Main Satellite Components and Their Functions

We depend on satellites for so many tasks, from mapping and navigation to weather forecasting and Internet access, that we already started taking this technology for granted. Still, like most technologies we use, spacecraft is an engineering marvel that relies on a series of complex satellite components to ensure its smooth operation in orbit. And while digging into all the specifics would take pages, the essential satellite components and functions can be explained in simple terms — which is exactly what we will do below.

What are the main components of a satellite system?

To better understand the essential satellite components, it’s important to consider spacecraft goals first. All in all, two main parts of the satellite are the bus, hosting its must-have electronics, and the payload that carries mission-specific equipment. A bus, also called a spacecraft platform, has a more or less universal design we will discuss a bit later. In essence, its components are necessary to ensure the spacecraft can operate in space and transmit data back to Earth.

Payload components are less universal because they are tailored to specific functions a satellite will have to perform in orbit. But what are the main functions of satellites? While the details may differ, it’s possible to categorize all essential functions, aka mission goals, into:

● Communication: depending on a specific mission, satellites can be used to broadcast TV signals, ensure mobile connectivity, or provide wireless internet access.

● Earth observation: here, the range of applications is practically limitless — from analyzing vegetation levels on land and marine ecosystems at seas to responding to natural disasters or tracking illegal activities, such as poaching, unsanctioned mining, etc.

● Navigation: GPS system we all take for granted also works from space, but it’s not the only example of a global positioning system — the EU has its Galileo, and Russia uses GLONASS.

● Astronomic research: depending on specific mission goals, scientific satellite components may include anything from high-resolution cameras to remote sensors because scientific research implies studying cosmic radiation levels, atmospheric composition of other planets, etc.

● Military & defence: most advanced technologies we use today have their origins in the military, and satellites are not an exception. Military space components usually include cameras, ranging from low to extremely high resolution. These are used to track troop movement, watch out for missile launches, as well as for other types of surveillance.

These are the main uses of satellite components installed as spacecraft payloads. Most often, the actual components are cameras, capturing images in different light spectrums and resolutions. However, there can be additional components, depending on a mission — especially so in scientific missions that rely on advanced equipment.

But what about the standard components every spacecraft should have, regardless of its mission goals?

Essential satellite components list in detail

Equipment installed on a satellite bus is more universal because it acts as a satellite’s structural body. If the payload is always determined by mission parameters., electronics that ensure spacecraft operation is more uniform and include the following components:

● Power supply: this system provides power to all other satellite components through a power distribution unit (PDU). Depending on satellite placement, the actual power source could be either batteries, solar panels (provided there is enough sunlight), or both.

● Communication segment: this segment is responsible for receiving commands from Earth and sending data back for analysis. Here, the main components are antennas, transponders, receivers, transmitters, etc. — depending on satellite design specifics.

● Attitude and Orbit Control System (AOCS): this vital component ensures a satellite can maintain its proper position in orbit. To ensure this, AOCS is normally equipped with gyroscopes, thrusters, reaction wheels, and inertial measurement units. More complex satellites may also be equipped with manoeuvring mechanisms to adjust their orbit when necessary — for example, when moving on to another part of a mission or to avoid collision with space debris.

● Thermal control: temperature fluctuations in space can range from −220°C to +220°C, which requires advanced thermal control components to ensure the spacecraft can cope with its goals. Usually, those include thermal blankets, radiators, and sometimes — cooling systems.

● Command and Data Handling: finally, there is an onboard computer that processes commands from Earth and sends ‘internal’ commands to other satellite components. Together with the power supply, these two are the ‘brain & energy’ components of any spacecraft. 

All of these essential components are installed on a special structure, referred to as a bus or platform. Often, this bus will also carry several deployable structures, i.e., solar power arrays or antennae. Once again, the specific components are determined by satellite mission. Some spacecraft may deploy their antennae and arrays just once, shortly after launch, while some others may stow and redeploy them following commands from ground stations.

Of course, this is but a quick overview of satellite components and functions. Depending on a specific mission and orbital placement, additional satellite components can be necessary. Yet, if you want to understand the basics of how satellites work and what they’re used for, this list should have you covered!