Alternate Classroom

Space System

Space SystemA space system is a broad term that refers to a complex network of interconnected components, technologies, and operations designed to operate in outer space. These systems are typically built and operated by space agencies, governments, or private companies to achieve specific goals and objectives related to space exploration, communication, Earth observation, scientific research, or national defense. Key components of a space system may include:Spacecraft,Launch Vehicles,Ground Control Stations,Ground Infrastructure,Mission Control,Space Stations,Communication Networks etc. Basic of Orbital MechanicsOrbital mechanics, also known as celestial mechanics or space mechanics, is the branch of physics that deals with the motion of objects in space under the influence of gravitational forces. It specifically focuses on understanding and predicting the behavior of objects, such as spacecraft, satellites, planets, and other celestial bodies, as they move through space and orbit around one another.Key principles and concepts in orbital mechanics include:1. Kepler's Laws of Planetary Motion: Johannes Kepler formulated three fundamental laws in the early 17th century that describe the motion of planets and other celestial objects in elliptical orbits around a central body (typically a star like the Sun). These laws are:

(a) Kepler's First Law (Law of Ellipses): Planets orbit the Sun in elliptical paths, with the Sun at one of the two foci of the ellipse.(b) Kepler's Second Law (Law of Equal Areas): A line segment connecting a planet to the Sun sweeps out equal areas in equal times. This implies that a planet moves faster in its orbit when it is closer to the Sun (perihelion) and slower when it is farther away (aphelion).(c) Kepler's Third Law (Law of Harmonies): The square of the orbital period of a planet is directly proportional to the cube of its semi-major axis (the long radius of the elliptical orbit).(c) T

∝ a

2. Newton's Laws of Motion: Isaac Newton's laws of motion, particularly his law of universal gravitation, explain how objects in space interact gravitationally. Newton's laws provide the foundation for understanding how celestial bodies attract each other and determine their trajectories.Orbital mechanics is essential for the design, planning, and execution of space missions, whether they involve launching satellites into Earth orbit, exploring other planets, or sending spacecraft into deep space. It plays a critical role in determining the trajectory, timing, and energy requirements for space travel and exploration. Concept of OrbitAn orbit is the path that an object, typically a celestial body like a planet, moon, satellite, or spacecraft, follows as it revolves around a more massive object, usually a star like the Sun or a planet. The concept of an orbit is central to understanding how objects move in space under the influence of gravitational forces.To fully describe an object's orbit, a set of parameters known as orbital elements is used. These elements include:

Semi-major Axis(a): Half of the longest diameter of the elliptical orbit.Semi-minor Axis(b): Half of the shortest diameter of the elliptical orbit.Eccentricity: A measure of how elliptical the orbit is, with values between 0 (perfect circle) and 1 (highly elongated).Inclination: The tilt of the orbital plane relative to a reference plane (usually the plane of the central body's equator).Satellite that orbit earth, including the moon , do not always stay the same distance from the earth. The closest point a satellite comes to earth is called its perigee and the farthest point is the apogee. For planets, the point in the orbit closest to the sun is perihelion and and the farthest point is aphelion. Note: Earth reaches its aphelion during summer in the northern Hemisphere and perihelion in winter. The general form of orbit is (in cartesian coordinates)

=1 In Polar formr=

(

1-e

)

