What is a satellite?
A satellite is an object that orbits another object; for example, the Earth orbits the Sun, and the moon orbits the earth. We can say that a satellite is a moon, planet, or machine that orbits a planet or star.
Types of satellites
There are two types of satellites.
1) Natural Satellites
2) Artificial Satellites
Natural Satellites are those that are present naturally. For example, the moons of different planets
Artificial Satellites are satellites made by humans and released into the orbits of the earth and other planets to collect information from them. Currently, more than 2500 man-made satellites are orbiting the earth.
Artificial satellites are of further 2 types mainly.
- Geostationary Satellites
- Polar Satellites
Geostationary satellites are placed in the orbit of the Earth. They revolve in the same direction as the earth with the same speed, and one revolution of such satellites is equal to one revolution of the earth. This means that, as seen from Earth, these satellites will appear to be in the same place. Hence, the name “geostationary” satellites.
Polar satellites are satellites that orbit around the earth in polar orbits. Polar orbits are perpendicular to the equilateral plane. As the earth rotates on its axis, a polar satellite passes through different points on the Earth’s surface, thus scanning the entire Earth.
Satellite Functions and Applications
The following are some of the most effective satellite applications:
Navigation Satellites:
These satellites are used for navigation and pinpointing the earth’s surface.Some examples of navigation satellites are
- BeiDou/ BDS (China)
- Galileo (Europe)
- Glonass (Russia)
- IRNSS / NavIC (India)
- QZSS (Japan)
Communication Satellites:
These satellites are used for communication purposes, such as distributing television signals, transmitting radio signals, broadcasting, etc.
Weather satellites:
These satellites are used to monitor climate change or to provide weather reports from Earth.These satellites revolve around the earth and gather information related to weather.
Earth Observation Satellites:
These satellites are designed to observe the earth while revolving around it. These satellites gather information related to the Earth’s physical, chemical, and biological systems.
International Space Station (ISS)
According to the European Space Agency (ESA), the ISS is not owned by a single country and is a “cooperative program” between Europe, the United States, Russia, Canada, and Japan. It is like a laboratory revolving around the earth’s lower orbit. It serves as a home for astronauts.
In 1998, the International Space Station (ISS) was launched into orbit.
Facts about satellites
After the satellites are launched into the earth’s orbits, only gravitational force acts on them.In the end, the satellites are projectiles in nature.
Altitudes of Satellites
Important information :
Satellites orbiting at 35,786 km have a period of exactly one day.
Orbit of The Earth is divided into 3 parts:
LEO ( Lower Earth Orbit )
- Ranges From 160 km – 2000 km
- Time for one revolution is nearly 90 mins to 2 hours
- The speed required for a satellite is almost 28,000 km/h
MEO ( Medium Earth Orbit )
- The altitude is approximately 20,000 km.
- The time required for one revolution is nearly 12 hours.
- The speed required for a satellite is almost 7,000 miles per hour (3.13 km per second).
- The satellites revolving in these orbits can see more of the Earth’s surface at the same time than LEO orbital satellites.
GEO ( Geosynchronous Earth Orbit )
Satellites orbiting at 35,786 km have a period of exactly one day. Satellites in this orbit, called geosynchronous earth orbit, or GEO, observe the earth as if it were not rotating. Because of this feature, the satellites in GEO have a continuous field of view for about one-third of the planet’s surface.