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Launch Vehicles and Sensing Technology. How Rockets Work. Newton's Laws of Motion are: An object at rest tends to remain at rest An object in motion tends to remain in motion For every action there is an equal and opposite reaction . Conservation of Momentum.

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How rockets work
How Rockets Work

  • Newton's Laws of Motion are:

    • An object at rest tends to remain at rest

    • An object in motion tends to remain in motion

    • For every action there is an equal and opposite reaction


Conservation of momentum
Conservation of Momentum

  • Newton's Laws are all contained in a more general principle called conservation of momentum.

  • Momentum is mass times velocity

  • In a system that is not disturbed from outside, the total momentum stays constant.


Conservation of momentum means
Conservation of Momentum Means:

  • If velocity is zero, momentum is zero (Newton's First Law)

  • If velocity is not zero, and mass doesn't change, then velocity doesn't change (Newton's Second Law)


Conservation of momentum and newton s third law
Conservation of Momentum and Newton’s Third Law

  • If mass changes somehow, then so does velocity.

  • If an object is stationary, and flings off mass, the rest of the mass moves in the opposite direction.

  • The flung off mass has positive momentum, the rest has negative momentum, and the total momentum remains zero (Newton's Third Law).



Rockets and jets
Rockets and Jets

  • Rockets and jets work according to Newton's Third Law.

  • They fire mass out at high speed and acquire velocity in the opposite direction.

  • They do not need something to push against. They move because they are expelling exhaust gases at high speeds.

  • Tthe rocket or jet is pushing mass away, and the mass is pushing back (equal and opposite reaction.)


How rockets and jets differ
How Rockets and Jets Differ

  • Rockets and jets expel mass by burning fuel.

  • A jet gets the oxygen for combustion from the atmosphere

  • A rocket carries oxygen in some form with it.

  • Thus rockets can function outside the Earth's atmosphere; jets can't.


Rockets are mostly fuel and oxygen
Rockets are Mostly Fuel (and Oxygen)

  • A rocket or jet has to carry all its remaining fuel with it. (And oxygen, if it’s a rocket).

  • Most of the mass of the Space Shuttle is fuel, and most of that is used to get the remaining fuel off the ground.

  • The miles-per-gallon fuel economy of the Space Shuttle in its first foot off the ground is pretty terrible!


About orbits and satellites
About Orbits and Satellites

  • Satellites travel elliptical paths with the center of the Earth at one focus (Kepler's First Law)

  • Inertia causes object to continue moving in a straight line

  • Gravity pulls object to Earth

  • Balance between the two = orbit



Important orbits
Important Orbits

  • Low vs. High Inclination

  • Almost all are Prograde

  • Polar Orbits for global coverage

  • Circular Orbits strongly preferred

    • Constant altitude

    • Constant speed

  • Sun-Synchronous

  • Geosynchronous


About orbits
About Orbits

  • You do not need to expend fuel to stay in orbit

  • Satellites need attitude control fuel to correct for atmospheric drag, lunar and solar gravity, etc.

  • May want thrusters to help maintain orbits

  • Spin stabilization helps

  • Once below 200 km, atmospheric braking leads to re-entry


Three pioneers of rocketry
Three Pioneers of Rocketry

  • Konstantin Tsiolkovsky (1857-1935)

    • Worked out theoretical problems of spaceflight

  • Robert Goddard (1882-1945)

    • First Liquid Fuel Rocket

  • Hermann Oberth (1894-1989)

    • Helped create operational rockets


Robert goddard first liquid fuel rocket 1926
Robert Goddard -First Liquid-Fuel Rocket, 1926







From sapwood to sputnik
From Sapwood to Sputnik

  • An existing rocket, the SS-6, was used.

  • The warhead section was removed

  • A cluster of four more SS-6 engines was bolted around a central engine

  • Very Dependable


Sputnik i
Sputnik I

  • October 4, 1957

  • S- (with) + put’ (path) +-nik (one who) =Sputnik

  • Literally, one who follows the same path





Sensor technology
Sensor Technology

  • Passive (senses only ambient signals)

  • Active (emits signals)

  • Imaging

  • Non-Imaging

  • Scanning (mechanical or electronic)

  • Non-scanning








A noble myth
A Noble Myth

“In my life, I've seen the images from space of a blue-white-green world — there are no political lines drawn on this planet.

  • Luis J. Rodriguez

    “The border between the United States and Mexico is an imaginary line. It cannot be seen from space”

  • The Border Zone:A History of Trade between the United States and Mexico, Julia Albright; Age of Irony, Winter 2004




















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