 Every single rocket that has ever launched anything into space, orbital mission, deep space, manned, unmanned, big, small, every one of those rockets has one thing in common, staging. Staging is a fundamental part of any mission launching, whether you're talking about a heavy lift vehicle like the Saturn V or the Falcon Heavy, or something much smaller like an Atlas. Staging is quite simply when one part of the rocket fires before another, so that the cumulative thrust on that payload is what gets it up into orbit. The reason rocket stage is because of weight, or more specifically mass, because a rocket would have to stage leaving another planet just like it does on Earth. Let's take my favorite rocket, the Saturn V, as an example. This was the only part of the payload that actually had to reach Earth orbit. The rest of the rocket, all this down here, was just designed to get that rocket up off the ground and into space. So when designing the launch vehicle, engineers had to take into consideration the mass of the payload that had to reach orbit. But that wasn't it. As soon as you start adding lower stages that have to provide the thrust to get that payload into orbit, that adds mass. And it's not only the mass of the structure of the rocket, it's also the mass of the propellant that has to fire to lift that mass off the ground. Do you see where this is compounding to make things a little bit difficult? It becomes a very interesting balancing act. That only is the payload part of the mass. The rocket structure and the propellant also add mass. But as the rocket burns that propellant, the mass changes. It's that changing mass that opens the door for staging. So let's look back to our Saturn V. As the Saturn V is launching and everything's perfect and beautiful and lovely, all of the propellant in that first stage is being used and burned up. Well once it's done, now the Saturn V is carrying that extra dead weight of the spent stage. There's no point in using more propellant to get more of the rocket off the ground if you don't need it. So what do you do? You ditch the spent stage. That's where staging comes in. Staging is really just a clever way to get rid of dead weight when you're doing something complicated, like putting a payload into space. Now all that being said, there are different ways a rocket can go through staging. Let's start again with the Saturn V. That uses a kind of staging called serial staging. The stages are stacked one on top of the other. The first stage fires first and then separates from the rest of the payload once its propellant is exhausted. Explosive bolts and retro rockets create clear separation between the spent stage and the active second stage, which then has room to fire. Now the Saturn V in this specific case was a three stage rocket, but the exact same thing happens for a two stage rocket or a four stage rocket. It's just that sequence of staging all the way up the rocket's body. Another type of serial staging is called hot staging. It's what the Titan II that launched the Gemini program used. If you look closely at this rocket, you notice, like I was shocked to find the first time I've really looked at a picture, that there are holes in the rocket's body. While it turns out that unlike the Saturn V, which gained distance between the rocket stages when one was finished before the other one fired, the Titan II fired while the stages were still connected. Those holes are vents for when the next stage fired to separate from the spent stage. There are rockets that marry serial and parallel staging. A great example is the Titan III. The main core stage of that rocket called the sustainer stage was a Titan II, and it had solid rocket boosters on either side. Those two boosters separated, parallel staging, before the main stage went through serial staging. Another kind of staging is parallel staging, and we're all familiar with that one because that's what the space shuttle used. The space shuttle's main tank fed the engines on the orbiter, but it needed a bit of an extra boost to get into orbit. Enter the solid rocket motors that flanked the side of the main tank. The boosters as well as the main engine fired to get the shuttle off the launch pad, and then once the SRBs had exhausted their fuel, they were detached and left to fall into the ocean. Now, there's another kind of staging that's pretty rare, but also familiar, though we may not realize it. This is stage and a half staging, and we know it because the Atlas D rocket that launched John Glenn, Scott Carpenter, Wally Shira, and Gordon Cooper into orbit on the Mercury program used stage and half staging. With the Atlas D, the main engine acted as the sustainer. It was the only one that burned to get the payload into orbit. Around the sustainer engine was a sort of booster stage with two extra engines. Now these were side by side, so sort of parallel, but they also fell away vertically, sort of like serial. So basically all three engines would fire to get the rocket off the launch pad, and then once the first stage or half stage was done, it fell away, and that sustainer stage continued on to put the payload into orbit. Of course, the dream, because it would be much simpler and potentially more efficient, would be a single-stage-to-orbit rocket. That is exactly what it sounds like. One single stage would be enough to power a payload into space. That is not something that exists yet, although there are companies that are trying to bring that dream to reality. If you guys like this video, be sure to subscribe so you never miss an episode, and also I want to hear from you. Do you have other questions about rockets, about staging, about the Saturn V, the Titan, the Atlas? Let me know all of your thoughts in the comments below. And of course, don't forget, you can follow me across social media for daily vintage-based content on Facebook, Instagram, and on Twitter. All right guys, thank you so much for watching.