Oh, you also asked how to get out of Jupiter.
I haven't much fuel left (I didn't take into account the return part), but I could still make it.
To get out of Jupiter once in Europa's orbit, the most direct method (injection burn from Europa, directly onto a transfer trajectory to Earth) is also the most inefficient
It will literally cost you tons of fuel if you do that.
A more subtle way is by using the Oberth effect from Jupiter. First I set Jupiter as a target, and burn so that I'm on such a trajectory:
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Then, once I reach the periapsis above Jupiter, I burn enough to quit the Jovian system:
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The problem is that you have to anticipate, as your trajectory must be correctly oriented in the end.
That maneuver is more efficient, but from Europa it still costs a lot (I had to use infinite fuel to be honest).
There's an even more efficient trajectory, but that also requires more anticipation: the bi-elliptic transfer.
From Europa orbit, put your ship on a highly elliptical trajectory:
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To know when you should burn, you can select Jupiter as a target, and burn prograde when your ship is at the opposite of the transfer window.
Then once you reach the apoapsis, lower your periapsis to Jupiter level:
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And once you're at the periapsis, burn to quit the jovian system, until you cross the Earth's trajectory:
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That last burn is very cheap.
Globally, it's significantly more efficient: I didn't have to use infinite fuel this time, and I even have a reserve left.