Re: #DJO
It just has to be below the melting point of iron/nickel (with a pinch of sulfur to taste) under god-almighty pressure to kill the magnetic field. That could mean there is enough heat coming up through the Mantle to allow partial melting and volcanism. But without knowing how much heat is radiating out and how much water is slopping round in the Mantle, its very hard to work out just how much melting could take place.
NASA's next lander, InSight which will fly in 2018 is equipped with a drill and heat flow probe which will give us some idea of the former. It'll also have a seismometer which might mean we can get a glimpse of the planet's interior structure and its state - provided we are lucky enough to either experience a big 'quake or something from the asteroid belt the size of a large house decides to become friends with the Martian surface.
Biting the hand that feeds IT
