Satellites are objects in Space that orbit around more significant things.
By the above definition, we can safely say we reside on a satellite, i.e., planets are also satellites since they orbit around the Sun.
The planets that we learn about in school, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and our dwarf planet, Pluto, being satellites themselves have more satellites revolving around them.
1 About Satellites
There are two types of satellites in our space, Natural Satellites and Artificial or Man-made satellites. Let us take a look at them.
1.1 Natural Satellites
While Mercury and Venus do not have moons of their own, other planets have one or more.
- Earth has one moon, the largest among the moons of rocky planets.
- Mars has two moons.
- Jupiter has 95 moons.
- Saturn has 146 moons.
- Uranus has 27 moons.
- Neptune has 14 moons.
- Pluto has 5 moons.
The moons of the planets bring us to a total of 290 moons. But these moons aren’t the only natural satellites in our space. There are other objects like the asteroids, Kuiper Belt, and Trans-Neptunian objects that add up to 462.
This will bring us to a total of 752 natural satellites in our solar system.
1.2 Artificial Satellites
The space is currently filled with man-made satellites. At least the space around our planet is filled with these satellites.
Artificial satellites were not part of our reality till the middle of the 20th century. The first was Sputnik, a beach ball-sized Russian Satellite. Their next massive satellite carried along the beloved dog Laika.
Following the Russian Satellite, the US launched their satellite, Explorer 1.
Many other countries followed through and sent their own satellites as the benefits of having a satellite played a major role. Below are some of the countries that have been a part of today’s Space Age.
These are the advancements made in the last decade. The 21st century is truly advancing at a magical rate.
2 More about Artificial Satellites
There are three levels in our immediate space, around our planet, that the Artificial Satellites occupy.
2.1 Geostationary Earth Orbit
This particular orbit is the farthest positioned. It is at an altitude of 36000km. This orbit is great for weather data, Television Broadcasts, and low-speed communication.
The satellites in this orbit move along with Earth’s rotation. This causes the illusion of its stationary property since we cannot actually perceive the rotation of Earth.
2.2 Medium Earth Orbit
This layer of satellites is at an altitude between 5,000 to 20,000 km height.
Historically, GPS and other navigational apps have employed MEO. Recently, HTS MEO constellations have been put into operation to provide service providers, governmental organizations, and commercial firms with low-latency, high-bandwidth data communication.
MEO satellites provide fiber-like performance in remote locations where laying fiber is impractical, such as cruise, commercial marine, aircraft, offshore platforms, network backhaul in challenging terrain, and humanitarian relief operations.
2.3 Low Earth Orbit
The Low Earth Orbit is at an altitude of 500 to 1200 km from our planet.
Thousands of satellites are now in service in LEO, mostly serving demands for science, imaging, and low-bandwidth communications.
Broadband internet for businesses and general consumers is one of the communication industries that the upcoming generation of HTS LEO satellites is intended to service.
Since there are so many uses for satellites, and have different zones with different purposes, we can picture the number of satellites out there.
2.4 Geostationary Transfer Orbit
A geostationary satellite transfer orbit is the most common kind and is used to move a satellite from a transition orbit to GEO. When sent from Earth into space by launch vehicles, spacecraft are not always put into their final orbit.
Transfer orbits, which are midpoints on the trajectory to its ultimate location, are where rockets launching a payload to GEO dump it down.
The satellite then starts its engine to enter its final orbit and modify its inclination.
2.5 Sun Synchronous Orbit
At a height of 600 to 800 km above the surface of the Earth, satellites in the Sun-synchronous orbit type travel from north to south via the polar regions.
The SSO spacecraft’s orbital inclination and altitude are adjusted such that they always pass at a certain place at the exact same local solar time.
This type of satellite is perfect for earth observation and environmental monitoring since the illumination conditions are stable for imaging.
When sending something into space, space organizations must carefully take orbital paths into account.
NASA and other organizations are informed if an errant piece of orbital debris is at risk of colliding with a critical object by organizations like the United States Space Surveillance Network, which monitors orbital junk from the ground. As a result, the ISS occasionally needs to execute evasive maneuvers to get out of the path.
Some people propose employing air bursts or nets to disrupt the debris from a defunct satellite’s orbit and push it closer to Earth in order to bring it down.
Others are thinking about the robotically proven technique of recharging defunct satellites for reuse.
4 Types of Artificial Satellites
Every spacecraft is launched into orbit to carry out a specific mission, such as communication, scientific investigation, weather prediction, or field observation.
The size, type of orbit, and general design of the satellite will be determined by its intended use.
Although there are many different kinds of artificial satellites and orbits, once they are in space, they all follow the same physical principles and mathematical computations.
4.1 Large Satellites
The industry’s established workhorses, strong Earth observation satellites like GOES-R, and the two current LANDSAT spacecraft are also massive satellites, weighing around 6,500 kg each. ViaSat-1 and ViaSat-2 are also large satellites.
These satellites are mostly in the GEO zone.
4.2 Medium Satellites
An extremely broad group made up of satellites serving a variety of functions. For instance, the Canadian atmospheric sciences satellite SCISAT-1 and the American-European Earth observation spacecraft Jason-3 both have weights of roughly 550 kg.
The three zones, MEO, LEO, and GEO have medium satellites considering their versatility.
