That Lucky Old Sun

 is a quest in Fallout: New Vegas. It is also an achievement on the Xbox 360 and PC; and a bronze trophy on the PlayStation 3.

Background
The solar power station Helios One is apparently important to multiple factions in the Mojave Wasteland. When the player first encounters it, it is held by the NCR, who are having trouble getting it to produce very much power. The NCR acquired it by force from the Brotherhood of Steel, who fought hard to keep it. The Followers of the Apocalypse have an interest in it as well, and Caesar's Legion would certainly like to gain control of it.

Initiating the quest
At the entrance on the south side of Helios One is an NCR officer named Lt. Haggerty, who is the head of the NCR detachment guarding the plant. The player can ask her for access to the plant. She is inclined to turn the player away, but the player can convince her otherwise via several options:
 * Speech 30 - Lie and say the player's brother works there.
 * Science 30 - Point out that the tower isn't working right, and offer to help.
 * If the player's NCR reputation is more positive than negative, or with speech 35 or more, the player can claim to be with the NCR and be let in.

Once the player has convinced her, she tells the player to talk to the "idiot wearing sunglasses".

Optionally, the player can sneak in through a back door with a very easy lock. From there the player should find the idiot with the sunglasses, Fantastic, and talk to him to begin the quest.

Fantastic is his name
In the back of the plant is a science lab of sorts, where Fantastic and Ignacio Rivas are trying to get the output of the plant up. Fantastic is a transparent fraud who clearly has no idea what he's doing. Rivas is an actual scientist, but is really working for the Followers of the Apocalypse, who worry that the plant is not merely a power plant, but a pre-war super-weapon. As it turns out, they're right; it is.

Fantastic and Rivas explain that to get the plant running, the remote mirror control systems need to be connected to the mainframe, and then the mirrors retargeted from the mainframe terminal in the plant itself. The two mirror control terminals require a password. Each man holds a password for one of the two mirror control terminals. Fantastic will give his up easily enough, but Rivas will only give the player his if the player gains his trust by professing to be peaceful (or at least not violent), or if the player claims to be with the Brotherhood of Steel. The player can also pickpocket the password from him, or a duplicate password can be found in a second floor office, lying on a desk. Note that Fantastic's password is not in his inventory; it must be obtained via dialogue.

The outside terminals
Both terminals are inside small shacks on the outer perimeter of the mirror field. The west mirror control terminal requires the password obtained from Fantastic. The east one can be unlocked with the password obtained from Ignacio Rivas or from the office of the main building, or is hard locked and can be hacked with 75 science.

The western shack has multiple traps, including three Frag mines, a rigged shotgun with a tripwire, and two bear traps. Once the traps have been disarmed or avoided, the terminal just needs to be activated and "Reset Mainframe Connection" selected.

The eastern shack contains several hostile NCR guard dogs. It is possible to kill them or let the player's companion kill them without resulting in aggression from the nearby NCR soldiers, but this is not guaranteed; killing them can result in hostility from the soldiers. It may be wiser to use a stealth boy to sneak past them. Another strategy that may work is to open the gate, then leave the area and come back. The dogs may attack NCR soldiers and be killed.

This second terminal is activated just like the first, via selecting "Reset Mainframe Connection".

Get to the mainframe
The player then enters the tower via a door near the base. Just past the door and a short hallway is an area with multiple turrets and hostile robots. By moving quickly to a door across from the entrance hall, the player can reach a easy terminal that can shut off the turrets or make them attack the robots indiscriminately. (Warning: there are frag mines in the room with the terminal.) Once the robots and turrets are done killing each other, the player then can mop up the survivors.

The player then must wind through the rest of the building, destroying many robots along the way, until arriving at an elevator in the basement that takes the player to the observation level. Along the way it is handy, but optional, to get a Poseidon Energy Employee ID, of which there are two, both lying on the floor in a room adjacent to the room with the elevator. There is a door in the elevator room with an average lock that leads to the room with the IDs, or the player can go back through a room filled with robots and down a hall to reach the back door of the room.

Repair the mainframe
The observation level contains not much more than the mainframe itself and stairs to reach the exit door to the outer viewing deck. The mainframe is not working, as it doesn't have enough power because the attached generator is malfunctioning. The player can either repair the generator with a piece of scrap metal and 35 repair, or can go up the stairs to find a maintenance bot called Python, which can be activated with a Poseidon Energy Employee ID or with 45 science skill. Once activated, the robot will repair the mainframe.

Choose a side
The terminal on the mainframe contains some notes the player has probably already seen on previous terminals in the building, and an option Configure Power Grid. Selecting it reveals 5 options:


 * 1) McCarran and Las Vegas. This is what the NCR wants.
 * 2) Fremont and Westside. This pleases the Followers of the Apocalypse, though not as much as if the power went to everyone.
 * 3) Full region. The terminal will warn of brownouts, but at least everyone gets a little power. This is the best solution from the Followers' point of view.
 * 4) ARCHIMEDES II. This diverts power to the next-generation space laser system mentioned in the terminal notes and will give the player the option of calling down space-laser strikes once per day, provided the player has also obtained Euclid's C-Finder. Strangely, the Followers of the Apocalypse will still be happy with this solution.
 * 5) Full Region (Emergency Output Level). This overloads the plant, which prevents Archimedes I from being activated (about which see further notes). This gains no reputation with any faction, but Ignacio Rivas will still give the player some rewards.

