Project Details
1.1) Introduction – Tathagat
1.2) Objectives – Aakrity Singh
2.1) Space Shuttle Introduction – Aakrity Singh
2.2) Crew – Upvan
2.3) Components of Space Shuttle – Tathagat
2.4) Phases of Space Shuttle – Tathagat
2.5) Orbiter Vehicle – Aakrity Singh
2.5.1) Remote Manipulator System (RMS) – Lali
2.5.2) Thermal Protection System (TPS) – Harsha
2.5.3) why does shuttle remain stable in earth’s orbit – ?
2.5.4) Reaction Control System (RCS) – Lali
2.5.5) Landing on Earth – Tathagat
2.5.5.1) Challenges during landing – Tathagat
2.5.5.2) Heating by the plasma – Aakrity
2.5.5.3) Process of Reentry – Tathagat
2.5.6) Pressurized Cabin – Harsha
2.5.7) Propulsion System – X
2.5.7.0) Simple Physics Involved – Rishav
2.5.7.1) Solid Rocket Boosters (SRBs) – Lali
2.5.7.2) Space Shuttle main engines (SSMEs) – Tathagat
2.5.7.3) Orbital Maneuvering System (OMS) - ?
2.5.7.4) External Fuel Tank (EFT) – Tathagat / Rishav
2.5.7.5) Hydraulic System – Upvan
2.5.8) Docking – Aakrity
3.1) Challenges – Lali
3.2) Solution – Lali
3.3) Space suits – Tathagat
1.1) Introduction – Tathagat
q Aerospace engineering is the science of spacecraft. It is further divided into aeronautical engineering and astronautical engineering. The former deals with the science of spacecraft in earths atmosphere while the later deals with science behind spacecrafts outside the earth’s atmosphere.
q Space Shuttle was developed by NASA in 1970 as a reusable rocket for transporting humans and cargo (i.e. satellites) to and from earth’s orbit. It is designed for 100 flights.
q NASA has made 5 space shuttles till date : Columbia, Challenger , Discovery, Atlantis, Endeavour . Columbia was the first to make its flight .Challenger disintegrated 73 seconds after launch in 1986, and Endeavour was built as a replacement for Challenger from structural spare components. Columbia broke apart during re-entry in 2003.
q NASA is collaborated by many countries which include Russia, Canada, England , Japan, India.
1.2) Objectives - Aakrity
a) Advancing human exploration and providing safe access to space in support of human operations in low Earth orbit.
b) The Shuttle’s primary role is to complete the assembly of the International Space Station (ISS)
c) Building of lunar bases, nuclear interplanetary rocket stages, and manned Mars expeditions
d) Aeronautics : pioneers and proves new flight technologies that improve our ability to explore and which have practical applications on Earth.
e) Exploration Systems : creates capabilities for sustainable human and robotic exploration.
f) Science : explores the Earth, solar system and universe beyond; charts the best route of discovery ,and keeps the human world updated with the latest space happening of the Universe.
g) Threats to Earth : Identifies the threats the universal constituents might posses to earth.
h) Climate : Climate change research and observations.
i) Aviation : Exploring reliable, increasing commercial spaceflight capabilities, green aviation.
j) Payloads : Numerous satellites and interplanetary probes, space station components, space science experiments are called payloads .They are sent as cargo in space through the shuttles.
2.1) Space Shuttle Introduction - Aakrity
q Space shuttle or Space Transportation System (STS) is a reusable system and orbital spacecraft operated by NASA for human spaceflight missions.
q Shuttle leaves the earth vertically. It weights about 2.0 million kg with 3 million kg of thrust from its multiple propulsion systems. It lands on earth on a conventional airport runway.
2.2) Crew - Upvan
q Crew forms the integral part of a space mission and is crucial for its success.
q There are around 7 crew members in the space mission.
q The Crew is lead by the commander and the pilot. Their primary responsibility is to fly the shuttle as a launch vehicle, spacecraft, and aircraft.
q The Remaining five members are experts in that mission's objectives and cargo, which are usually space experiments or artificial satellites. They are led by the lead astronaut who ensures that mission achieves all its objectives. Often the 5 members are payload scientists from other nations
2.3) Components of Space Mission - Tathagat
2.4) Phases of Space Shuttle – Tathagat
2.5) Orbital vehicle – Aakrity
q The orbiter is a reusable winged "space-plane", a mixture of rockets, spacecraft, and aircraft. This space-plane can carry crews and payloads into Earth orbit, perform on-orbit operations, then re-enter the atmosphere and land as a glider, returning her crew and any on-board payload to the Earth.
q Challenger, Columbia, Discovery, Endeavour and Enterprise all made by the Rockwell International Company .
q Body of shuttle is made from the aluminum alloy; engine thrust structure is made from titanium alloy; windows are made of aluminum silicate glass and fused silica glass, comprising of internal pressure pane, mid 1.5 inch thick optical pane and external thermal pane.
q Its belly and nose is made from thermal insulating tiles.
q The orbiter vehicle has primarily three sections:
(a)Flight deck : Commander and pilot occupy the flight deck surrounded by computer controls and switches. In a seven member crew 2 astronauts are positioned just behind the pilot and commander to control the craft in case of emergency.
