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You might have noticed the very large building just north of here. That's HELIOS One. The NCR runs the place, so it's off-limits to prospectors.Old Lady Gibson

HELIOS One is a pre-War Poseidon Energy concentrated solar power plant that used to, and potentially still could, generate and provide power to the New Vegas Strip and the regional power grid. It also contains the control system for two experimental satellite weapon systems, ARCHIMEDES and ARCHIMEDES II.


Before the War

Established before the Great War as a next-generation solar power plant, hailed as the Dawn of a Golden Age, HELIOS One was more than just a renewable source of energy. It doubled as a research and development facility for the U.S. Army's top-secret orbital energy weapon, ARCHIMEDES. Having joined the "Poseidon Family" when they began work, employees of HELIOS One were expected to keep company projects a secret, as carelessly discussing developments could pose a threat to national security if the communists got wind of Poseidon projects.[2]

The military side of affairs was handled by Brig. Gen. Scott Lowe, who oversaw the testing of the weapon on site.[3] Tests of ARCHIMEDES were successful, but caused a 2.5-minute downtime at the facility and system-frying power fluctuations in nearby installations, including Hidden Valley and Black Mountain. Further development was precluded by the destruction brought by the Great War.[4][5]

Operation: Sunburst

After centuries of disuse, the Brotherhood of Steel discovered the facility. The occupation of HELIOS One was a decision made by Elder Elijah who intended to unlock the secrets of the power plant. The Mojave chapter operated freely amid the Vegas wastes for several years, carrying out many reclamation missions without serious opposition.[Non-canon 1] By 2274, the war between the New California Republic and the Brotherhood had broke out, with the former officially setting up a base at McCarran International Airport and eventually setting its sights on the solar plant. Elijah, still believing that the plant contained an unprecedented military advantage, refused to leave the plant, and forced the paladins to continue defending it. Two years of guerilla fighting against the NCR followed, culminating in Operation: Sunburst in 2276.[Non-canon 1]

The NCR launched the operation to capture HELIOS One, and a pitched battle took place. Despite the Brotherhood being in possession of far superior equipment, such as energy weapons and power armor, they were severely outnumbered, had no reinforcements to replenish their losses, and were gradually worn down by the NCR's attacks. By the time the retreat signal was given by Paladin McNamara, more than half the chapter had died, and Elder Elijah disappeared without a trace. As the NCR seized HELIOS One, the remaining Brotherhood defenders retreated to Hidden Valley and hid themselves away in the underground bunker, evading destruction from the pursuing NCR forces.[Non-canon 2][6]

Under NCR control

As NCR soldiers explored the interior of the plant, they discovered that the Brotherhood had disabled the plant and activated the solar towers security systems to keep the NCR away from the main controls.[7] Unwilling to divert manpower and resources towards such a hazardous undertaking, and with no way of remotely shutting down the security system, the NCR command ordered the tower to be on lock-down, and had it secured in a way that required permission from two separate security terminals before it could be entered.

The NCR established a firm foothold in HELIOS One and its vicinity, although due to a stroke of bad luck, an incompetent chem addict managed to con them into hiring him as the facility's principal engineer. He was unable to bring the facility to even moderate operational status, leaving it stuck at 1% efficiency.[8] Ignacio Rivas was posted by the Followers of the Apocalypse to research the facility independently, and ensure that the addict hired by the NCR would not discover the facility's purpose in developing a weapon.


Power plant

The power plant is a large pre-War industrial complex, serving as an NCR stronghold in the area. Several NCR troopers patrol the perimeter and a small detachment guards the entrance to the facility. Access to HELIOS One is gained by speaking with Lieutenant Haggerty at the main entrance or by picking the lock of a side door. Another way to enter through the front entrance is to use a Stealth Boy to sneak inside.

The lower level of the building consists of several winding hallways leading to a pool room, where a unique toolbox that spawns either a sawed-off shotgun or a 10mm pistol can be found on a nearby shelf. Traveling further into the building will lead the Courier to the plant's "technician," Fantastic, who is struggling to bring the power plant to a functioning state. The room adjacent to Fantastic's contains a scientist, Ignacio Rivas. A nearby door leads to the mirror yard.

