Pretty good movie, I think. Not sure if it was direct-to-DVD but I first saw it in the bargain bin. Wondered why I never heard of it (so it seems to me that it wasn't all that popular)
But on not knowing what's in the mantle... what exactly do they think they will find that's different from the lava flows of any active volcano? What happens if/when they get close enough that the magma pressure bursts through on its own, destroying whatever tool(s) they think they will be drilling into it with? Is their goal to make a man-made volcano?
I will be the last person to die in my lifetime.