The High Frequency Active Auroral Research Program (HAARP) is an ionospheric research program jointly funded by the US Air Force, the US Navy, the University of Alaska and the Defense Advanced Research Projects Agency (DARPA). Its purpose is to analyze the ionosphere and investigate the potential for developing ionospheric enhancement technology for radio communications and surveillance purposes (such as missile detection). The HAARP program operates a major Arctic facility, known as the HAARP Research Station, on an Air Force owned site near Gakona, Alaska.
The most prominent instrument at the HAARP Station is the Ionospheric Research Instrument (IRI), a high power radio frequency transmitter facility operating in the high frequency (HF) band. The IRI is used to temporarily excite a limited area of the ionosphere. Other instruments, such as a VHF and a UHF radar, a fluxgate magnetometer, a digisonde and an induction magnetometer, are used to study the physical processes that occur in the excited region.