Space Weather poster.
Aug 8, 2022
The forecast of "space weather" in the XXI century has ceased to be exotic. At least the author of these lines remembers well that a few years ago, in an interview on this topic, prominent scientists preferred to say that the issue still requires careful study. What now?
The expression “What has space weather prepared for us today?” has been in our lexicon ever since bad health was associated with geomagnetic storms and solar activity. However, the degree of influence of these phenomena on human health is still a matter of debate. At the same time, it is difficult to deny that power outages, failures in the operation of oil and gas pipelines resulting from a global space storm have a negative impact on all of us. Keeping track of space weather becomes vital. And the key role in observations belongs to the ionosphere.
A hundred years ago it was known that the Earth is surrounded not only by an air atmosphere, but also by a shell consisting of a mixture of neutral and ionized (charged) particles - electrons and ions. Thanks to her, in particular, radio communication became possible. This shell is called the "ionosphere".
The ionosphere is located at an altitude of about 60 km to 2000 km and has a complex structure. It is customary to divide it into several layers, which differ in plasma concentration and features of its behavior. The ionosphere "sensitively" reacts to various changes in the geomagnetic field, which, in turn, changes under the influence of solar activity. Therefore, the boundaries of the ionospheric layers either rise or fall, and the entire ionosphere, as it were, “breathes”.
Most of the electric currents resulting from increased solar and geomagnetic activity close in the ionosphere. Therefore, it can be called a natural laboratory for monitoring near-Earth space. If we know the state of the ionosphere, that is, the main parameters of space plasma - the concentration of particles, their composition and temperature, the parameters of electromagnetic fields and wave radiation in its different areas, then we can judge what is happening around the Earth.
However, "getting" to the ionosphere is very difficult. In fact, this can only be done from the board of an artificial Earth satellite. But if we take measurements only in orbit, then we will get data only from a fixed height, and one can only guess about what happens above and below it. It is necessary to create an instrument capable of sounding the ionosphere at different heights and presenting the results in the form of an altitude profile, that is, in other words, a graph showing the electron density as a function of altitude. Such a device exists, and it is called "ionosonde".
Ionosondes: From Earth to Space
The ionosonde emits short radio pulses in a wide frequency range and then registers the reflected signals from the ionosphere. Reflection occurs at the point at which the frequency of the probing radio pulse is in resonance with the oscillations of free electrons. The frequency of these oscillations depends on the concentration of electrons at a given height. By measuring the duration of the delay between the time of pulse emission and the moment of arrival of the reflected signal, one can determine the reflection height, and from the frequency of the reflected pulse, the electron concentration at this height.
The first ionosondes were ground-based. The creators of the technology and the first ionosonde were American scientists Gregory Bright and Anthony Tuve (in 1925). They conducted the first experiments of sounding the ionosphere from the Earth's surface in the 30s of the XX century.
Today, there is a global network of ionosondes all over the Earth, the data of which is processed by the corresponding geophysical services. Thus, in Russia, a network of 16 ionosondes is currently operating in the state observation network subordinate to Roshydromet. There is a similar network in the system of the Russian Academy of Sciences.
But ground-based ionosondes are stationary and therefore do not provide information about the entire ionosphere. Russia, for example, does not have ionosondes that would be located in the Southern Hemisphere and in the ocean areas. In addition, their capabilities are limited: being on the Earth, the ionosonde can receive information only about the lower part of the ionosphere, up to a height of 250–400 km. Therefore, it is quite natural that with the beginning of the space age, scientists wanted to put these devices into orbit.
Ionosphere
The first "Lark" (this is how the name of the device is translated from the French) was the Canadian-American satellite Alouette. It has been developed since 1958 and launched in September 1962.
Canadian-American satellite Alouette
In the USSR, the first ionosonde was installed on the Kosmos-381 satellite (1970), and then on the Interkosmos-19 satellite (1979). Interkosmos-19 became the first integrated laboratory not only in the country, but also in the world. In addition to the ionosonde, it was equipped with instruments for measuring the parameters of electromagnetic fields and particles. The device worked for more than three years and gave a lot of scientific information.
Kosmos-381 satellite
Further, in 1987, the Cosmos-1809 satellite was launched. It was a copy of Interkosmos-19, but with a slightly modified set of instruments. "Kosmos-1809" was supposed to be the first device of a new satellite constellation for systematic monitoring of the ionosphere. The observation program was drawn up in the interests of not only the Academy of Sciences, but also the State Committee for Hydrometeorology and Environmental Control (Goskomgidromet) of the USSR.
