Hope they remembered to convert from centimeters to inches.
I remember scientists' concern years ago with "life" contained within comets and asteroids - perhaps only bacteria, perhaps more, but to arbitrarily slam a projectile into an unknown entity wouldn't have been proper in those days. It's like a boy shooting a cat in the head to "see" what will happen." NASA's justifications are usually scripted long before costly project proposals are submitted to the wounded taxpayer. I'm surprised that a "it's for the kids" reason wasn't tested for public acceptability on this comet game.