Mirror yard

Behind the main building are the solar collection tower and an array of computer-controlled mirrors. There are 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 NCR attack dogs. There are also a number of broken solar panels that can be collected for the Sunshine Boogie quest. The solar panels are located near the tents behind the western terminal, along the outer row and the fence towards the eastern terminal, and by the tents near the eastern terminal.

Solar collection tower

Inside the solar collection tower are three hostile automated turrets and several level-dependent security robots. At lower levels several Protectrons and a single Mister Gutsy prototype will spawn, while at higher levels a mix of Protectrons, one robobrain, Mister Gutsies and sentry bots will spawn. Moving forward leads to the 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 alternatively activated to fire at all targets, including the security robots. Near the entrance is a water fountain with no radiation. Downstairs is a room with two pulse grenades on a shelf, and an Average locked safe containing more pulse grenades and pulse mines in addition to miscellaneous loot.

The hallway 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, entering into another multi-level room with stairways and catwalks, guarded by a Mister Gutsy.

At the bottom of the catwalks, past the Mister Gutsy, is a door leading to a corridor that branches left and a shorter one to the right ending at a door. The corridor to the left contains a single Protectron in a shielded charging station. Next to the station is a laser tripwire door, disarmed with an 85 Repair or 67 Science skill. The room beyond contains four more Protectrons in shielded charging stations. The tripwire releases the shields and activates all five robots. The door to the right in the initial corridor opens into a room containing some desks, skeletons, and two Poseidon Energy employee ID cards. Both paths have doors that adjoin the final room, which contains an elevator leading 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. There is a door at the top level that leads to the observation deck. A desk by the generator has a wooden box with embossed red symbols([!]-[X]-[H]-[A]-[H]-[X]-[@]) on it. It cannot be picked up but may be interacted with.

Observation deck

This is a circular deck circling 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 the quest That Lucky Old Sun.

Notable loot

Helios One loc map.jpg

Solar collection tower map

  • D.C. Journal of Internal Medicine - Upstairs in the main building, lying on a bed in the same room with the reflector control terminal password, found by heading to the right from the main entrance, through the pool room, and up the stairs.
  • Big Book of Science - Acquired from Ignacio Rivas during the That Lucky Old Sun quest, if the Courier chooses to distribute the energy to the full region along with a large number of Followers of the Apocalypse fame.
  • Poseidon Energy employee ID card - In the solar collection tower, on the bottom floor, in the room just prior to the elevator. It is on the floor next to a skeleton in the corner.

Related quests


  • If the ARCHIMEDES is activated, all NCR troopers stationed at the plant will be killed. Subsequently, Caesar's Legion will occupy HELIOS One two days later and will hold it until the end of the game. One of the Legion recruits will mention that in his opinion they do not even need the plant, they are just holding it to scare the NCR. They still keep Fantastic on hand though, suggesting they want to keep the station operational.
    • Even if the Legion takes over the plant, the player's reputation with the NCR will still be affected by actions taken within the plant, such as stealing owned items.
    • If Arcade Gannon is a companion when ARCHIMEDES is activated, he will leave the Courier's party, and he will never be recruitable again. Depending on the player's response, he may even attack. Arcade has no such reaction upon activating ARCHIMEDES II, however.
    • Although the Legion occupies HELIOS One after ARCHIMEDES is activated, no Legion fame is awarded. Nevertheless, Caesar will mention this upon the Courier's first trip to the Fort.
    • The ending slides reveal that under certain circumstances the Brotherhood of Steel or NCR will retake it after the events of the main game.
  • The observation deck is considered an outside location, so the player character can fast travel from there. It is not recommended to do so during the ARCHIMEDES startup sequence, as this can cause glitches.
  • Inside the fenced in area that holds terminal 2, an invisible wall exists near the gate until the gate is opened. If the Courier jumps over the fence before opening the gate, they will not be able to get close enough to open it from the inside.
  • If the Courier sides with Father Elijah during the add-on Dead Money, a special cutscene is shown at the end explaining that Elijah makes widespread use of holograms along with the lethal effects of the Cloud to kill all living things in the Mojave Wasteland before turning on the NCR. It also mentions HELIOS One was returned to full operational capacity.
  • Above the solar collection tower, a Mark II/IV/VI/VIII turret with a Stealth Boy cloak can be found. It won't attack the Courier and cannot be destroyed. It causes a red tick mark around the tower.
  • Being seen attempting to enter the facility without clearance will turn the guards hostile.
  • The hologram map in the ARCHIMEDES room is a map of the Capital Wasteland from Fallout 3, with some of the pyramid shapes on the map representing Raven Rock, Vault 101, Megaton, Rivet City, the Mall and the Citadel.
  • There are two smaller than average lockers located in a hallway near the room where Fantastic can be found.
  • God (from Dead Money) is aware of HELIOS One and expresses disbelief that Elijah wanted to harness the power of the sun to use it as a weapon.