(b) Mid deck : It is below the flight deck. The galley toilet, sleep stations, and storage and experiment lockers are found in the mid-deck. Side hatches for passage to and from the vehicle is located in the mid deck.
(c) Utility Area : It has air and water tanks. Cargo bay carries satellites, scientific laboratories, foundations and components of space stations. It also serves as a workstation for astronauts to repair and assemble satellites.
2.5.1) Remote Manipulator System – Lali
q Remote Manipulator System (RMS) is developed by Canadian Government
q It is a robotic arm of 15.2m(s) running along the cargo bay area / utility area. It has a diameter of 15 inches and weights 450 kg(s).
q The RMS has six joints that correspond roughly to the joints of the human arm.
q The RMS can move anything from satellites to astronauts to and from the cargo bay or to different points in nearby space. It is the carrier of the components of the ISS from the cargo area to astronauts in space. The Canadarm can also retrieve, repair and deploy satellites .It inspects the surface of the space shuttle by the high precision camera attached to its head.
q It is also called Canadarm.
2.5.2) Thermal Protection System (TPS) – Harsha
q The orbiter not only encounters extreme temperatures of 3500°F but also as low as -250°F , the part of the shuttle which is exposed to the direct rays of the sun faces very high temperatures whereas the part of shuttle in the silhouette faces temperatures which much low than freezing point.
q The orbiter's outer structural skin is constructed primarily of aluminum and graphite epoxy which cannot withstand temperatures over 350°F.
q TPC components : namely Reinforced Carbon-Carbon , Black high temperature reusable surface insulation tiles, felt reusable Nomex are spread over the shuttle selected surfaces to encounter a temperature range of -250 °F cold space and 3500 °F heat of reentry.
q Reinforced Carbon-Carbon is made from carbon as a result pyrolised resin and furfural alcohol. Its outer surface is made from alumina, silicon and silicon carbide. It is present on wing edges, nose cap, external tank structural attachment area and protects are exceeding 3000°F.
q Black high temperature reusable surface insulation tiles tiles are made of a low-density, high-purity silica 99.8-percent made strong by ceramic bonding. It is used underside the orbiter, RCS pods and some parts of OMS, elevon edges, upper body flap and upper side of wings. They are black for better emission. These tiles at 2300°F can be held with bare hands without injury as they rapidly dissipate heat.
q Nomex is a white blanket covering about 50% of the shuttles' surface and encounters temperatures below 700°F and even negative temperatures.
2.5.3) Why does shuttle remain stable in Earth Orbit -
q The stability of the shuttle in an earth’s orbit is based on the simple principle of centripetal and centrifugal force.
q The orbit in which the shuttle moves experiences a force of gravity just a bit less than that which is experienced on earth.
q In order to counteract the gravitational force of earth it has to move with a critical velocity of 8km/s.
q Due to this astronauts feel the weightlessness. The whole system moves with this speed so that there is no relative motion.
q The critical velocity of 8 km/s is called orbital speed.
2.5.4) Reaction Control System (RCS) – Lali
q RCS is composed of 44 small liquid fueled rocket thrusters controlled by a very sophisticated system called fly-by-wire.
q RCS makes use of monomethylhydrazine which is oxidized by nitrogen tetroxide.
q The RCS provides fine pointing and attitude control along the pitch , roll and yaw axis during all phases of flight “ launching , orbit and re-entry .”
q It is used for station keeping of the orbiter.
q It is responsible for pumping and pressurizing fuel in zero gravity.
q RCS monitors the conservation of fuel through-out the mission.
2.5.5) Landing on Earth – Tathagat
q Shuttle lands on a conventional runway cleared by the Federal Aviation Administration and the Air Force. The Orbiter nearly always lands at either Edwards Air Force Base (California) or near to the Patrick Air Force Base (Florida).
q Biggest challenge in landing is to prevent the shuttle to make a high speed landing while descent through a great height while it doesn’t burn up.
q Although there are elevons on the delta wings, airbrake, movable body flap but these are effective only in earths lower levels of atmosphere where the air density is thick.
q In order to deorbit shuttle has to lose most of it’s orbital speed.
