Probe 'Grand Tour' of Joolian system - are there any tools to help with this?

[Esme]

Hello!

I've succesfully got a set of probes (one 'bus' element with the main propulsion (plus SCANsat mapper, materials lab, goo), and 2 landers (both with materials science units and goo units), one of which has a certain amount of propulsion plus a SCANSAT mapper which the other lander lacks) into the Joolian system, and their path is arcing up over the top and to one side of Jool before arcing down for a 4,000km periapsis encounter with Tylo. Shame that isn't Laythe, I thought, as I could then drop the unpowered lander,and leave one of the other units in orbit to map, sending the third on elsewhere.

So then I thought hmmn, wonder if I can use the Tylo encounter to slingshot over to Laythe? Now, in reality, I'm going to play things as safely as possible, to try to maximise my science haul (I'm still in v0.9 btw), and quite what I can do obviously very much depends on the relative positions of each of the bodies in the Joolian system at this point in my game. But it did make me wonder whether some clever and kind person has already created a useful tool for working out how best to do a 'grand tour' of as much of the Joolian system as possible, minimising dV usage.

Failing that, are there any generally good strategies for tackling exploring the Joolian system with moderately limited means? Ellipitical orbit a degree or two out of the plane of the sattelites with perijool same as Laythe and apojool same as Pol, maybe?

Edited May 15, 2015 by Esme

[Red Iron Crown]

This delta-V map by JellyCubes is very helpful for tooling around the Jool system. (The Laythe landing/ascent values haven't been updated for the new aero, though.)

Calculating gravity assists is more complex, the only tool I know of for that is Trajectory Optimization Tool. It's for Windows and Mac only and a bit complicated to use, though.

[Esme]

This delta-V map by JellyCubes is very helpful for tooling around the Jool system. (The Laythe landing/ascent values haven't been updated for the new aero, though.)

Calculating gravity assists is more complex, the only tool I know of for that is Trajectory Optimization Tool. It's for Windows and Mac only and a bit complicated to use, though.

Many thanks, Red! Hmmn, those dV values look a tad lower than I was expecting, which is good, I might get to map more than I expected. I'm not bothered about landing/ascent values at this point - my landers are strictly one-way by chute only, or suitable for landing on engines only on low-grav bodies. I might try giving the Windows version of that trajectory tool a try using Wine...

[PLAD]

My entry in the Jool-5 challenge made extensive use of flybys of Jool's moons to reduce the total dv requirements quite a bit. The trick was that I never put the carrier in orbit around any moon, it would drop of the lander during one flyby of a moon, then pick it up at a later flyby. It sounds like you want to flyby all the Jool moons as cheaply as possible, so you want to follow the carrier's path. Note that my carrier's total mission requirement for this was:

1070m/s : Kerbin low orbit to first flyby of a Jool moon (this depends on the Kerbin-Mun-Eve-Kerbin-Kerbin-Jool path I took to get there)

245m/s :total of all maneuvers between the moons

100m/s :last Jool moon flyby to Kerbin atmosphere.

Here is my secret- this is much easier to do than you would think! I did not calculate the whole flight ahead of time. (Except for getting from Kerbin to Jool, I had to calculate all of that.)

Rule #1- Use a node editor. You have to make little bitty adjustments when setting up a flyby, only a node editor (I use Mechjeb's, but there are others) can do that easily.

Rule #2 is to get exactly into the plane of the inner 3 moon's orbits. I did that cheaply by approaching Jool fairly close to that plane and then flying way out after my aerobraking pass. This way I was moving quite slowly when I crossed through the moon's plane and the plane-adjust was cheap. This is the strictest rule-any error in inclination will be multiplied by each flyby. I still had to do small plane corrections every now and then.

Rule #3- the first moon flyby is the most important. My first, long orbit around Jool went so far out that it was easy to adjust it so that I swung back in past Laythe's orbit at the right time to encounter Laythe. Once you have that first good encounter with Laythe the rest is searching for the simplest next encounter.

Rule #4- Never do one flyby without already knowing what the next flyby will be. The game's accuracy usually prevents you from seeing 3 flybys ahead, but if you keep in the right plane you can always see 2 flybys ahead. You may have to circle Jool several times between flybys, but you will note I never had to do more than 5 Jool orbits between flybys. Place dummy nodes if you have to to see the path after a future flyby. I never had to see more than 2 flybys ahead, the moons are close enough together that there is always something.

The rest are rules of thumb. Your Jool orbit ought never be such that it crosses less than 2 moon's orbits, or is entirely outside Tylo's orbit. Patience in looking for the next flyby. Sometimes I would be surprised by a better option that would pop up as I was carefully adjusting a flyby, it was good to search through a wide range before settling on the best path. Flying by the two outer moons is tricky, you have to do it where they cross the plane of the inner moon orbits, check out how I rotated the Jool-orbit apsis to do that.

Enough of my yakking. Good luck, and may the force (of gravity) be with you!