We believe they hold the most primitive materials in the solar system and that they played a role in shaping some of the planets, but we really have more ideas about comets than facts.

We did this mission to collect the most primitive materials we could in the solar system. We went to a comet that formed at the edge of the solar system, far from the sun under very cold conditions. We're confident that it was made out of the initial building blocks of our solar system.

They are primitive un-evolved bodies, so by studying these bodies we can learn more about how the solar system came to be in a way that's not otherwise possible.

When we see comets up in the sky they're really spectacular. But unless you get close to a comet, you can't really figure out what's going on.

The damn thing is layered like a frozen onion.

For example, some boulders seem to have just disintegrated on the surface. We've also seen that some of the fine surface material moves downhill, filling low areas and creating flat surfaces in craters, even with Eros' low gravity. These are big puzzles and we need to get a better look.