The whole spacecraft is about six foot tall. It's making all kinds of measurements. In fact, one of the most important things it will be doing is trying to figure out if the asteroid Eros is made up of material that's been around basically since before even the earth formed, from the very beginning of the solar system. And so we're taking measurements that will tell us whether this material has undergone the main process of planet formation. So, that's the process in which the planet inside gets hot enough to melt.
Different liquids separate out.
So that it's very similar to what happens in your salad. Your oil and your water don't mix together. They separate out. The same thing happens when you have a planet. Inside it's warm enough to melt the rock.