Chapter 4 The Space Shuttle. Components – The Orbiter The main components of the shuttle are the orbiter, the external tank, and the solid rocket boosters.components.
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Components – The Orbiter The main components of the shuttle are the orbiter, the external tank, and the solid rocket boosters.components The Orbiter is 112 feet long, 56 feet high, and 78 feet wide from wingtip to wingtip. It serves as the crewmembers headquarters and to transport large payloads to space. The orbiter is designed to carry from two to eight crewmembers on a ten to fourteen day mission.
Components – The Orbiter In the front of the orbiter is a three level crew compartment. The upper level, called the flight deck, houses maneuvering controls, mission monitors, six windshields, two overhead windows. The second level, the mid-deck, is where the crew eats, sleeps, exercises and conducts some experiments. The mid-deck also features an outside hatch and airlock leading to the cargo bay. The lower level serves to store equipment.
Components – The Orbiter Behind the crew compartment is the payload bay. It measures 60 feet long, 17 feet wide, and 13 feet deep and can carry up to 51,600 pounds. The wings, also known as delta wings, are “D”-shaped which are the most efficient for traveling at speeds well beyond the speed of sound.
Components – The Orbiter The orbiter also contains the space shuttle’s main engines. These three engines, located on the rear of the orbiter, burn a propellant of liquid hydrogen and liquid oxygen. They are essential in getting the orbiter into orbit burning up to 45,300 gallons per minute. They can be throttled from as low as 65% of rated thrust up to 109% which allows the shuttle to provide a much smoother ride. The orbiter is covered by 32,000 heat tiles that protect the shuttle upon reentry.
Components – The External Tank Orange in color, this tank provides the fuel for the shuttle’s main engines. Thus, once the external tank is discarded, the main engines are no longer of use. The external tank is covered by a foam slightly stiffer than the material in a Styrofoam cooler. This serves as insulation for the liquid hydrogen and oxygen held inside which needs to remain at temperatures as cold as 420 degrees below zero. This is the only non-reusable part of the shuttle.
Components – The Solid Rocket Boosters (SRBs) Twin boosters attached to the external tank serve to help to lift the shuttle in the initial stage of launch. They are the largest solid rockets ever made. The solid propellant contains by weight, 16% aluminum powder fuel, 70% ammonium perchlorate oxidizer, 12 % polybutadiene acrylic acid acrylonitrile which is a binding agent, 2% epoxy used for curing, and iron oxide to help control the burning rate.
Components – The Solid Rocket Boosters (SRBs) The mixture of these materials looks like a dense viscous plaster which is poured into a mold where it is dried (cured) for several days resulting in a material that looks and feels like a rubber eraser or hard putty. The SRBs are for one time use only and can burn at a 100% rate until all the fuel is exhausted.
Configuration Total Configuration is 184 feet tall, 79 feet wide from either side, and weighs 4.4 million pounds. When the launch finally occurs 6.425 million pounds of thrust lift the entire ship into the air very quickly because of the excess power.
Shuttles Each orbiter is named for a famous American/British sailing ship of exploration. Challenger (OV-99) was supposed to be the original test vehicle, but during construction, NASA decided to make this orbiter into an operational spacecraft. The first shuttle to launch into space was the Columbia (OV-102) on March 12, 1981. Since then the Challenger, Discovery (OV-103), Atlantis (OV-104) and replacing the Challenger Endeavor (OV-105) have become part of the fleet.
Launch Preparation Each space shuttle flight requires years of mission planning and months of getting the shuttle prepared or processed to go into orbit. Over a month is spent inspecting every system on the orbiter and repair or replace items failing the rigorous exams. Every one of the 32,000 heat tiles must be inspected and replaced if they are damaged or missing.
Launch Preparation The shuttle engines and their respective fuel pumps must be removed, inspected, and refurbished. The engineers may install the same engines, new engines, or previously refurbished engines. The process of integrating the major shuttle parts is called stacking and takes about four to six weeks.
