General Features of Satellite Buses

The evolution of satellites application has always depended on the development of more sophisticated spacecraft platforms or buses. The development of these three-axis body-stabilized bodies has allowed scientists to deploy more precise navigational payloads, higher gain communications antennas, and high-resolution meteorological and remote sensors.

This article will look into everything there is to know about satellite buses, how they work, their essential components, etc.

What Is a Satellite Bus?

To start this article, let us first learn what a satellite bus is. When you look at a satellite, you will notice two main components — the satellite bus and the payload. The former can be defined as the physical structure containing the payload and the scientific equipment.

The payload refers to all the components that are required for the successful completion of the mission. In most cases, the payload will consist of a communication system, an antenna, a sensor, and/or a camera. The name ‘space bus’ is derived from the fact that the satellite body transports the payload into space, similar to how regular buses transport passengers from one destination to another.

While there are several satellite bus types, they all have one common purpose — protecting and housing the payload. Without a well-designed bus, most spacecraft will not be able to carry out the mission. While the bus is the main component of the unit, it does not cost more than 25% of the entire spacecraft.

How Does Satellite Bus Work?

So, how does a satellite bus work? It is launched into space via a space shuttle or a rocket. Once the bus is released from the rocket, the satellite or spacecraft will start orbiting the Earth once it finds an optimum altitude. Once the spacecraft has reached the required altitude, it will begin fulfilling its mission, like powering the internet, monitoring the crops or climate, taking pictures of the Earth, etc. The type of payload will dictate the satellite bus cost.

What Are the Uses of a Satellite Bus?

There are many reasons why satellite buses are useful. However, the primary use is to protect and transport the scientific equipment and payload to the desired location. The two components rely on one another to carry out the desired mission. Without a satellite bus and a rocket the payload will be unable to reach space, and in turn, it will not be able to measure the required data and send it back to Earth.

Alternatively, the satellite bus would just be unnecessary junk if there was no payload. It’s why manufacturers need to design the bus according to the payload. Otherwise, the mission will never be completed. Typically, it will be very lightweight but robust enough to handle the pressures of the launch. When designing the bus, the manufacturers have to consider various factors like longevity, functionality, cost, and weight.

What Are The Components Of A Satellite Bus?

There are several satellite bus components that you can see within a typical spacecraft satellite. As mentioned previously, the purpose of the spacecraft will be defined by the payload. For example, satellites created for Earth Observation applications will have a camera as the payload, which will be used to collect the relevant data.

Now, let us take a quick look at all these components so that we can better understand how a satellite bus functions:

1. Structures and Mechanics Subsystem (S&MS)

The S&MS provides the required mechanical structure and support to the bus to withstand the pressures during the launch, orbital maneuvers, and re-entry to the Earth’s atmosphere. The primary facility of the satellite bus will house the components of the payload. While its design will be adopted based on the requirement of the mission, it will be used typically to minimize the mass and survive the brutal forces.

2. Electrical Power Subsystem (EPS)

The EPS, as you can guess by the name, is the electrical power generation system that distributes power to the different subsystems in the spacecraft. Apart from the bus, this satellite bus power subsystem will also power the payload. In most cases, solar panels convert solar radiation from the sun to electrical power. Since these solar panels are large, they are folded and hinged during the launch process. The subsystem uses batteries when the satellite is in the Earth’s shadow.

3. Command and Data Handling (C&DH)

<img alt=”Satellite Bus Work”>

The C&DH is the ‘brains’ of the satellite bus that controls how the data is transported from one subsystem to another. The information is transferred via hundreds of feet of wiring routed throughout the satellite bus.

4. Communications Subsystem (CS)

As you can guess, the CS will contain communication components like transmitters and receivers to allow for communication with the controllers on Earth. Most devices utilize radio signals and related software to send and receive commands to and from the Earth stations.

5. Attitude Control Subsystem (ACS)

The ACS contains specialized sensors that determine the exact location and position of the satellite via the position of the Earth, Sun, and the stars. Most satellites utilize this subsystem for various other precise pointing purposes, like determining the exact positioning of imaging devices.

6. Propulsion Subsystem (PS)

The propulsion subsystem adjusts and maintains the satellite in orbit for many years. Various propulsion systems are used in a satellite bus station; most of them consist of rocket thrusters that produce the required thrust by burning special fuel. The PS will provide the maneuvers needed for momentum management, inclination adjustment, and altitude adjustment.

7. Thermal Control Subsystem (TCS)

The TCS is the subsystem that maintains the proper temperature of the satellite bus and all the payload components. Small heater strips, special coatings, and paints absorb or reflect the heat from the Sun and the Earth. The multi-layered blankets protect the payload from the extreme cold in space. The TCS may also include thermal control from actuators and electrical heaters to control the temperature ranges for payload equipment that require a specific temperature.

Final Thoughts

As you can see, the satellite bus is the physical structure that will protect the payload. Without the buses, the payloads would never reach space, and we will not be able to gather the required data.

If you have questions about this article, drop them in the comment section below!

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