The landing procedure for Discovery while returning to earth from ISS

Courtesy: NASA

Deorbit and Landing Preliminary Advisory Data (DOL PAD)

Automated DOL PAD For STS-XYZ - this data is for the STS-XYZ mission
Deorbit To KSC On Orbit N - deorbit will occur on the Nth orbit of this
mission
Generated MET 000/00:00:00 - the Mission Elapsed Time in
days/hours:minutes:seconds that this information was generated by computers
in Mission Control.

Deorbit TIG - Time of Ignition - the orbiter will fire its orbital
maneuvering system engines to slow itself down and begin its descent to
Earth. The time of the deorbit burn is shown in both MET
(days/hours:minutes:seconds) and Central time (Julian
Day/hour:minute:second). The location over the Earth at which this event
will occur is shown by Latitude (degrees:minutes) and Longitude
(degrees:minutes). The altitude (H - height) of the event is given in
nautical miles (NM) or thousands of feet (KFT). Note: To find statute
miles, multiply nautical miles by 1.15. Velocity is shown in thousands of
feet per second (KFPS). 1.47 feet per second equals 1 statute mile per
hour. Comments Section - DV (delta velocity) is the change in velocity the
burn will cause and DT (delta time) is the duration of the burn. XR is the
crossrange, the distance away from what would have been the shuttle's
normal orbital groundtrack that the shuttle will fly during its descent
through the atmosphere in order to reach the landing site.

TDRS West AOS - The orbiter will be in range (Acquisition Of Signal) of one
of the NASA Tracking and Data Relay Satellites (TDRS West). Comments
Section - EI Minus is the time in minutes:seconds until Entry Interface
occurs.

EI - Entry Interface - that point at which the orbiter begins to encounter
the first effects of the Earth's atmosphere, usually at an altitude of
roughly 400,000 feet. Comments Section - Range is how far away the orbiter
is from the landing site in nautical miles (NM).

MACH 2.5 TAEM - the orbiter has decelerated to a velocity of two and one
half times the speed of sound and has reached a phase of descent called
Terminal Area Energy Management (TAEM). TAEM is the second of three phases
that the shuttle's entry and landing process is divided into because of the
unique onboard software requirements for each phase. The first phase of
descent is labeled simply Entry and extends from five minutes before Entry
Interface to the start of TAEM. TAEM is a phase that takes the orbiter from
about 83,000 feet and two and half times the speed of sound to a point
where the shuttle is at an altitude of about 10,000 feet and aligned with
the runway centerline. Approach and Landing phase extends from 10,000 feet
to touchdown on the runway.

MACH 1 - the orbiter has decelerated to a velocity equal to the speed of
sound (approximately 740 miles per hour at sea level). The time that the
shuttle commander takes manual control of the spacecraft's approach and
landing usually coincides with the point that the shuttle has slowed to
Mach 1. Comments Section - how many minutes:seconds after reaching Mach 1
before the orbiter reaches the HAC I/C point.

HAC I/C - The point at which the orbiter intercepts the Heading Alignment
Cylinder, an imaginary cylinder created by the Microwave Scan Beam Landing
System (MSBLS) that is installed at primary shuttle landing sites. The HAC
is a tool to assist with guiding the shuttle's final approach to the
runway. Comments Section - the shuttle normally performs a turn following
the HAC as it aligns with the runway and rapidly descends. The turn angle
refers to how much of a turn will be performed by the shuttle around the
HAC as it aligns with the runway. The shuttle can turn as much as almost a
full circle (360 degrees) before aligning with the runway and descending to
touchdown, but the amount of turn required is usually between 200 to 300
degrees for most landings.

Landing - the scheduled landing time is given in both MET
(days/hours:minutes:seconds) and Central time (Julian
Day/hour:minute:second). Landing occurs just a little over an hour after
the deorbit burn.

Roll Schedule - as the orbiter descends through the atmosphere to a level
where air pressure has built sufficiently and slows to where heating has
subsided somewhat, it begins a series of four steep banks to slow down. The
shuttle, in essence, fishtails through the atmosphere as it descends to
dissipate its speed. The first couple of banks that the shuttle performs
can often be very steep, as much as 80 degrees, that result in the
shuttle's side facing toward the ground. The second, third and fourth banks
are referred to as "roll reversals," since they basically reverse the
shuttle's roll angle, i.e. from 80 degrees left to 70 degrees right. It is
important to understand that although the shuttle is performing these steep
banks, its angle of attack -- the angle of its nose toward the oncoming air
pressure -- is very high, at 40 degrees for much of the entry, to protect
the spacecraft from the intense heat that is generated. The angle gradually
decreases, i.e. the nose is slowly brought down, as the shuttle descends
and slows.