Not to get off-topic here, but, If you think Hubble is for spying, then you are more misguided than I thought. :facepalm:
My friend works for the Space Telescope Institute, in Baltimore, and they are the ones who control hubble. He, along with his colleagues use hubble for space research, not spying. I've been there myself.
Now if they find life on another planet, then it may remain top-secret until the President gives the OK to release that type of information to the public.
Besides, If hubble were to look at the earth, it would just be a huge blur because it was not designed for close pictures like that. :)