4.3 Mini Satellites
Mini satellites include a large number of satellites in LEO mega-constellations. In recent decades, national space agencies from France, Brazil, and a variety of other countries have also launched small satellites for Earth and sun observation.
4.4 Micro Satellites
These carry out a variety of tasks, the majority from conveniently located LEO locations. A section of the popularly discussed CubeSat subcategory, which is sometimes divided into five sub-sub-categories, is included in this category.
4.5 Nano Satellites
Small, affordable items have extremely specialized uses in fields like signal monitoring, communications, and geolocation.
Nanosatellites are constrained to low-earth orbit (LEO) due to their limited technical capabilities, and some need a “mother satellite” to transmit data down to ground stations.
5 Functions of Artificial Satellites
Several different kinds of satellites have been launched in recent years for a range of scientific reasons, including Earth monitoring, meteorological study, navigation, examining how space travel affects living things and gaining an understanding of the universe.
Radio signals from Earth can be received by satellites with built-in receivers and transmitters, which can then retransmit the signals to the planet.
As a result, it creates communication pathways connecting areas that were previously separated by great distances or other barriers.
The transmission of many media, including radio, television, telephone, and the Internet, is made possible by several types of communication satellites.
5.2 Planet Observation
Satellites that are designed for Earth observation are used to keep an eye on our world from above and report on any changes they see.
These satellites help with the quick examination of what happens in emergency situations like armed conflicts and natural catastrophes.
Depending on the kind of sensor used and the frequency bands that are available, different information is obtained.
For the purpose of tracking, predicting, and giving real weather data, weather satellites are used.
Geographic mapping and environmental monitoring of all kinds are the two main uses of remote sensing satellites. Remote sensing equipment travels around the planet in one of three orbits: polar, non-polar LEO, or GEO.
A particular class of remote sensing spacecraft called a geographic information system (GIS) satellite’s primary job is to gather data for GIS mapping and spatial analysis.
The constellations of the GNSS are situated between 20,000 and 37,000 kilometers from the surface of the Earth.
Global coverage is provided by the Global Navigation Satellite System (GNSS), whose satellites transmit signals that GNSS receivers pick up and use for localization.
Examples of GNSS include the European Galileo, the American GPS, and the Chinese BeiDou Navigation Satellite System.
An independent regional navigation system that offers coverage at the regional level is the Regional Navigation Satellite System (RNSS). For instance, the IRNSS initiative in India seeks to offer Indian residents a trustworthy location-based service.
The astronomy satellite has a vision that is up to 10 times more advanced than the most potent telescope on Earth.
Through the mapping of the surfaces of stars and planets, the imaging of the planets in our solar system, and the research of black holes, astronomy satellites explore a variety of celestial bodies and phenomena in space.
Biosatellites make it feasible to conduct investigations on the cells and structures of plants and animals from space. This kind of spacecraft is essential to the advancement of biology and medicine since it enables experts from many fields to collaborate.
6 Satellites falling to Earth
The best way to think of a satellite is as a projectile, or as an object with simply gravity acting on it.
A satellite will continually “fall” toward Earth if it is moving quickly enough, but because of the curvature of our globe, it will fall around it rather than smashing to the surface.
Satellites that orbit closer to Earth run the risk of colliding with the planet because atmospheric drag causes them to move more slowly. Fewer molecules are an issue for objects that orbit further from Earth.
There are a few recognized orbital “zones” that round the Earth. One is referred to as low-Earth orbit, and it is between 160 to 2,000 kilometers long.
However, geostationary or geosynchronous orbit is the ideal location for communications satellites. At a height of 35,786 kilometers (22,236 mi), this region is located above the equator of the planet.
The satellite may virtually always remain over the same location on Earth at this height since the Earth’s rate of “fall” around it is about equal to that of its rotation.
Some satellites are best employed in equatorial orbits, while others are better suited to more polar orbits, which circle the Earth from pole to pole and encompass the north and south poles in their coverage zones.
The service life of satellites will be extended from the present 10-15 years to 20-30 years with further advancements in their propulsion and power systems.
Additionally, new technological advancements like inexpensive reusable launch vehicles are being developed.
There is no shortage of new applications that will increase demand for satellite services in the years to come as increased video, audio, and data traffic necessitates higher quantities of bandwidth.
The long-term survival of the commercial satellite business well into the twenty-first century will be guaranteed by the need for increased bandwidth as well as the ongoing innovation and development of satellite technology.
Ground-based communications networks are the obvious substitute for satellite transmission. These could include terrestrial infrastructures like coaxial cable, fiber optics, and copper wire.
Microwave, radio waves, free-space optics (laser), and subsea communication technologies are available options.
Drone technology for the stratosphere has the potential to replace several satellite tasks. Drones powered by solar energy are being developed to fly to altitudes of at least 65,000 feet.
It is intended for these planes to remain in the air for up to a year and replace some of the monitoring and communication duties currently carried out by satellites.
While this is the future of artificial satellites, the natural satellites might remain while we might stumble upon more of these satellites.
Natural satellites can also be considered as bodies that circle stars like our Sun, such as planets, asteroids, and comets. In addition to the eight recognized planets in our solar system, there are many asteroids, comets, and minor planets that circle the Sun.
You may consider each of these as a natural satellite and it is only right to assume more of these exist out there and we simply haven’t got to get to know them.