Trip to Jool. How to hit two birds with one stone.

[Motokid600]

well..two stones I should rather say. Im currently developing a land and return home trip out to Jool. In this mission I actually want to do three things. I want to dive a small probe into Jool and I want to land another small probe on Vall. Then the heart of the mission is the manned landing on Laythe where a two man crew will explore with a rover then return back to orbit to dock with the return stage. But so far all I have built is the lander.

What I want to know is what is the most efficient way possible to hit the two moons? My priority is Laythe. But for when it comes to my Vall probe exactly when is the best time to unlatch the probe from the ship and have it course correct for a Vall intercept? Before I enter Jools SoI? after the areobrake? Moon to moon transfer? The Jool suicide probe is a no brainer, but this one may be tricky. Also.. roughly how large of a probe will this have to be in order to do the job? The Dv map seems to be hit or miss id like some personal experiences if at all possible.

Edited July 29, 2013 by Motokid600

[stupid_chris]

Alright, that's how I'd do it:

When you enter Jool's SOI, set your PE to aerobrake so that you end up with an orbit that goes just a bit further out than Laythe's After that, decouple the Jool impactor then Rasie the main ship's PE above Jool's atmosphere. Then switch to the impactor, time warp until it comes back around and into the atmosphere and watch it flam it's way down. Step one is done.

Go back to the main ship and plan a Hohmann transfer to Vall, that shouldn't take you too much delta V once you enter Laythe's SOI, set your periapsis so that the gravity slingshot would send you just past Vall's orbit. Decouple the Vall probe then, and then lower your main ship's periapsis for your aerobrake. Do that and adjust the orbit, and by then the Vall probe should be zooming past Laythe and should be on it's way out of the SOI. Then, just plan another Hohmann transfer, and you know the rest.

[Motokid600]

Well you just planned out my whole mission sir lol. Thanks that was exactly was I was looking for.

[stupid_chris]

No problem, always glad to help!

[maccollo]

I always go for a tylo intercept instead of aerobraking on Jool, since doing so correctly can send you anywhere within the Jool system with far more retained energy than an aerocapture.

It take a little more preparation to intercept on the right side of Jool than doing an aerobrake, but once you got that set you have absolute control over where you want to go with almost no additional delta V needed, and with no uncertainty like you get with an aerocapture. At this point you can detach everything and no micro adjustments to get them wherever you want them to go.

Edited July 29, 2013 by maccollo

[Motokid600]

Wouldnt the Tylo intercept cost to much Dv as opposed to just letting atmosphere do it? Also.. would it be possible to just aerobrake right through Laythe's atmosphere? And then what would it take for a craft to jump from the orbit of Laythe to Vall?

[stupid_chris]

You could Aerobrake at Laythe, but it would likely take more delta V to do so. The only delta V required above is adjusting your intercept, and fiddling with your PE for aerobrake concerns. If you were to Aerobrake at Laythe, you'd have to get the other craft to reach Laythe escape velocity.

[Jean Deaux]

Sounds like rocket science to me...