ИСТИНА

A concept for a new type of active experiment for recording ULF-ELF-VLF signals from extended ground antennas, both on a network of ground stations and on low-orbit satellites, is presented. Transmission lines temporarily down for repairs in the Murmansk region will serve as the radiating dipoles. Under a program coordinated with satellite overflights, a powerful generator will supply current to the antenna at night at frequencies ranging from fractions of a Hz to a few hundred Hz, with the potential to extend the frequency range to 5 kHz on shorter lines (similar FENICS experiments were previously conducted in the Murmansk region). The feasibility of the satellite-ground experiment is supported by a numerical model for calculating the electromagnetic response in the ionosphere from a grounded linear current of finite length L above a high-resistance Earth surface. The simulated response amplitudes of the FENICS array (L = 100 km), generating a 100 A current with a frequency of 10-100 Hz, in the nighttime ionosphere can reach magnitudes up to ~60-70 μV/m. FENICS experiments on generating ULF-ELF signals were conducted using two deactivated orthogonal power transmission lines as horizontal radiating antennas. The generator frequency varied from session to session from ~1 Hz to ~200 Hz. ULF (<10 Hz) and ELF (>10 Hz) signals were reliably recorded at stations located at a distance of up to ~2000 km from the transmission lines. Theoretical estimates using a numerical model of the ULF/ELF field in the atmosphere and ionosphere created by a linear near-ground current were in good agreement with observations. The obtained results demonstrated the potential of this type of active experiments for conducting magnetotelluric sounding over a large area using artificial ULF-ELF signals. The effectiveness of horizontal mega-antennas for ionospheric sounding was demonstrated by the successful recording of ZEVS transmitter radiation with a carrier frequency of 82 Hz on the DEMETER, CSES-1, and Ionosfera-M satellites. Ionosfera-M No. 3 (orbit altitude of ~820 km) and CSES-1 (~500 km) satellites, during flights over the Kola Peninsula, recorded ZEVS transmitter radiation with amplitudes up to |E| ≈ 7 μV/m, |B| ≈ 3 pT at distances of up to ~1000 km from the source along the Earth's surface. It turned out that the ZEVS signal decays in the ionosphere rather slowly with distance, following a ρ^(-S) power law with an exponent of S~1.7±0.8, and illuminates a large region of the ionosphere. Satellite and ground-based observations and the accumulated experience of the FENICS experiments demonstrate the potential of a new type of active experiment for influencing near-Earth plasma with artificial signals and stimulating the precipitation of relativistic electrons from the radiation belts to a level safe for satellite electronics.