Even though I have 15,000 excess science.. it's not enough.  I found I had not yet landed on any of the Jool moons.   Bad Kerbals!   So, i decided I would take a lab with me, and make a single lander that can hit all the moons except Laythe (requires a specialized design).   Tylo being the biggest challenge, because of its very high gravity/size, it's like landing on Kerbin without an atmosphere.    So I designed a lander with some jettisonable fuel, with the idea I would go to Tylo FI