The Illustrated Guide to Criminal Law
Chapter 9: At Least You Tried
Attempt pg 22: Impossibility Defense

One other thing: Remember Joe?

Old-timey voodoo doctor waving “come back soon,y’hear?” while Joe sticks pins in an effigy.

He tried to kill Simon by sticking pins in a voodoo doll. Is he guilty of attempt?

He had the right mens rea, and he certainly took steps to carry out his intent. But there is no way his action could conceivably work.

It’s IMPOSSIBLE.

So no, he’s not guilty of attempt. He has the defense of impossibility.