Page 190 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

• Amateur radio
• Internet access
• Military
• Disaster Management
Type of satellite and its orbits

In most cases, after being launched, a satellite is placed in one of several predetermined orbits around the Earth.
But in some cases, it may be directed to interplanetary journey, following a path around the Sun until it reaches
its ultimate destination.
Satellites are usually classified based on their orbital altitude (distance from the Earth’s surface), which directly
affects their coverage and the speed at which they travel around the planet. When choosing the type of orbit,
spacecraft developers should consider its intended purpose, the data it acquires, and the services it offers, as well
as the cost, coverage area, and feasibility of different orbits.

The 5 main types of satellites based on their orbits are:
• low Earth orbit (LEO)
• medium Earth orbit (MEO)
• geostationary orbit (GEO)
• Sun-synchronous orbit (SSO)

• geostationary transfer orbit (GTO)
Let’s dig deeper into the nature of these 5 different types of satellites’ orbits to learn more about their characteristics
and potential uses.

Low Earth Orbit (LEO) Satellites
Low Earth Orbit satellites are moving at an altitude of roughly 160–1,500 kilometers above the Earth’s surface.
They have a short orbital period, between 90 and 120 minutes, meaning they can travel around the planet up
to 16 times a day. This makes them particularly well-suited to all types of remote sensing, high-resolution earth
observation, and scientific research, as data can be acquired and transmitted rapidly.
Medium Earth Orbit (MEO) Satellites

A Medium Earth type of orbit is located between low Earth and geostationary orbits, typically at an altitude of
about 5,000 to 20,000 kilometers. Positioning and navigation services, like GPS, extensively use MEO type of
satellites. Recently, high-throughput satellite (HTS) MEO constellations have been put into operation to enable
low-latency data communication to service providers, commercial and government organizations.
Geostationary Orbit (GEO) Satellites

Spacecraft in geostationary Earth orbit are positioned 35,786 kilometers above Earth’s surface, precisely over
the equator. Three evenly spaced machines in GEO can give nearly worldwide coverage thanks to the huge area
they cover on Earth.
Objects in GEO appear motionless from the ground because their orbital period is identical to Earth’s rotation —
23 hours, 56 minutes, and 4 seconds. This allows a terrestrial antenna to always point toward the same device
in space. That’s why this type of satellites is perfect for always-on communication services like TV and phones.
Also, this type can be used in meteorology to keep an eye on the weather in particular regions and track the
development of local patterns. The downside of GEO type of spacecraft for real-time communication is the longer
signal delay caused by their great distance from Earth.
Sun-Synchronous Orbit (SSO) Satellites

The Sun-synchronous orbit type of satellites goes from north to south across the polar regions at an altitude of
600 to 800 km above the Earth. The orbital inclination and altitude of SSO spacecraft are calibrated so that they
always cross any given location at precisely the same local solar time. Thus, the lighting conditions are consistent
for imaging, making this type of satellite ideal for earth observation and environmental monitoring
This also implies that SSO’s current and historical satellite images are well-suited for change detection. Scientists

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CITS : E & H - Electronics Mechanic - Lesson 108 - 117