Sling-shooting from planet to planet -- Gravity Assist

[adjit]

So I was wondering how I could possibly calculate a way to use the planets gravitational forces to 'slingshot' a spacecraft from planet to planet.

Theory behind the idea:

I want to build a massive interstellar puller, attached several HOME stations to it, point it and with one burn get that puller on target to several planets. While passing by each planet and getting a new course I would detach the HOME base that I have set up and land it on each of the planets.

The main benefit of this would be to use only one burn, when leaving Kerbins gravitational influence and then just being able to coast to the planets dropping off things when the time comes.

If anyone would like to join in on the idea and help me out that would be great, because I feel like this could be a really cool and challenging mission to get perfectly right. Of course, it would need a lot of set up, and a lot of docking while in orbit around kerbin. The difficulty with that is now with all of this added weight it may be a little difficult to pull everything out of Kerbin orbit.

Let me know your ideas, thoughts and what not. Curious too see what you guys think.

[Xaiier]

So...this? http://en.wikipedia.org/wiki/Interplanetary_Transport_Network

Not sure if possible or feasible. A small craft maybe, but anything too large would struggle with the initial burn.

[Spaceisbeautifulul]

I like to use gravity slings as much as possible, it is an easy way to go far.

[adjit]

I like to use gravity slings as much as possible, it is an easy way to go far.

How do you generally calculate your gravity slings?

So...this? http://en.wikipedia.org/wiki/Interplanetary_Transport_Network

Not sure if possible or feasible. A small craft maybe, but anything too large would struggle with the initial burn.

It is possible, every planet will eventually come into paths of one another to achieve this. Its just a matter of calculating when. Is it feasible, probably not, but maybe with a few extra pushes along the way it could be.

My large puller will have to obviously have a good amount of powerful rockets, as well as fuel. I could also assemble the puller in space instead of having to launch a gigantic rig.

Edited June 26, 2013 by adjit

[AustralianFries]

Well I first establish a circularized orbit around Kerbin. Then I transfer to the Mun, keeping an eye on the projected path in the map view. I'll just burn in whatever direction is required in order to get where I need to go.

[A Fat Pokemon]

If the vessel is going to be hard to maneuver whilst in Kerbin orbit, start building it just near the Mun's orbit, but not able to intersect it. Albeit the docking taking a bit longer, it won't take as long to reach escape velocity, and you could also use the Mun's gravity to help.

[adjit]

If the vessel is going to be hard to maneuver whilst in Kerbin orbit, start building it just near the Mun's orbit, but not able to intersect it. Albeit the docking taking a bit longer, it won't take as long to reach escape velocity, and you could also use the Mun's gravity to help.

My idea was to use the Mun as the first slingshot. Shoot for the moon, wrap around it and its new trajectory should take me outside of Kerbins sphere of influence.

[Mr Shifty]

My idea was to use the Mun as the first slingshot. Shoot for the moon, wrap around it and its new trajectory should take me outside of Kerbins sphere of influence.

There was a thread last week where the upshot was that gravity assist around the Mun doesn't really gain you anything.

http://forum.kerbalspaceprogram.com/showthread.php/36627-Mun-slingshots/page3

[SRV Ron]

It certainly can be done but will be very challenging. Keep in mind that every slingshot will have to be done in a precise manner. The slightest misalignment from the orbital plane will radically change your course. The real Voyager probes used several slingshot maneuvers over several years using just thruster fuel to hit solar system escape velocity. That should be your challenge as well for your first attempt. Probably would be better to use Duna and or or Jool for the first slingshot attempts although Mum will work if you can catch it in the right trajectory. You might even want to try using eve, Kerbin, and Jool as the multiple slingshot. Good luck and keep us informed on your progress.

[SRV Ron]

There was a thread last week where the upshot was that gravity assist around the Mun doesn't really gain you anything.

http://forum.kerbalspaceprogram.com/showthread.php/36627-Mun-slingshots/page3

I have has several probes in elliptical orbits to Mum's orbit that have shot off to deep space after several orbits around Kerbin. So, there is something happening when an encounter takes place to give the probe enough of a boost to send it off into deep space. Lost a couple of Kerbals that way as well.

[Mr Shifty]

I have has several probes in elliptical orbits to Mum's orbit that have shot off to deep space after several orbits around Kerbin. So, there is something happening when an encounter takes place to give the probe enough of a boost to send it off into deep space. Lost a couple of Kerbals that way as well.

If you're already on an orbit that crosses the Mun's orbit, it can certainly help lots. If you're starting at a circular LKO, the delta-V you expend getting up to the Mun's altitude offsets what you gain with the gravity assist.

[metaphor]

I had an explanation of the basics of doing a gravity assist in a post on this thread(3rd post from the top). This is the mission I was talking about.

It's not too hard to do gravity assists from planet to planet, but it does take time.

[ProjectGO]

How do you generally calculate your gravity slings?

For one planet, it's easy. You just line up to pass behind it like this:

For more than two, you'd have to calculate the orbital alignments, which gets complicated fast.