Space Shuttle - The First 100 Flights

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3|Space Shuttle Main Engines|delete section|The Space Shuttle´s Main Engines are reusable, high-performance, liquid-fueled rocket engines - the most reliable and highly tested large rocket engines ever built. With a maximum thrust at sea level of more than 418,000 pounds each, they work in tandem with the solid rocket boosters from liftoff until SRB separation, about two minutes after launch, after which they are the sole means of propelling the Orbiter into space. The engines are gimbaled to steer the Shuttle during the climb to orbit and have the capability to be throttled to reduce structural loads on the vehicle. Normal engine operating time during ascent is about 8.5 minutes, and each engine has a designed operating lifetime of about 7.5 cumulative hours. The engines are generally referred to as the center (engine 1), left (engine 2), and right (engine 3). They use liquid hydrogen for fuel and cooling and liquid oxygen as an oxidizer. The propellant is carried in separate tanks within the external tank and is supplied to the main engines under pressure. Each is 14 feet long and 7.5 feet in diameter at the nozzle exit, and weighs approximately 7,000 lbs - only one-seventh as much as a train engine - but delivers as much power as 39 locomotives. The SSME major components are the fuel and oxidizer turbopumps, preburners, a hot gas manifold, main combustion chamber, nozzle, oxidizer heat exchanger, and propellant valves. The turbopump on a Space Shuttle main engine is so powerful it could drain an average family-sized swimming pool in 25 seconds. The energy released by the three Space Shuttle main engines is equivalent to the output of 23 Hoover Dams. |delete section 4|External Tank|delete section|The ET, which is the only major component of the Space Shuttle that is not reusable, is 154 feet long and 28.6 feet in diameter. Weighing slightly more than 71,000 pounds without fuel, the ET weighs 1.67 million pounds with a full load of liquid propellant and oxidizer. Thousands of gallons of liquid hydrogen and oxygen are drawn from the tank by the Shuttle´s main propulsion system during the 8.5 minute ascent phase. The largest and heaviest (when loaded) element of the space shuttle, the ET has three major components: the forward liquid oxygen tank, an unpressurized intertank that contains most of the electrical components, and the aft liquid hydrogen tank. The ET is attached to the orbiter at one forward attachment point and two aft points. In the aft attachment area, there are also umbilicals that carry fluids, gases, electrical signals and electrical power between the tank and the orbiter. Electrical signals and controls between the Orbiter and the two solid rocket boosters also are routed through those umbilicals. When the SSMEs are shut down, the ET is jettisoned, enters the Earth´s atmosphere, breaks up, and impacts in a remote ocean area. It is not recovered. To meet the needs for flights to the International Space Station, a new super lightweight tank was recently developed that incorporates aluminum-lithium in its internal structures, reducing the overall tank weight by 7,500 pounds. |delete section 5|Solid Rocket Boosters|delete section|Each Shuttle is equipped with two Solid Rocket Boosters that provide the initial thrust and acceleration to allow the main engines to carry the Orbiter into space. The boosters are the largest solid rocket propellant motors ever built and the first to be used on a human-rated spacecraft. They are 116 feet long, 12 feet in diameter and contain more than one million pounds of solid propellant. The propellant burns at 5,800 degrees and each SRB delivers 2.65 million pounds of thrust at liftoff. After two minutes, at an altitude of about 24 miles, the boosters separate from the ET and descend by parachute into the ocean, where they are collected for refurbishment and reuse. Primary elements of each booster are the motor (including case, propellant, igniter and nozzle), structure, separation systems, operational flight instrumentation, recovery avionics, pyrotechnics, deceleration system, thrust vector control system and range safety destruct system. Each SRB is made up of four solid rocket motor segments. The pairs are matched by loading each of the four motor segments in pairs from the same batches of propellant ingredients to minimize any thrust imbalance. The propellant mixture in each SRB motor consists of an ammonium perchlorate (oxidizer), aluminum (fuel) and iron oxide (a catalyst). The aft section contains avionics, a thrust vector control system that consists of two auxiliary power units and hydraulic pumps, hydraulic systems and a nozzle extension jettison system. The forward section of each booster contains avionics, a sequencer, forward separation motors, a nose cone separation system, drogue and main parachutes, a recovery beacon, a recovery light, a parachute camera on selected flights and a range safety system. Each SRB has two integrated electronic assemblies, one forward and one aft. After burnout, the forward assembly initiates the release of the nose cap and frustum and turns on the recovery aids. Each integrated electronic assembly has a multiplexer/ demultiplexer, which sends or receives more than one message, signal or unit of information on a single communication channel. SRB separation is initiated when the solid rocket motor chamber is less than or equal to 50 psi. A backup cue is the time elapsed from booster ignition. The separation sequence is initiated, and the SRBs separate from