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The '''Space Transportation System (STS)''', also known as space shuttle, was developed by [[NASA]] as a meant to move both crew and cargo into [[low earth orbit]].  
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The '''Space Transportation System (STS)''', also known as space shuttle, was developed by [[NASA]] as a means to move both crew and cargo into [[low earth orbit]].  
At launch the space shuttle was attached to an ET (external tank) and two SRB (solid rocket booster).
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At launch the space shuttle is attached to an ET (external tank) an two SRB (solid rocket booster).
The SRB jettison at 126 seconds in-flight and fall back down to earth where they would be picked up and refurbished for another launch.
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The SRB jettison at 126 seconds in-flight and fall back down to earth where they will picked up and refurbished for another launch.
 
The ET will not be reused.
 
The ET will not be reused.
  
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[[File:ShuttleVibrations.png|right|thumb|200px|Shuttle vibration amplitudes during ascent in g]]
 
[[File:ShuttleVibrations.png|right|thumb|200px|Shuttle vibration amplitudes during ascent in g]]
  
The STS Orbiter was the primary component of the STS and the only part of the STS stack, which reached orbit. It was a mixture between spacecraft and aircraft, landing as a glider after a long lifting reentry.
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The STS Orbiter is the primary component of the STS and the only part of the STS stack, which reaches orbit. It is a mixture between spacecraft and aircraft, landing as a glider after a long lifting reentry.
  
 
==Orbital Maneuvering System (OMS)==
 
==Orbital Maneuvering System (OMS)==
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[[Image:OMS_diag.png|right|thumb|200px|Diagram of the OMS plumbing]]
 
[[Image:OMS_diag.png|right|thumb|200px|Diagram of the OMS plumbing]]
  
The OMS would provide propulsion for the orbiter during the orbit phase of flight. The OMS wass used for orbit insertion, orbit circularization, orbit transfer, rendezvous, and deorbit. The OMS may be used to provide thrust above 70,000 feet altitude. Each OMS pod could provide more than 1,000 pounds of propellant to the RCS. Amounts available for interconnect depend on loading and number of OMS starts during the mission.
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The OMS provides propulsion for the orbiter during the orbit phase of flight. The OMS is used for orbit insertion, orbit circularization, orbit transfer, rendezvous, and deorbit. 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 RCS. Amounts available for interconnect depend on loading and number of OMS starts during the mission.
  
The OMS was housed in two independent pods on each side of the orbiter’s aft fuselage. The pods,
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The OMS is housed in two independent pods on each side of the orbiter’s aft fuselage. The pods,
which also housed the aft reaction control system (RCS), are referred to as the OMS/RCS pods.
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which also house the aft reaction control system (RCS), are referred to as the OMS/RCS pods.
Each pod contained one OMS engine and the hardware needed to pressurize, store, and
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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 were
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distribute the propellants to perform OMS engine burns. Normally, OMS maneuvers are
done using both OMS engines together; however, a burn could be performed using only
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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 fps (2 m/s), RCS was used. For velocity
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one of the OMS engines. For velocity changes less than 6 fps (2 m/s), RCS is used. For velocity
changes greater than 6 fps, a single OMS engine burn was preferred, because engine lifetime
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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 were used for large
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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 could be fed to the
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velocity changes, or for critical burns. Propellant from one pod can be fed to the
engine in the other pod through crossfeed lines that connected the left and right OMS pods.
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engine in the other pod through crossfeed lines that connect the left and right OMS pods.
The OMS had important interfaces with the data processing system and the electrical power
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The OMS has important interfaces with the data processing system and the electrical power
system. The OMS valves and gimbal actuators received commands, and the system returned some
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system. The OMS valves and gimbal actuators receive commands, and the system returns some
 
data to the general purpose computers through multiplexer/demultiplexer units. Electrical
 
data to the general purpose computers through multiplexer/demultiplexer units. Electrical
power was supplied to the OMS through main buses, control buses, and alternating current
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power is supplied to the OMS through main buses, control buses, and alternating current
 
buses for the operation of switches, valves, instrumentation, gimbal actuators, and heaters.
 
buses for the operation of switches, valves, instrumentation, gimbal actuators, and heaters.
  
The OMS/RCS pods were designed to be reused for up to 100 missions with only minor repair,
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The OMS/RCS pods are designed to be reused for up to 100 missions with only minor repair,
refurbishment, and maintenance. The pods were removable to facilitate orbiter turnaround,
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refurbishment, and maintenance. The pods are removable to facilitate orbiter turnaround,
 
if required.
 
if required.
  
 
===Engines===
 
===Engines===
The OMS engines were designated left and right, descriptive of location. The engines were 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 provided 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.
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The OMS engines are designated left and right, descriptive of location. 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.
  
