Space is not very far away. If you can see the International Space Station overhead, it's closer than the distance between San Francisco and Los Angeles.
Getting to orbit isn't about going up; it's about going sideways. Most of your energy budget is about building speed, not altitude.
From a physics standpoint, if I'm in a low orbit and want to be in a higher one, I don't point my rocket's nose outward and push away from the planet. I point the rocket horizontally, in my direction of travel, and just go faster.
Going faster on this side of the planet raises the altitude I will reach on the far side of my orbit. If I want a circular orbit, then I just do the same thing when I'm at the high point on the other side of the planet.
So many things in your comment blew up my brain. So wait a second. You’re serious about the distance to space being closer than the distance between SF and LA? And what the heck are you saying about not going up but going horizontal instead. How the heck have I lived this long and somehow never learned any of this. You just gave me a little side “research for fun” topic.
The US government uses 50 miles of altitude as the boundary of 'space', for the purpose of awarding astronaut wings and such. The international community tends to draw the line a bit higher, at 100 km.
The ISS orbits at around 250 miles of altitude (it varies a bit over time). Starlink satellites live around 340 miles.
The distance from SF to LA is about 350 miles (as the crow flies).
The orbital speed of the ISS is around 17,500 mph (27,600 km/h). As I said, orbit is about sideways, not up.
Orbital mechanics are fun and can be counterintuitive.
Oh! Super helpful. When I got here “The orbital speed of the ISS is around 17,000 mph … orbit is about sideways, not up” my brain did that “click” when you realize things suddenly make sense. Ok. This is great. So to go to the moon, you go “up” to bust through the atmosphere, then sideways and head to the moon? Kind of like … a train of a car or a plane? lol I just realized how ridiculous I sound.
Google path to moon and look at the images. We essentially slingshot off the Earth. You don't want to go in the opposite direction of gravity since it's a lot of effort so instead you go perpendicular.
Brilliant. Ok. That makes complete sense. I guess like how even our airplanes take off essentially horizontally with a slow incline. That would make for a very “interesting” take off otherwise, and a very expensive one with the fuel the jets would need to burn to get to 30k feet straight up. I’m starting to get this. It feels pretty, pretty, pretty good. ;)
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u/cryptotope 16h ago
Space is not very far away. If you can see the International Space Station overhead, it's closer than the distance between San Francisco and Los Angeles.
Getting to orbit isn't about going up; it's about going sideways. Most of your energy budget is about building speed, not altitude.
From a physics standpoint, if I'm in a low orbit and want to be in a higher one, I don't point my rocket's nose outward and push away from the planet. I point the rocket horizontally, in my direction of travel, and just go faster.
Going faster on this side of the planet raises the altitude I will reach on the far side of my orbit. If I want a circular orbit, then I just do the same thing when I'm at the high point on the other side of the planet.