That Lucky Old Sun

 is a quest in Fallout: New Vegas.

Quick walkthrough
You head to Helios One and talk to the guards outside. They Direct you in to find some crazy scientist name Fantastic. He tells you that the mainframe controls need to be connected and the mirrors have to be fixed. You head out side and fix the mainframe (Watch out when you go to the objectives, there are many booby traps all around). When you go to the last terminal, there are 3 NCR guard dog's waiting inside. once you get past them you have to hack the terminal, which is a HARD lock.

Detailed walkthrough
When you first approach the HELIOS one station from the south, you will automatically start a conversation with [female NCR officer] with either a successful speech check or a science skill option 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, fallowing your 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 fantastic, who explains that he got his position at the power plant when the NCR was desperate for anyone to work with. among other things you will learn the password to the computer for the western set of mirrors, and he asks that if you do get the power running, that you direct it to New Vegas. Next you must speak to [scientist] in the next room. he will explain that the HELIOS 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. Be Careful!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 and fight your way through gun-turrets and protectrons till you get to the bottom of the basement, were their is a working elevator that takes you to the top of the tower, and the mainframe.

It says here that the eastern password was from [scientist], but i found eastern password on a desk on the second floor, there is a staircase iat the end of the hallway to the right of the front desk that takes you to the second floor, then the password looks like a holotape and is sitting on top of the desk.