A satellite measuring weather factors such as storms and hurricanes (Shorstock)

A satellite is a device that is sent into space to orbit the Earth in specific orbits, and performs various tasks, including sending and receiving electromagnetic radio signals from ground stations built for this purpose, in addition to other specialized tasks.

It is a self-contained communications system that derives its energy from the solar panels it is equipped with, which in turn convert light energy into electrical energy that is stored in batteries, or through nuclear sources.

The satellite has the ability to re-transmit and distribute these signals again to other ground stations within its scope of work.

Origins and history

Before the satellite revolution, communications were very limited. Television signals did not cover long distances, and natural and created barriers obscured and distorted them.

The same goes for phone calls;

The distance was also limited, and it was very expensive to install telephone wires over long distances, whether above ground or under water.

It was necessary for a new technical revolution that would take communications to a greater extent and on a broader scope, so the satellite revolution came.

Satellites were just theoretical ideas in the imagination of scientists and writers, until the Soviets launched the first satellite the size of a beach ball on October 4, 1957. Its mission was to measure the density of different layers of the atmosphere. The Soviets called it “Sputnik-1,” and it was the beginning of a series "Sputnik" for Soviet satellites.

A month later, specifically on November 3, 1957, the Soviets launched the “Sputnik-2” satellite, which was larger and heavier than its predecessor, and carried the famous dog “Laika,” which is considered the first living creature to reach space.

Then NASA launched the Explorer-1 satellite in January 1958. The launch of these Explorer series satellites continued, until the first satellite image of the Earth came from NASA's Explorer-6 in 1959.

In a relatively short period of time, satellite technology has evolved from experimental, such as Sputnik, to sophisticated and powerful.

With qualitative improvements in the propulsion and energy systems of satellites, their life span has increased to 20-30 years.

Other technical innovations, such as low-cost, reusable launch vehicles, and bandwidth expansion that increased the number of channels and the volume of data transmitted, increased demand for satellite services in the coming years.

Huge constellations of thousands of satellites designed to provide Internet access to anywhere on Earth are currently being developed.

Future communications satellites will have more processing capabilities on board, more power, and larger aperture antennas that will enable the satellites to handle more bandwidth.

the components

The main parts that make up a satellite can be summarized as follows:

  • The power system, which may be solar, with the necessary batteries to conserve energy, or nuclear, can keep the satellite and its operating systems in operation throughout the life of the satellite in orbit.

  • A system for controlling the position of a satellite, which keeps it in its correct orbit.

  • A communications system consisting of information transmitters and receivers, including the necessary antennas, in order to send and receive data and information to and from the ground station.

  • Information collection systems, such as cameras, various detectors, sensors, spectrum analyzers, and various measuring devices.

  • Propulsion systems, which include the necessary rockets and fuel types, in order to deliver the moon to its correct orbit, and make the necessary corrections on site.

The way of work

The Tracking, Measurement and Remote Control System acts as a two-way communication link between the satellite and the ground station.

This allows the ground station to track the satellite's position and control the satellite's propulsion, thermal and other systems.

It can also monitor the temperature, electrical voltages and other important information of the satellite.

Launching a satellite into space requires a powerful multi-stage rocket to propel it into the correct orbit.

Satellite launch providers use special rockets to launch from locations such as Kennedy Space Center at Cape Canaveral Air Force Base in Florida, Baikonur Cosmodrome in Kazakhstan, Kourou in French Guiana, Vandenberg Air Force Base in California, Xichang in China, and Tanegashima Island in Japan.

Types and uses

 Satellites can be classified according to their location into two categories:

First:

geosynchronous satellites, that is, they orbit around the Earth synchronously with the Earth’s rotation around its axis. They are placed in orbit up to an altitude of 35,800 kilometers above the surface of the Earth, and they rotate in the same direction every day around the planet from east to west, and because of this type of The movement appears constant to those observing it from the ground, and this type is used in communications and studying the weather.

Second:

Polar satellites that orbit the Earth from north to south between the poles, and are of great importance in forming a perception of the state of the planet Earth, as they are used to study weather and natural disasters and provide the Earth with information about emergency situations and data on temperature, pressure and humidity of the atmosphere.

These polar satellites are used as space stations, as is the case with the International Space Station, which reached orbit in 1998. They can be monitored from the surface of the Earth on clear nights, and the polar satellites appear in the same position twice a day, once during the day and once at night.

From a functional standpoint, the most prominent satellites are:

  • Communications satellites:

It is the most widespread today, and the need for it is constantly increasing, and communications include television broadcast satellites, telephone calls, and Internet connection via satellite.

Most communications satellites use “low Earth orbit,” which is best suited for calls and mobile devices, while television broadcast satellites use “geosynchronous orbit” to cover the same geographical spot continuously.

  • Astronomical observatories:

With the increase in environmental, light and radio pollution on Earth, the difficulty of observing space has increased, so a number of satellites were launched as space telescopes into low Earth orbit. Because they are outside the atmosphere, these satellites can monitor space better than ground-based observatories, and are credited with several scientific discoveries. During recent decades.