HELIOS One appears only in Fallout: New Vegas and is mentioned in Dead Money.

Behind the scenes

  • HELIOS One is located in the same geographical area as the real world Nevada Solar One, southwest of Boulder City, Nevada along Highway 95. The facility bears a strong resemblance to the Ivanpah Solar Power Facility located along Interstate 15 near Primm, Nevada.
  • In Greek mythology, Helios was the god and personification for the sun. The Greek word Ἥλιος translates to "sun."
  • The password for the western tower computer terminal is in hexadecimal, "Too many secrets", and the password for the eastern terminal is also in hexadecimal, "My voice is my password." Both of these passwords are references to the movie "Sneakers."


  • Playstation 3Playstation 3 Xbox 360Xbox 360 The NCR will be hostile towards the Courier, even if they have achieved "Idolized" status.[verified]
  • Xbox 360Xbox 360 Protectrons within the room with the laser tripwire seem to be immune to explosive damage. [verified]
  • PCPC Xbox 360Xbox 360 Disarming the laser tripwire with the Science skill does not prevent it from opening the forcefields and letting other Protectrons out to attack the Courier. [verified]
  • PCPC The hostile Protectrons in the blue glowing holding containers can be disabled with Robotics Expert while inside the container. Somewhere between the waist and the feet, the cursor will typically change to red and you can "activate" the Protectron and receive the option to disable it, as usual with the Robotics Expert perk. [verified]
  • Playstation 3Playstation 3 The southwest room with the Mister Gutsy has two filing cabinets occupying the same place next to the sink. [verified]
  • Xbox 360Xbox 360 When entering the area with the solar panel, the Courier may be attacked by a few of Old Lady Gibson's dogs, including Rey, Colmillo, Basura, and Audaz, as well as a couple of mole rats. It is also possible to witness Old Lady Gibson appearing along with her dogs. Reverting to a previous autosave will prevent this, but reverting to a hard save (not auto) will make this occur. It is also possible to be attacked by just mole rats. It is also possible to obtain the Big Boomer Shotgun, from killing Old Lady Gibson [verified].
  • Xbox 360Xbox 360 Old Lady Gibson's dogs may alternatively spawn at the back door facing the tower and become hostile. [verified]
    • Xbox 360Xbox 360 Also seen once where dogs were not hostile, but Gibson was sitting in mid-air. Also, upon exiting HELIOS One there were sounds of metal objects colliding with one another. Upon looking to the ground the cursor displayed info on multiple junk items, such as paint guns and tin cans. However, these items were invisible. [verified]
  • Xbox 360Xbox 360 Any Protectrons deactivated prior to setting off the laser tripwire may reactivate and become immediately hostile. However, this does not prevent them from being deactivated a second time.[verified]



