Possibilities of lidar sensing of the upper atmosphere and the F-layer of the ionosphere using compact optical-range lidar able to be mounted on nanosatellites, are studied. Methods of mathematical modeling of processes of attenuation (absorption) of pulsed lidar radiation are applied. It is shown that the problem of reconstruction of the spatial distribution of the coefficient of light absorption by atmospheric inhomogeneities may be reduced to Radon-type inverse problem, and that fast reconstruction algorithms of convolutional type may be applied to solve the problem.

A brief review of methods of diagnostics and monitoring of space weather in the Earth's magneto-sphere, and the diagnostic instruments currently in use, is presented. The large scale of the magnetosphere, the presence of several mutually related regions and processes, the variability of the structural variations are shown to necessitate monitoring of these magnetospheric regions simultaneously or with a slight enough time delay. Considering the large spatial scale of the three-dimensional space system of the Earth's magne-tosphere (7 radii of the Earth in the direction of the Sun, 10 radii of the Earth in the perpendicular direction, and practically 15 radii in the anti-solar direction), it is possible to roughly estimate the required number of diagnostic stations (satellites) as 100. It is concluded that creation and launch of such a number of modern research and service-class satellites is very expensive enterprise and not an obligatory for complex monitoring of the magnetosphere. The discussed rational approach to the problem suggests creation of a system of magnetospheric nanosatellites equipped with a minimum number of diagnostic instruments. 

Results of development of onboard control system for nanosatellite are presented. The system is a single-board device corresponding to dimensional specifications of CubeSat-class Spacecraft. The main idea of the development is creating of such an onboard control system that the CubeSat general operational requirements are maximally satisfied. Moreover, the used technologies are to satisfy prospects of future development of domestic electronic instrument making industry. The hardware components are represented by two FPGAs, included two „systems-on-chip“ which are interconnected by SpaceWire interface. The first FPGA includes an onboard computer based on the LEON3 processor; the second FPGA includes a power system controller and a subsystem for collecting information from analog sensors. The SpaceWire technol-ogy allows creating onboard network of nanosatellite with routing switches included in „system-on-chip“ of the onboard control system. To ensure the fault tolerance of the complex, the external and internal memory (cache and register file of the LEON3 processor) of the onboard computer are protected by a single-error detection and correction device. The power-switching device allows removing power from all nanosatellite systems including the onboard computer. Technical characteristics achieved in experimental model of the on-board control complex are not inferior to those of small, medium and heavy spacecraft. However, the consumed power of the developed onboard control system exceeds capabilities of solar panels of a 1U-nanosatellite, so it can be recommended for CubeSat-class spacecrafts starting from 3U and above.  

A modified algorithm of nanosatellite uniaxial attitude estimation based on the analysis of geometric visibility of navigation satellites of the Global Navigation Satellite Systems GLONASS and GPS is presented. The algorithm modification consists in changing the navigation antenna pattern width. The proposed algorithm allows to increase the uniaxial attitude determination accuracy. 

The problem of improvement of target efficiency of small-size space vehicles (nanosatellites) for informational support (observation and data transmission) is studied. Considered ways to increase the target efficiency include an increase in the spatial resolution of optical equipment, an increase in the power capabilities of airborne systems, an increase in noise immunity of the communication channels "onboard-Earth" and "board-board," compensation for the instability of ballistic clustering of nanosatellites such as a "distributed space vehicle" ensuring the stability of nanosatellites to failures. Implementation of the proposed approaches to the problem of increasing target efficiency of nanosatellites is anticipated to allow, to some extent, to compensate for the shortcomings of small-size spacecraft due to low mass, dimensions, available electrical power and low reliability.

A new CubeSat architecture is proposed, which makes it possible to increase the efficiency of nanosatellite manufacturing, assembling, and testing. The proposed architecture makes it possible to simplify the development process and simplify significantly the nanosatellite assembling process. The onboard cable network in the nanosatellite is completely, or almost completely, eliminated, which guarantees the correct assembly at the design stage. The problems of testing of nanosatellites manufactured in the proposed architecture are considered. An example of a universal tool for carrying out a wide range of functional tests for individual onboard systems, assemblies process and nanosatellite preparation on the launch complex is presented. Possibilities for improving the pre-launch preparation of the nanosatellites, including through automated monitoring of all connections, are considered.

An optical-electronic telescopic lens-type complex is proposed for creating a domestic group of Earth remote sensing satellites with ability to obtain timely imagery on-demand. Thermal control system based on electric heaters is chosen to maintain the optimal thermal conditions of the lens telescope. Thermal mode calculations of objective are carried out based on 3D model with the account for the real spacecraft operational conditions and its orbital motion. Transient temperature fields of objective are calculated by finite elements method under various operating conditions of the microsatellite: achieving established thermal regime, Earth's remote sensing in normal and extended modes. It is shown that the thermal control system maintains a predetermined temperature range of the optical elements under nominal operating conditions with moderate energy consumption.

Possibilities of the use of a nanosatellite with on-board receiver of global navigational satellite systems for determination of parameters of the Earth gravitational field are discussed. Configurations of space measuring instruments on the base of nanosatellites under consideration include space gravimeter, space gradient meter along the line “satellite — satellite”, and bi-static radio altimeter.

A concept of universal payload platform for scientific experiments to be carried out by university students is proposed. The class of problems solved by our universal platform includes research of new devices of micro- and nanoelectronics, testing prototypes of semiconductor devices, analysis the possibility of remote sensing of the Earth. The use of such a universal platform when conducting scientific experiments on small satellites of the CubeSat standard for educational purposes is anticipated to allow forming new competencies for students of different training areas.

A method of selection of the program of nanosatellites separation from an undirected space platform at the stage of a flight task formulation is proposed. The method is based on statistical researches and provides a predetermined character relative motion of nanosatellites. The choice of the nanosatellite separation parameters is based on the application of a criterion that describes the maximum distance between each pair of nanosatellites, with the exception of the possibility of their dangerous approach both with each other and with the platform from which they are separated. As a result, the separation parameters are selected, for which the maximum value of the distance between the nanosatellite is minimal and thus the flight safety is ensured. The method is demonstrated in details by the example of nanosatellites group separation from the orbital stage of "Soyuz" carrier rocket.

Resonance modes of motion relative to the center of mass of an aerodynamically stabilized nanosatellite of the CubeSat format in low circular orbits are investigated. A feature of such satellites, with the shape of rectangular parallelepipeds, is the dependence of the aerodynamic torque on the spatial angle of attack and angle of proper rotation, which creates the prerequisites for the resonance appearance. Resonance manifests itself in a sharp change in the amplitude of oscillations along the spatial angle of attack, when a linear integer combination of the frequency of oscillations of the spatial angle of attack and the mean frequency of proper rotation turns out to be close to zero. Formulas are obtained for determining the critical value of the longitudinal angular velocity of the nanosatellite, under which the conditions for the appearance of resonant motion are satisfied.