Reports that the High Frequency Active Auroral Research Program (HAARP) had been shut down permanently were apparently a bit premature. According to HAARP program manager James Keeney, the facility is only temporarily off the air while operating contractors are changed. So why does anyone care? Despite being associated with various natural disasters over the past two decades by the conspiracy fringe, HAARP is in reality a facility for studying the ionosphere. Let's take a look at the goings on at HAARP – past, present, and future.

HAARP was established in 1993 by the US Air Force, the US Navy, DARPA, and the University of Alaska. Located outside of Gakona, Alaska, the facility houses a high frequency (HF) transmitter together with a phased-array antenna to focus and direct the radiated RF power. The transmitter is roughly as powerful as the largest military radars, generating up to 3.6 MW of RF power in the 2.8 to 10 MHz band. HAARP is restricted to operations only at specified frequencies in this band.

Power isn't everything

The power isn't what makes HAARP different. Rather, the credit for that goes to HAARP's phased array antenna. Consisting of 180 individual dipole antennas placed in a field roughly 13 hectares (33 acres) in size, this antenna array acts as a highly directional antenna, with a beamwidth of about five degrees. By the time the RF energy reaches the ionosphere (say, at an altitude of 200 km /124 mi just for this example), the size of the radiated spot is about 18 km (11 mi) in diameter, and the power density is roughly 14 mW/sq m. As the ionosphere is opaque in HAARP's frequency band, it absorbs nearly all of the incident power.

A tricky point, the misunderstanding of which has led to various HAARP conspiracy theories, is the difference between radiated power and effective radiated power. HAARP's radiated power, the amount of actual RF power it can emit, is 3.6 MW. However, because HAARP's antenna focuses the radiated power on a small portion of the ionosphere, the power density on that spot is much larger than would result if HAARP's antenna were non-directional so that its RF power were directed uniformly in all directions.

A fictional "effective radiated power" can be calculated, which is the power that would have to be sent through a non-directional antenna to provide HAARP's power density to the entire sky. This value is about 5.8 GW. The value is much larger than HAARP's actual RF power, as only 0.06 percent of the sky is illuminated by HAARP's antenna. But the effective radiated power appears in many conspiracy theories simply as a scary large number.

How big is the actual power density in HAARP's ionospheric spot? The total irradiance of the Sun's electromagnetic radiation (everything from x-rays to extremely low frequency (ELF) radio signals) is 1,360 W/sq m, measured by satellite outside the bulk of the Earth's atmosphere. HAARP's power density is about 0.001 percent of the Sun's irradiance – a nearly negligible quantity. Further, while local heating of the ionosphere is caused by HAARP (indeed, that is HAARP's purpose), the overall effect is rather like focusing the Sun's light using a magnifying glass – impressive if one is an ant, but not very significant on larger size scales.

HAARP is designed to test the response of a patch of the ionosphere at varying altitudes to the application of a few mW/sq m excitation in the high frequency (HF) radio band. One known effect is the generation of extremely low frequency (ELF) radio waves through modulated heating. By turning the HAARP array off and on (or more simply, by wiggling the focal point around in a repetitive pattern, a procedure known as geometric modulation), the local ionospheric temperature rises and falls, changing the conductivity in that portion of the ionosphere at whatever frequency corresponds to the pattern. The frequencies are typically in the vicinity of a few to a few hundred Hertz.

HAARP is located where large natural electrical currents flow through the atmosphere. This auroral electrojet flows from the position of the Sun at noon to the position of the Sun at midnight in the north and south polar regions of the ionosphere. The flowing currents circle the poles, rather than passing over them, and may be thought of as sheets of current with a typical current density of 1-2 amperes per meter.

Given HAARP's spot size of about 18 km, the heated region has passing through it a current of about 30 kA, depending on geomagnetic conditions. When the ionospheric conductivity changes from HAARP's transmissions, the current in and around the spot also changes its distribution. That makes the region near the spot an antenna that radiates ELF radio waves from the ionosphere. HAARP is not, however, an efficient source of ELF radiation – starting with 3.6 MW, the yield of ELF radio waves is less then 10 W.