the external tank within 30 milliseconds of the ordnance firing command. There are four booster separation motors on each end of each SRB. The motors separate the SRBs from the external tank. Location aids are provided for each SRB, frustum/ drogue chutes and main parachutes. These include a transmitter, antenna, strobe/ converter, battery and salt water switch electronics. The location aids are designed for a minimum operating life of 72 hours and when refurbished are considered usable up to 20 times. The flashing light is an exception. It has an operating life of 280 hours. The battery is used only once. |delete section 6|Data Processing Systems|Data Processing Systems|The DPS, consisting of various hardware components and self-contained software, provides the entire Shuttle with computerized monitoring and control. The DPS hardware consists of five general-purpose computers (GPCs), two mass memory units (MMUs) for large-volume bulk storage, and a network of serial digital data buses to accommodate the data traffic between the GPCs and vehicle systems. The DPS also includes 20 Orbiter and four SRB multiplexers/demultiplexers (MDMs) to convert and format data from the various vehicle systems, three Space Shuttle Main Engine (SSME) interface units to command the SSMEs, four multifunction CRT display systems used by the flight crew to monitor and control the vehicle and payload systems, two data bus isolation amplifiers to interface with the ground support equipment/launch processing system and the SRBs, two master events controllers, and a master timing unit. DPS software accommodates almost every aspect of space shuttle operations, including Orbiter checkout, prelaunch and final countdown for launch, turnaround activities, control and monitoring during launch, ascent, on-orbit activities, entry, and landing, and aborts or other contingency mission phases. A multi-computer mode is used for the critical phases of the mission, such as launch, ascent, orbit, entry, landing, and aborts. DPS functions: - Support the guidance, navigation, and control of the vehicle, including calculations of trajectories, SSME burn data, and vehicle attitude control data - Monitor and control vehicle subsystems, such as the electrical power system and the environmental control and life support system. - Process vehicle data for the flight crew and for transmission to the ground, and allow ground control of some vehicle systems via transmitted commands. - Check data transmission errors and crew control input errors, support annunciation of vehicle system failures and out-of-tolerance system conditions. - Support payloads with flight crew/software interface for activation, deployment, deactivation, and retrieval. - Process rendezvous, tracking, and data transmissions between payloads and the ground.|Data Processing Systems 7|Extravehicular Mobility Unit|delete section|The extravehicular mobility unit (EMU) is an independent anthropomorphic system that provides environmental protection, mobility, life support, and communications for the crewmember to perform EVA in Earth orbit. The EMU is designed to accommodate an EVA mission with a total maximum duration of 7 hours, consisting of 15 minutes for egress, six hours for useful EVA tasks, 15 minutes for ingress, and a 30-minute reserve. The EMU is an integrated assembly, primarily composed of the space suit assembly, life support system, and numerous items of associated support and ancillary equipment. Space Suit Assembly The space suit assembly (SSA) is the anthropomorphic pressure vessel that encloses the crewmember´s torso, limbs, and head. The SSA provides a variety of functions while the crewmember performs an EVA, including suit pressure retention, crewmember mobility, crew-member liquid cooling distribution, oxygen ventilation gas circulation, downlink of crew-member´s electrocardiogram data via EMU radio, crewmember interface with EMU radio, crewmember in-suit drinking water, and urine containment. The SSA operates under specific pressure requirements and leakage criteria. An enhanced EMU has been developed to provide an on-orbit capability of EMU resizing by using various arm/leg segments and sizing rings. operations. Life Support System The life support system (LSS) provides a safe living environment inside the EMU. The LSS provides a variety of functions while the crewmember performs an EVA, including providing breathing oxygen, suit pressurization, crewmember cooling, crewmember communications, displays and controls for crewmember operation of the EMU, and monitoring of EMU consumables and operational integrity. The primary oxygen system, oxygen ventilation circuit, liquid transport system, feed water circuit, electrical interfaces, extravehicular communicator, and the caution and warning system make up the primary life support subsystem (PLSS). The secondary oxygen pack is a separate unit that is attached to the bottom of the PLSS. Together, the PLSS and the secondary oxygen pack make up the backpack of the EMU. The primary oxygen system provides a crewmember with breathing oxygen and satisfies pressure requirements for EVA. EVA Facts For generic orbiter missions, two suits are included with consumables provided for three, two-person, 6-hour EVAs. There are three basic categories of EVA: scheduled, unscheduled, and contingency. The orbiter´s airlock permits EVA flight crewmembers to transfer from the middeck crew compartment into the payload bay in EMUs without depressurizing the orbiter crew cabin. The airlock also provides launch and entry stowage of up to three EMUs. The airlock´s support functions include air-lock depressurization and repressurization, EVA equipment recharge, LCVG water-cooling, EVA equipment checkout, donning, and communications.