Narrator: This is Science Today. To measure the melting point of iron at the Earth's core, physicists at the Lawrence Livermore National Laboratory used what's called a two-stage gas gun. Neil Holmes says these guns were originally built for Earth re-entry programs for satellites.
Holmes: They would actually use this to accelerate things that would look like a satellite and simulate re-entry by making a really long tank that had 500 thousand foot elevation air in it.
Narrator: The gun itself is about eighty feet long and housed in its own building. It launches an ice cube-sized projectile at a target, which consists of samples inside a chamber that can be looked at optically or on the computer.
Holmes: If you go through the Earth, you find you have a crust and then a mantle, which are silicates, not iron. It's the center of the Earth that's mostly iron. So what we can do is actually design the projectile to make a shock – to bring us right up to a point inside the core, then squeeze gently as if we were moving right to the center. And then we can, in the same experiment, move out again.
Narrator: For Science Today, I'm Larissa Branin.