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U.S. Plan to Protect Satellites Could Knock Out HF Communications

RF Report has described the danger to orbiting satellites from coronal mass ejections from the sun and geomagnetic storms in previous articles. High altitude nuclear explosions (HANEs) have also been found to cause satellite failures. The operational lifetime of orbiting satellites is shortened when high-energy electrons are trapped in the earth's Van Allen radiation belt. As the number of satellite orbiting the earth has increased, so have efforts to protect them from HANEs and unusual natural events such as large geomagnetic storms. These efforts, referred to as Radiation Belt Remediation (RBR), work by precipitating high-energy electrons from the natural or HANE-induced radiation belts into the upper atmosphere.

One of the proposed RBR techniques would probably involve use of a constellation of approximately 10 satellites transmitting very low frequency (VLF) waves to dump electrons from the HANE-induced radiation belt. However, this intense energized particle precipitation would lead to large ionization changes in the ionosphere, disrupting HF communications.

The effect of RBR systems on the atmosphere and HF communications is outlined in the paper The atmospheric implications of radiation belt remediation by C.J. Rodger and his team at the Department of Physics, University of Otago, Dunedin, New Zealand. The paper contains detailed models of atmospheric and HF propagation changes from both satellite and ground based RBR systems using VLF transmitter. Charts also show the effects of varying the duration of the VLF transmissions.

Obviously there is great interest in protecting satellites, especially those used for strategic communications and navigation. Since HF communications are used for long-range communication with aircraft and also to link many isolated communities in the Pacific, disrupting HF communications for several days could also cause problems. The paper discusses the trade offs between the length and nature of RBR operations and disruption of HF communications.