I saw a meme that stated that, if you’re mad at someone, it take less Delta-V to launch them out of the solar system than in does to fire them into the Sun.
Why is that? Wouldn’t the attraction of the Sun’s mass be greater and provide assistance?
In: Physics
It’s a fun meme, but it’s actually ~~incorrect~~. Edit: it’s actually correct
What is very difficult is to *orbit* close to the sun. Because when you approach the sun, you will gain a lot of speed, which you’ll need to lose if you want to enter a stable orbit. In space, accelerating and decelerating is the same problem, so decelerating a lot requires a lot of energy, more than what is needed to leave the solar system.
But if you want to get rid of someone, you don’t need them to orbit within the sun. If they hit the sun very fast, it works just as well, and ~~you don’t need the expensive deceleration phase~~.
So, from earth, you can simply move them to an elliptical orbit with high eccentricity, so that the orbit intersects the sun’s surface. ~~That’s actually much cheaper in energy than exiting the solar system~~ (but it’s still a very expensive way to get rid of someone).
But in practice, there is more or less zero use in impacting the sun or a planet at high speed. So that’s why when people discuss space, they always implicitly consider the cost of orbiting close to the sun or a planet, and not just the cost of hitting the surface at full speed.
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