|delete section 8|Environmental Control and Life Support System|delete section|The Environmental Control and Life Support System (ECLSS) maintains the orbiterÆs thermal stability and provides a pressurized, habitable environment for the crew and onboard avionics. The ECLSS also manages the storage and disposal of water and crew waste. ECLSS is functionally divided into four systems: 1. Pressure control system, which maintains the crew compartment at 14.7 psia with a breathable mixture of oxygen and nitrogen. Nitrogen is also used to pressurize the supply and wastewater tanks. 2. Atmospheric revitalization system, which uses air circulation and water coolant loops to remove heat, control humidity, and clean and purify cabin air. 3. Active thermal control system, which consists of two Freon loops that collect waste heat from orbiter systems and transfer the heat overboard. 4. Supply and wastewater system. The supply water system stores water produced by the fuel cells for drinking, personal hygiene, and orbiter cooling. The wastewater system stores crew liquid waste and wastewater from the humidity separator. The system also has the capability to dump supply and wastewater overboard. The crew compartment provides a life-sustaining environment for the flight crew. The crew cabin volume with the airlock inside the mid-deck is 2,475 cubic feet (2,325 cubic feet for the orbiter cabin and 150 cubic feet for the airlock). For EVA, the airlock is depressurized and repressurized. Under normal circumstances, the cabin may be depressed to 10.2 psia to ease pre-breathe requirements prior to an EVA. When the airlock is located outside the middeck in the payload bay, the crew cabin volume is 2,625 cubic feet. The external airlock volume varies and is based on mission-specific configuration. |delete section 9|Auxiliary Power Unit/Hydraulics|delete section|The Orbiter has three independent hydraulic systems. Each consists of a main hydraulic pump, hydraulic reservoir, hydraulic bootstrap accumulator, hydraulic filters, control valves, hydraulic/Freon heat exchanger, electrical circulation pump, and electrical heaters. Each system provides hydraulic pressure to position hydraulic actuators for: 1. Thrust vector control of the main engines by gimbaling the three SSMEs 2. Actuation of various control valves on the SSMEs 3. Movement of the Orbiter aerosurfaces (elevons, body flap, rudder/speed brake) 4. Retraction of the external tank/orbiter 17-inch liquid oxygen and liquid hydrogen disconnect umbilicals with-in the orbiter at external tank jettison 5. Main/nose landing gear deployment (system 1)/(system 1 or 2) 6. Main landing gear brakes and anti-skid 7. Nose wheel steering (system 1 with backup from system 2). Each hydraulic system is capable of operation when exposed to forces or conditions caused by acceleration, deceleration, normal gravity, zero gravity, hard vacuum, and temperatures encountered during on-orbit dormant conditions. Three identical, but independent, improved auxiliary power units (APUs; also called IAPUs) provide power for the orbiter hydraulic systems. The APU is a hydrazine-fueled, turbine-driven power unit that generates mechanical shaft power to drive a hydraulic pump that produces pressure for the orbiterÆs hydraulic system. The three APUs are started 5 minutes before lift-off. They continue to operate throughout the launch phase, and are shut down after the main engine propellant dump and stow are completed (post OMS-1). The APUs are restarted for entry: one APU prior to the deorbit burn, and the other two prior to entry interface. Each APU fuel tank load is approximately 325 pounds of hydrazine. Each unit weighs approximately 88 pounds and produces 135 horsepower. Each APU consists of a fuel tank, a fuel feed system, a system controller, an exhaust duct, lube oil cooling system, and fuel/lube oil vents and drains. Redundant electrical heater systems and insulation thermally control the system above 45░ F to prevent fuel from freezing and to maintain required lubricating oil viscosity. Insulation is used on components containing hydrazine, lube oil, or water to minimize electrical heater power requirements and to keep high surface temperatures within safe limits on the turbine and exhaust ducts. The three APUs and fuel systems are located in the aft fuselage. Each APU fuel system supplies storable liquid hydrazine fuel to its respective fuel pump, gas generator valve module, and gas generator, which decomposes the fuel through catalytic action. The resultant hot gas drives a single-stage, dual pass turbine. The turbine exhaust flow returns over the exterior of the gas generator, cooling it, and is then directed overboard through an exhaust duct at the upper portion of the aft fuselage near the vertical stabilizer. The turbine assembly provides mechanical power through a shaft to drive reduction gears in the gearbox. The gearbox drives a fuel pump, a hydraulic pump, and a lube oil pump. The hydraulic pump supplies pressure to the hydraulic system. The fuel pump increases the fuel pressure at its outlet to sustain pressurized fuel to the gas generator valve module and gas generator. The lube oil system supplies lubricant to the gearbox reduction gears and uses the reduction gears as scavenger pumps to supply lube oil to the inlet of the lube oil pump to increase the pressure of the lube oil system. The lube oil of each APU is circulated through a heat exchanger in a corresponding