Understanding Satellites and Their Systems
Due to the services they provide, satellites have become essential tools in our modern economies. They allow us to use the internet, television, GPS, and mobile communication from anywhere in the world. Additionally, the most powerful military forces rely on satellites for visual and signal reconnaissance, as well as communication. However, these efficient devices are not exempt from hacking and communication interceptions; they can even be susceptible to control and command. Therefore, their protection is necessary, but first, we must understand them better.
Satellite: Meaning and Origin
Any object that orbits a planet is a satellite; in fact, the Moon is Earth’s natural satellite. However, in popular language, when this word is mentioned, it refers to man-made artificial satellites.
The first artificial satellite was launched on October 4, 1957, by the then Soviet Union. This satellite was named Sputnik (which translates from Russian as “travel companion”); subsequently, Sputnik 2 was launched on November 3, 1957. These satellites were quite simple objects compared to today’s space communication systems. The United States launched its first satellite, Explorer I, on January 31, 1958. These were designed for scientific use, but with the ultimate goal of being used by military forces during the Cold War.
Currently, several countries have developed and launched their own satellites, including Algeria, Argentina, Australia, Austria, Brazil, Canada, Chile, China, Denmark, Egypt, Finland, France, Germany, India, Iran, Israel, Italy, Japan, Kazakhstan, South Korea, Malaysia, Mexico, Netherlands, Norway, Pakistan, Poland, Russia, Saudi Arabia, South Africa, Spain, Switzerland, Thailand, Turkey, Ukraine, the United Kingdom, and the United States.
Satellite Sub-Systems
Satellites are computer-controlled systems with subsystems for:
Power Generation: Due to the continuous need for electricity to power computers and communication equipment, modern satellites generally use solar panels for practically unlimited and eternal generation (solar electricity technology was initially developed to power these satellites).
Thermal Control: In space, temperatures are extremely low, and many components cannot operate under these thermal conditions. Therefore, the system must provide some heat to components that are away from the sun and cool those exposed to the sun to maintain proper functioning.
Telemetry: This system transmits equipment operation data to control stations on Earth and receives commands from these stations.
Altitude Control: Measures the vehicle’s orientation and uses actuators to reorient the vehicle to the correct altitude, orbital position, and antenna orientation.
Communication: This is considered the most important. This subsystem consists of:
A receiver to “capture” signals from ground stations
An amplifier to increase the signal strength
Classifying the signals and directing the output signals to the appropriate downlink antenna(s) and transmitting the signal to Earth.
The failure of any of these subsystems can render the satellite completely useless.
Orbits
Most satellites are geocentric; although there are missions to other planets and solar systems, generally for scientific purposes. Those that orbit the Earth can be classified by the type of orbit they maintain. Low Earth Orbit (LEO) is generally defined as those satellites within 2000 km of the Earth’s surface, Medium Earth Orbit (MEO) is between 2000 km and 36,000 km from the Earth’s surface, and High Earth Orbit (HEO) are those satellites above 36,000 km. Many of the newer satellite technologies, such as Starlink and Google’s (SkyLo) and Verizon’s mobile phone satellite connectivity, rely on low Earth orbit satellites to minimize connectivity latency. Additionally, there are geostationary or GEO orbits. These satellites are over 36,000 km from the Earth’s surface and travel at a speed that keeps their relative position to Earth fixed. This way, the satellite’s position is always known, and antennas can be pointed in that direction. Older satellite television and internet services used geostationary satellites (Elon Musk’s Starlink uses low Earth orbit satellites that are NOT geostationary).
Author: Jordan Rodgers- Lead Technologist at Black Hat
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