Converting the Ionosphere into a Laboratory without Walls—Active Ionospheric Research with HAARP

Active ionospheric experimentation using high power HF transmitters has an enormous potential to explore a wide range of plasma science in the upper atmosphere, ionosphere, and magnetosphere. Distinct from conventional ionospheric remote sensing or in-situ measurement, active ionospheric “heating” temporarily modifies a small region overhead to observe how it relaxes back to its quiescent state. By modulating the HF frequency and amplitude, the ionosphere can be used as an antenna to generate low frequency waves (ULF, ELF, VLF, Whistler, etc.) and inject them into the earth-atmosphere waveguide or up along magnetic field lines into the magnetosphere. Selected frequencies of high power HF energy can create optical emissions and drive a wide array of plasma instabilities, irregularities and turbulence. Active heating facilities can address science and applications in radio science, mesosphere and thermosphere science, space weather, magnetospheric and radiation belt science. These facilities can be used to address a range of applications including communication and navigation, over-the-horizon radar, and radiation belt effects on space systems.

With a capability to radiate 3.6 MW net power, High frequency Active Auroral Research Program (HAARP) is the most powerful ionospheric heater in the world. It has the widest selectable frequency range: 2.8MHz to 10MHz and is constructed as a phased array to form multiple beams that can be modulated and steered rapidly for the desired application. HAARP has been used to create artificial airglow, artificial ionospheric layers, instabilities, irregularities and turbulence and a wide range of low frequency waves. The Geophysical Institute of the University of Alaska Fairbanks (UAF/GI) recently took ownership of HAARP from the Air Force Research Laboratory, restored the facility to operational status. This past February the UAF/GI carried out a campaign with multiple experiments and multiple sponsors. A follow-on campaign is planned for this fall. The status of HAARP and a summary of recent experiments will be presented.