(CNN) -- Going behind the scenes at Kennedy Space Center is like visiting another planet. The employees working on the shuttle fleet speak their own language -- a language made up of acronyms.
Space shuttle Discovery is scheduled to launch Wednesday evening.
The orbiter is maintained in the OPF (orbiter processing facility) before it goes to the VAB (vehicle assembly building), where the ET (external tank) and SRBs (solid rocket boosters) are attached to it.
As NASA prepares for the scheduled launch of the space shuttle Discovery about 9 p.m. Wednesday, Kennedy Space Center employees have been busy keeping the shuttle fleet in tip-top condition. CNN visited the facility recently to learn about shuttle maintenance and launch preparation.
In the orbiter processing facility, the team was readying the orbiter Atlantis, which is scheduled for flight after Discovery's mission to the international space station. Atlantis' first launch was in 1985, and it has flown 29 times.
This processing facility is a hangar where employees thoroughly inspect the orbiter. The vehicle is towed into the building, where it is surrounded by platforms that are several stories high, allowing access to all parts of the craft. Watch a NASA astronaut talk about the upcoming launch »
The entry of dirt, dust and debris into the facility is a concern that goes by the acronym FOD, or foreign object debris. There are workers who pass the day wiping down the steel structure with alcohol.
"The minute we go into zero gravity, the astronauts are now breathing it and eating it," said Terry White, a project lead for the United Space Alliance.
Instead of a welcome mat, people entering the orbiter processing facility walk on a piece of sticky tape that picks up dirt and debris from the soles of their shoes. Anyone entering the building must also "tether," or tie eyeglasses on and tape watches to wrists to ensure that loose items are not dropped. Even the smallest item can become a problem in zero gravity. See what it takes to keep the shuttle fit to fly »
White explains that something as tiny as a washer could short out an electrical component in the shuttle.
"You know, you get a short in your car, you can pull over to the side of the road. There's no place to pull over up there," White said, a line he has surely used before.
After each flight, the orbiter's engines are removed and sent to another building to be refurbished, and the main tires are replaced.
"The orbiter sees an average of about 4½ million miles in each flight," according to White. "The tires get rolled on the ground less than 10 [miles], and we replace them."
The orbiter's tires are specially made and are slightly larger than the tires on a freight hauling truck. The orbiter touches down on its main landing gear tires, and then the drag chute opens before the nose tires hit the runway.
Because the runway is grooved and the tires slick, the weight of the shuttle puts tremendous stress on the main gear tires, wearing them down after one landing. Since there is less stress on the nose tires, they are usually replaced after two flights.
Atlantis has more than 20,000 small individually numbered tiles attached to its belly to shield the orbiter's body from heat. Some of the tiles experience temperatures up to 3,000 degrees Fahrenheit during re-entry. White says each one is inspected several times.
"We have quality [control personnel] that do it with their eyes and with flashlights and 10 times magnifying glasses, if required."
The inspectors are looking for any nicks, gauges and other defects. A couple hundred tiles are removed and replaced after each flight.
Another thing White says people don't realize: "There's 600 panels that come on and off as part of processing the orbiter." These panels cover everything from avionics compartments to wiring, and Atlantis has more than 200 miles of wiring on board.
Once the team in the processing facility is finished checking, maintaining and refurbishing the orbiter, it is sent over to the vehicle assembly building (VAB). This is where the orbiter will be "mated" with the solid rocket boosters and the external tank on its final stop before the launch pad.
At 525 feet high and covering 8 acres, the assembly building is one of the largest buildings in the world. The orbiter is towed into the building with precision, as there are only a few inches of clearance between the wings and the building.
Once inside, the vehicle is lifted to a vertical position by a bridge crane. There are four cranes in the building, and two are strong enough to pick up 105 full-grown elephants each.
Crane instructor Del Dewees says it takes two years to train those responsible for lifting and stacking the orbiter. Sitting 467 feet in the air, the crane operator works blindly. And that's the easy job, Dewees said.
"The hard part is the guy down below telling you what to do. You got a ground controller -- he's your eyes; he's your ears; he's everything."
The external tank is the heaviest and largest part of the shuttle. Filled with liquid hydrogen and oxygen, it powers the shuttle's main engines.
Seven minutes into the launch at main engine cutoff, the tank detaches and re-enters the atmosphere in pieces that land in the Indian Ocean. The two solid rocket boosters (SRBs) burn for only the first two minutes of the shuttle's flight.
The orbiter is lowered vertically onto the solid rocket boosters and the external tank to complete the shuttle. This process takes a day and a half, according to Dewees.
Once assembled, the shuttle is 76 feet high and 184 feet long. A "crawler-transporter" moves the massive shuttle to the launch pad. This huge metal platform would take up about eight lanes in a freeway.
While Atlantis sits in the vehicle assembly building, space shuttle Discovery sits on the launch pad, awaiting liftoff. The orbiter can barely be seen more than 12 hours before launch as it is encased in a rotating service structure.
The service structure allows for access to the cargo bay and is used to install payload. The payload can be anything the shuttle is carrying into space, from science experiments to new hardware and components for the space station.
The structure isn't the only thing on the pad for protection; a 24-hour birdwatcher is also keeping an eye on the shuttle.
"They're actually just making sure there are no birds actually getting on to the ET tank to cause any problems," said Christopher Liones, a launch pad manager.
In 1995, a woodpecker caused the delay of Discovery's launch when it pecked holes in the foam insulation on the external tank. Like the tiles, this insulation is part of the shuttle's thermal protection system, protecting the orbiter from heat.
Liones says the birdwatcher on duty is equipped with a horn to scare birds away. The loud noise will usually do the trick, but if that doesn't work, a plan will be devised to safely remove the birds from the vehicle.
When the astronauts enter the shuttle on the day of the launch, they will have a beautiful view. Wednesday's launch is at night, and the astronauts will be able to see the lights of cities up and down the coast. During a daytime launch, the pristine nature reserve and the Atlantic Ocean are visible.
Travis Thompson, a member of the Close Out Crew, one of the last people the astronauts see before liftoff, would know whether they stop and appreciate their last moments on Earth.
When asked whether any astronaut has had a last-minute change of heart, he said, "they do. Sometimes they get up here, and they think about it."
"I won't mention any names," he said, laughing.
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