HELIOS One

 is a Poseidon Energy solar plant that can generate and provide power to New Vegas Strip or other settlements in the Mojave Wasteland. It also contains the control system for two space-based weapon platforms, Archimedes I and Archimedes II.

Background
A pre-war installation, Helios was hailed as the "Dawn of a Golden Age" by Poseidon Energy. The Brotherhood of Steel discovered the facility and were actively working on understanding its workings until the New California Republic (NCR) launched Operation: Sunburst to take Helios One. Before the Brotherhood abandoned the facility, they put it in a nearly inactive state and armed the pre-war security system. Despite the NCR's best efforts, they have had no luck in either bringing the power level up or deactivating the security system.

Main building
At the beginning of the events of Fallout: New Vegas the facility is controlled by the NCR, who have a detachment guarding the facility. At the front entrance is Lt. Haggerty, who must be convinced to allow the player character in, or the player can lockpick a side door for entrance.

In the back of the building is a "technician" named Fantastic, who is working on getting the power plant functioning. The room adjacent to Fantastic's contains another scientist, Ignacio Rivas. A nearby door leads to the mirror yard.

Mirror yard
Behind the main building is the solar collection tower and an array of computer-controlled mirrors. There are also two mirror control terminals in small shacks, and several tents set up by the NCR troopers guarding the facility. The western terminal is guarded by mines, bear traps, and a rigged shotgun, while the eastern terminal is guarded by attack dogs.

Solar collection tower
Inside the solar collection tower, past a small straight path there are three hostile automated turrets and several (level-dependent) security robots, a mix of protectrons, robobrains, Mister Gutsys, and/or sentry bots. Going straight ahead leads to an unlocked door to a small room containing several frag mines (both active and inactive) and an easy locked terminal. The terminal can be hacked to shut off the turrets or get them to fire indiscriminately at all targets (including the security robots). Near the entrance is a water fountain with no radiation. Downstairs is a small room with two pulse grenades on a shelf, and an average safe containing more pulse grenades and pulse mines plus miscellaneous loot.

The level continues through a double-wide door and down a sloping corridor guarded by a leveled security bot. The door at the bottom leads into another narrow corridor, leading to another multi-level room with stairways and catwalks, guarded by a Mister Gutsy. At the bottom is a door leading to more corridors and three small rooms. One contains five protectrons and their charging stations, one contains some desks, skeletons and two Poseidon Energy ID cards, and one has an elevator that leads to the observation level of the tower.

Observation level
The observation level contains the mainframe computer used to activate the plant and direct its power, plus a broken generator that can provide power to the mainframe and a repair robot called Python. See That Lucky Old Sun for more about repairing and using the mainframe. There is a door at the top level that leads to the observation deck.

Observation deck
This is a circular deck all around the top of the solar collection tower. A spiral catwalk leads down from the entrance door. There is a reflector control panel that must be activated to complete the retargeting of the mirrors during That Lucky Old Sun. This location is outside, so the player can fast travel from here, though it is not recommended to do so during the Helios One/Archimedes I startup sequence, as this can cause quest glitches.

Notable loot

 * D.C. Journal of Internal Medicine upstairs in the main building, lying on a bed in the same room with the east terminal password. (Head to the right from main entrance, through the pool room, and right up the stairs.)
 * Programmer's Digest on the upper level before big doors inside the Solar Collection Tower
 * Fixin' Things on the table in the second flight of stairs after the tunnel with the cots in Solar Collection Tower
 * Meeting People on one of the troopers stationed outside the entrance to HELIOS One (can be pick-pocketed)

Appearances
appears in Fallout: New Vegas and is mentioned in Dead Money.

Behind the scenes

 * Helios was the Greek god of the sun and in Greek the same word still means "the sun".
 * This location is based on The Solar Project located in the Mojave Desert.

Bugs

 * Sometimes when leaving the building via the back door, various NPCs, creatures or invisible objects will fall out of the air and will become hostile. These may include Rey, Audaz, Colmillo, No-bark Noonan, Basura, Old Lady Gibson, Molerats, Radscorpions, barrels, a tin can or a combination of the above. Reloading the autosave made when you exited the door will correct this problem. Also, it can freeze up the game.
 * Inside the Solar Collection Tower, the stools may not be sat upon, unlike all other chairs in the game.
 * A hostile Protectron may be found in one of their blue glowing holding containers, and if you kill him while he is still in it you may become trapped inside. The only way to fix this is by reloading your last save (possibly the autosave upon entering).
 * Protectrons within the room with the laser tripwire seem to be immune to explosive damage.
 * Disarming the laser trip wire within the room with Protectrons with science skill does not however prevent it from opening the forcefields and letting Protectrons out to attack player.
 * The southwest room with the Mister Gutsy has two filing cabinets occupying the same place next to the sink.

Gallery
Helios Jeden ГЕЛИОС Один