The curvature of spacetime does wild shit to how you would expect physics to work. If you want to fall into a gravity well, you have to slow down or you’ll just slingshot past it.
Picture going for a very tight periapse in a highly elliptical orbit. Now make the periapse lower. Lower still, within the atmosphere or below the surface of the thing you’re trying to hit. If you don’t plan on arriving alive it’s much cheaper to arrive like a meteor
The reason you need to slow down is because you’re starting on Earth, which means you’re moving fast enough parallel to the sun’s surface that for every foot you fall downwards toward the sun, the sun’s surface curves away by 1 foot. This results in the nearly circular orbit around the sun we exist in.
If you start speeding up, the orbit becomes more elliptical, except your aphelion starts raising away from the sun because now you’re moving fast enough that you’ve moved more than 1 foot sideways in the time you’ve fallen 1 foot downwards.
Slowing down has the opposite effect. If you get your speed down to 0, you’ll fall straight down toward the sun as normal with gravity. But you don’t need to go all the way down to 0 velocity to enter the sun, you just need to slow down until your elliptical orbit brushes up against the sun’s surface. If you then want to speed back up to avoid falling into the sun, you need to do it parallel to the sun’s surface. At this point, speeding up toward the sun will actually make you fall into the sun faster.
So basically the problem isn’t that you’re moving too fast to fall into the sun. By virtue of Earth’s orbit, you’re moving too fast in a direction away from hitting the sun’s surface.
So you have ~30km/s in a near circular orbit. You interact with a gravity well to point your vector at the Sun (a highly elliptical orbit). Sure you’re carrying enough energy to come out of that with a very high aposol, but with the perisol within the Sun that energy will convert to heat
You don’t need to kill all your earth orbit speed to hit Earth, just enough to aerobrake
You don’t need to kill all your lunar orbital energy to hit the moon if you’re happy to lithobrake
No one is talking about reaching the surface of the sun alive
the issue is not counteracting gravity, the issue is decelerating enough to hit the sun
What’s wrong with them striking the sun at full speed?
The curvature of spacetime does wild shit to how you would expect physics to work. If you want to fall into a gravity well, you have to slow down or you’ll just slingshot past it.
Picture going for a very tight periapse in a highly elliptical orbit. Now make the periapse lower. Lower still, within the atmosphere or below the surface of the thing you’re trying to hit. If you don’t plan on arriving alive it’s much cheaper to arrive like a meteor
This sounds an awful lot like the the idea that you can never actually catch up to anything because all you can ever do is close the distance by half.
This sounds an awful lot like the the idea that you can never actually catch up to anything because all you can ever do is close the distance by half.
The problem is, you have so much speed that you keep missing.
The reason you need to slow down is because you’re starting on Earth, which means you’re moving fast enough parallel to the sun’s surface that for every foot you fall downwards toward the sun, the sun’s surface curves away by 1 foot. This results in the nearly circular orbit around the sun we exist in.
If you start speeding up, the orbit becomes more elliptical, except your aphelion starts raising away from the sun because now you’re moving fast enough that you’ve moved more than 1 foot sideways in the time you’ve fallen 1 foot downwards.
Slowing down has the opposite effect. If you get your speed down to 0, you’ll fall straight down toward the sun as normal with gravity. But you don’t need to go all the way down to 0 velocity to enter the sun, you just need to slow down until your elliptical orbit brushes up against the sun’s surface. If you then want to speed back up to avoid falling into the sun, you need to do it parallel to the sun’s surface. At this point, speeding up toward the sun will actually make you fall into the sun faster.
So basically the problem isn’t that you’re moving too fast to fall into the sun. By virtue of Earth’s orbit, you’re moving too fast in a direction away from hitting the sun’s surface.
That’s a very good explanation.
So you have ~30km/s in a near circular orbit. You interact with a gravity well to point your vector at the Sun (a highly elliptical orbit). Sure you’re carrying enough energy to come out of that with a very high aposol, but with the perisol within the Sun that energy will convert to heat
You don’t need to kill all your earth orbit speed to hit Earth, just enough to aerobrake
You don’t need to kill all your lunar orbital energy to hit the moon if you’re happy to lithobrake
No one is talking about reaching the surface of the sun alive