We're trying to understand the structure of a comet and also its composition. Once we hit it, we will open up surface areas that are exposed to the sunlight and see new subsurface ices for the first time.  -   Don Yeomans     Quotes
We're trying to understand the structure of a comet and also its composition. Once we hit it, we will open up surface areas that are exposed to the sunlight and see new subsurface ices for the first time. Don Yeomans
 Composition