Existing space monitoring systems usually consist of Earth remote sensing spacecraft that operate in low orbits and provide consumers with high-resolution information about ground objects. However, the work of spacecraft in low earth orbit is characterized by such negative factors as a high rate of change of the parameters of the working orbit due to atmospheric effects and other perturbations, constraints on the bandwidth of the review, a short time of stay of the device in the zone of radio visibility of ground point to transmit the information. Continuous monitoring of specified areas of the Earth is provided by the spacecraft in geosynchronous, in particular in geostationary orbit. It is known that projects of information systems of this kind are actively developed in the interests of the US Department of defense (e.g. "MOIRE" project) [1].

At the same time, such a system is a large-sized structure, the deployment of which in space is associated with the solution of a set of fundamental problems in the field of space flight mechanics and control of position and orientation in orbit. At the moment, it is difficult to provide the space grouping with a sufficient number of spacecraft with a diffraction optical system. The use of low-orbit small spacecraft, for example, on the basis of the developed in Space-Rocket Center "Progress" together with Samara University unified platform "AIST-2" [2], will make it possible to create a constellation of the necessary number of Earth remote sensing spacecraft in a short time. Equipping spacecraft with an electric propulsion system will increase their active life time and flexibly manage the configuration of the orbital grouping in low orbits up to 500 km high.

Thus, the problem of rapid, flexible and effective monitoring of the Earth is solved by creating a multi-level constellation of spacecraft consisting of small maneuvering Earth remote sensing spacecraft equipped with electric propulsion systems and operating in low orbits, as well as spacecraft with a diffraction optical system operating in high-elliptical (geosynchronous) or geostationary orbits. Bringing high-orbit spacecrafts to the point of standing and then holding them is another task that can be solved using electric propulsion systems.