Does the gravity sling require rocket guidance to be non-negligible?

[Jonathan212]

Is the gravity sling possible without rocket propulsion which dynamically guides the object to the right point? Ie, if instead of using a rocket, you shoot the object with an accurately aimed cannon from the moon, will it either hit the planet or miss it but never get slung/accelerated substantially?

 

[phinds]

Is the gravity sling possible without rocket propulsion which dynamically guides the object to the right point? Ie, if instead of using a rocket, you shoot the object with an accurately aimed cannon from the moon, will it either hit the planet or miss it but never get slung/accelerated substantially?

Slingshot depends only on the rocket having the right trajectory as it approaches the large object. If you can aim a cannon to put it there then it will get the gravity assist.

 

[Jonathan212]

Did the spaceships that used the slingshot make a turn with the rocket propulsion to get the right angle of approach?

 

[phinds]

Did the spaceships that used the slingshot make a turn with the rocket propulsion to get the right angle of approach?

Depends on whether or not they were already on the right trajectory.

 

[jbriggs444]

Taking the question in a broader context, a spacecraft using a slingshot maneuver is an example of a three-body problem. You have the craft, the object being sling-shotted around and, presumably, a primary (e.g. the sun) about which the object is orbiting.

Except for a few special cases, the three body problem has no stable solutions. It yields a result which can depend critically on small variations on the initial position, speed and direction of the craft. A tiny margin of error can, over a sufficiently long period, make the difference between an eventual collision, a temporary capture or an eventual ejection on an escape trajectory.

 

[Jonathan212]

How do we define a stable solution of an N-body problem?