These motors make rockets work in space #shorts #science

Most people aren't going to be able to recognize the most important technology in this video. Did you see it? Let's look again. It's this right here. I'm going to get nerdy on you, but these are ullage motors and they basically allow spaceflight to happen. Most rockets use cryogenic fuels in their upper stages, which just means super cooled fuels that are stored in insulated tanks. These tanks are deliberately not filled to capacity to allow for some expansion in microgravity. And something else weird happens in microgravity. That fuel starts existing in a weird state between liquid, solid, and gas. And it also doesn't stay pushed up against the feed lines that push it into the engine where it needs to burn. So this can ultimately lead to gases in the fuel lines and into the engines, which means that they're not going to burn and something is going to go wrong. This is why we need ullage motors. Ullage motors fire to basically create a border between the liquid and the gas and to force the fuel or the oxidizer against the fuel lines so that when the engine starts to burn, what they need to burn is pushed up and ready to be fed into them. You can see the ullage motors in action in this incredible shot as the S4B stage leaves behind the S1B stage on AS203. The ullage motors fire partially to give the stage a little bit of distance from the spent stage and also to make sure that the fuel is in the right position and the right state to start burning. Then the rocket engine starts to burn. These little technical bits of spaceflight are just so endlessly fascinating to me, but I will also admit that I am a huge nerd for Apollo.