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.

Objectives and Walkthrough
When you first approach the Helios One station from the south, you will be approached by a female NCR officer by the name of Lt. Haggerty. With either a successful speech check, a science skill option, or good reputation with the NCR you can convince her to allow you inside, and that you should talk to the "idiot wearing sunglasses".

Proceed to the back of the factory, following the compass. You will soon come across a door with a light above it; this leads to the NCR's de-facto science lab at the power station. The "Idiot wearing sunglasses" is a man by the name of Fantastic, who explains that he got the job by lying to NCR when they were going door to door, asking if anybody knew a scientist.

You will get the password to the other (western terminal) from him and the place you can direct the power to. Next you must speak to Ignacio Rivas in the next room. He will explain that the HELIOS One-station is not only a power plant, but also a developmental facility for a weapon known as "ARCHIMEDES", and that he has kept the NCR in the dark about the weapon, fearing what they may do with it. He will also give you the password for the eastern set of mirrors, and explain that you must go to the control computers for the mirrors, attempt to reconnect with the mainframe, then go to the mainframe to redirect the mirrors, and direct the power.

Proceed out the back door into the mirror field, and head for the control computers, which are each located in small shacks nestled among the mirrors. The shacks are guarded with traps and attack dogs, and can be dangerous, and possibly lethal to an unwary player. After you reset the mirror control computers, you must enter the tower through a door at the base. If you go straight (quickly) and make it the door (past the turrets) you can hack a terminal to turn off the Mark III turrets. (Note: disabling the turrets does not disable the Protectrons.) Or you can simply fight your way through Mark III Turrets and Protectrons till you get to the bottom of the basement, where a working elevator takes you to the mainframe.

NOTE: You need at least 35 Repair to access the mainframe due to lack of sufficient power which requires you to use an auxiliary generator next to the mainframe. Or if you go to the upper level of the same room, towards the back there is an offline Mr. Gutsy named Python, which you can interact with if you possess a Poseidon Energy employee I.D. or having at least 45 Science, the robot will then fix the generator for you.

NOTE: To find the Poseidon Energy Employee I.D.:  After entering the tower eventually you will come to a long tunnel. After going down the long tunnel turn left, and left again. You will have to fight a sentry bot, Mr. Gutsy and Protectron to get through. Then there will be a set of metal stairs. Descend the stairs and enter the doorway. Take the hallway right, this will lead to offices on the left. Around the corner and to the right of the first one there is a half skeleton, right next to it is the Poseidon Energy employee I.D. If you are backtracking from the generator room then simply go back through the metal door, through the room with the bunker and go to the left side of the left room.

NOTE: The eastern terminal password can also be found on a desk on the second floor. Go right from the front desk, to a staircase to the second floor and take the holotape that is on a desk.

Time for some choices.

McCarran and Las Vegas Strip
Select the first option, "McCarran and Las Vegas Strip", exit the mainframe, take the stairs up and follow your compass to outside. Once outside, go down the spiral stairs and activate the Reflector Control Panel and enjoy the show. After your screen turns normal, go back to Fantastic and listen how he tells you he's going to take most of the credit. This will get you 350 XP and New California Republic reputation.

Fremont and Westside
Select the second option, "Fremont and Westside", as your grid configuration, go outside and activate the Reflector Control Panel to enjoy the show. When you have seen enough, return to Ignacio Rivas to be congratulated on your well made choice. He will tell that hopefully NCR's curiosity in the plant has been satisfied and they won't dig any deeper. You will gain 350 XP, 3 Stimpaks, 2 Doctor's Bags and a moderate amount of Followers of the Apocalypse reputation.

Full region
Select the third option, "Full region", as your grid configuration, go outside and activate the Reflector Control Panel to enjoy the show. When you have seen enough, return to Ignacio Rivas to be congratulated on your very admirable choice. He will tell that hopefully NCR's curiosity in the plant has been satisfied and they won't dig any deeper. You will gain 1 Big Book of Science, 350 XP, 3 Stimpaks, 2 Doctor's Bags and A LOT OF Followers of the Apocalypse reputation (this will get you to the status of Accepted if you haven't had a previous encounter with them).

Archimedes II
Select the fourth option, "Archimedes II", as your grid configuration. A new menu item called "Arm ARCHIMEDES II Plant Defense System" will appear. If it is chosen, an alarm will sound warning personal to get inside. Go outside and activate the Reflector Control Panel to enjoy the show. When you have seen enough, return to Ignacio Rivas. Ignacio won't interact with you and Fantastic will yell at you for killing his employers. You will gain 350 XP and the ability to use the Archimedes II as a weapon if you acquire the Euclid's C-Finder. You will lose reputation points with the NCR and you will not receive any of the rewards from Ignacio. Alternatively you can activate the Archimedes II without the defense grid granting the same reward as full region (emergency output) while still being able to use the Euclid's C-Finder.

Full region (Emergency output level)
Select the fifth option, "Full region (Emergency output level)" as your grid configuration, go outside and activate the Reflector Control Panel to enjoy the show. When you have seen enough, return to Ignacio Rivas who will be disappointed of all the energy wasted, but he will be relieved as the plant can not be used as a weapon anymore. You will gain 350 XP, 3 Stimpaks, 2 Doctor's Bags and Followers of the Apocalypse reputation. However, you will also lose some NCR reputation.

Bugs

 * Full Region (Emergency output level) has a glitch. When you talk to Ignacio and tell him that "I overloaded the plant. No one will be able to use it to power a weapon.", the option will stay meaning that you can get infinite Experience Points, Stimpaks, Doctor's Bags. Confirmed on xBox 360. Update: works on PS3 too.