What can you do with 10 W of ELF radio waves? Well, a typical ELF submarine communication system uses several megawatts of ELF RF power with a frequency of 70-90 Hz. This is directed into the surface of the Earth at points separated by about 50 km (31 mi) in order to use a large area of the Earth's crust as a transmitting antenna. Despite the huge power and massive antennas, the actual transmitted power of such a system is only a few watts. So one reason for HAARP's development was to prototype a (relatively) small ELF transmitter.

Magnetospheric wave injection

Another phenomenon studied by HAARP is called magnetospheric wave injection. While most of the ELF waves generated in the ionosphere by HAARP are directed down toward the Earth's surface, a small fraction leaks into the surrounding magnetosphere. In the inner magnetosphere, wave interactions are dominated by the Earth's static magnetic field.

Most study has been directed to a whistler-mode instability. Imagine you have a PA system with the volume turned up just short of the point when spontaneous feedback will occur. If you whisper into the microphone, you will hear your amplified whisper. However, immediately on speaking loudly into the microphone, your voice will be drowned out by feedback at the characteristic frequency of the PA system. The potential power output of the PA was always available, but requires a small push to tilt the system into runaway feedback. This behavior is rather like that of a whistler-mode instability.

Non-linear magnetospheric amplification of such waves can be caused by resonant interactions with energetic electrons. This being a non-linear interaction, one of the signatures is a change of the frequency of oscillation. The one-hop (Alaska to the South Pacific) and two-hop waves (back to Alaska) detected at the surface both show non-linear smearing of the wave frequency as well as amplification from the whistler-mode instability. It appears that the magnitude of the amplification has not been firmly established, but it is not enormous.

Ionospheric and magnetospheric structures and effects are the subject of ongoing study at HAARP, with a number of experiments being scheduled for later this year. Hints of interesting behavior have emerged, such as the possibility of generating ELF radio waves at times when the auroral electrojet has very little current, suggesting that interesting physics is yet to be discovered and understood.

Mind control and earthquakes

Getting back to the conspiracy theories for a moment, these come in a plethora of bizarre and unfounded varieties. To name just a few, HAARP is accused of triggering earthquakes by lifting the ionosphere over a tectonically active region, then letting it fall so that the pressure wave will trigger the earthquake. There are two problems with this. First, HAARP is pretty well limited to heating the ionosphere directly over its physical location. Second, a falling object can at best deliver the energy that went into lifting it. As we know that energy was delivered via a 3.6 MW RF beam, it seems incredibly unlikely that an earthquake could be triggered by turning off HAARP.

Mind control is also supposed to be within HAARP's capabilities. This would be accomplished by altering the 7.8 Hz Schumann resonance, which is the Earth's lowest frequency electromagnetic resonance. After stating as fact a totally evidence-free relationship between life itself and the Schumann resonance, one conspiracy theorist says that "1,700 billion watts" will apparently drive HAARP's mind-altering effect. That is a rather remarkable claim, as HAARP's maximum power is about one-five-hundred-thousandth of that amount. And don't forget the claim that HAARP caused Hurricane Sandy, triggered massive tornado activity, and brought down the Twin Towers on 9/11. Personally, I don't intend to lose much sleep over the dark side of HAARP.

According to HAARP program manager James Keeney, the "Defense Advanced Research Projects Agency (DARPA) is expected on site as a client to finish up some research in fall 2013 and winter 2014." The temporary shutdown was described as being due to "a contractor regime change." The Alaska Native corporation Ahtna, Incorporated is reportedly in talks to take over the facility administration contract from Marsh Creek, LLC. I am sure that the new operators will continue to keep us in touch with what really happens at HAARP.

Sources: American Radio Relay League, The Alaska Dispatch, and Magnetospheric Wave Injection by Modulated HF Heating of the Auroral Electrojet (PDF)