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Space Shuttle Launch System and Failures
 Space Shuttle
consists of:
 Reusable orbiter with a
large 15 ft diameter by 60
ft long cargo bay for
payloads.
 Expendable external
tank supplies fuel to the 3
orbiter engines.
 Two reusable solid-fuel
booster rockets provide
71.4% of the thrust at liftoff and during first-stage
ascent.
 External tank and
booster rockets are
jettisoned during
ascent. Only the
orbiter goes into orbit.
External
Tank (ET)
Solid Rocket
Booster
(SRB) (SRB)
Orbiter
Space Shuttle
Main Engine
(SSME)
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Solid Rocket Booster
 Each SRB consists of:
 Nose cap and frustum include the
pilot, drogue and 3 main parachutes.
 Forward skirt contains avionics,
range safety system and ET attach
fitting.
 Four solid rocket motor segments
with propellant.
 Aft attach ring includes provisions for
ET attachment.
 Aft skirt bolts the SRB to the launch
pad prior to lift-off.
 Nozzle is gimbaled for control.
 Orbiter SSMEs are ignited while
SRBs are bolted to the launch
pad.
 Thrust bends the shuttle assembly
creating loads.
 SRBs are ignited after the thrust
level of the SSMEs is verified.
 SRBs separate from the launch
pad and shuttle assembly springs
back creating “twang” motion.
Nose Cap
Frustum
Forward Skirt
Forward ET
Attach Ring
Forward Field
Joint
Center Field Joint
Aft ET Attach Ring
and Aft Field Joint
Aft Skirt
Launch Pad
Separation Motors
(4 Places)
Nozzle
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Solid Rocket Booster – Challenger Accident
STS-51L, Challenger, January 28, 1986
 Gray smoke comes from the right SRB
aft field joint 0.68 seconds after ignition.
 Challenger explodes 73 seconds into
the flight.
 The cause of the accident was cold
weather and the right SRB aft field joint
sealing, shown below.
 The SRB aft field joint sealing is
redesigned as a result of the accident.
Primary
Segment Tang
O-ring
Leak Check Port
O-ring
Grease
Bead
Shim
Clevis Pin
Cork
Insulation
Gray
Smoke
Segment Clevis
Insulation
Propellant
Filled
Insulation
Gap
Putty
Insulation
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Space Shuttle Main Engines
 Liquid oxygen (LOX) oxidizer at -298 OF from the External Tank enters the orbiter
at the umbilical disconnect and flows to the orbiter's LOX feed line. There it
branches into three parallel paths, one to each engine.
 Liquid hydrogen fuel at -423 OF from the External Tank flows into the orbiter at the
liquid hydrogen feed line disconnect valve. It then enters the orbiter hydrogen feed
line manifold and branches out into three parallel paths to each engine.
Space Shuttle
Main Engines
External
Tank LOX
Feed Line
Flight Deck
Mid Deck
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External Tank
 The 27.5 ft diameter by 154 ft long ET is the largest single piece of the Space Shuttle.
 During launch the ET acts as the backbone supporting the orbiter and SRBs.
 The ET holds the liquid hydrogen fuel and liquid oxygen oxidizer for the orbiter’s three engines in
separate pressurized tanks.
Propellant Feed,
Pressurization Lines and
Electrical Umbilicals
Orbiter Aft
Attachment
Liquid Oxygen
Feedline
Orbiter Forward
Attachment Not
Shown
Liquid Hydrogen
Tank
Solid Rocket Booster (SRB)
Forward Attachment
Intertank
Liquid Oxygen
(LOX) Tank
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External Tank Debris – Columbia Accident
STS-107, Columbia, February 1, 2003
 Falling foam, the size of a suitcase, from the
orbiter forward attachment opened a hole in
Columbia’s left wing, leading to the orbiter's breakup
on entry.
 The forward attachment, shown top right, used a
foam ramp to prevent ice on the fitting.
Orbiter Forward
Attachment
 The new design, shown
below, uses heaters instead
of foam to prevent ice buildup.
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External Tank Debris - Discovery
STS-114, Discovery, July 26, 2005
 Large piece of ET foam separated from an area of the tank
called the the Protuberance Air Load (PAL) ramp near the liquid
oxygen feed line.
 Debris did not impact Discovery but the Shuttle fleet was grounded.
 NASA currently plans to replace the PAL ramps with an enhanced
manual foam spraying process.
 In November 2005, NASA investigators found 9 cracks in the
PAL on the ET originally slated for the STS-114 mission.