water spray boiler. Three water spray boilers (WSBs), one for each APU, cool the lube oil systems. The hydraulic fluid of each hydraulic pump driven by an APU is also circulated through a hydraulic heat exchanger in the corresponding water spray boiler to cool hydraulic fluid during hydraulic system operation. The three WSBs are also located in the aft fuselage of the orbiter. |delete section 10|Electric Power System|delete section|The electrical power system (EPS) consists of the equipment and reactants that produce electrical power for distribution throughout the orbiter vehicle, and fulfill all the orbiter external tank, solid rocket booster, and payload power requirements, when not connected to ground support equipment. The EPS operates during all flight phases. For nominal operations, very little flight crew interaction is required by the EPS. The EPS is functionally divided into three subsystems: power reactants storage and distribution (PRSD), three fuel cell power plants (fuel cells), and electrical power distribution and control (EPDC). Electrical power transfers from ground power supplies to the onboard fuel cells 3 minutes and 30 seconds prior to launch. Through a chemical reaction, the three fuel cells generate all 28-volt direct-current (DC) electrical power for the vehicle from launch through landing rollout. Each fuel cell supplies an associated bus structure to ensure redundancy in the electrical system. The power reactants storage and distribution system stores cryogenic hydrogen and oxygen and supplies them to the fuel cells. It also supplies oxygen to the ECLSS. The components are located in the orbiter mid-body underneath the payload bay. The fuel cell system converts hydrogen and oxygen to electricity through a chemical reaction. The system also supplies potable water to the ECLSS as a byproduct of the chemical reaction. The electrical power distribution and control system distributes electrical power throughout the orbiter. It has five types of assemblies: power control, load control, motor control, main dc distribution, and ac distribution and control. Each assembly is a housing for electrical components such as remote switching devices, buses, resistors, diodes, and fuses. Remote switching devices distribute bus power to subsystems located. Three-phase, 110-volt alternating power for pumps, fans and other motors is supplied by solid state DC to AC converters. The converters are supply three independent AC busses for redundancy. |delete section 11|Guidance, Navigation and Control|delete section|Guidance, Navigation and Control (GNC) systems determine the current state of motion of the vehicle, compute actions to change it, and execute maneuvers to achieve the change. GNC elements are navigation (NAV) and flight control system (FCS) hardware and digital autopilot (DAP) software. Guidance is the computation of maneuvers to reach the desired vehicle state in terms of proper motion and relative position (to the Earth and/or an orbiting object). Mission requirements usually specify a particular orbit or rendezvous point to which the present state of the vehicle can be compared as a basis for determining maneuvers. Navigation is the determination of the state of motion of the vehicle in terms of relative velocity, position and attitude. The current state of the vehicle is determined using motion sensors, radar, beacons and sighting equipment. Navigation hardware includes: (1) Inertial Measurement Units (IMUs), which sense vehicle orientation and accelerations (2) Star trackers, which sense vehicle line of sight vectors (3) Crew Optical Alignment Site (COAS), which allows the crew to manually determine line of sight vectors (4) Tactical Air Navigation (TACAN), which senses vehicle position with respect to a ground-based station (5) Global Positioning Satellite (GPS), which senses satellite-ranging signals to determine orbiter position and velocity (6) Air data system, which senses temperature and pressure (7) Microwave Scanning Beam Landing System (MSBLS) (8) Radar altimeters. Control is the actual execution of maneuvers to obtain the desired state, as commanded by guidance. Flight control for the orbiter converts guidance computations into system commands to point and translate the vehicle. Control software frequently employs navigation data to determine the progress and outcome of the maneuvers. The flight control system hardware includes four accelerometer assemblies, four orbiter rate gyro assemblies, four SRB rate gyro assemblies, rotational and translational hand controllers, rudder pedal transducer assemblies, two speed brake/thrust controllers, two body flap switches, panel trim switches, aerosurface servo amplifiers, and ascent thrust vector control. Digital Autopilot software interprets maneuver requests, compares them to what the vehicle is doing, and generates commands for the appropriate effectors. |delete section 12|Orbital Maneuvering System|delete section|The Orbital Maneuvering System OMS) provides propulsion for the orbiter during the orbit phase of flight, such as orbit insertion, orbit circularization, orbit transfer, rendezvous, and de-orbit. The OMS may be used to provide thrust above 70,000 feet altitude. Each OMS pod can provide more than 1,000 pounds of propellant to the Reaction Control System. The OMS is housed in two independent pods on each side of the orbiterÆs aft fuselage, designated left and right. The pods, which also house the aft reaction control system (RCS), are referred to as the OMS/RCS pods. Each pod contains one OMS engine and the hardware needed to pressurize, store, and