Interkosmos-19 satellite
The need to monitor the "space weather" was understood even then, but, unfortunately, the main instrument of the satellite - the ionosonde - did not work as long as we would like. The rest of the instruments operated successfully for six years, and rich material was obtained on the local parameters of the ionospheric plasma.
In the 1990s, it was not possible to create a satellite constellation for monitoring the ionosphere for a number of reasons, mainly economic ones. True, in 1998-1999, scientific experiments were carried out to study the ionosphere with the help of an ionospheric station installed on the Nature module of the Mir orbital complex. She also gave a lot of scientific results, including because it was somewhat different from what was done on satellites.
The experiment on radio sounding from the Mir orbital complex is referred to as internal sounding of the ionosphere. The fact is that the station's orbit passed at altitudes in the range from 330 km to 380 km and in many areas, especially at low latitudes, was below the height of the maximum electron density. The orbits of the satellites were higher.
Four "Ionospheres" and one "Probe"
So, in the 1980s and 1990s, it was not possible to create a full-fledged system for monitoring "space weather" in our country. But the need for it remains and, moreover, has become even more urgent. The consequences of the vagaries of "space weather" can be unpredictable, first of all, for the technical infrastructure and for spacecraft, on which we are increasingly dependent. And in Russia, whose territory is located at high latitudes, these phenomena can be especially noticeable.
The space project "Ionozond-2025" is included in the Federal Space Program for 2016-2025. The main customers are the Russian Federal Service for Hydrometeorology and Environmental Monitoring and the Russian Academy of Sciences. The head organizations for the complex of scientific equipment are the Institute of Applied Geophysics named after E. K. Fedorov of Roshydromet and the Space Research Institute of the Russian Academy of Sciences.
The first Russian Ionosphere satellites will go into space in 2023
The project is designed to solve both scientific and applied problems. Researchers hope to gain new knowledge about the Earth's ionosphere, where there are still many unresolved issues. For practitioners, this is the first step towards the creation of a satellite geophysical service for continuous monitoring of near-Earth space.
It is assumed that the Ionozond satellite constellation will consist of four identical Ionosphere-M devices designed for sounding and monitoring the ionosphere. The system will be supplemented by a fifth satellite, Zond-M, designed to observe the Sun.
Spacecraft are created by VNIIEM Corporation. Scientific equipment is being developed in Russian research institutes.
All four satellites will be put into circular orbits with a height of about 820 km. The orbits will be sun-synchronous: the measurements are “tied” to certain sectors of local time. It is planned to use two planes: the satellites will be launched in pairs with subsequent separation by 180° along the meridian, which will double the longitudinal resolution of the measurements.
Zond-M
A sun-synchronous orbit is a circle around the Earth with such parameters that an object located on it passes over any point on the earth's surface at the same local time. Thus, the angle of illumination of the earth's surface will be approximately the same on all satellite passes. Such constant lighting conditions are suitable for devices that observe the earth's surface, meteorological satellites.
The first two Ionosphere-M vehicles to go into space in 2023 from the Vostochny cosmodrome. In a few years, the constellation is planned to be supplemented with a second pair and the Zond-M satellite.
Eight scientific instruments are installed on each Ionosphere-M spacecraft of the first pair. The satellites of the second pair will already have ten instruments each.
The main scientific instrument is the LAERT ionosonde. It will "enlighten" the ionosphere, and according to its data, vertical profiles of the electron concentration will be built. Other instruments will measure the fluxes of energetic particles, their spatial and energy distributions. To measure electromagnetic fields and radiation, it is planned to use the NVK2 low-frequency wave complex and the LAERT ionosonde in the radio spectrometer mode.
Zond-M
The data from the Ionosonde project are intended to be used together with information from ground-based observations. It will also be possible to carry out ground-space experiments, studying the response of the ionosphere to the influence "from below" in the form of hurricanes, volcanic eruptions, dust storms and earthquakes.
You can see what the Ionosphere-M looks like at the exhibition at the IKI RAS. A full-size model of the spacecraft was created with a grant from the Foundation for the Promotion of Small Innovative Enterprises in the Scientific and Technical Sphere, and today it has become one of the key exhibits for excursions that tell about space weather in general and methods for studying it. Open days at IKI RAS are held every year in April and October.
This article was published in the journal "Russian Space".
Related links:
Russian Space: https://www.roscosmos.ru/tag/russkiy-kosmos/
ROSCOSMOS Press Release: https://www.roscosmos.ru/38060/
IKI RAS: https://www.roscosmos.ru/tag/iki-ran/
Ionosphere: https://www.roscosmos.ru/tag/ionosfera/
Images, Text, Credits: ROSCOSMOS/Orbiter.ch Aerospace/Roland Berga.
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