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Reference Information
END
The Space Shuttle Operator’s Manual, Kerry Mark Joels, Random House,
1982
Report of the Presidential Commission on the Space Shuttle Challenger
Accident, William Rogers, U.S. Government, 1986
Columbia Accident Investigation Board, U.S. Government, 2003
Foam Puzzle, Aviation Week & Space Technology, November 28, 2005
Images and Text:
http://grin.hq.nasa.gov/
http://spaceflight.nasa.gov/
http://history.nasa.gov/rogersrep/v6p14.htm
http://www.jlhs.nhusd.k12.ca.us/Classes/Social_Science/Challenger.html/Challenger.html
http://www.nasa.gov/centers/marshall/multimedia/photogallery/photos/photogallery/shuttle/
/shuttle.html
http://www.nasa.gov/returntoflight/multimedia/external_tank_images.html
Text only:
http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/srb.html
http://science.ksc.nasa.gov/shuttle/missions/51-l/mission-51-l.html
http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts-mps.html#sts-mps-ssme
http://www.braeunig.us/space/propel.htm
http://www.nasa.gov/centers/marshall/multimedia/photogallery/photos/photogallery/shuttle/
/shuttle.html
http://www.space.com/missionlaunches/ft_051001_et_fixes.html
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Space Shuttle Statistics
 Length
 Space Shuttle: 184.2 feet
 Orbiter: 122.2 feet
 Height
 Orbiter on runway: 56.7 feet
 Wingspan:
 78.1 feet
 Weight*
 At liftoff: 4.5 million pounds
 End of mission: 230,000 pounds
 Maximum cargo to orbit:
 63,500 pounds
 SRB Separation:
 2 minutes after launch
 External Tank Separation:
 8.5 minutes after launch
 Altitude: 69 miles
 Velocity: 17,440 miles/hour
 Orbit:
 115 to 400 miles
 Velocity: 17,321 miles/hour
* Weight dependent on payloads and on-board consumables.
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Solid Rocket Booster
 The SRBs, 12.2 ft in diameter by 149.2 ft long, are the largest solid-propellant
motors flown and the first designed for reuse.
 Each SRB weighs about 1,300,000 pounds at launch. The propellant for each solid
rocket motor weighs about 1,100,000 pounds.
 2 SRBs carry the entire weight of the ET and orbiter and transmit the weight load
through their structure to the launch pad.
 Each booster is attached to the mobile launcher platform at the aft skirt by four bolts and nuts
that are severed by small explosives at lift-off.
 2 SRBs provide the main thrust to lift the space shuttle off the pad to an altitude of
about 28 miles.
 Each booster has a thrust at sea level of about 3,300,000 pounds at launch. They
are ignited after the thrust level of the three space shuttle main engines is verified.
 75 seconds after SRB separation, SRB apogee occurs at an altitude of about 41
miles with SRB impact in the ocean about 141 miles downrange.
 Primary elements of each booster are the motor (including steel case, propellant,
igniter and nozzle), separation systems, operational flight instrumentation, recovery
avionics, pyrotechnics, deceleration system, thrust vector control system and range
safety destruct system.
 Each booster is attached to the ET at the SRB's aft frame by two lateral sway
braces and a diagonal attachment. The forward end of each SRB is attached to the ET
at the end of the SRB's forward skirt.
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Challenger Accident Timeline
 6.6 seconds before launch - Challenger's three main engines are ignited and
run up to full thrust while the Shuttle structure is bolted to the launch pad. The
thrust of the main engines bends the Shuttle assembly forward from the bolts
anchoring it to the pad. When the Shuttle assembly springs back to the vertical,
the SRBs' restraining bolts are explosively released. During this pre-release
"twang" motion, structural loads are stored in the assembled structure. These
loads are released during the first few seconds of flight. The maximum structural
loads on the SRBs’ aft field joints occurs during the "twang.“
 0.68 seconds after lift-off - strong puff of gray smoke spurted from the vicinity of
the right SRB aft field joint facing the ET.
 2.73 seconds - vaporized material streaming from the joint indicated the field
joint was not sealed. The black color and dense composition of the smoke puffs
suggest the grease, joint insulation and rubber O-rings in the joint seal were being
burned and eroded by the 5000 0F propellant gases.
 64.66 seconds - swirling flame from the SRB breached the ET indicating the
flame was mixing with leaking hydrogen from the ET. Within 45 milliseconds of the
breach, a bright, sustained glow developed on the black-tiled underside of
Challenger.
 72 seconds - Challenger struggled futilely against the forces that were
destroying the orbiter.
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Challenger Accident Timeline (Continued)
 72.20 seconds - the lower strut linking the SRB and the ET was severed or
pulled away from the weakened hydrogen tank permitting the right SRB to rotate
around the upper attachment strut.
 73.12 seconds - a circumferential white vapor pattern bloomed from the side of
the ET bottom dome beginning the structural failure of the hydrogen tank. The
failure culminated in the entire aft dome dropping away, releasing massive
amounts of liquid hydrogen from the tank. This created a sudden forward thrust
pushing the hydrogen tank upward into the ET intertank structure. At about the
same time, the rotating right SRB impacted the intertank structure and the lower
part of the liquid oxygen tank.
