How Does the Space Shuttle Come Back Earth?
The Shuttle, when it comes back Earth just behave like a spatial glider! It has no way to brake between the orbit and the landing! Latest procedures concerning the mostly ISS-bound flights the Space Shuttle flew before retirement had the orbiter performing some flight in close vicinity of the space station, after undocking, to image it as the orbiter's thrusters were eventually fired to perform a final separation between the ISS and the Space Shuttle. From that, the crew usually spent about 2 days in orbit, taking time to check for the thermal protection and integrity of their vessel, a procedure prescribed after the dramatic loss of shuttle Columbia in February 2003. When it's time to go home, the Shuttle usually is orbiting upside down. On the other hand, it's rotated tailfirst and its engines are fired. This is called a 'deorbit burn'. The deorbit burn just slows the Shuttle, and... the Shuttle begins its descent out of orbit. The Space Shuttle is slowed by 148 miles per hour (217 feet per second) (237 km/h -66 m/s) This is taking place half-the planet -and one hour- before the landing site. This means that, for a landing at the Kennedy Space Center, the deorbit burn is performed over the Indian Ocean! The orbiter, then, is turned nose forward, in an upright position as it descends towards the upper layers of the Earth's atmosphere. 25 minutes later, the Space Shuttle just is reaching the point of its altitude where it meets the atmosphere! The orbiter is then at 400,000 ft -80 miles (129 km) of altitude- and 5,000 miles (8,000 km) from the landing site. The entry phase, strictly speaking, has begun a little earlier, at 557,000 ft. When reaching the 400,000-ft mark, the orbiter's nose is raised at an angle of 40°. This is to that the thermal shield, which protects the Shuttle, be correctly oriented

click for a a sketch illustrating the descent of the Space Shuttle

The re-entry into the atmosphere occurs between 265,000 ft and 162,000 ft. The radio contact then is interrupted, due to the heat, during about 16 minutes as the heat shield tiles are heated up to 3,000°F (1,650 °C). Then comes the time when the Shuttle performs a series of four tight turns. Such turns aim at slowing the Shuttle down. It's at 140 miles from the runway, at an altitude of 150,000 ft, that the orbiter begins to catch the landing site's TACAN -that is a radio-navigation aid of the military type, helping the Shuttle to steer home. The Shuttle's speed gets down to Mach 3 -about 1,870 mph (3,000 km/h). When the Shuttle has come to 25 miles from the runway, at an altitude of 50,000 ft -with a speed now under Mach 1 -321 mph, (1,000 km/h), it's the mission's commander who takes the control of the orbiter, disconnecting the autopilot which conducted the operations until then. The commander, then, flies the approach and the landing! He uses an instrument aid called the 'Scanning Beam Landing System'. As far as the weather for landing is concerned, NASA is monitoring a 30-mile zone around the Kennedy Space Center. To get aligned with the runway, the Shuttle sometimes has to make a full 360° turn, of 4 miles (6,5 km) in diameter. The altitude, during the turn, is passing from 50,000 to 10,000 ft. During its descent towards the runway threshold, the orbiter may have the nose up by as much as 19° or it may have the nose down. The angle of the slope to the runway is larger than, for example, the one of an airliner, as the orbiter is descending 20 times faster -and with a speed of about 300 kts!

At 2,000 ft and 1 mile (1,6 km) from the runway's threshold, the commander flares the Shuttle to a shallow nose-up/tail-down position for the landing. This has the effect of slowing the descent. Gears down! The touchdown occurs at a speed of 220 mph (about 190 knots, 354 km/h). An airliner usually touches down at about 140 knots. A parachute deploys. It's braking the speed of the orbiter, as the nose if lowered unto the runway. The Shuttle keeps rolling for a 1.5 mile (2.4 km) as it eventually comes to a slow stop by the end of the runway. Here we are! The Space Shuttle has landed!

see a more detailed view of the Shuttle's reentry process

For to where the Space Shuttle is landing, the Shuttle Landing Facility (SLF) - a 15,000-foot-long runway and about as wide as the length of a football field- in the Kennedy Space Center (KSC), Fla. is the prime landing site as its construction wrapped up in 1976. Initially, at the beginning of the program, all Shuttle landings were conducted at the Edwards Air Force Base, adjacent to NASA's Dryden Flight Research Center in California. The first landing at KSC took place in 1984 only. White Sands Space Harbor, N.M., also is a alternate landing runway. Both Edwards and White Sands are featuring a Mating-Demating Device used to settle a orbiter atop a NASA's specially modified Boeing 747 which is then bringing it back into Florida. Open air conditions in California, or sand in New Mexico are factors as 46 days in total are needed at the New Mexico site due to blowing gypsum. White Sands Space Harbor in New Mexico, is too where astronauts practice landing their Shuttle Training Aircraft, a modified business jet allowing to figure how a orbiter behaves while returning to land, because of its close proximity to NASA's Johnson Space Center in Houston

