.
  • In Alien: Descent, LV-178 is erroneously referred to as Acheron and shown as being in the Zeta Reticuli system.




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