Ionospheric effects from rocket launches against the background of geospace storms

Ionospheric effects accompanying launches and maneuvering system thruster firings of large rockets have been studied for about 60 years. Fairly complete and adequate models of generation and propagation of disturbances, which are caused by launches and maneuvering system thruster firings of large rockets in the Earth–atmosphere–ionosphere–magnetosphere (EAIM) system, are absent at present. It turns out a number of physical effects during ionospheric storms and rocket launches are similar. Therefore, the presence of ionospheric storm significantly complicates the search for the ionospheric response to the spacecraft launches. The aim of this study is to describe the results of observation of the ionospheric processes that accompanied rocket launches and maneuvering system thruster firings against the background of ionospheric storms. To analyze the measurements, observational data of the state of the ionosphere before, at the time, and after Soyuz and Proton rocket launches from the Baikonur cosmodrome (the Republic of Kazakhstan) were used. Observations were made at the Radiophysical Observatory of V. N. Karazin Kharkiv National University (near Kharkiv city, Ukraine). The Doppler vertical sounding radar was used for the measurements. Observations were made during solar cycle 24 (2009—2021). The number of the Soyuz rocket launches is 81, and 53 launches of the Proton rocket. Identification of the ionospheric response to the launch and maneuvering system thruster firings of a large rocket 2000 km away from the observation site against the background of a geospace storm by the Doppler method is usually possible at Kpmax   5, and at its larger values is very complicated or even impossible. In a number of cases, even though Kpmax = 4 the determination of the ionospheric response is complicated. To increase the detection reliability of the response to the launch and maneuvering system thruster firings of the rocket, the Doppler radar has to operate on a number of frequencies in the frequency range from 1.5...2 to 4…6 MHz. The existence of several groups of horizontal apparent speeds of disturbance propagation is confirmed: 1.7...3 km and more, 700...1000, 300...700, 150...260 m/s.