Comment on The fastest ever human-made object keeps breaking its own speed record
PetDinosaurs@lemmy.world 1 year agoSo, it doesn’t work the way you think.
It’s only going that fast because it’s near the sun. You can’t use that to go elsewhere. It had to lose a lot of energy to get as close to the sun as it is. It would need to gain that back to even earth.
I’m really blanking on a way to explain this concisely and I can’t explain orbital mechanics in a Lemmy post.
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.
👍. 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 the 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 any the firing of the rocket.
You’ve got some pretty good intuition though.
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.
stepintomydojo@sh.itjust.works 1 year ago
Drop a ball. It goes fastest just before and after it hits the ground, and slows down until it gets back to near the height you dropped it from
The probe is the ball, and slingshotting around the sun is like bouncing off the ground. The potential energy (height of ball/distance from sun) gets converted to and from kinetic energy (speed).
PetDinosaurs@lemmy.world 1 year ago
That’s a pretty good answer. I was definitely overthinking it.
stepintomydojo@sh.itjust.works 1 year ago
Seeing an annular eclipse is an excellent application of orbital mechanics! Enjoy!
PetDinosaurs@lemmy.world 1 year ago
I intend to. Provided I don’t get trapped in the desert for days. We’re bringing extra food, water, and eclipse glasses to auction to the highest bidder.
AngryCommieKender@lemmy.world 1 year ago
Glad you are having fun. I never want to fly through Vegas again. That airport was outrageous, even by airport standards.
PetDinosaurs@lemmy.world 1 year ago
Oh. I hate it here. I’ll never be back.
It’s awful. I don’t party or gamble or smoke or really do much but outdoor and educational, and I particularly hate people trying to extract more money from me.
I’m fine with paying what it costs, even if that’s a lot, but once I’ve paid, you don’t talk to me about money again.
The airport was bad, then we realized that the Lyft driver ran up the meter on us by going the long, more trafficy way. I didn’t even know that was possible.
Plus I now am away from home without a pair of glasses and with a bilateral case of pinkeye that I must’ve picked up at the optometrist on Wednesday.