## 2 Astrophysical Conditions  
The universe has a diameter of approximately 93 billion light-years [14]. It contains around 2 trillion galaxies [15], while only our galaxy consists of about 300 billion stars [16]. However, the term space, as used in the title of this paper, will have a much more down-to-Earth meaning. When discussing the space economy, even in the most optimistic forecasts, it will certainly not extend beyond our planetary system in the coming decades (a diameter of about 9 billion kilometers or around 500 light minutes) [17]. In practice, however, the bulk of current human activity in space does not exceed the limit of geostationary orbit, i.e., 35,786 km from the equator (a diameter of 0.24 light seconds). From a geocentric perspective, it can be conventionally assumed that space begins 100 km above our planet's surface. This altitude is the so-called Karman line [15,18]. From the perspective of the whole, the dynamics of the solar system \"is governed mainly by gravity\" [17] (p. 19). In the second place, however less important, are electromagnetic forces [17]. These forces determine any activity in space; thus, let us look at both of them. The pull of gravity could be visualized by the concept of a gravity well. Anything on Earth (or other celestial bodies) is considered to be at the bottom of such a well, and escaping it requires enough energy to achieve escape velocity. The vast majority of economic activity in space is based on satellites. The movement of a satellite can be imagined as its continuous descent toward the center of the Earth while moving parallel to its surface. As a result, the satellite's trajectory curves. If the speed of this parallel motion is properly selected, this trajectory will be a closed curve, that is, an orbit. The satellite will orbit around the Earth, constantly falling towards it but never hitting its surface. A satellite having reached a given orbit needs no further propulsion. On the other hand, this principle also applies to space junk, which tends to accumulate over time. If the velocity is even higher, the object's trajectory opens up and follows the hyperbolic shape [19]. From the economic activity point of view, the most important is the following classification of the Earth's orbits:  
* Low Earth Orbits (LEOs);
* Medium Earth Orbits (MEOs);
* Geostationary Orbit (GEO). The delineations between the above categories are conventional (except for GEO) and thus fuzzy and vary depending on the literature source. The space starts at 100 km above the Earth's surface (Karman line), while the maximum value of the upper limit of LEO is 2000 km. However, most LEOs will be between 500 and 1000 km in practice. The problem with orbits below 500 km is their low longevity due to the effects of the residual atmosphere in the lower reaches of space, which has an inhibitory effect leading to deorbiting satellites or forcing the use of correction maneuvers (this is disadvantageous due to the propulsion needed, which is costly itself and increases the weight of the satellite and thus the cost of its launch). The problem with orbits higher than about 1000 km, on the other hand, is the inner van Allen belts with their radiative effects. LEOs are characterized by the highest satellite velocity and thus shortened period time (around one and a half hours) [10,20,21]. The altitude range of Medium Earth Orbits (MEOs) is from about 2000 km up to 35,786 km. They are characterized by lower satellite velocity and thus longer periods (from a few to nearly twenty-four hours). While the residual atmosphere ceases to be a problem in MEO, it is undoubtedly the radiation associated with the Van Allen belts. The inner belt extends from about 1000 to 12,000 km (the highest density is about 3000 km), while the outer belt extends from about 13,000 to as much as 60,000 km, while its highest density is at altitudes between 15,000 and 20,000 km. Therefore, the most commonly used range of MEOs is between the inner and outer Van Allen belts, i.e., between 8000 and12,000 km.