distribute the propellants to perform OMS engine burns. Normally, OMS maneuvers are done using both OMS engines together; however, a burn can be performed using only one of the OMS engines. For velocity changes less than 6 feet per second (fps), RCS is used. For velocity changes greater than 6 fps, a single OMS engine burn is preferred, because engine lifetime concerns make it desirable to minimize engine starts. Two OMS engines are used for large velocity changes, or for critical burns. Propellant from one pod can be fed to the engine in the other pod through crossfeed lines that connect the left and right OMS pods. The OMS/RCS pods are designed to be reused for up to 100 missions with only minor repair, refurbishment, and maintenance. The pods are removable to facilitate orbiter turnaround, if required. The engines are located in gimbal mounts that allow the engine to pivot left and right and up and down under the control of two electromechanical actuators. This gimbal system provides for vehicle steering during OMS burns by controlling the direction of the engine thrust in pitch and yaw (thrust vector control) in response to commands from the digital autopilot or from the manual controls. In the OMS engine, fuel is burned with oxidizer to produce thrust. The OMS engines use monomethyl hydrazine as the fuel and nitrogen tetroxide as the oxidizer. These propellants are hypergolic, which means that they ignite when they come in contact with each other; therefore, no ignition device is needed. Both propellants remain liquid at the temperatures normally experienced during a mission, however, electrical heaters are located throughout the OMS pods to prevent any freezing of propellants during long periods in orbit when the system is not in use. Each of the two OMS engines produces 6,000 pounds of thrust. For a typical orbiter weight, both engines together create an acceleration of approximately 2 ft/sec2 or 0.06 gÆs. Using up a fully loaded tank, the OMS can provide a total velocity change of approximately 1,000 ft/sec. Orbital insertion burns and de-orbit burns each typically require a velocity change of about 100û500 ft/sec. The velocity change required for orbital adjustment is approximately 2 ft/sec for each nautical mile of altitude change. Each OMS engine is capable of 1,000 starts and 15 hours of cumulative firing. The minimum duration of an OMS engine firing is 2 seconds. |delete section 13|Payload Deployment and Retrieval System|delete section|The Payload Deployment and Retrieval System is used to maneuver itself or an attached payload in orbit. It consists of the hardware, software, and interfaces required to remotely hold and control the movements of an object, and to remotely observe or monitor objects or activities. The PDRS includes the remote manipulator system (RMS), the manipulator positioning mechanisms (MPM), and the manipulator retention latches (MRL). The PDRS also interfaces with other orbiter systems, such as the general purpose computers, the electrical power distribution system (EPDS), and the closed-circuit television. The RMS consists of the arm itself and the controls and interfaces needed to maneuver it. It is located on the port side of the payload bay. The RMS arm is 50 feet 3 inches long and 15 inches in diameter. The arm has 6 degrees of freedom: three translational (X, Y, and Z) and three rotational (P, Y, and R). The arm consists of six joints connected via structural members and has a payload capturing device on the end. It weighs 905 pounds, and the total system weighs 994 pounds. Operations fall into six categories: contingency-only unloaded operations, unloaded operations, loaded operations, deploy operations, retrieve operations, and deploy and retrieve operations. The arm has three basic modes of operation: single joint modes, manual-augmented modes, and auto modes. The MPM consists of a torque tube, pedestals, MRLs, and the jettison system. The MPM must be stowed whenever the payload bay doors are closed and must be deployed for any loaded operations. The pedestals contain the MRLs and the jettison electronics and mechanics and are the supports on which the RMS rests while it is cradled. The MRLs latch the arm to the MPM and restrain it during periods of RMS inactivity. The jettison system allows the arm, the pedestals, or the arm/payload combination to be non-impulsively separated from the orbiter if the arm cannot be cradled and stowed prior to payload door closure. All RMS operations involve a two-person operator team. Each member is vital to the success of the mission.|delete section 14|Reaction Control System|delete section|The OrbiterÆs Reaction Control System (RCS) consists of forward and aft control jets, propellant storage tanks, and distribution networks located in three vehicle modules: forward, left, and right. The forward module is contained in the nose area, forward of the cockpit windows. The left and right (aft) modules are collocated with the orbital maneuvering system (OMS) in the left and right OMS/RCS pods near the tail of the vehicle. The RCS units provide propulsive forces from a collection of jet thrusters to control the motion of the orbiter. Each jet is permanently fixed to fire in a general direction: up, down, left, right, forward, or aft. The selective firing of individual jets or specific combinations of jets provides thrust for: Attitude control Rotational maneuvers (pitch, yaw, roll) Small velocity changes along the orbiter axes (translational maneuvers) Manual RCS use is accomplished through the rotational and translational hand controllers, and automatic use is