1+ecos𝜃

Where, e= eccentricity a = semi major axis b = semi minor axis r= distance of object (earth) from central object (sun) 𝜃 = angle between 'r' and major axis Orbits PropulsionThe method by which a thrust is produced to push an object forward is called propulsion system. Orbit propulsion refers to the use of propulsion systems on spacecraft to change or maintain their orbits in space. It plays a crucial role in various aspects of space exploration and satellite operations. Types of Propulsion Systems:1. Chemical Propulsion: This is the most common form of propulsion for launching spacecraft into orbit. Chemical rockets use chemical reactions to produce high-speed exhaust gases that are expelled from the rocket nozzle to generate thrust. Liquid rocket engines (using liquid propellants like liquid hydrogen and liquid oxygen) and solid rocket motors (using a solid propellant) are examples of chemical propulsion. 2. Electric Propulsion: Electric propulsion systems, such as ion thrusters and Hall-effect thrusters, use electricity (typically from solar panels) to accelerate charged particles (usually ions) to high velocities to produce thrust. While electric propulsion generates lower thrust compared to chemical rockets, it is highly efficient and can provide continuous thrust over extended periods, making it suitable for deep space missions and orbital adjustments. Aerodynamics, Navigation , Guidance and Control systemAerodynamicsAerodynamics is the branch of science and engineering that deals with the study of the behavior of air (or other gases) as it interacts with solid objects, such as aircraft, cars, buildings, and various other structures. It is a subfield of fluid dynamics and is primarily concerned with understanding how air flows around and interacts with these objects. It is a science involved with the study, design and manufacuring of air flight-capable machines and techniques of operation aircraft and rockets within the atmosphere. In aerodynamics there are some major forces involved:• Lift: Lift is the upward force generated on an object moving through a fluid, usually air. It is the force that enables aircraft to overcome gravity and fly.• Drag: Drag is the resistance or retarding force experienced by an object moving through a fluid. It opposes the object's motion .• Thrust: Thrust is the force produced by engines or propulsion systems to propel an object forward through the fluid.• Weight: Weight is the force due to gravity acting on the object.What is Guidance, Navigation and Contro (GNC) system?Guidance, Navigation, and Control (GNC) is a critical subsystem or discipline in various fields, like aerospace which work together to guide, navigate, and control vehicles or platforms to achieve specific objectives, whether it's reaching a destination, maintaining stability, or performing complex maneuvers ( operations usually war). In may cases these functions can be performed by trainned humans. However, because of the speed, for example, in a rocket's dynamics , human reaction is too slow to control this movement. Therefore nowadays this is controlled by programmed digital electronics. • Guidance :Guidance is the process of providing instructions or commands to a vehicle or system to ensure it follows a desired path, trajectory, or mission profile.• • Navigation: Navigation involves determining the vehicle's position, velocity, and orientation relative to a known reference frame or coordinate system.• Control: Control refers to the process of managing the vehicle's actuators (e.g., engines, thrusters, control surfaces, motors) to ensure that it follows the guidance commands and maintains stability.History and development of Manned and unmanned Space TravelHumans have always looked at the heavens and wondered about the nature of the objects seen in the night sky. With the development of rockets and the advances in electronics and other technologies in the 20th century, it became possible to send machines and animals and then people above Earth’s atmosphere into outer space. Unmanned Missions• October 4, 1957 - The Soviet Union succesfully launches Sputnik 1, the first artificial Earth satellite.• January 31, 1958 - Under pressure to keep up with the Soviets, the United States launches Explorer 1, the first American satellite.• On January 2, 1959 - The Soviet Union began a massive campaign to the Moon with the launch of Luna 1.• August 27, 1962 - NASA launches the Mariner 2 spacecraft to Venus. • July 14, 1964 - Mariner 4 encounters Mars,• July 28, 1964 - NASA sends the Ranger 7 spacecraft to the Moon.• May 30, 1966 - NASA sends Surveyor 1 to the Moon. The versatile spcaesraft successfully lands on the lunar surface, becoming the first spacecraft to achieve a soft landing on another celestial body.