Rocket Science Rocket Science Dr. Martin Hendry Glasgow University Reach for the Stars

To ISS: £20 million To Elgin: £20

Isaac Newton

Galileo Galilei

How do things move?…. Aristotle’s Theory: 1.Objects move only as long as we apply a force to them 2.Falling bodies fall at a constant rate 3.Heavy bodies fall faster than light ones

How do things move?…. Aristotle’s Theory: 1.Objects move only as long as we apply a force to them 2.Falling bodies fall at a constant rate 3.Heavy bodies fall faster than light ones Galileo’s Experiment: 1.Objects keep moving after we stop applying a force (if no friction) 2.Falling bodies accelerate as they fall 3.Heavy bodies fall at the same rate as light ones v

Aristotle’s Theory: 1.Objects move only as long as we apply a force to them 2.Falling bodies fall at a constant rate 3.Heavy bodies fall faster than light ones Galileo’s Experiment: 1.Objects keep moving after we stop applying a force (if no friction) 2.Falling bodies accelerate as they fall 3.Heavy bodies fall at the same rate as light ones How do things move?….

Aristotle’s Theory: 1.Objects move only as long as we apply a force to them 2.Falling bodies fall at a constant rate 3.Heavy bodies fall faster than light ones Galileo’s Experiment: 1.Objects keep moving after we stop applying a force (if no friction) 2.Falling bodies accelerate as they fall 3.Heavy bodies fall at the same rate as light ones v How do things move?….

Apollo 15 astronaut David Scott

Newton built on Galileo’s work and proposed 3 laws of motion: 1.A body moves in a straight line unless acted on by some force How do things move?….

Newton built on Galileo’s work and proposed 3 laws of motion: 1.A body moves in a straight line unless acted on by some force 2.The acceleration of a body is proportional to the force on it F = ma How do things move?….

Newton built on Galileo’s work and proposed 3 laws of motion: 1.A body moves in a straight line unless acted on by some force 2.The acceleration of a body is proportional to the force on it F = ma 3.To every action there is an equal and opposite reaction How do things move?….

Isaac Newton: 1642 – 1727 AD The Principia: Every object in the Universe attracts every other object with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them Law of Universal Gravitation

So to get into space, we need a lot of energy, to overcome the Earth’s gravity

Gravity lets the Earth hold onto its atmosphere

Above 30km there is no atmosphere

The Space Shuttle burns Oxygen, Just like a car engine!

Getting from A to B….. Car engine burns petrol, releases chemical energy

Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface

Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface The car moves forward

Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface The car moves forward

Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface The car moves forward

Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface The car moves forward

Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface The car moves forward

Getting from A to B….. Car engine burns petrol, releases chemical energy Applies a force to turn the car’s wheels – they push against the road surface The car moves forward

Getting from A to B….. Aircraft engine burns petrol, releases chemical energy, turns turbines

Getting from A to B….. Aircraft engine burns petrol, releases chemical energy, turns turbines These draw air into engine, which gets compressed and heated – pushed out with great force and great speed

Getting from A to B….. Aircraft engine burns petrol, releases chemical energy, turns turbines These draw air into engine, which gets compressed and heated – pushed out with great force and great speed The plane moves forward

Getting from A to B….. Aircraft engine burns petrol, releases chemical energy, turns turbines These draw air into engine, which gets compressed and heated – pushed out with great force and great speed The plane moves forward

Getting from A to B….. Aircraft engine burns petrol, releases chemical energy, turns turbines These draw air into engine, which gets compressed and heated – pushed out with great force and great speed The plane moves forward

Getting from A to B….. Aircraft engine burns petrol, releases chemical energy, turns turbines These draw air into engine, which gets compressed and heated – pushed out with great force and great speed The plane moves forward

Getting from A to B….. Aircraft engine burns petrol, releases chemical energy, turns turbines These draw air into engine, which gets compressed and heated – pushed out with great force and great speed The plane moves forward

Getting from A to B….. Aircraft engine burns petrol, releases chemical energy, turns turbines These draw air into engine, which gets compressed and heated – pushed out with great force and great speed The plane moves forward

Getting from A to B….. Aircraft engine burns petrol, releases chemical energy, turns turbines These draw air into engine, which gets compressed and heated – pushed out with great force and great speed The plane moves forward