handled by the digital autopilot (DAP) and the general purpose computers (GPCs). Normal uses of the RCS occur during ascent, orbit, and entry. There are a total of 44 RCS jets - 38 primary and 6 vernier. The vernier jets are only used on orbit for fine attitude control. The forward RCS has 14 primary and 2 side-firing vernier jets. The aft RCS has 12 primary and 2 vernier jets in each pod for a total of 28. One set of aft vernier jets is side-firing, and the other set is down-firing. The primary RCS jets provide 870 pounds of vacuum thrust each, and the vernier RCS jets provide 24 pounds of vacuum thrust each for precise maneuvering. The vernier jets are used for tight attitude dead bands and fuel conservation. The propellants are toxic, liquid at room temperature, and hypergolic (they ignite upon contact with each other). The propellants are supplied to the jets, where they atomize, ignite, and produce a hot gas and thrust. |delete section 15|Escape Systems|delete section|Escape systems refer to equipment and systems intended to facilitate emergency and contingency egress of the flight crew. Escape systems include equipment worn by the crewmembers, hardware built into the orbiter, and external systems located on the launch pad. Types of escape or emergency egress from the orbiter depend upon the mission phase - pre-launch, in-flight, and post-landing. The pre-launch phase implies the crew must perform an emergency egress while the orbiter is still positioned on the launch pad. The in-flight phase requires that the crew can safely bail out of the orbiter during controlled gliding flight at altitudes of 30,000 feet and below. A special in-flight crew escape system is devised for this phase. It includes pressure suits, oxygen bottles, parachutes, life rafts, pyrotechnics to vent the cabin and jettison the orbiter side hatch, and an escape pole to allow the crewmembers to clear the vehicle. The most likely uses of the system would be during a return-to-launch-site (RTLS) abort, transatlantic abort landing (TAL), or abort once-around (AOA) when the orbiter has insufficient energy to achieve a runway landing or after an emergency deorbit made regardless of landing site opportunities. During the post-landing phase, the crew exits the orbiter following an emergency landing or landing at a contingency site. The orbiter-based hardware associated with the in-flight crew escape system was installed after the Challenger accident. Launch Pad Egress Systems In the event of a potential catastrophe on the launch pad, escape by the flight crew and any pad technicians is facilitated by slide-wire baskets descending to a safe area. The emergency egress system, on the same level as the Orbiter Access Arm, uses seven separate slide-wires and seven three-person basket assemblies to effect rapid escape of personnel from the 195-foot level of the Fixed Service Structure (FSS) to a landing zone 1,200 feet west of the FSS. A braking system catch net and drag chain slow and then halt the baskets sliding down the wire at about 55 miles per hour in about half a minute. Once stopped, the flight crew leaves the slide-wire baskets and proceeds to the bunker, which is provided with breathing air, first aid supplies, and communications equipment. The flight crew will only leave the bunker upon instructions by the NASA Test Director. An M-113 military armored personnel carrier is positioned near the slide-wire termination area, and can provide protected evacuation from the launch pad area. Launch and Entry Suits The launch entry suit (LES) and the advanced crew escape suit (ACES) are the two types of suits designed to provide protection to a crewmember during ascent and entry for the following problems: ╖ Loss of cabin pressure ╖ Environmental extremes ╖ Effects of prolonged zero gravity ╖ Contaminated atmosphere ╖ Loss of orbiter O2 supply The LES is a partial pressure suit and, as such, provides protection through a series of interconnected pressure bladders that place mechanical pressure on the crewmember. The ACES is a full pressure suit that provides an atmosphere of pressure all over the crewmember´s body. Personal Parachute Assembly Crewmembers wear the personal parachute assembly (PPA) in the event of bailout. The PPA is designed to work automatically with the crew egress pole system or with manual backups as needed. The parachute pack contains the parachutes, risers and associated items, a small life raft, and a radio beacon. The pack doubles as a back seat cushion and is already in the orbiter when the crew ingresses prior to launch. During a bailout, the crewmember needs only to rotate the lap belt connector to release the shoulder harness/lap belt to egress the seat, taking the parachute with him. Upon water landing, two standard U.S. Air Force seawater activated release system (SEAWARS) units, one for each riser, are used to release the risers and canopy from the harness. For a ground egress, the crewmember releases the parachute attach points and leaves the parachute pack in the seat. Egress Pole System The crew escape system orbiter-based hardware includes the egress pole - a curved, spring-loaded, telescoping, steel and aluminum cylinder. The purpose of the egress pole is to guide escaping crewmembers on a trajectory that will clear the orbiter´s left wing. The pole, extending downward 9.8 feet from the side hatch, is contained within an aluminum housing attached to the mid-deck ceiling (above the airlock hatch) and at the side hatch 2-o´clock position. A magazine holding eight lanyards is attached to the hatch end of the pole. The lanyards are the means