 73.14 seconds – The intertank structure and liquid oxygen tank fail. Within
milliseconds there is a massive, almost explosive, burning of the hydrogen
streaming from the failed tank bottom and liquid oxygen breach in the area of the
intertank. Challenger was totally enveloped in the explosive burn at this point in its
trajectory traveling at a Mach number of 1.92 at an altitude of 46,000 ft. The
Challenger's reaction control system ruptured and a hypergolic burn of its
propellants occurred as it exited the oxygen-hydrogen flames. The orbiter, under
severe aerodynamic loads, broke into several large sections which emerged from
the fireball. Separate sections included the main engine/tail section with the
engines still burning, one wing of the orbiter, and the forward fuselage trailing a
mass of umbilical lines pulled loose from the payload bay.
 The explosion, 73 seconds after liftoff, claimed crew and vehicle.
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Space Shuttle Main Engines
 Main Engine Statistics:
Thrust
Sea level:
375,000 pounds
Vacuum:
470,000 pounds
Nominal operating time
8.5 minutes after liftoff
Life
7.5 hours, 55 starts
Propellant Mixture (by weight)
6 parts liquid oxygen to 1 part liquid hydrogen
Weight
Approximately 6,700 pounds each
Dimensions
14 ft long
7.5 ft wide at mouth of nozzle
 After the SRBs are jettisoned, the main engines provide thrust accelerating the
Shuttle from 3,000 mph to over 17,000 mph in just six minutes to reach orbit.
 The 3 engines create a combined maximum thrust of more than 1.2 million pounds.
 Engine exhaust is primarily water vapor as the hydrogen and oxygen combine.
 As the engines push the Shuttle toward orbit, they consume liquid fuel at a rate draining an
average family swimming pool in under 25 seconds generating over 37 million horsepower.
 Engines can be throttled over a thrust range of 65% to 109%.
 The range provides for a high thrust level during liftoff and the initial ascent phase but allows
thrust to be reduced to limit acceleration to 3 g's during the final ascent phase.
 The engines are gimbaled to provide pitch, yaw and roll control during the ascent.
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External Tank
 The three main components of the ET are a liquid oxygen tank, located in the
forward position, an aft-positioned liquid hydrogen tank, and a collar-like intertank.
 Intertank connects the two propellant tanks, houses instrumentation and processing
equipment, and provides the attachment structure for the forward end of the SRBs.
 ET is attached to the orbiter at one forward attachment point and two aft points.
 Umbilicals that carry fluids, gases, electrical signals and electrical power between the ET
and the orbiter are located at the aft attachment.
 Electrical signals and controls between the orbiter and the two SRBs are routed through the
umbilicals.
 ET includes a propellant feed system to duct the propellants to the orbiter
engines, a pressurization and vent system to regulate the tank pressure, an
environmental conditioning system to regulate the temperature and render the
atmosphere in the intertank area inert, and an electrical system to distribute power
and instrumentation signals and provide lightning protection.
 ET propellants are fed to the orbiter through a 17 inch diameter connection that branches
inside the orbiter to feed each main engine.
 ET skin is covered with a Thermal Protection System (TPS) that is a 1 inch thick
coating of spray-on foam. The purpose of the TPS is to maintain the propellants at
an acceptable temperature, to protect the skin surface from aerodynamic heat, and
to minimize ice formation.
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Columbia Accident
 Physical cause of the loss of Columbia and its crew was a breach in the
Thermal Protection System (TPS) on the leading edge of the left wing.
 A piece of insulating foam separated from the left bipod ramp section of the ET 81.7
seconds after launch, and struck the wing in the vicinity of the lower half of Reinforced
Carbon-Carbon panel number 8.
 During re-entry this breach in the TPS allowed superheated air to penetrate
through the leading edge insulation and progressively melt the aluminum
structure of the left wing, weakening the structure.
 Increasing aerodynamic forces caused loss of control, failure of the wing, and break-up of
the orbiter.
 Breakup occurred in a flight regime where there was no possibility for the crew to survive.
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Discovery ET Debris
 PAL ramp runs along the side of the ET ensuring smooth airflow and minimizing
vibration around nearby pipes and cables.
 Three fixes are being considered for the PAL ramps:
 Current plan - replace all PAL ramps with an enhanced manual foam spraying process.
 Possibility for future use - a robotic spraying system is being tested, similar to the system
that sprays foam on the ET.
 Under study - PAL ramps will be removed if aerodynamic studies show they are no longer
needed.
 9 cracks were found in the hydrogen tank PAL ramp of the ET that was replaced
for STS-114.
 Inspection of an ET that had been stacked on the launch pad and filled with cryogenic
propellants and pressurized is rare.
 Cracks in the PAL ramp were not found in another ET that was not filled with cryogenic
propellants and not pressurized.
 Cryogenic temperatures shrink the tank, causing stress on the foam, and alter its strength
as well.
 Tests will determine if the cracks are significant or can be ignored.
 Shuttle fleet remains grounded while NASA determines how to stop big pieces
of foam insulation from breaking off the tanks during liftoff.
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