Izawwlgood wrote:Can someone post some info on the Jupiter slingshot to the sun maneuver?

Starting from an orbit similar to the Earth's, you need 30 km/s delta-v to kill your orbital velocity and drop into the Sun.

However, that's not the most efficient method. Instead, you can put yourself into an elliptical orbit with the closest approach to the Sun (perihelion) the same as Earth (1 AU), and the furthest distance from the Sun (aphelion) some way further out. Once you reach aphelion, you then kill your orbital velocity and drop into the Sun.

For example, you could add 5 km/s (from 30 km/s to 35 km/s) to put yourself into an elliptical orbit with an aphelion of 2 AU. At aphelion your orbital velocity would be 17 km/s, so that's what you need to lose to drop into the Sun. The two orbit changes require a combined delta-v of 5 + 17 = 22 km/s, so you've saved 8 km/s.

In fact, the bigger the initial burn, and hence more eccentric the elliptical orbit, the more efficient it is. The most efficient way is a 12 km/s burn to very almost escape from the Sun, followed by a few m/s deep in interstellar space to drop back into the Sun. It would of course take a very very long time.

Here's some different aphelions you could chose, the delta-v needed to reach them, and the velocity at aphelion you need to kill to drop into the Sun:

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`Target Aphelion Delta-V Required Velocity to kill Total`

of Elliptic Orbit to reach the orbit at Aphelion Delta-V

----------------- ------------------ ---------------- -------

1 AU 0 km/s 30 km/s 30 km/s

2 AU 5 km/s 17 km/s 22 km/s

3 AU 7 km/s 12 km/s 19 km/s

5 AU (Jupiter) 9 km/s 8 km/s 17 km/s

10 AU 10 km/s 4 km/s 14 km/s

19 AU (Uranus) 11 km/s 2 km/s 13 km/s

Light year 12 km/s 0 km/s 12 km/s

There is another short cut. If you pick an aphelion of around 7 AU to 10 AU, you need about 10 km/s of delta-v to reach your elliptical orbit. As you pass Jupiter on your way out, you'll be doing something like 11 km/s. Jupiter orbits at 13 km/s. If you imagine your 11 km/s split into radial (10 km/s) and tangential (5 km/s) components, then you approach Jupiter like this. The Sun is 5 AU below the bottom of this diagram, and Jupiter is orbiting anti-clockwise.

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` < 13 J -------......_ _ _ _`

^

10

< 5 \

\

\

If you then subtract 13 km/s from the tangential components to convert from Solar to Jupiter co-ordinates, and if you've been careful with your aiming, you get a Jupiter flyby like this. Relative to Jupiter you come in 13 km/s and leave at 13 km/s in a different direction.

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` _.------ -13 >`

.'

/ J

/

^ /

10/

-8 >

If you add the 13 km/s to your tangential velocity after the flyby to convert back to Solar co-ordinates, you find the flyby has stopped you dead in space (relative to the Sun). From now on it's just a long, long fall to a fiery end.

That's a Jupiter slingshot to the Sun maneuver.