  1. Order of Withdrawal
  2. HELIOS One terminal entries, terminal, "Can I Tell Him?"
  3. HELIOS One terminal entries, terminal, terminal 1 and terminal 2, Upcoming Visit
  4. HELIOS One terminals, terminal, ARCHIMEDES Testing
  5. HELIOS One terminals, terminal, Results
  6. The Courier: "I thought the Brotherhood were all wiped out at HELIOS One. How could they have survived?"
    Cassandra Moore: "After the battle, we consolidated our hold on the plant before pursuing our enemies. It was a mistake, to be sure, but there wasn't really any place for them to go. When we finally gave chase, however, they had simply vanished. Some of our people think they had some means of conveyance, like the vertibirds the Enclave used, and hightailed it out of here. I think that they found someplace to hide close to HELIOS, and never went that far at all. Any other questions?"
    (Cassandra Moore's dialogue)
  7. The Courier: "Why would you trust me with this?"
    Ignacio Rivas: "I'm a man of letters. I'd be torn to pieces by the security system they have in that tower. I'd never reach the mainframe. But eventually the NCR will, or if not them, Caesar's Legion. They will use this place for war. Because the possibility exists you might do anything else, you're the only choice I have."
    (Ignacio Rivas' dialogue)
  8. The Courier: "What are you trying to accomplish?"
    Fantastic: "Well, see, we're getting power, because the guy running this place is Fantastic. But the mirrors outside aren't aimed right, so we're running at one percent efficiency. And I guess that just isn't good enough for some assholes. Trouble is, most of the controls for this place aren't here - they're in the tower. And that place has some crazy Pre-War security system that the dumbshit NCR set off when they took over. Killed two guys. Now they won't go near it. They want me to make an omelet, but I can't break any of their eggs, know what I'm saying?"
    (Fantastic's dialogue)


  1. 1.0 1.1 Fallout: New Vegas Official Game Guide Collector's Edition p. 43: Brotherhood of Steel
    "The Brotherhood of Steel is a militant organization devoted to the preservation of pre-war technology and human knowledge. Their professed mission is to preserve pre-war technology and human knowledge for the benefit of future generations. In practice, its definition of technology is strangely selective, ignoring basic but potentially useful technologies (genetic modification of crops and civil engineering, for example) in favor of combat technology such as energy weapons and power armor: and even now, nearly two centuries after the Great War, the Brotherhood zealously restricts the use and knowledge of such technologies to its own membership.
    The Mojave Brotherhood operated freely amid the Vegas wastes for several years, carrying out many reclamation missions without serious opposition. The balance of power shifted in 2251, when a large contingent of NCR troops entered the region and occupied Hoover Dam. Conflict was inevitable. Nearly two years of guerrilla skirmishes culminated in a pitched battle at HELIOS One, a solar energy plant the Brotherhood had been refurbishing for several months with the goals of bringing it back online and activating its hidden offensive capabilities, ARCHIMEDES. The battle for HELIOS One (Operation: Sunburst) proved a disaster for the Mojave Brotherhood. More than half its Paladins and Knights were killed. The chapter's leader, Elder Elijah, disappeared without a trace. The Brotherhood was driven from the facility, which suffered extensive damage. Survivors retreated to Hidden Valley.
    Since that defeat, the chapter's leader, Elder McNamara, has restricted activity outside the bunker to occasional reconnaissance missions and high-value raids. All operations take place at night, and engagement of NCR forces is strictly forbidden. Though the Brotherhood's ascetic lifestyle has prepared its members for a sequestered existence better than most, the passivity of their current situation has proved highly stressful."
    (Fallout: New Vegas Official Game Guide faction profiles)
  2. Fallout: New Vegas Official Game Guide Collector's Edition pp. 404-406: [5.13] HELIOS One
    "Constructed Pre-War by Poseidon Energy, HELIOS One is a concentrated solar energy plant consisting of an enormous array of reflectors and the power plant itself (housing steam turbines and all of the machines required to transform the energy into usable electricity). The plant has been damaged extensively since the war (including recent incursions between the NCR and the remaining Brotherhood of Steel forces in the Mojave). Now, only a third of its reflectors still fully intact and able to fully rotate. To make matters worse, various issues in the plant itself make the energy transfer inefficient, meaning the plant is operating far under potential. NCR doesn't possess the scientific knowledge to get the plant in ideal shape and both the Followers of the Apocalypse and Brotherhood of Steel are reluctant to help for political reasons. Due to its fragility, Caesar has no serious interest in HELIOS One, but his troops perform occasional raids on it to keep NCR's forces spread out."
    (Fallout: New Vegas Official Game Guide Collector's Edition Tour of the Mojave Wasteland)