"Segmentation fault" -> That is not nice at all.
This happens when the program attempts to access forbidden memory addresses (like address 0 or addresses that do not exist). It is a bug. It looks like it has already been reported and confirmed by Ubuntu users... but nobody apparently works on it. Trisquel is based on Ubuntu but has not the manpower to fix bugs that are not Trisquel specific.
If I were you, I would try to install Stellarium 11.2 from this PPA and see if it better works.
If it crashes too, you can try to install Quantal's Stellarium 11.3. It is not guaranteed to install at all (it may rely on newer versions of some libraries).
