Going to the outer planets

[G'th]

So, I've been making preparations to finally start visiting some of the planets I've never actually sent anything too legitimately, and my first attempt I want to actually be a Voyager 1 esque mission (using the Voyager from the Real Probes mod no less ).

Now, my question is to get that key transfer from Jool to Sarnus. Now the easiest way would be to just wait until they're aligned right so that you can send the probe and just let it go. However, if what I've been reading in various places is correct, then I should be able to just use Jool to fling me over to Sarnus regardless right?

(also, though I know I shouldn't because i'm making it that much harder on myself, I'll also be using remote tech for this)

[viktor19]

While Jool is pretty heavy, which means it can bend your trajectory a lot, I still recommend finding that chart which shows alignment of planets.

Even better would be if you downloaded Trajectory optimization tool, it has Multiple flyby maneuver sequencer which comes pretty handy. You'll just need to create a new bodies database from your KSP

[FungusForge]

I think the hardest part about hitting both (although I know nothing about Sarnus, the only mod world I use ATM is Arkas) is that you need to wait for a Kerbin-Jool transfer that will have a kinda close Jool-Sarnus transfer when you get there. Otherwise you'll need a lot more Delta V or end up waiting much longer than needed. This is just my experience with planets in general, I've never actually attempted to go from Kerbin to a slingshot fly-by of a second planet to end up at a third planet.

[cantab]

Unless you want to go round the Sun several times you can't just do such a mission at any time, there will be limits. Since it just did flybys Voyager 1 wasn't using fuel-efficient Hohmann transfers, but "express" ones with a solar apoapsis way beyond the target planet. I'm not really sure how to work them out yourself.

[Motokid600]

I just did direct ejections to Sarnus and Urlum. Not all that more expensive then Jool. The challenge for me was with TACLS. It's a 18 year round trip to Urlum.

[MaxwellsDemon]

That's the catch with the "Grand Tour" alignments like the ones the Voyagers exploited. They're rare, and we were fortunate to be able to exploit the one that occurred in the 1970s-80s. Similarly, the New Horizons probe was fortunate in taking advantage of a time when Pluto is near the ecliptic. The lucky break isn't something you can always count on...

[PLAD]

I've been studying Kerbin-Jool-Sarnus paths as part of testing my Flyby Finder program, which I just recently upgraded to include the OPM planets. I've made a little summary below.

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I found that you can go K-J-S during every single K-J window (these repeat on average every 467 Kdays, the Kerbin-Jool synodic period) but that the KJS windows are only fast for a few times every 8132 Kdays (the Jool-Sarnus synodic period). I throw a K-J-S-U chart in there, it gets much more complicated with three planets but fast windows are there. I Haven't found a good K-J-S-U-N window yet, either Neidon or Urlum is in a bad spot when the other planets are good, at least during the first 30 Kyears or so that I've looked in. As someone noted, in our Solar System the outer 4 gas giants repeat positions roughly every 179 years (very roughly, after a couple of repeats Uranus gets too far out of place) so you might have to search a similar period in KSP.

Edited September 30, 2015 by PLAD

[xtoro]

I haven't had luck finding a window like that so far and just go straight for Sarnus. It takes long enough to get there, I couldn't imagine how long it would take with an entire orbit around the sun on the way there! And I'm not patient enough to time warp that far just for a window like that to pop up

[Snark]

The dV to get to Sarnus directly isn't that much higher than the dV needed to go directly to Jool.

Where a Jool slingshot can make a difference is in reducing the Sarnus-relative velocity at arrival time-- i.e. in theory, a well-executed Jool slingshot ought to mean less braking to do at Sarnus.

That said, it'll be very challenging to pull off, and the opportunities will be few and far between. In my own game I never bothered with trying this, just ejected straight to Sarnus.

[Richmountain112]

On 9/30/2015 at 8:35 AM, Motokid600 said:

I just did direct ejections to Sarnus and Urlum. Not all that more expensive then Jool. The challenge for me was with TACLS. It's a 18 year round trip to Urlum.

Tried doing a direct injection to there and back, but aerobraking often causes my craft to explode during  the return to Kerbin.

[Motokid600]

Well this is a blast from the past. XD. I suppose I could say dont aerobrake coming home. You need to burn engines. Going from outer system to inner system is ALOT of energy. You're diving down the gravity well. Aerobraking is nice when going from inner to outer on destination arrival because its the opposite. If you're going to gas giants and their moons you should consider a refueling plan so you can burn out and burn in.

Edited November 5, 2022 by Motokid600

[king of nowhere]

alternatively, you could aim for duna and aerobrake there; duna is a lot more forgiving on aerobraking due to its lower gravity, so you may be able to survive. of course, then you need to go from duna to kerbin. fairly cheap if you have some fuel left, but not feasible if you discarded all the ship to keep only the reentry pod.

Aiming for eve and using its gravity assist to go to kerbin at a lower speed is also possible

Edited November 5, 2022 by king of nowhere

[Richmountain112]

Now I know to stack more heat shields when going to the Outer Planets. Does that even work?

Edited November 5, 2022 by Richmountain112

[king of nowhere]

3 hours ago, Richmountain112 said:

Now I know to stack more heat shields when going to the Outer Planets. Does that even work?

it works partially.

but really, you don't need to stack heat shields. a properly made reentry pod still works. i reentered safely at up to 9 km/s with nothing but a pod and a thermal shield.

[Richmountain112]

Cool.