this post was submitted on 13 Oct 2023
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Thanks! I didn't think about the fact that it'd lose velocity to gravity as it gets further away.
I wonder if you could slingshot a probe by firing it to fly by the sun and then shedding mass at its perihelion. The idea being that the craft would be mostly dead weight, increasing the force exerted on the craft by the sun's gravitational pull. Once you reach the perihelion, you eject the mass behind the craft so that there's less force acting on the craft as it moves away from the sun.
๐. I like science.
You wouldn't just drop mass along side you in space. It would just continue to float along beside you.
You definitely have to throw it behind you, like you said, but that's what rockets do. They throw mass behind them to make them move forward. That's a rocket.
When you throw mass behind you at one point in your orbit, you raise the height of your orbit on the opposite side of the orbited object (this is simplified).
So you're basically right, it's partially about the mass of the object, but it's mostly the firing of the rocket.
You've got some pretty good intuition though. That's basic orbital mechanics.
It even has a name, the Oberth effect
Just "shedding mass" won't do it. Uncouple a payload from the mass of the ship at perihelion, and they will just float along together, side by side in their original orbit.
But, if that "mass" is "rocket fuel", and you "shed" it by burning it behind you, you've got the right idea. As the other commenter said, the Oberth effect means the closer you are to the sun, the faster you are moving, and the greater the effect that burning will have.
Yes, the Oberth effect means that firing a rocket at the periapsis changes your orbit more than at any other point in the orbit.