Launch Preparation A specific vehicle, called the crawler, is used to move the completed shuttle assembly to the launch pad. It is described as the biggest, slowest, strongest, strangest and noisiest land vehicle ever created by mankind, it is unlike any other moving vehicle on earth.crawler Built in the 1960s, the crawler typically rolls at around 2 mph. (Video) It takes several hours for the crawler to take the completed shuttle on the 4 mile journey to the launch pad.Video
The Launch All shuttle launches take place at the Kennedy Space Center in Florida. Once the tower is cleared, the control of the shuttle flight goes to Johnson Space Center (JSC) in Houston, Texas.launches At two minutes into the launch both SRBs begin to burn out at an altitude of 29 miles. After the boosters burn completely out, they fall into the Atlantic Ocean beneath large parachutes where they are recovered by two NASA ships. Video of launch of Atlantis (10/02): Parts 1, 2, 3.123
The Launch The main shuttle engines completely shut down at eight minutes and thirty seconds into flight. Soon after the external tank is released. At 45 minutes after launch the orbiter reaches apogee and two thrusters located in the blisters at the left and right of the craft's vertical stabilizer begin to fire to raise the shuttle's orbit. This rocket system is called the orbital maneuvering system (OMS) and it increases the spacecraft's velocity by 150 miles per hour.
In Orbit Once arriving at this orbit, the payload bay doors must be opened to allow the orbiter to cool by removing the excess heat caused by electrical equipment and life support systems operations. Now the space shuttle may begin serving its purpose. This typically is one of the following:
In Orbit Dock with another spacecraft ( ie. International Space Station, Mir) DockMir Carry out experiments (usually a laboratory such as Spacelab has been then included in the payload bay) Release a satellite in the payload bay. This is sometimes done using the robotic arm. Trap another spacecraft. This was done for example with the Hubble Space Telescope so that it could be serviced.
In Orbit The OMS continues to control the orbit of the shuttle, however, attitude is controlled by the reaction control system (RCS). These are a series of small rockets which burn hydrazine and nitrogen tetroxide. There is one RCS pod in the shuttle's nose and two RCS pods in the tail that contain different rocket nozzles that thrust up, down, left, and right. Once an RCS thruster is activated and a movement starts an equal and opposite RCS thruster must be activated to stop the motion (Newton's third law is paramount in zero g).
The Return Flight The space shuttle cannot land in rainy weather. The weather resisting coating burns off during launch and re-entry. Thus while the preferred landing site is back in Kennedy Space Center, the shuttle sometimes needs to be diverted to White Sands, New Mexico or Edwards Air Force Base in California. A specially redesigned Boeing 747 would then piggyback the shuttle to Florida. (Video)Video
The Return Flight A number of checklist items must be performed before the space shuttle can return to Earth. Among these the astronauts must put back on the pressure suits which they wore during ascent and close the payload bay doors. The RCS then places the shuttle in the proper attitude and the OMS slows the shuttle into a decaying orbit. (Video of “go-for de-orbit burn”). From a point halfway around the world the shuttle begins its entry.“go-for de-orbit burn”
The Return Flight As the shuttle enters the atmosphere, the RCS maneuvers the nose at an attitude of about 30º nose up. This insures that the thermal energy is concentrated on the heat tiles underneath the orbiter. Upon reentering the atmosphere temperatures as high as 3,000 degrees Fahrenheit may occur outside the shuttle as it races at speeds in excess of 17,000 miles an hour. It’s a controlled glider as it does its landing (Video). The whole maneuver from de-orbit burn to touchdown takes about an hour.Video
The Tragedies Two shuttles have been destroyed, both with the loss of all astronauts on board: Challenger - lost 73 seconds after lift-off, January 28, 1986. Due to unusually cold weather, one of the O-rings in the SRBs became brittle. One minute after lift-off the ring failed allowing hot gas to escape the SRB and pierce the external tank. Some 73 seconds after the launch began, a colossal explosion ensued that destroyed the shuttle.
The Tragedies Columbia - lost during re-entry, February 1, 2003. Eighty-one seconds after lift-off a briefcase-sized piece of insulation foam from the external tank possibly containing ice detached and impacted the left wing of the orbiter. It is believed that this damaged tiles vital in protecting the shuttle during re-entry. As the shuttle returned, data indicates that the left wing suffered severe damage that eventually led to the loss of control and destruction of the orbiter.
The Tragedies Missions are hopeful to restart around May of this year with the shuttle Discovery making a trip to the International Space Station. Designated, mission STS-114, the crewmembers will deliver supplies to the station, but the major focus of their mission will be testing and evaluating new Space Shuttle flight safety, which includes new inspection and repair techniques. The first spacewalk is set to demonstrate repair techniques of the shuttle’s Thermal Protection System.