What are the Chain of Events From Orbit to Landing?

The diagram below illustrates what the space shuttle has to do in order to go from being in orbit around the earth to landing at an airport.

From http://www.cbc.ca/news/features/shuttle_columbia/columbia_reentry.html

When in orbit the shuttle is positioned so that it is moving nose-first and the top of the shuttle is pointing towards the earth. The shuttle is positioned "bottom up" so that the black bottom will radiate the heat from the sun more effeciently. Step one for the shuttle is to turn around so that it is moving stern-first and then it fires it's engines in order to slow the shuttle so that it will drop out of orbit. Next the shuttle flips over so that it is right-side-up when it enters the atmosphere. Between step three and four the shuttle burns any excess fuel that it may still have so that there is less of a danger of explosion when the fuel tanks get hot durring re-entry. Step four is where the shuttle maintains an angle of about 40 degrees from the vertical and maintains an approach so that the shuttle slows down. After slowing to a speed where the shuttle can maneuver it will "fly" (remember, the shuttle has no more fuel so it has only one chance to land) in some final S shaped curves to slow some more and then land at a designated airport (as shown below).

http://www.howstuffworks.com/space-shuttle12.htm

How Does the Shuttle Turn or Maneuver in Space?

The basic means of movement for the space shuttle can be explained in Isaac Newton's laws F=Ma and for every action, there is an equal and oposite reaction. The force, on the space shuttle, is equal to the mass of the shuttle multiplied by its acceleration. By burning fuel in a rocket engine on the back of the shuttle, a force on the shuttle equal to the mass of fuel being "thrown" out the stern of the craft multiplied by its acceleration. This basic physics formula is very important to the shuttle getting up into space and to the beginning of its deceleration on its return to earth. Thus it has a very real impact on weather the shuttle will survive the trip through the earth's atmosphere back to land. When the shuttle first enters the earth's atmosphere it is traveling at speeds topping 30,000 km/h. The shuttle has to decelerate to 0 km/h after it lands. The acceleration that it must endure to slow the shuttle is an incredibly large force on the structure of the craft.

When the shuttle is entering the atmosphere it must enter at an angle window of only a few degrees. It needs to enter at about an angle of 40 degrees to the vertical. If that angle is greater the shuttle may "bounce" off the atmosphere and get sent back out into space. If the angle is less, the shuttle will have too fast a drop into the atmoshere, and the forces on the shuttle with create too much heat for the structure to withold and the shuttle will either be torn apart or burn up before it can land.