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How does delta-v prevent you from aiming in a direction that intersects with the sun? That's all that's required for trash disposal. You aerobrake in the solar

How does delta-v prevent you from aiming in a direction that intersects with the sun? That's all that's required for trash disposal. You aerobrake in the solar atmosphere, if your want to think of it that way

lxgr 3y ago
To reach the sun, you need to shed a lot of kinetic energy - and given that you’re in a vacuum on most of the way there, the only way to do that is through a lot of deceleration, which is really the same thing as retrograde acceleration, and maybe some gravitational slingshots, but these aren’t free either (you need delta-v to execute them) and therefore have limited gains. (Technically it’s cheaper by a factor of three to go to escape velocity out of the solar system and then plunge back into the sun, but at that point, why go through the trouble and come back if your concern is trash disposal?)
- lupusreal 3y ago
  > To reach the sun, you need to shed a lot of kinetic energy - and given that you’re in a vacuum on most of the way there, the only way to do that is through a lot of deceleration, which is really the same thing as retrograde acceleration If you can fenagle yourself into a highly elliptical solar orbit, then a relatively small retrograde burn at apoapsis could get you into the sun.
  - JumpCrisscross 3y ago
    > If you can fenagle yourself into a highly elliptical solar orbit Getting to that orbit is more expensive than leaving the system.
teraflop 3y ago
"Aiming in a direction that intersects with the sun" requires a huge momentum change when an object already has a large orbital velocity around the sun.
JumpCrisscross 3y ago
> aiming in a direction that intersects with the sun? We are moving really fast relative to the sun. Perturb your orbit to seem to intersect with the Sun and you’ll tend to fly past it. (Loose analogy: swimming in a current and aiming for a point on shore.)
glatisaint 3y ago
Kurzgesagt has a video that explains why it isn't a good idea. https://www.youtube.com/watch?v=Us2Z-WC9rao https://www.youtube.com/watch?v=Us2Z-WC9rao
- o11c 3y ago
  That's once again repeating the same misunderstanding as far as orbital mechanics. Yes, a collision-only slingshot needs precision. But we're good at precision maneuvers with modern computers. (it is correct that getting past Earth's orbit in the first place requires a bit of delta-v though, which I suppose I glossed over.)
  - JumpCrisscross 3y ago
    > collision-only slingshot needs precision. But we're good at precision maneuvers with modern computers That precision doesn’t get around the physics. Why do you think none of our missions to the inner Solar System have tried this?
  - lxgr 3y ago
    You don't need to just "get past Earth's orbit", you need to deorbit out of Earth's orbit around the sun if you want to reach the sun. This requires a much higher (at least double) delta-v than leaving Earth's gravity well alone.

lxgr 3y ago

To reach the sun, you need to shed a lot of kinetic energy - and given that you’re in a vacuum on most of the way there, the only way to do that is through a lot of deceleration, which is really the same thing as retrograde acceleration, and maybe some gravitational slingshots, but these aren’t free either (you need delta-v to execute them) and therefore have limited gains. (Technically it’s cheaper by a factor of three to go to escape velocity out of the solar system and then plunge back into the sun, but at that point, why go through the trouble and come back if your concern is trash disposal?)

lupusreal 3y ago
> To reach the sun, you need to shed a lot of kinetic energy - and given that you’re in a vacuum on most of the way there, the only way to do that is through a lot of deceleration, which is really the same thing as retrograde acceleration If you can fenagle yourself into a highly elliptical solar orbit, then a relatively small retrograde burn at apoapsis could get you into the sun.
- JumpCrisscross 3y ago
  > If you can fenagle yourself into a highly elliptical solar orbit Getting to that orbit is more expensive than leaving the system.

teraflop 3y ago

"Aiming in a direction that intersects with the sun" requires a huge momentum change when an object already has a large orbital velocity around the sun.

JumpCrisscross 3y ago

> aiming in a direction that intersects with the sun? We are moving really fast relative to the sun. Perturb your orbit to seem to intersect with the Sun and you’ll tend to fly past it. (Loose analogy: swimming in a current and aiming for a point on shore.)

glatisaint 3y ago

Kurzgesagt has a video that explains why it isn't a good idea. https://www.youtube.com/watch?v=Us2Z-WC9rao https://www.youtube.com/watch?v=Us2Z-WC9rao

o11c 3y ago
That's once again repeating the same misunderstanding as far as orbital mechanics. Yes, a collision-only slingshot needs precision. But we're good at precision maneuvers with modern computers. (it is correct that getting past Earth's orbit in the first place requires a bit of delta-v though, which I suppose I glossed over.)
- JumpCrisscross 3y ago
  > collision-only slingshot needs precision. But we're good at precision maneuvers with modern computers That precision doesn’t get around the physics. Why do you think none of our missions to the inner Solar System have tried this?
- lxgr 3y ago
  You don't need to just "get past Earth's orbit", you need to deorbit out of Earth's orbit around the sun if you want to reach the sun. This requires a much higher (at least double) delta-v than leaving Earth's gravity well alone.