Once one of the 5 options has been selected, the terminal returns to the main menu. A new option comes up at this point, Arm ARCHIMEDES Plant Defense System. If it is activated, then the Archimedes I plant defense system will be triggered as soon as the player activates the Reflector Control Panel on the outside of the tower. Doing so will call down a laser strike on the area around the plant (unless power option 5 was selected), killing all the NCR personnel in the area. The result will be massive infamy gain with the NCR and no rewards from either Fantastic or Ignacio Rivas, even if the power is diverted to their preferred location. (It is a nifty sequence, so choosing it at least once is recommended, even if the player chooses to reload a previous save game afterward.)

Until the choices are locked in by activating the Reflector Control Panel, the status of the Archimedes I defense system can be changed and the options for where the power goes can be changed.

Time to switch it on
Once the player has chosen the final power grid disposition and whether to activate Archimedes I, the final step is to go up the stairs and through the door to the outside of the tower. The Reflector Control Panel is down a spiral ramp to the left. Once the player activates the control panel, one of three things will happen:
 * If the player has chosen to activate the Archimedes I defense system, and has chosen option 5 (overload) for the power grid, horns will blare and a warning will play about the imminent weapon test, but shortly thereafter everything grinds to a halt. If the player is trusted by Ignacio Rivas, they can now go talk to him to receive awards. Otherwise the quest ends.
 * If the player has chosen to activate the Archimedes I defense system, and has chosen any of options 1-4 for the power grid, the horns blare and warnings sound, and this time everything works perfectly. All of the NCR troops in the area of the plant (inside and out) are obliterated in a massive display of pyrotechnics. The quest ends and the player gains NCR infamy. Fantastic and Ignacio Rivas will not have been killed, but will refuse to talk to the player. If the player goes away for two days after this and returns, the plant will be occupied by Caesar's Legion, who have stepped in to fill the void.
 * If the player has not chosen to activate Archimedes I, but has chosen any power grid option, the plant powers up.
 * If the player chose anything other than option 1, and is not trusted by Ignacio Rivas, the quest will end.
 * If the player selected option 1 (McCarran and the Strip), they can talk to Fantastic, who will be thrilled, claim all the credit, and give the player nothing. The player will gain a lot of NCR reputation.
 * If the player selected option 2 (Fremont and Westside), and are trusted by Ignacio Rivas, they can talk to him to get 3 Stimpaks, 2 Doctor's bags, and a moderate amount of Followers of the Apocalypse reputation.
 * If the player selected option 3 (Full Region), and are trusted by Ignacio Rivas, they can talk to him to get a Big Book of Science, 3 Stimpaks, 2 Doctor's bags, and a large amount of Followers of the Apocalypse reputation.
 * If the player selected option 4 (Archimedes II), and are trusted by Ignacio Rivas, they can talk to him to get a 2 Stimpaks, a Doctor's bag, and a small amount of Followers of the Apocalypse reputation. Apparently they're just happy the NCR isn't hogging all the power.
 * If the player selected option 5 (Full Region, Emergency Output Level), and are trusted by Ignacio Rivas, they can talk to him to get 3 Stimpaks, 2 Doctor's bags, and no reputation gain.
 * No matter how the quest ends, the player gains 350 xp.

Behind the scenes

 * The title of this quest is a reference to a 1949 song, "That Lucky Old Sun", by Beasley Smith and Haven Gillespie.
 * The passwords to the Eastern and Western Reflector Control Terminals can be converted from hexadecimal into ASCII, producing the phrases "My voice is my passport." and "Too many secrets". The phrases are originally from the movie Sneakers (1992), starring Robert Redford. They were used as computer passwords in that movie.

Bugs

 * When the player sets the power to Full Region (Emergency Output Level), then tells Ignacio that "I overloaded the plant. No one will be able to use it to power a weapon.", the option will stay and can be used over and over to get XP and loot.
 * Sometimes the quest finishes with no rewards, even if the player didn't activate Archimedes I.
 * Not necessarily a bug. If the player isn't trusted by Rivas, then no rewards are forthcoming from him (see walkthrough).
 * It is advised that you tell ED-E to wait outside of the Helios One tower, as it is possible for him to get stuck in the pipes on the ceiling in certain places.
 * Sometimes do not get the lockpick and/or terminal interface when trying to lockpick or hack terminals.
 * Seen on PC on other doors/terminals; probably global bug.
 * If you are doing the NCR quest chain and go to Hoover Dam to talk to the Commander before you finish That Lucky Old Sun, Fantastic will be there instead of Helios One, meaning it is impossible to finish if it tells you to talk to Fantastic. Sometimes, it actually seems to work to go to the Hoover Dam and simply kill Fantastic to complete the quest. The guards will not get hostile if this trick works. Unclear however, how this fix affects any further quests.
 * Random creatures such as Mole Rats or Old Lady Gibson and/or her dogs may spawn outside the back door when leaving the main building.
 * After enabling Archimedes I Defense System, if the player fast travels away before the sequence finishes, the NCR will not be killed and the infamy will not be gained.
 * Note that if the player returns to the area, the sequence will eventually complete and the infamy with the NCR will be raised. Also note that activating the Archimedes I system is optional; it doesn't do anything useful other than kill a bunch of NCR, so if the player doesn't want to kill NCR, the best solution is not to activate it in the first place. Archimedes II is separate, and can still be powered without harming the NCR.
 * Choosing to disarm the Archimedes defense system after activating it may not work; the sequence may play anyway.
 * Test firing Archimedes laser can cause the game to freeze.
 * If the player leaves the room after activating Python, but before he does the fixes to the generator, he will be deactivated when walking back inside again, and will not perform the fixes
 * Solution: don't do that.

Video
thumb|300px|left|note: this video is part 1 of 3 thumb|302px|right|Infinite XP, Stimpaks, and Doctor Bags