LV 426, formerly known as LV-426, is one of three known moons orbiting 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.

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.

LV-426 was first detected by Weyland Corp astronomers on May 14, 2039.  The moon was subsequently cataloged by a French deep-space probe. The first comprehensive survey was not carried out until the 2130s, after the USCSS Nostromo set down on the moon in 2122.

The Nostromo touched down on LV-426 allegedly in response to a mysterious signal emanating from the moon, per standard Weyland-Yutani protocol. In reality, the signal had previously been detected and decoded by Weyland-Yutani, and the Nostromo had been pre-selected to investigate, with the android 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, proceeded to explore the moon’s surface and discovered a Derelict spacecraft that was responsible for transmitting the signal. While exploring the derelict’s interior, the crew came across the fossilized remains of the 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 Nostromo 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. This, coupled with the fact the derelict’s beacon was later deactivated by the crew of the Anesidora, meant that, in time, LV-426 passed back into obscurity.

LV-426 was later selected for terraforming and human colonisation. This process began with the establishment of the colony of Hadley’s Hope in 2157, with large-scale terraforming efforts beginning two years later with the construction of a number of Atmosphere Processing Plants to make the moon’s atmosphere breathable.

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. It wasn’t for another twenty years that Russ and Anne Jorden, residents of the Hadley’s Hope colony, were sent to investigate the derelict on company orders, after its location was deduced from the testimony of Ellen Ripley, the only survivor of the Nostromo, who had just been rescued from deep space. Russ was subsequently impregnated by a Facehugger during his investigation of the ship, sparking a full-scale outbreak at the colony. A Queen established a Hive in the colony’s Atmosphere Processor, and the Xenomorphs killed or captured, cocooned and impregnated nearly all of the colonists.

After many battles with the Xenomorphs, the hive was destroyed when the atmospheric processor’s power source exploded. Ripley, Newt (the sole surviving colonist), Corporal Dwayne Hicks, and an android (“Bishop”) escaped LV-426 in time onboard the USS Sulaco.