->Re-Entry Chronology
. A day-before-entry systems check of flight control system and thruster jets, generally, is occurring. One of the ship’s three auxiliary power units is activated and performed a checkout of the orbiter’s flight control surfaces to ensure elevons and speed brake will provide control once the shuttle enters the atmosphere, as the 44 Reaction Control System thruster jets are each fired in a standard two-pulse checkout to verify their ability to steer the shuttle through its entry -deorbit and entry-profile before it encounters the atmosphere
. The 'go' is given for the Shuttle's payload bay doors to be closed as the Mission Control instructs the mission's commander to go for "Ops 3," the portion of the orbiter's flight control software that manages entry and landing. A entry team of flight controllers is responsable for the re-entry, from the Houston’s Mission Control Center
. The scheduled time of the landing has been determined as have been the landing opportunities at the chosen landing site, those determined by the Flight Dynamics Officer in Mission Control
. About 2 hours after the beginning of the process, the go/no-go decision for the deorbit burn is given, with a scheduled time, after the Entry Flight Director poll his teamed for the deorbit burn. That is followed with a go/no go for crew suit up. Weather conditions at the landing site may delay the decision to just before the burn occurs as a astronaut is flying weather reconnaissance at the landing site. About 2 hours and 40 minute before the deorbit burn, the payload doors of the Space Shuttle have been closed. End of mission weather flight rules, for example, state that daylight crosswinds may not exceed 15 knots, headwinds may not exceed 25 knots and tailwinds may not exceed 15 knots. Also, peak winds may not be greater than 10 knots over the average wind
. Crewmembers begin 'fluid loading', that is that they drink large amounts of fluids to aid them in their re-acclimation into Earth's gravity. Each crew member will drink approximately 40 ounces of water -- about eight ounces every fifteen minutes -- and take salt pills to help them increase their fluid volume. The fluids are under the form of chicken consume, orange-aid or water
. The crew dresses in their pumpkin-orange launch and entry suits and processes to seat ingress
. A go/no-go poll is conducted about 30 minutes before the planned time for the deorbit burn
. The commander is instructed to maneuver to the deorbit burn attitude. The Shuttle, during the deorbit burn, is flying upside down and backwards
. Then goes the 'go' for the deorbit burn! The Shuttle is 'go' for deorbit burn and cleared for landing! The deorbit burn is to ignite the shuttle's two Orbital Maneuvering System (OMS) engines to slow down the Shuttle on the orbit, hence it begins its descent Earth. The crewmembers are strapping themselves on their seats and get ready for the one-hour ride, as the Auxiliary Power Unit (APU) 1 is up and running (the APU propel pumps used to power the Shuttle's hydraulic system)
. The deorbit burn occurs. It last 3 minutes as it slows the Shuttle down by approximately 205 mph (330 km/h). Beginning now, the Shuttle has no means to act upon its trajectory, except through its steering jets and then its aerosurfaces once entered back into atmospheric conditions
. Deorbit burn (DO, from now)+9mn: the orbiter begins to feel the effects of the atmosphere already. The crew is given the go to dump the excess propellants from the Shuttle's forward maneuvering thrusters
. DO+15mn: the Shuttle is 400,000 ft high and 52 minutes from touchdown. We are at 20 minutes of encountering the 'entry interface'
. DO+24mn: all three APUs are fired and begin powering the aerosurfaces
. DO+26mn: the orbiter begins to feel increasing drag and friction as it gets into an ever-thickening atmosphere
. DO+36mn: we are at 80 miles in altitude and 5,000 miles (8,000 km) from the runway. It's the beginning of the 'entry interface'. The landing site is in 31 minutes and 4,600 miles (7400 km)! The Shuttle's protective tiles are exposed to extreme heat as it enters the top fringes of the atmosphere. The speed is Mach 24.8!
. DO+41mn: the Shuttle has begun the first of four tight rolls to slow its speed. The altitude is 50 miles (80 km) and we are 3,000 miles from the runway
. DO+43mn: the three APU are at work. Speed is Mach 24.3
. DO+47mn: speed is 15,000 mph (24,100 km/h) and we are 2,000 miles (3,200 km) from the runway, which is at 20 minutes
. DO+58mn: speed is now Mach 6.2 (4,650 mph -7,500 km/h), at an altitude of 25 miles (40 miles) and 214 miles (344 km) from the runway. 9 minutes until touchdown
. DO+59mn: speed is Mach 4.5 (3,300 mph -5,430 km/h) and the altitude 21 miles (34 km) and rapidly descending
. DO+1:03hr: 5 minutes and 30 seconds to touchdown! Speed Mach 1.7 (1,275 mph -2,051 km/h) and altitude 12.5 miles (20 km)
. DO+1:04hr: twin sonic booms occur. The orbiter begins to make its final approach. 3 minutes to touchdown!
. DO+1:07hr: at the 90 degrees mark, the orbiter is at 15,000 ft of altitude at a speed of 420 mph (675 km/h)
. DO+1:08hr: touchdown! Main landing gear first, nose gear then. About one minute later, the Shuttle comes to a halt on the runway. The runway's heading at the landing site to be used for landing may be chosen during the re-entry process

->After Landing
. Touchdown+3mn: the astronauts shut down the orbiter's systems
. T+7mn: the Space Shuttle service vehicle convoy approaches the orbiter, carrying support crews and equipment
. T+13mn: the crew has safed the landing gear as the 'go' is given to the commander and pilot to configure the Shuttle's computers for "Ops 9 Transition"- a post-landing software package. The convoy crew members are approaching the aft (back) end of the Space Shuttle. A medical staff and a Astronaut Support Person (ASP) participate into those operations
. T+16mn: the crew is cleared to remove their flight and entry suits. Work to safely shutdown the Shuttle's systems is continuing
. T+28mn: the orbiter's APU are shut down
. T+44mn: the Shuttle's hatch is open as the crew prepares and begins to depart the vehicle and get into the Crew Transport Vehicle. There are beds and comfortable seats inside the transporter so that the astronauts can receive medical checks immediately after returning to Earth
. T+1:10mn: the commander and some crewmembers perform a walk around of the orbiter for a post-flight inspection. The crew, then, awaits the arrival of the Astrovan, this bus which takes them from and to their quarters in the Operations and Checkout Building. Before returning there however, the crewmembers, during the following about 1 hour and 45 mn, usually leave the Crew Transport Vehicle, are greeted back Earth as they give a press conference. A post-landing press conference with NASA officials also occurred before