Behold, a hastily assembled model of the Saturn V, constructed out of printer paper, #rubbercement, and #gumption! This is the rocket that took us to the Moon. Swipe to see the stages. From L to R, we have the emergency escape rocket, the Apollo Command/Service Module, the S-IVB (stage 3) S-II (stage 2) and the S-IC (stage 1.) Although the last one launched in 1973, Saturn V remains the most powerful #rocket ever built.
Why so many pieces? Getting into orbit takes a LOT of fuel; #SaturnV was 85% fuel by weight. About 80% of that fuel was in the first stage, 16% in the second stage, and 4% in the third stage. Getting off the ground is the hardest part, not only due to gravity but also due to the weight of the rocket. Much like a can of soda when you start drinking it, the rocket gets lighter as it burns fuel. Stages allow us to ditch those big fuel tanks after they empty. The lighter we can make the rocket, the faster we can accelerate it, and we need to it to go REALLY REALLY fast to get into orbit and stay there. (tldr; of the Tsiolkovsky rocket equation.)
Stage 1 gets us up 42 miles (67 km) of altitude, before Stage 2 takes over. Shortly thereafter, we ditch the emergency rocket (since we can’t use it above 19 miles anyway.) Stage 2 gets us to over 100 miles (170 km) up, and nearly 16000 mph (25k kph.) Stage 3 gets us into a stable “parking orbit” around Earth of ~119 miles (191 km) and over 17400 mph (28k kph.)
So how do we get from orbit to the moon? Instead of ditching the 3rd stage after we reach Earth orbit, we fire it a second time to catch up to the moon. We make sure to time and angle it just right so that if we stop after this step, we’ll automatically slightshot around the moon and head back to Earth (this saved #Apollo13.) We then fire the little engine on the Service Module to get into (and out of) a circular orbit around the moon.
Original post: https://www.instagram.com/p/BdPC_RkgZEs/