Transcript
Welcome back. We've now covered the where and the how of rocket science. That is where do satellites orbit and the answer was three main orbital regions low earth, medium earth and geocynchronous orbits and how do they get there and the answer was like you know rockets. We'll now turn our attention to what that is what is sent into orbit. The next few segments we will focus on satellite payloads. That is what are the instruments and components on a satellite that make them work. Fun fact, the word payload was originally a seaf fairing term for the cargo on a ship which provided like the income in revenue which I guess is pretty good for space context as well. We've noted that for a rocket sitting on the launchpad, the payload, the stuff that makes it into orbit is only a tiny fraction, usually a few percent of the total weight of the rocket. And if you Google satellite payloads or satellites in space and you look at the search images, you'll notice some common features across most satellites in orbit around the Earth. So the first most obvious feature are solar panels. That is the things extending out from the satellite, usually in some version of a flat rectangular shape. The electronics and computers on board a satellite need power. And since there's no electrical wall outlets in space, most Earth orbiting satellites use solar power. Another feature you might notice is that most satellites have one or two small satellite dishes or transmitter thingies. And a feature that's generic to most satellites is a box or cylinder holding the whole thing together. This is called the satellite bus or the spacecraft bus. The bus is the main structural component and holds the guts and the brains of the satellite. What's not obvious from googling images is the huge physical range of satellite sizes. from tiny cute little cubats you can hold in your hand to satellites that weigh several elephants and are more than the size of a school bus. While we've just mentioned components of satellites that are generic. All satellites need a source of power and some way to communicate. The rest of the payload really depends on what the satellite is trying to do. And the range of things that satellites can do is really wide. from telecommunication, so providing cell phone service, TV signals or broadband internet, navigation, such as a GPS satellites we've covered in medium earth orbits. Earth monitoring satellites for weather forecasting or monitoring extreme events like flooding or wildfires. The world's militaries have satellites in orbit, whether it's for spying or gathering intelligence to satellites which are exclusively for military communication. And my personal favorite of satellite is for scientific research from astronomical telescopes pointed outwards towards the cosmos or similar satellites pointed towards Earth to monitor things like air pollution or animal migrations. We've noted in previous segments that 60 to 70% of all currently active satellites are involved in communication. 20% are Earth monitoring or taking images and most of the remainder are for navigation. The goal of your mission sets your payload requirement. So, if your goal is to broadcast TV signals, your payload will likely include a high-powered transmitter to make sure your customers get a super strong signal and don't need to go out and like jiggle their satellite dish. Whereas, if your goal is weather forecasting, maybe you want to have a few different imaging cameras to monitor cloud cover and precipitation so I can figure out whether or not I should bring an umbrella to work. No matter what your satellite does, in all cases, you need to strap your payload to a rocket, have it blast off, and then operate in the cold vacuum of space. And you might imagine this is a rather wild ride. So, it's a good idea to test the whole payload system to make sure it can survive the journey into space and accomplish the desired mission. So, in the next few segments, we'll focus on different payload components and then discuss how these components are integrated together and tested before blasting off into space.