25 years ago, on August 3, 1995, the implementation of the international scientific project “Interball” began. It was on this day that the launch of the first Interball-1 apparatus, developed and manufactured at NPO Lavochkin (today it is part of the State Corporation Roscosmos), took place. In fact, the satellite was a modernized version of the Prognoz series spacecraft (1972-1995), that is, while maintaining the structural and layout scheme, a number of onboard systems were replaced on the Interbol spacecraft in order to increase their resource, and improvements were made to significantly reduce electromagnetic and electrostatic interference.
The satellite’s orbit had an apogee of 200,000 km, a perigee of 500 km, and an inclination of 63. Such orbital parameters are optimal for studies of the solar wind, the tail of the Earth’s magnetosphere and the boundary layer of our planet’s magnetosphere. The main goal of the project was to study the physics of near-earth space and solar-earth connections. With the help of the Interball spacecraft, the world scientific community wanted to study the physical mechanisms responsible for the transfer of solar wind energy to the magnetosphere, its accumulation there and subsequent dissipation in the tail, in the ionosphere and in the upper atmosphere.
With the accumulation of experience in this area of space research, it became clear that further progress in the study of the relationships between various geophysical phenomena occurring in the magnetosphere can only be achieved using measurements from many satellites. Awareness of the importance of an integrated approach to the study of the above problems led the international scientific community to create an extensive research program, which peaked in the mid-90s and which is similar in scale to the International Geophysical Year.
One of the central places in this program was taken by the Interball project. Scientists from 20 countries directly participated in the scientific experiments of the Interball project and at the same time the project itself was one of the key elements of the international program for the study of solar-terrestrial relations. The coordination of work on this program was carried out under the leadership of the Space Research Advisory Group, which consisted of representatives of the space agencies of Russia, the USA, Europe and Japan.
In addition to the Interbol-1, -2 spacecraft, the system for researching solar-terrestrial relations included: the Japanese-American satellite (GEOTAIL), the American WIND satellite, the Russian-Ukrainian KORONAS-I and KORONAS-F, the European the American solar observatory SOHO, the American satellite POLAR, as well as the Magion-4 and Magion-5 subsatellites separated from the Interbol-1, -2 spacecraft (Czech Republic).
The first pair – the Interbol-1 satellite and the Magion-4 subsatellite – moved in an elongated elliptical orbit crossing the equatorial region of the magnetosphere tail at distances from the Earth of the order of several dozen Earth radii. This made it possible to study the process of interaction of the solar wind plasma with the outer shell of the magnetosphere and monitor the development of magnetic substorms. The distance between them varied during the flight from several hundred to several tens of thousands of kilometers, due to which it was possible to study both waves and plasma structures of short length, and large-scale phenomena.
The scientific equipment installed on the satellites of the “Interball” series was created in the framework of extensive scientific cooperation and included magnetometers, devices for measuring plasma waves and spectrometers of charged particles. Scientific institutes of a number of European countries, Canada and Cuba took part in the creation of the equipment. The Interball project became a part of the International Research Program on Solar-Terrestrial Physics and took its rightful place in the unique “constellation” of satellites operating in orbit at that time.
Scientific research was carried out both in communication sessions in the mode of direct transmission of information, and offline. The scientific equipment operated throughout the entire orbit, with the exception of the zone of the radiation belts, in which the devices of the plasma complex were turned off. The flight program of the spacecraft “Interbol-1” was successfully completed with a significant excess of the scope of the assigned tasks.
