HAARP was the prototype (Hypothetical) of what is now the mature weapon system called American Association of Retired People (AARP).

No joke, AARP is a powerful lobbying force that will just about automatically enroll you when you reach 50 years of age. It is the quasi official notification that you are about to enter senior citizenry.
(WARNING: Acronym Diversion follows [not quite a thread hijack]): The two main problems with acronyms are too many groups share them, and too many groups don't sufficiently spell out what their acronym means. Even SAC sometimes represented things much different from the "Peace Is Our Profession" Strategic Air Command.
Acronyms can breed arrogance. Even in its internet home site, periodicals, mastheads, and advertisements, AARP is rarely spelled out. That's pretty brazen for an organization that sounds like a seal (arctic, not Easter). For example, the definition in the first sentence of this post is wrong.
AARP apparently stands for the Association of American Retired Persons. But don't bet on it unless somewhere it shows up in an official AARP site or publication. Good luck finding that.
When a search gets that frustrating, the result is often "Who cares?" Close enough.