Comets are thought to be icy dirtballs made up of exotic ices, dust, and rock particles.
The rocky and rough surface of the asteroid was surprising. The 16-minute light travel time between Earth and the spacecraft makes real-time communications very difficult.
The mission is to understand what a comet is made of and how it's put together.
It was assumed that, after the Late Heavy Bombardment let up, comet impacts which were then 1,000 times more numerous than today delivered Earth's water.
There's a few nervous people, to be sure. There's a lot of things that could go wrong.
Ten years ago, we would have been blissfully ignorant.
The field of planetary science is currently enjoying an intense period of readjustment and discovery.
The beauty of comets is that they are important to us. We probably would not be here were it not for comets. Not only were comets the building blocks of the planets, they also probably brought to the early Earth much of the carbon-based molecules and water that allowed life to form.
The beauty of this mission is that we don't know what to expect. But whatever happens, we'll learn something.
Presidential Quotes: Iconic Quotes from United States Presidents