• August 17, 1970 - The Soviet Union launches Venera 7 to Venus. When it arrives, it ejected a capsule that transmitted data back to Earth. It was the first successful transmission of data from the surface of another planet. Manned MissionQ. Write the developmen of Manned space mission in brief. (TU)• August 19, 1960 - The Soviet Uion launches Sputnik 5, the test vehicle for the new Vostok spacecraft that will carry cosmonauts into space. It carries two dogs that become the first living creatures to successfuly return from orbital flight.• April 12, 1961 - Soviet cosmonaut Yuri Gagarin becomes the first human to orbit the Earth inside the Vostok 1 spacecraft.• February 20, 1962 - John Glenn, Jr., becomes the first American to orbit Earth.• September 12, 1966 - NASA launches the highly productive Gemini 11 mission which was completely computer controlled.• December 21, 1968 - NASA launches the Apollo 8 spacecraft. The three crew members are the first people to leave Earth's gravitational influence..• July 16, 1969 - Apollo 11 lifts off, and four days later on July 20, Neil Armstrong and Buzz Aldrin become the first humans to set foot on the Moon. • April 19, 1971 - The Soviet union launches the world's first space sattion, Salyut 1.• April 12, 1981 - NASA inagurates the era of reusable space transportation with the launch of the space shuttle Columbia. At the end of its successful two day test mission, Columbia becomes the first spacecraft to return to Earth by gliding through the atmosphere, and landing like an airplane.• February 20, 1986 - The Soviet Union introduces its third-generation space station, a sophisticated facility called Mir (peace).• April 24, 1990 - The space shuttle Discovery successfully deploys the Hubble Space Telescope• December 4, 1998 - NASA launches the shuttle Endevour on the first assembly mission of the International Space Station. Challenger disasterOn January 28, 1986, the Space Shuttle Challenger broke apart 73 seconds into its flight, killing all seven crew members aboard. The spacecraft disintegrated 14 km above the Atlantic Ocean, off the coast of Florida. It was the first fatal accident involving an American spacecraft while in flight. Columbia DisasterOn Saturday February 1, 2003, Space Shuttle Columbia disintegrated as it reentered the atmosphere over Texas and Louisiana, killing all seven astronauts on board. It was the second Space Shuttle mission to end in disaster, after the loss of Challenger and crew in 1986. Rocket Launch TechnologyQ. Explain rocket Launch Technology. (TU) A rocket is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely from propellant carried within the vehicle; therefore a rocket can fly in the vacuum of space. Multistage rockets are capable of attaining escape velocity from Earth and therefore can achieve unlimited maximum altitude. Rockets for military and recreational uses date back to at least 13th-century China. Significant scientific, interplanetary and industrial use did not occur until the 20th century.Mission Operations PhasesInterplanetary mission operations may be considered in four phases: the Launch Phase, the Cruise Phase, the Encounter Phase, and, the Extended Operations Phase. • The launch phase – this starts from the selection of crews and preparations of all the equipments to be used in the flight up to the day of the spacecraft’s launching.• The cruise phase comes between the launch phase and the encounter phase. It may last only for a few months or for years. • the Encounter Phase - includes the period of closest approach to the target. It is marked by intensely active observations with all of the spacecraft's science experiments, including onboard instruments and radio science investigations.• Extended or Ending Phase -The primary aim of mission is completed when data is gathered. In many cases after it complets its job, the rocket is still in good operable condition. Since it has completed all the basic stages and is in space, it can be forther sent to collect new data for another mission. This is called mission extention. Structure of Rocket

There are four major parts or systems in a rocket. They are: • Structural system• Payload system.• Guidance system.• Propulsion system.1. Structural system (Frame):It is the frame that covers the rocket. It is made up of very strong but light weight materials like titanium or aluminum. Fins are attached to some rockets at the bottom of the frame to provide stability during the flight. 2. Payload system:It is the object that the satellite is carrying into the orbit. Payload depends on the rocket’s mission. The rockets are modified to launch satellites with a wide range of missions like communications, weather monitoring, spying, planetary exploration, and as observatories. Special rockets are also developed to launch people into the Earth’s orbit and onto the surface of the Moon. 3. Guidance system:Guidance system guides the rocket in its path. It may include sensors, on-board computers, radars, and communication equipments. 4. Propulsion system:It takes up most of the space in a rocket. It consists of fuel (propellant) tanks, pumps and a combustion chamber. There are two main types of propulsion systems. They are: liquid propulsion system and solid propulsion system.