How A Rocket Is Launched To Space?

Introduction Of Presenters

Introduction• Rockets are engines which generate thrust force for missiles,

aircraft, space shuttle and other objects to move.

• Thrust is generated by propellants combusting inside the engines and expelling out the high pressure gas through the nozzle at high pressure.

• This creates an unbalanced force acting on the object attached to the rocket. Therefore, producing a net force.

• Rockets work on Newton’s Third Law of Motion to produce thrust. To every action there’s an equal and opposite reaction.

Action

Reaction

-- Since rockets are a little too general, the space shuttle’s solid rocket boosters (SRBs) are used as an example for rockets in this presentation.

Solid Rocket Boosters

How Does It Work?

How Does It Work?• Rocket propellant is known as the fuel to power up the rocket

engines.

• A typical rocket such as SRBs usually carry multiple propellants :- Aluminum powder (Fuel) Liquid oxygen (Oxidizer) Zinc Oxide (Catalyst)

• The propellants are purged into the combustion chamber by using helium gas.

• The mixtures of the propellants are then ignited to initiate a reaction.

• The fuel is burned with the oxidizer in order to achieve a continuous reaction.

• The catalyst is used to increase the rate of reaction of the propellants.

How Does It Work?

• A large amount of gas/fume is produced when the propellants react and is pushed out of the nozzle at high speeds.

• It all comes down to Newton’s Third Law of Motion.

• When the engine pushes the gas out of the nozzle, a force is also generated in the opposite direction and is of the same size of the first action force.

• This force is called as thrust force.

How Does It Work?

How Does It Work?An example based on Newton’s Third Law

A 500kN force is generated downwards by expelling the gas out downwards.

A 500kN force is also generated upwards and is known as “lift” or “thrust” force as a result of the force generating downwards.

Upwards motion

This is the action force.

This is the reaction force.

How Can It Reach Space?

How Can It Reach Space?Getting Rockets Into Space

• Rockets launched into space can be suborbital (brief visit to space) or orbital (staying in motion around the Earth) or can escape Earth’s gravity to travel deeper into space.

How Can It Reach Space?What Is Space?

• The official beginning of space is 100 km above the Earth’s surface.

• The gases that make up the Earth’s atmosphere thin out rapidly as height increases. If you were in a rocket travelling upwards, at a height of 11 km, you would have passed 77.5% of the Earth’s atmosphere.

• At 31 km, you would have passed 99%. At this height, you would see the blackness of space above you rather than the blue of the sky.

How Can It Reach Space?Gravity And Space

• The Earth is a massive object (6 x 1024 kg), and its gravitational influence extends well into space. The gravitational influence of Earth changes only a little for heights at which most low Earth orbit (LEO) satellites and the International Space Station operate.

• At a height of 1000 km above the Earth’s surface, the gravitational force on a 10 kg mass is about 75% of its value on Earth.

This means that, even if a rocket reaches space, the force of gravity will still pull it back 

How Can It Reach Space?Suborbital Rockets – Visiting Space Briefly

Ariane 5 is an European rocket used to launch satellites

• Rockets that reach space and then return to Earth are classed as suborbital rockets. They are usually sounding rockets (‘sounding’ refers to taking measurements).

• Sounding rockets are designed to take measurements of the atmosphere or to perform microgravity experiments as they travel up through the atmosphere and then fall back to Earth.

• Sounding rockets can travel much higher than weather balloons (another way of measuring the atmosphere), which can only travel up to an altitude of 40 km. Some sounding rockets travel up to 950 km or higher before falling back to Earth.

How Can It Reach Space?Getting Rockets Into Orbit

• To get rockets into orbit, they need much more thrust than the amount that will get them up to the required altitude. They also need sufficient thrust to allow them to travel with very high orbital speed.

• For example, the International Space Station (ISS) is at an altitude of about 360 km. To build the ISS, each rocket carrying people and parts needed enough thrust to give it an orbital speed of 28 000 km/h. At this speed, an object at that height will stay in orbit around the Earth. If speed is less than this, an object will fall back to the Earth.

• To help visualise this, Newton imagined a cannon placed on a very high mountain. If the cannon ball is fired with enough speed, it will travel so fast that it falls towards the Earth but misses it entirely. This is what satellites are doing.

• There are approximately 3000 man-made satellites orbiting the Earth. Each of these has been placed into orbit by a rocket. Some are as big as a washing machine, some as big as a bus, and the International Space Station is as roomy as a 5-bedroom house and, with its solar panels extended, is the size of a rugby field.

How Can It Reach Space?Getting Rocket Deeper Into Space• To travel beyond the Earth towards other planets and beyond, very large multistage rockets

are needed to give a probe such as Voyager 1 enough thrust to escape the gravitational pull of the Earth and the Sun.

• Voyager 1 is a 722 kg space probe that was launched in 1976 on a tour of the Solar System. More than 30 years later, it continues to transmit data and to travel into interstellar space.

• Recent NASA launches have included the Juno mission on 5 August 2011. Juno will take 5 years to reach Jupiter, having travelled a distance of 2800 million km.

Juno Launch

Can It Work In Space?

Can It Work In Space?

If space is basically a vacuum and void of atmosphere, how do rockets alter the direction and speed of space craft? In other words, how do they "push off" against nothing?

This is a very good question. Sir Isaac Newton worked out the solution

and published it in 1687 in his Principia Mathematica. It is phrased as

Newton's 3rd law.

1st: A body will remain at rest or at motion with a uniform speed unless

it is acted on my an external force.

2nd: The acceleration of a body with a force acting on it is that force

divided by the mass of the body (F=ma)

3rd: Every action has an equal and opposite reaction.

Other Uses of Rockets

Other Uses of RocketsA Weapon of War

•Used by the Military for War -Shoulder-fired rocket launcher -Rocket Pod [used by attack aircrafts]

Research and Science

•Sounding rockets -Research in aeronomy -Track the rocket that launched to the space

Other Uses of Rockets

Emergency

-Rocket used to launch emergency flare- propel a line to a stricken ship so that a Breeches Buoy can be used

Hobby

-Fireworks-rockets model kit

The End