Rockets And Satellites (Basic Electronics)

CONTENT

• Satellite and their functions
• Components of a satellite
• Semiconductors.

SATELLITES AND THEIR FUNCTIONS

The word satellite refers to a body orbiting a larger one. There are natural satellites (e.g the Earth and other planets orbiting the Sun), and artificial satellites such as; Communication Satellites (that transmit telecommunication signals), Global Positioning Satellites (that allow for the identification of locations on the Earth) and Meteorological Satellites (that monitor weather and climate patterns). Examples of Nigeria satellite includes; Niger-SAT 1 (a disaster-monitoring  microsatellite), NICOM-SAT 1 (for mobile phone and internet services. However due to the failure of its solar cells system, the satellite has ceased to function).

COMPONENTS OF A SATELLITE

All satellites have some common basic components that work together to form the following systems;

1. Power generation and distribution system
2. Command and data handling system
3. Payload
4. Protective shielding
5. Rocket thruster system.

Other components include; solar cells, batteries, command antenna, communication antenna, radio receivers and transmitters, rocket fuel, rocket motor, rocket thrusters, cameras.

BASIC ELECTRONICS; SEMICONDUCTORS

Semiconductors are crystalline or amorphous solids with distinct electrical characteristics.

They are of higher of higher resistance than the typical conductors but of lower of lower resistance than the insulators. Their resistance decreases with temperature – a behavior opposite to that of metals.

Their conducting properties can be altered in useful ways by the deliberate introduction (‘’doping’’) of impurities into the crystal structure.

Doping greatly increases the number of charge carriers (holes and electrons) within the crystal.

There are two major types of impurities; the donor and the acceptor. Antimony, Arsenic and Phosphorus are typical donor elements while Aluminum, Boron and Gallium are good acceptors. Addition of donor element produces the n–type semiconductor while the addition of acceptor element results in the p–type semiconductor.

The n-type semiconductor contains mostly free electrons, it has excess electrons (i.e its charge carriers are the excess electron), and a p-type semiconductor contains mostly free holes, it has a shortage of electron (i.e its charge carriers are the excess holes).

A single semiconductor can have many p- and n- type regions when doped under precise conditions. The junction between these regions are referred to as the p-n junction.

Doping lowers the resistance of a semiconductor but also permits the creation of semi-conduction junction. The behavior of charge carriers at this junction is responsible for its usefulness in diodes, transistors and all modern electronics.

The most widely used semiconductors are Silicon, Germallium and compounds of Gallium. Elements located where the metalloids are on the periodic table are usually used as semiconductors.

GENERAL EVALUATION

1. With the aid of a diagram, describe how continuous current can be generated from mechanical energy
2. With the aid of a diagram, describe how continuous current can be generated from chemical energy.

WEEKEND ASSIGNMENT

1.   Most satellite depend on ….. for the generation of their electrical energy supply. (a) d.c generators (b) Leclanche cells (c) solar cells (d) hydroelectricity.    

2.   The following are components parts of a rocket except (a) fins (b) nozzle (c) propellant tank

(d) turbine.

3.   One of the following is a component of a satellite (a) camera (b) fins (c) command antenna

(d) solar cells.

4.   The function of the fins in a rocket is to (a) beautify it (b) make it fly (c) stabilize it and maintain its direction of motion (d) increase its mass.

5.   What is the function of the power generation and distribution system in a satellite?

(a) capturing solar energy and converting it to the electrical energy needed (b) increase the weight of the engine (c) receiving and transmitting of data (d) to beautify the satellite.

THEORY

1. Draw a satellite and a rocket, labeling at least five parts on each.
2. What are satellites used for?