2.5.5.1) Challenges during landing – Tathagat
q Strategy of safe landing is based on the principle of losing the orbital speed of 8 km/ hour , i.e. , losing maximum of its kinetic energy.
q As soon as the thrusters decrease the critical velocity the shuttle starts descending into the earth’s atmosphere.
q There are 4 ways in which the OV can shed its K.E. and P.E.
1. POWER DECELERATION : This can be achieved by the rocket thrust opposed to the direction of motion , this can be done at the very beginning of the reentry. However this method proves to be quite ineffective as most of the fuel is consumed in maneuvering.
2. ENERGY EXCHANGE : This method is the conversion of kinetic energy of the shuttle into potential energy. However no technique has proved useful in harnessing such a large magnitude of energy in small intervals of time.
3. MASS SHEDDING : This method is conceptually exemplified by a pilot ejecting from his damaged plane by smaller portable shuttle which ejects from the main one - most of the system's energy remains invested in the part that carries on and crashes. However the principle of NASA STS program of the “reusability of shuttle” and “leaving no debris in space” rules out this idea. European Space Agencies make use of this technique.
4. ENERGY DISSIPATION : This method is based on the principal of converting the K.E. of shuttle into useless forms heat and sound. This method is most feasible as the thermal tiles enclosing the shuttle has a rapid heat dissipation capability. In the lower atmospheres the where the density of air column increases the elevons , rudder and air brake comes into play. The shuttle releases the parachutes and wheel-brakes are employed to lower the speed from 350 km/Hr to 150 km/hr.
2.5.5.2) Heating by the Plasma – Aakrity
q It is assumed that most of heating is a function of friction, i.e., viscous drag of the atmosphere. But most of the heating is done by the plasma, heating by friction is dominant only in the lower levels of atmosphere.
q The Orbiter vehicle thus descends into a sea of superheated plasma.
q Plasma , being the fourth state of matter has proportionality of pressure and temperature
q Energy density at such high speed is enough to dissociate and ionize atmospheric molecules.
q Pressure wave in the upper level of the atmosphere and extreme speed of the shuttle leads to high pressure and intensifies the effect of plasma.
q The plasma stream is electrostatically charged and causes intense local heating on the acute contours of the shuttle’s body
2.5.5.3) Process of Re-entry – Tathagat
q Initial height of the space shuttle : 150 km ; Initial speed of the space shuttle : 29000 km/ hr.
q A speed trim of 300 km/ hr unsettles the critical velocity and is enough to initiate descent.
q Trimming is done but firing up the large rocket motors opposite to the sense of motion. By moving in yaw and pitch fashions the shuttle directs the main engines against the direction of motion . After trimming the speed the shuttle , the shuttle directs it nose towards the face of earth. This process utilizes the remaining fuel of the shuttle taking the shuttle to an altitude of 120 km.
q At this point of time plasma flare begins.
q Now the angle of attack is critical. The shuttle is maintained at an critical angle of 40° by automatic thrusters. Any shallower , the shuttle will face excessive lift and will overfly it’s destination ; any steeper , it will burn up.
q At an altitude of 85 km , the flight surface becomes usable , the automated system performs 4 S-Bends with banking at maximum 80° on a full extent roll. This drastically decreases the speed of the shuttle
q The shuttle is never shrouded completely with plasma flare so communication with NASA space control is always maintained.
q At an altitude of 40 km and craft clocking 10000 km/ hr , plasma flare has ceased; now factors like atmospheric drag comes into play. Air brakes ,elevons ,rudders are employed to bring down the speed to 4000 km/ hr into stable supersonic regime.
q Shuttle is 40 km away from the runway ; pilot directs the nose in landing mode , employs the landing gear and the parachutes ; the speed of touchdown is 350 km/hr ; Finally shuttle comes to a halt.
2.5.6) Pressurized Cabin - Harsha
q The whole craft is pressurized at around 1.14 atm
q An Airlock mechanism depressurizes the space-suits before a walk in space and repressurizes before and astronaut enters the shuttle. It also prevents the shuttle from losing pressure to the outer space as the astronauts move in and out of the shuttle.
2.5.7.0) Simple Physics Involved – Rishav
IN EARTH’s ATMOSPHERE
q Based on Newton's 3rd law , the burning fuel exerts the reaction force on the shuttle and makes it’s ascent.
