2. Once the ensemble lands in Florida, you’ve got to get the shuttle off the back of the jet, which is done with a special “Mate/Demate Device.” An identical device in California is what put the shuttle on the jet in the first place.

3. From the runway at Kennedy Space Center (KSC), the shuttle gets towed to the Orbiter Processing Facility (OPF). This is where the bulk of the work of preparing a shuttle for launch takes place.

4. Inside the OPF, the first thing that happens is to purge any leftover gasses and reactants from the engines, fuel cells, and environmental systems.

6. The shuttle’s thermal protection system requires special care. There are nearly 25,000 unique silica tiles that keep the orbiter cool during re-entry. The numbers on each tile denote its position, and can be fed into a computer which will then create an identical replacement tile. If you’ve ever noticed how the shuttle’s belly has a slightly checkered appearance in pictures, it’s because the solid black tiles haven’t been put through reentry yet, while the lighter tiles have.

8. There are approximately 2,000 switches in the shuttle’s cockpit, and specially trained technicians called spacecraft operators run tests on every single computer system they’re attached to. This testing continues all the way out to the launch pad, even when the shuttle is vertical, meaning that the technicians are reading all the switches upside-down and backwards.

9. Meanwhile, other space shuttle components are making their way to KSC. The solid rocket boosters arrive by train. After parachuting into the ocean, they were sent to Utah to be fixed up and repacked with propellant.

10. The external tank gets brought in by barge from New Orleans. A new tank is constructed for each launch by Lockheed Martin.

15. The orbiter gets lifted several hundred feet into the air inside the VAB, and then set down on top of the mobile launcher platform and hooked up to the external tank and solid rocket boosters.

16. The payload is often loaded into the shuttle while it’s vertical in the VAB. In the case of STS-135, this consists of the Raffaello Multi-Purpose Logistics Module, which is essentially just a big shipping container for supplies. Other payloads can be loaded in the OPF, or even on the launch pad itself.

17. To get from the VAB to the launch pad, a crawler-transporter drives under the mobile launcher platform, picks it up, and drives out the door. The crawler-transporter has four tracks, each track has 57 shoes, and each shoe weighs 2,000 pounds. It burns approximately 125 gallons of fuel per mile, and at a top speed of one mile per hour, it takes six hours to make the trip. There are two of them: one is named Hans, one is named Franz, and together they have traveled some 3,400 miles, or about the distance from Miami to Seattle.

19. Now’s the time for everything to be tightened up and buttoned down, with last minute payload stowage and preparations for fueling. The crew arrives, and gets to practice a simulated launch as well as an emergency exit procedure using the slide wire basket system.

20. With 43 hours to go, the launch countdown officially starts. At T-27 hours (27 hours to go), the launchpad is cleared and the orbiter’s fuel cells are charged. At T-11 hours, the fuel cells are activated and the blast danger area is cleared. Fueling begins at T-6 hours. T-3 hours sees the flight crew into the shuttle, and the close-out crew departs the pad. At T-9 minutes, the automatic ground launch sequencer is activated.

14. To get from the OPF to the vehicle assembly building (VAB), the shuttle is moved on an “orbiter transporter system,” sort of like a giant flatbed truck.

13. Back at the Orbiter Processing Facility, the shuttle gets loaded up with mission supplies and consumable fluids and gasses, and then weighed to determine its center of gravity.

1. First thing’s first: if the shuttle landed at Edwards Air Force Base in California, it’s got to get back home to Kennedy Space Center in Florida. You can’t very well drive it back, which is why it’s got its own personal transport plane, a heavily modified Boeing 747.

5. The orbiter’s engines are pulled out one by one, and sent off to their own separate processing facility. The forklift, called a Hyster forklift, was specially designed to do just this and nothing else. Usually, the engines are then completely replaced with a refurbished set.

7. Hydraulic jacks lift the shuttle off the ground to test the landing gear deployment. The wheels cannot be automatically retracted once they’ve been deployed, and since an accidental deployment in space would be a disaster (since the gear comes down through the heat shield), the landing gear is one of the few things on the shuttle that can only be operated manually by the astronauts.

18. Once at the pad, the crawler-transporter sets the mobile launcher platform down on pedestals and then drives off, and service structures swing in to allow access to the shuttle.

21. At T-5 minutes, the solid rocket boosters are armed. As of T-50 seconds, the orbiter is running on internal power. With 16 seconds to go, the sound suppression system system activates (dumping 300,000 gallons of water into the launch platform’s exhaust port in 41 seconds), and the main engines start at T-6.6 seconds. At T-0, the solid rocket boosters ignite, and finally, the shuttle lifts off.

11. Since the solid rocket boosters come in segments, they can simply be stacked up one on top of another to build two complete rockets.

12. Inside the massive Vehicle Assembly Building, the external tank is lifted into place on top of the mobile launcher platform, in between the two SRBs.