Gravity lets the Earth hold onto its atmosphere Above 30km there is no atmosphere

Gravity lets the Earth hold onto its atmosphere There is no air to push against

Rockets move because of the Reaction Principle NASANASA Rocket engines burn oxygen; exhaust gas pushed backwards at enormous speed Oxygen

Rockets move because of the Reaction Principle NASANASA Rocket engines burn oxygen; exhaust gas pushed backwards at enormous speed Newton’s 3 rd Law: rocket pushed forwards

Rockets move because of the Reaction Principle NASANASA Rocket engines burn oxygen; exhaust gas pushed backwards at enormous speed Newton’s 3 rd Law: rocket pushed forwards

Rockets move because of the Reaction Principle NASANASA Rocket engines burn oxygen; exhaust gas pushed backwards at enormous speed Newton’s 3 rd Law: rocket pushed forwards

Rockets move because of the Reaction Principle Rocket engines burn oxygen; exhaust gas pushed backwards at enormous speed Newton’s 3 rd Law: rocket pushed forwards

Rockets move because of the Reaction Principle Rocket engines burn oxygen; exhaust gas pushed backwards at enormous speed Newton’s 3 rd Law: rocket pushed forwards Rockets can operate in space

A rocket reaches orbit and no longer needs to burn any more fuel. No net force on rocket

A rocket reaches orbit and no longer needs to burn any more fuel No net force on rocket

A rocket reaches orbit and no longer needs to burn any more fuel No net force on rocket

A rocket reaches orbit and no longer needs to burn any more fuel No net force on rocket Gravity exactly balanced by rotation force: Weightlessness!!

Moon’s orbit Earth This same balance explains why the Moon orbits the Earth…..

….and why planets orbit the Sun

Orbit of the Moon The gravity of the Sun and the other planets makes the Moon’s orbit appear like a giant ‘Hula Hoop’: one complete cycle takes about 18 years.

Moon’s orbit Earth But how does the Moon know to orbit the Earth?

Moon’s orbit Earth But how does the Moon know to orbit the Earth? How does gravity act at a distance across space?

Gravity in Einstein’s Universe Einstein’s theory of gravity was General Relativity, published in 1916 Albert Einstein ( ) Extension of Einstein’s 1906 Special Theory of Relativity

300,000 kms -1 The speed of light is:- Albert Einstein ( ) Extension of Einstein’s 1906 Special Theory of Relativity

Gravity in Einstein’s Universe Gravity and acceleration are equivalent Gravity is not a force acting through space and time, but the result of mass (and energy) warping spacetime itself

Gravity in Einstein’s Universe “Spacetime tells matter how to move, and matter tells spacetime how to curve”

Gravity in Einstein’s Universe v Differences between Newtonian and Einsteinian gravity are tiny, but can be detected in the Solar System – and Einstein always wins!

Hydrogen fusion – fuelling a star’s nuclear furnace E = mc 2 H = Hydrogen He = Helium

Nuclear fusion is also the energy source in hydrogen bombs. If we could control the energy release from fusion, it would make excellent rocket ‘fuel’

Nuclear fusion is also the energy source in hydrogen bombs. If we could control the energy release from fusion, it would make excellent rocket ‘fuel’ But the thrust would be insufficient to ‘lift off’ from the Earth

Nuclear fusion is also the energy source in hydrogen bombs. If we could control the energy release from fusion, it would make excellent rocket ‘fuel’ But the thrust would be insufficient to ‘lift off’ from the Earth The ISS could be the launch pad for the fusion rockets of the future

Hydrogen fusion – fuelling a star’s nuclear furnace E = mc 2 H = Hydrogen He = Helium

Solar sailing: Using sunbeams to explore the Solar System

The stars are VERY far away. The nearest star (after the Sun) is about 40 million million km from the Earth. It takes light more than 4 years to travel this distance. If the distance from the Earth to the Sun were the width of this screen, the next nearest star would be in Rome.

Einstein’s Relativity Matter causes space to curve or warp

Gravity in Einstein’s Universe ‘Black Hole’: warps spacetime so much that even light can’t escape

Warping spacetime Wormholes in spacetime predicted by theories of quantum gravity, but these are unimaginably tiny, and unstable. How do we fit a spaceship through a wormhole?……

Could we use To hold open wormholes?…