by which crewmembers are guided down the pole. The crewmember slides down the escape pole and off the end. Emergency Egress Slide The emergency egress slide provides a rapid and safe orbiter egress during post landing contingency or emergency situations. The slide allows the safe egress of the crewmembers to the ground within 60 seconds after the side hatch is fully opened or jettisoned and accommodates the egress of incapacitated crewmembers. The slide may be used after a normal opening of the mid-deck side hatch or after jettisoning the side hatch. The emergency egress slide replaces the emergency egress side hatch bar, which required the flight crewmembers to drop approximately 10.5 feet to the ground. This drop could cause injury to the flight crew and prevent an injured crewmember from moving to a safe distance from the orbiter. |delete section 16|Landing/Deceleration System|delete section|The orbiter, unlike previous space vehicles, has the capability of landing on a runway using a conventional type of landing system. Once the orbiter touches down, the crew deploys the drag chute and begins braking. The orbiter drag chute, first used on the maiden flight of OV-105, improves the orbiter´s deceleration and eases the loads on the landing gear and brakes. The landing gear system on the orbiter is a conventional aircraft tricycle configuration consisting of a nose landing gear and a main landing gear. The nose landing gear is located in the lower forward fuselage, and the main landing gear is located in the lower left and right wing area adjacent to the mid-fuselage. Each landing gear includes a shock strut with two wheel and tire assemblies. Each main landing gear wheel is equipped with a brake assembly. Braking is accomplished by a sophisticated system that uses electro-hydraulic disk brakes with an anti-skid system. Only the two main gear sets have braking capability, and each can be operated separately. Two primary steering options are available. By applying variable pressure to the brakes, the crew can steer the vehicle by a method called differential braking. Also, by selecting nose wheel steering, the crew can use the rudder pedal assembly to operate a hydraulic steering actuator incorporated in the nose landing gear. The crew can also use the rudder to assist steering while at higher ground speeds. |delete section 17|Crew Systems - Living, Working in Space|delete section|Personal equipment supplies and systems, which are used by astronauts in space, are critical elements to overall crew efficiency, productivity and survival. Crew Clothing/Worn Equipment The crew clothing/worn equipment consists of items that provide for the personal needs of all crewmembers. Prior to each flight, crewmembers select clothing and worn equipment from a list of required and optional flight equipment. Crew clothing used during on-orbit activities includes such items as trousers, jackets, shirts, sleep shorts, soft slippers, and underwear. Optional worn/carry-on equipment includes scissors, sunglasses, HP48 calculators, gray tape, flashlight, Swiss army knife, pens and pencils, and chronographs. Personal Hygiene Provisions Personal hygiene and grooming provisions are furnished for both male and female flight crewmembers. Ambient warm water for washing comes from a personal hygiene hose (PHH) attached to the galley auxiliary port. Other personal hygiene provisions are stowed in mid-deck lockers and/or the airlock stowage bag at launch and are removed for use on orbit. A personal hygiene kit is furnished for each crewmember for brushing teeth, hair care, shaving, nail care, etc. Additional grooming and hygiene items are available for female crewmembers in their personal preference stowage. Two washcloths and one towel per crewmember per day are provided. In addition, wet wipes, dry wipes and tissues are provided for personal hygiene. Sleeping Provisions During a one-shift operations mission, all crewmembers sleep simultaneously. At least one crewmember wears a communication head set to ensure reception of ground calls and orbiter caution and warning alarms. A 24-hour period is normally divided into an 8-hour sleep period and a 16-hour wake period for each crewmember. Three hours are allocated for pre/post sleep activities in which crewmembers perform housekeeping, orbiter cleaning, sleep and wake preparation, personal hygiene, and food preparation and eating activities. Sleeping provisions for flight crewmembers consist of sleeping bags and liners. Sleeping bags are installed on the starboard mid-deck wall and relocated for use on orbit. Some sleeping bags can remain on the starboard wall, and some can be attached via pip pins to the mid-deck lockers. Others can be relocated to the airlock, Spacelab, or flight deck (crew preference). A sleeping bag is furnished for each crewmember and contains a support pad with adjustable restraining straps and a reversible/removable pillow and head restraint. Velcro strips on the ends of both sides of the head restraint attach it to the pillow. A sleep kit is provided for each crewmember and is stowed in the crewmemberÆs clothing locker during launch and entry. Each kit contains eye covers and ear plugs for use as required during the sleep period. Exercise Equipment Two types of exercisers are available for use in flight: the treadmill and the cycle ergometer. Only one type is flown per mission, with selection dependent on crew preference, availability of on-orbit space, and science objectives. All exercisers are designed to minimize muscle loss in the legs and maintain cardiovascular fitness in a zero-g