OUTSIDE EARTH’s ATMOSPHERE
q Its based on the principle of the linear conservation of motion , i.e. , the product of mass and velocity remains constant. Conservation of momentum can be applied in an isolated system when no external force is acting. Considering the fuel and the shuttle in an isolated system the combined momentum of fuel and shuttle is zero. The fuel is jettisoned off from the engines have negative momentum , in order to nullify the total momentum to zero the space shuttle moves in the direction opposite to that of the outburst fuel.
2.5.7.1) SRBs – Lali
q They are located on either sides of the orange colored external fuel tank.
q The 2 SRB’s have a combined thrust of 26 million Newton and provide most of the power of the shuttle for the first two minutes of the flight.
q The solid rocket motor is the largest solid propellant motor ever made.
q Each SRB has about 450,000 kg of solid propellant which looks like a synthetic hard rubber. Solid Propellant consists of powdered aluminum mixed with oxygen and a chemical ammonium perchlorate.
q The SRB’s take the shuttle at a height of 45 km and 4828 km/ hr before they are separated by the booster separator motors and fall into the ocean to be refurbished and prepared for the next flight.
2.5.7.2) SSMEs
q Manufactured by Rocket-Dyne.
q The 3 main shuttle engines are in the shape of an equilateral triangle
q After the SRB’s are jettisoned off , the SSMEs provide the thrust for 8.5 min taking the velocity from 4828 km/ hr to 27400 km/ hr and altitude from 45 km to 150 km, i.e., in the orbit.
q The 3 engines have a combined thrust of 5.3 million Newton and is capable of achieving the 3g
q As the Shuttle accelerates, the main engines burn a half-million gallons of liquid propellant provided by the large, orange external fuel tank. The main engines burn liquid hydrogen -- the second coldest liquid on Earth at -252.8 degrees Celsius and liquid oxygen.
q The liquid fuel inside the craft is reserved for in-orbit operation and maneuvering .
q These engines are removed for maintenance , from the shuttle after the mission and is designed for 55 flights
q These 3 engines can be swiveled 10.5 vertically and 8.5 horizontally by the hydraulic system in order to change the direction of thrust
2.5.7.3) OMS - ?
q As soon as the shuttle achieves an altitude of 150 km , it starts orbiting the earth ; this point is called the orbital insertion point. The main engines are shut down and the OMS gets operational.
q OMS is handled on the basis of the RCS consisting of 44 small liquid fueled rocket thrusters which are cluttered around the nose and either sides of the tail.
q The main function of the OMS is to change the orbit in which the shuttle is moving. The orbital insertion point has to be tampered with to facilate shuttle’s important work.
2.5.7.4) ET – Tathagat / Rishav
q It is the gas tank/backbone of the shuttle providing it with most of the fuel during it ascent.
q The EFT contains oxygen and hydrogen in a ratio of 6:1.
q It carries 536,000 gallons of fuel.
q The EFT has 3 primary components oxygen tank , hydrogen tank and an intertank
q The previous design used foam ramp to prevent the buildup of ice , but it led to the breaking up of a foam particle which burned a hole in the OV leading to the most deadliest disaster in space “ the Colombia disaster .”The new design uses heater to prevent the buildup of ice.
q The skin of the EFT is covered with spray-on polyisocyanurate foam to keep the propellants at acceptable temperatures.
q The tank propellants are fed to the SSMEs for usage through a 17 inch thick pipe which branches inside the OV.
The EFT is the only part which is not reusable , it is released in the atmosphere once the fuel is exhausted and it burns up on it’s way to earth.
2.5.7.5) Hydraulic System – Upvan
q The hydraulic system consists of Auxiliary Power Unit (APU) which burn hydrazine to provide hydraulic pressure to all hydraulic devices
q Hydraulic Systems controls the calibration of the SSMEs under computerized flight control.
q It controls the aero surfaces (e.g. elevons , air brake , rudder).
q It controls the open and close of main cargo bay’s doors.
2.5.8) Docking – Aakrity
q Docking is the process in which the shuttle docks or joins the International Space Station.
q Docking systems are controlled by the RMS
q Docking is necessary for updating the Satellites ; adding new sections , solar panel , transmitters and arial ; overhauling damaged parts
3.1) Challenges in Space - Lali
q Debris (rubbish) from previous space missions and micrometriods posses’ threat.
q Astronauts have to face highly accelerated ascent and descent.
q Basic needs as breathing, eating and drinking, elimination of body wastes, and sleeping.
q Microgravity.
q Space Radiations
3.2) Solution (Self Explanatory ) – Lali
3.3) Space Suit - Tathagat
0 comments:
Post a Comment