Given current capabilities, is it possible for a missile launched from the surface of the Earth to impact the surface of the Moon?
I would imagine the same "rocket" used send stuff to the ISS could be redeployed (adding explosive, etc). All you really might need is for something to escape Earth safely.
Context: Humans are expected to establish bases on the moon at some point. Just like air defense systems on Earth, you might expect any base at the moon to have similar defense systems, particularly given the obvious vulnerabilities that a moon base would imply (costly, isolated, limited supplied, etc).