Bone
If you have a mustache and you hit your forehead on the moon, you’re probably going to break a bone. Ok, so it doesn’t matter so much if you have a mustache, but if you’re travelling fast enough to make it to the moon, you’re definitely breaking a bone if you run into it.
Imagine the force and mass of the moon hitting you right in the boney part of your forehead. Whomp! It sure would hurt.
こつ
ほね
None
Outer space is cold, and if you're traveling to the moon, you're going to need a lot of coats (こつ). All of these coats will keep you warm, even if you do end up breaking your forehead bone.
Again, feel your bones crack as you smash into the moon. At least you're warm though. Feel the cozy coats you're wearing and snuggle up in their warmth.