Key Points

• Satellites tend to be the same six systems used in different combinations. You can probably predict what they’ll be with a little time spent thinking about it..
• There hasn’t been much change in the types of systems for several decades so understanding things now will be useful to you throughout your career.

Introduction

This is the article for you if you want an entry-level overview of what makes up a satellite system. We’ll talk about everything at a high level and include links for things if you want to dig deeper.

Predict What You’d Need

Imagine you want to build a satellite that takes a picture of your house. And imagine you know absolutely nothing about satellites other than they go around the Earth. But you’re a problem solver, so you sit and think about what you’d have to do. What might you imagine you’d need? You might come up with the following systems:

• A Camera: If we’re going to take pictures, we should have a camera.
  
• Some sort of structure: Something has to hold the camera and whatever else
  
• A radio: We’ve got to be able to get our pictures

• A computer: Something has to run everything
  
• A way to twist the spacecraft to point at things: We need some way to get it to point at your house. Maybe we use little thrusters or something to twist the satellite around?
  
• Power: We’ve got to keep things running, at least until we get our pictures
  
• Maybe some sort of heater: Maybe it’s too cold up there and maybe it’s not. We don’t know, but we should make sure our camera doesn’t freeze
  
• Something about radiation? Is that important? Maybe yes, maybe no, but we’ll add it to the list of things to check.

Out of that list, there are just six things that it seems like we’d need and the other two are maybes. And it turns out that list covers most of the satellites that have ever flown in space. Even Hubble and JWST are just fancy cameras with radios, power, computers, a pointing system, a thermal system, and a structure that holds everything.

So why are satellites expensive and why do big programs have thousands of workers? We’ll have an article soon that talks about that more. For now, let’s go over the primary systems in a satellite.