The OMS engines could be used singularly by directing the thrust vector through the orbiter center of gravity or together by directing the thrust vector of both engines parallel to the X axis. During a two-OMS-engine burn, the RCS would come into operation only if the attitude or
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The OMS engines can be used singularly by directing the thrust vector through the orbiter center of gravity or together by directing the thrust vector of both engines parallel to the X axis. During a two-OMS-engine burn, the RCS will come into operation only if the attitude or
attitude rate limits are exceeded. However, during a one-OMS-engine burn, RCS roll control was required.  
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attitude rate limits are exceeded. However, during a one-OMS-engine burn, RCS roll control is required.  
  
Each of the two OMS engines produced 6,000 pounds of thrust (26.7 kN). For a typical orbiter weight, both engines together would create an acceleration of approximately 2 ft/sec<sup>2</sup> or 0.06 g’s. Using up a fully loaded tank, the OMS could provide a total velocity change of approximately 1,000 ft/sec (304.8 m/s). Orbital insertion burns and deorbit burns each typically required a velocity change of about 100–500 ft/sec. The velocity change required for orbital adjustment is approximately 2 ft/sec (0.61 m/s) for each nautical mile of altitude change. Each OMS engines were capable of 1,000 starts and 15 hours of cumulative firing. The minimum duration of an OMS engine firing wass 2 seconds.
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Each of the two OMS engines produces 6,000 pounds of thrust (26.7 kN). For a typical orbiter weight, both engines together create an acceleration of approximately 2 ft/sec<sup>2</sup> or 0.06 g’s. Using up a fully loaded tank, the OMS can provide a total velocity change of approximately 1,000 ft/sec (304.8 m/s). Orbital insertion burns and deorbit burns each typically require a velocity change of about 100–500 ft/sec. The velocity change required for orbital adjustment is approximately 2 ft/sec (0.61 m/s) 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.
  
The OMS engines used monomethyl hydrazine as the fuel and nitrogen tetroxide as the oxidizer.
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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
 
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 remained liquid at the
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each other; therefore, no ignition device is needed. Both propellants remain liquid at the
temperatures normally experienced during a mission, however, electrical heaters wre located
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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
 
throughout the OMS pods to prevent any freezing of propellants during long periods in
orbit when the system was not in use.  
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orbit when the system is not in use.  
  
Each OMS engine had a gaseous nitrogen tank that would provided pressurized nitrogen to operate the engine valves. The OMS engine would not have propellant pumps; propellant flow to the
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Each OMS engine has a gaseous nitrogen tank that provides pressurized nitrogen to operate the engine valves. The OMS engine does not have propellant pumps; propellant flow to the
engines was maintained by pressurizing the propellant tanks with helium.
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engines is maintained by pressurizing the propellant tanks with helium.
  
In the OMS engine, fuel was burned with oxidizer to produce thrust. The major elements of the
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In the OMS engine, fuel is burned with oxidizer to produce thrust. The major elements of the
OMS engine were the bipropellant valve assembly, the injector plate, the thrust chamber, and the nozzle.
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OMS engine are the bipropellant valve assembly, the injector plate, the thrust chamber, and the nozzle.
  
The [[Propellant|propellants]] ignite on contact, so theoretically the OMS engines could get ignited as often as desired, but the number of restarts were limited by the supply of N<sub>2</sub> used for operating the valves and purging the fuel lines of the engines, which was only enough for ten restarts.
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The [[Propellant|propellants]] ignite on contact, so theoretically the OMS engines could get ignited as often as desired, but the number of restarts gets limited by the supply of N<sub>2</sub> used for operating the valves and purging the fuel lines of the engines, which is only enough for ten restarts.
  
 
==Differences between the orbiters==
 
==Differences between the orbiters==
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=STS addons for Orbiter=
 
=STS addons for Orbiter=
*[[Shuttle Fleet]], a collection of the whole vehicle fleet, by David413.
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*[[Shuttle Fleet]], a collection of the whole vehicle fleet, by John Gattis.
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*The STS payloads project.
  
 
=References=
 
=References=
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*[http://en.wikipedia.org/wiki/Space_Shuttle Wikipedia article about the STS]   
 
*[http://en.wikipedia.org/wiki/Space_Shuttle Wikipedia article about the STS]   
  
[[Category: Articles]]
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[[Category:Historic spacecraft|Space]]
[[Category:Historic spacecraft]]
 
 
[[Category:Launch vehicles|Space]]
 
[[Category:Launch vehicles|Space]]
[[Category:Manned space program]]
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[[Category:Spaceplanes]]
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[[Category:historic spacecraft]]
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[[Category:manned space program]]

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