  • Earth observation satellites:

These satellites are usually used in the lowest possible orbits around the Earth with a unified goal of monitoring for civilian purposes, especially with regard to rapid changes, natural disasters, and limiting the spread of diseases. This category includes weather satellites, some of which are designed to draw weather maps and update them periodically, and these satellites are useful. In early warning of hurricanes or erupting volcanoes.

These civil purposes can be detailed as follows:

  • Monitoring air and water quality, mapping land use, development and infrastructure, while assessing compliance with land use rules and property rights.

  • Assess and monitor the potential for developing solar energy, wind energy, hydropower and biofuels.

  • Mapping and monitoring forests, by identifying their degradation, rehabilitation and recovery.

  • Providing early warning for insect-borne diseases and natural disasters.

  • Mapping and monitoring urban settlements and housing.

  • Providing information on crop health, agricultural yields, ability to access markets, and agricultural pests and diseases that affect crops.

  • Mapping potentially hazardous infrastructure, such as waste management facilities and nuclear facilities.

    • Military satellites:

    There is a great scarcity of information about this type of satellite, but most of it focuses on observing the Earth, monitoring the movements of land convoys and naval vessels, drawing maps, and spying on opponents.

    • Guidance and navigation satellites:

    Currently, there are several global navigation and positioning systems, including the famous GPS, Russian GLONASS, and European Galileo, in addition to local navigation systems for some countries such as China and Japan. All navigation systems include several satellites that use medium Earth orbit. So that it revolves at an altitude of approximately 20 thousand kilometers above the Earth's surface.

    • Mini satellites:

    These satellites are generally smaller than usual and are mostly used for limited research purposes. Many are built at universities as student projects and assembled from pre-existing materials.

    Satellites that weigh less than a thousand kilograms are usually classified as miniature, and there are newer divisions that place satellites weighing between 500 kilograms and a thousand kilograms under the name “mini-satellite,” and those that weigh less than 100 kilograms are called “micro-satellites,” and those that weigh no more than 10 are called “micro-satellites.” "Nano-satellite" kilograms.

    Various space stations

    In principle, space stations are artificial satellites, but the difference is that they are larger than usual satellites, and they are designed to be suitable for human habitation, and are used as a laboratory, observatory, landing station for expeditions, and a shelter for them.

    Satellites operate in 3 different orbits:

    • Low Earth orbit.

    • Medium Earth orbit and operates at a distance ranging from 10,000 to 20,000 kilometers from Earth.

    • A geostationary or geosynchronous orbit.

      It operates at an altitude of 35,786 kilometers above the ground.

    The satellites are placed at an altitude ranging between 160 km and 1,600 km above the Earth.

    We need only 3 geosynchronous type satellites to provide global coverage, while it takes 20 or more satellites to cover the entire Earth from low Earth orbit and 10 medium Earth orbit type satellites.

    While Early Bird had only one transceiver capable of transmitting only one TV channel, today the Boeing 702 series of satellites can contain more than 100 transceivers, and with the use of digital compression technology each can contain Transceiver on up to 16 channels, providing over 1,600 TV channels through a single satellite.

    Leading countries

    The United States of America ranks first in terms of countries that manufacture, launch, or operate satellites with more than 3,500 satellites, followed by China in second place with more than 550, and the United Kingdom comes in third place with about 480 satellites, followed by Russia in fourth place with 175 satellites, then Japan. About 90 moons.

    More than 6,500 satellites will be floating in space until 2023, but the effective ones do not exceed 4,000.

    Commercial purposes, such as communications and navigation, dominate 74% of uses, while military purposes account for 8% of satellite uses, and civil, governmental, and scientific purposes share the remaining percentage.

    Arabs and satellites

    Arab countries have several artificial satellites, the most important of which are Saudi Arabia and Egypt. It is worth noting that the first Arab satellite was launched in 1976, and was operated by the Arabsat group affiliated with the League of Arab States. Egypt launched the first satellite from the Nilesat group in 1998, but this Projects include financing and operation only, without design, manufacture and launch.

    But there is a group of small Arab-designed research satellites, such as the Iraqi satellite “Tigrisat,” which was made by Iraqi students in the Italian capital, Rome, and the Jordanian satellite, “JY1Sat,” designed by students from several Jordanian universities.

    After years of training in South Korea, a team of Emirati engineers was able to build the first true Arab satellite, the “KhalifaSat” satellite, which weighs 300 kilograms and is designed to observe the Earth. It was built at the Mohammed bin Rashid Space Center in Dubai, and was launched from Japan. In 2018, its mission extends for 5 years, and it orbits in a synchronous orbit with the sun, vertically around the Earth.

    In 2021, a Russian rocket was able to carry the first satellite made entirely by Tunisian hands, called “Challenge,” into space, starting from Kazakhstan, to carry out Internet-related missions.

    Saudi Arabia has 17 satellites, followed by the UAE with 14 satellites, the League of Arab States 14 satellites, Egypt 7 satellites, Algeria 6 satellites, Morocco and Qatar with two satellites each, and Iraq and Tunisia with one satellite for each country.

    Source: websites