Originally Posted by HenrikOlsen

If I remember right, the idea was to fuse part of Jupiters hydrogen all the way to iron then let it settle in the core.
Since this would increase the density of the core, it would bring the pressure near the center high enough to start fusion.

I have no idea whether this would actually work to bring the pressute high enough, but it's a lot more plausible that having Galileo trigger anything.