environment. The treadmill, which consists of a conveyor running track with force cords, waist belt, and shoulder straps, attaches to the starboard side of the mid-deck floor with quick disconnects. The running track is coupled to a rapid onset braking system that applies increased drag to the track once a crewmember reaches a preset speed. Resistance can be adjusted by dialing the speed control knob. The force cords, waist belt, and shoulder straps restrain the crewmember to the running track. A physiological monitor is used to track heart rate, distance run, and time run while exercising. Because of the space required for operation, the treadmill is now seldom flown. The cycle ergometer (CE) attaches to the tread-mill/entry mid-deck floor studs. The mounting frame is reconfigured on orbit to attach to standard seat floor studs on the flight deck or mid-deck. The CE uses a standard flywheel and braking band system to generate the required resistive force. Cycling resistance can be con-trolled electronically by a control panel or computer-driven exercise protocol or a manual adjustment similar to those found on exercise cycles used at home or in gymnasiums. An accessories bag, which is strapped to the top of the ergometer for launch and entry, contains the attachable hardware as well as crew clothing and shoes necessary for nominal operations. Food Storage & Preparation Systems The mid-deck of the orbiter is equipped with facilities for food stowage, preparation, and dining. The food supply is categorized either as menu food, pantry food, or fresh food. Meals are individually tailored, based on crewmember preference. Menu food consists of three daily meals per crewmember and provides an aver-age energy intake of approximately 2,700 calories per crewmember per day. The pantry food is a 2-day contingency food supply that also contains food for snacks and beverages between meals and for individual menu changes. Pantry food provides an average energy intake of 2,100 calories per crewmember per day. Fresh food items consist of perishable items such as fruits and tortillas. The types of food include fresh, thermo-stabilized, rehydratable, irradiated, intermediate-moisture, and natural form food and beverages. Three 1-hour meal periods are scheduled for each day of the mission. This hour includes actual eating time and the time required to clean up. Breakfast, lunch, and dinner are scheduled as close to the usual hours as possible. Dinner is scheduled at least 2 to 3 hours before crewmembers begin preparations for their sleep period. The Galley The galley is a multipurpose facility that provides a centralized location for one individual to handle all food preparation activities for a meal. The galley has facilities for heating food, rehydrating food, and stowing food system accessories. The galley consists of a rehydration station, oven, hot water tank, and associated controls. The galley rehydration station dispensing system injects water directly into food and beverage packages for rehydration and provides drinking water for crewmembers. The oven is divided into two principal compartments: an upper compartment designed for heating at least 14 rehydratable food containers inserted on tracks, and a lower compartment designed to accept up to 7 flexible packages. Three fans circulate warm air over a heat sink, thus providing forced convection heating for the rigid packages. The flexible packages are held against the heat sink by three spring-loaded plates, and warmed by conduction. The oven has a heating range of 160░ to 185░ F. The oven door is operated by "squeeze" latch requiring only 3 lb of pressure to open the door. Waste Management System The waste management system is an integrated, multifunctional system used primarily to collect and process crew biological wastes. The WMS is located in the mid-deck of the orbiter crew compartment in a 29-inch-wide area immediately aft of the crew ingress and egress side hatch. The system collects, stores, and dries fecal wastes and associated paper tissues. It processes urine and transfers it to the wastewater tank and processes EMU condensate water from the airlock and transfers it to the wastewater tank if an EVA is required on a mission. The WMS consists of a commode, urinal, fan separators, odor and bacteria filter, vacuum vent quick disconnect, and controls. The commode is 27 by 27 by 29 inches, and it is used like a standard toilet. The commode contains a single multi-layer hydrophobic porous bag liner for collecting and storing solid waste. When the commode is in use, it is pressurized, and transport air flow is provided by the fan separator. When the commode is not in use, it is depressurized for solid waste drying and deactivation. The urinal is essentially a funnel attached to a hose and provides the capability to collect and transport liquid waste to the wastewater tank. The fan separator provides transport air flow for the liquid. The fan separators separate the waste liquid from the air flow. The liquid is drawn off to the wastewater tank, and the air returns to the crew cabin through the odor and bacteria filter. The filter removes odors and bacteria from the air that returns to the cabin. The vacuum quick disconnect is used to vent liquid directly overboard from equipment connected to the quick disconnect through the vacuum line. The urinal assembly is a flexible hose with attachable funnels that can accommodate both men and women. The assembly can be used in a standing position, or it can be attached to the commode by a pivoting mounting bracket for use in a sitting position. |delete section