Описан программный комплекс Coulomb, предназначенный для моделирования электризации космических аппаратов (КА) в магнитосферной плазме на высоких и низких околоземных орбитах. Рассмотрены физические механизмы электризации КА и методы математического моделирования этого явления в разных областях космического пространства. Приведены примеры результатов расчета распределения электрического потенциала на поверхности и в окрестности КА для геостационарной орбиты и низких околоземных орбит.

The Coulomb software complex for modeling of spacecraft charging in magnetosphere plasma in high and low Earth orbits is described. Physical mechanisms of spacecraft charging and methods of mathematical modeling of this phenomenon in various areas of space are considered. Examples of the calculation results of electrical potential distribution on the spacecraft surface and in the vicinity of the spacecraft in geosynchronous and the low Earth orbits are presented.

Magnetosphere plasma electron and proton fluxes in the energy range 0.04–11.3 keV were measured using electrostatic spectrometers established onboard the geostationary Electro-L2 spacecraft (point of standing 76° EL). Measurements were done in the lit orbit segments and in the Earth shadow during the periods of vernal and autumn equinox in 2016–2017. In terms of the observation data, fluxes, and parameters of the plasma particles for different geomagnetic activity levels and potentials of the spacecraft metal base were determined. The measured values of the negative spacecraft metal base potential achieve 5–10 kV in the Earth shadow. Interpretation of the measurement results was done using the results of the spacecraft charging modeling obtained with the COULOMB-2 program package. Electric field gauges (EFGs) and electrostatic discharge (ESD) gauges were established on the spacecraft surface as well. The electrostatic spectrometers data and the COULOMB-2 results coincide with the EFGs data. ESDs were registered onboard the spacecraft during the spacecraft entrance into the Earth shadow and exit from the shadow.

Influence of electric field of charged spacecraft on secondary emission currents on the spacecraft surface is analyzed in terms of computation of secondary electron trajectories. Dependencies of the recollected electrons number on the electric field intensity at various distances from the emission point for standard secondary electron spectra are calculated. Criteria of the secondary electron emission suppression by the surface electric field which is applied for spacecraft charging modeling using the COULOMB-2 code are proposed. Modeling of the emitted electron trajectories in the electric field of the charged spacecraft having complex surface configuration enables to compute correction factors added to electric current balance equations (electron recollection).

This paper describes modeling of spacecraft charging dynamics which is used in COULOMB-2 code in the case of spacecraft surface complex shape. The modeling of spacecraft charging is carried out via numerically solving the system of differential equations for time variations of local electric charge on every discrete element of the spacecraft surface. The presented computation results are obtained for spacecraft charging in hot magnetosphere plasma for several spacecraft design elements in a time interval of 20-10000 s. The results are compared with the similar ones obtained with the NASCAP-2k and MUSCAT codes, and a good consistency was found.

In the paper, we discuss numerical modeling of spacecraft charging in geosynchronous orbit which was done using Coulomb-2, NASCAP-2K and SPIS codes, and present data obtained using the MUSCAT code too. The main distinctive features of the codes above are specified, description of the Coulomb-2 code is given in more details. We compare the results of calculations obtained for similar models of spacecrafts with identical surface materials and parameters of the space plasma environment. The possible reasons of divergence of the modeling results are discussed.

Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.

The mechanism of failures of microelectronic elements, caused by ionization of atoms by recoil nuclei and secondary fragments formed at nuclear interactions of cosmic-ray protons and light ions with substance, has been analyzed. Models of nuclear physics are used to calculate the macroscopic failure cross section.

The results of magnetospheric plasma fluxes measurement in geosynchronous orbit are presented. The measurements were done onboard the geosynchronous Russian "Electro" spacecraft (SC) in 1995-1997 years. The diurnal variations of the plasma density and temperature were observed at various levels of geomagnetic activity.Distortions of the measured electron and proton spectra caused by negative potential of the charged SC were registered. Typical electron spectra and plasma parameters were determined for various SC charging levels. Similar measurements in low polar orbits at the "Meteor" SC (launched in 2003 year) and the "Universitetskiy-Tatyana" SC (launched in 2005 year) were done. (C) 2008 COSPAR. Published by Elsevier Ltd. All rights reserved.

Charging of spacecrafts in near–earth orbits is determined by space environment in the orbit. Dominating physical processes are different in principle for various altitudes. So, the spacecraft charging model which is based on computation of external particle fluxes on the spacecraft surface should include (a) space environment data, (b) adequate description of physical processes of surface/environment interaction including secondary processes, (c) algorithm of the spacecraft surface model construction, and (d) numerical methods for solution of the problem. In this work, we consider items (b) and (c) mainly as the most actual to be solved for simulation of spacecraft charging in various orbits. Our model of spacecraft charging in geosynchronous orbit (GEO) [1–3] was implemented in the COULOMB program package successfully used for modeling of GEO satellites [2, 3]. The principle difference between spacecraft charging in GEO and one in low-earth orbits (LEO) is determined by the fact that plasma of magnetosphere is hot and rare, and one of ionosphere has low temperature and high density. In this case, new method for computation of primary particle fluxes on the spacecraft surface was developed and implemented in the program package NPI_LEO. To do the simulation of spacecraft charging in LEO, we need the procedure of mathematical description of real spacecraft surface. The procedure was developed earlier [3] and employed in the COULOMB package. In the NPI_LEO package, the method developed was generalized to provide a powerful tool for 3D modeling of spacecraft charging in LEO. Physical model of spacecraft charging was built after detailed analysis of principle physical peculiarities of the ionosphere plasma particle currents in the vicinity of spacecraft in LEO. Charging of real spacecrafts was investigated, and the results are presented in Sec. 4 below.

Cold plasma ion capture surface construction algorithm was developed in terms of the classical approach to solution of the severely charged body problem (Al'pert et al, 1964). The algorithm makes it possible to create the effective surface for complicated spacecraft outer surface. Peculiarities of the severe charging case modeling, as far as the computation results are presented and discussed.Computations reveal that noticeable distortions of the primary spacecraft surface arise in the case of differential charging corresponding to the spacecraft with dielectric elements on its surface.Effective method for color visualization of the electrostatic potential distribution on the spacecraft surface was developed for analysis of the spacecraft charging modeling. Typical screenshots of VRML images are presented in the work for various charging cases.

The peculiarity of spacecraft charging dynamic processes on GEO is determined by the mechanism of suppression of an secondary electron emission by a retarding electrical field and sharply differing timescales of charging processes, including fast change of external conditions (plasma, sunlight, spacecraft orientation), For numerical simulation of development of spacecraft charging processes in time the automatic multistep Gear method specially intended for the decision of "stiff" systems of the ordinal differential equations is used in this work.The increase of performance modem PC has allowed to use this method for spacecraft models with number of elements more than 1000. The tests show high stability and accuracy of the used methods even at influence of spacecraft model sampling degree. This algorithm is realized in the new version of spacecraft charging tool "Coulomb", constructed as the WWW client - server.The tools includes the interactive builder of spacecraft models and 3D display system of the information and results of accounts, material properties and space plasma parameter databases, tools for solution of electrostatic and dynamic problems, and scenario manager tool.The tool use HTML browsers with VRML by plug-in, WWW Apache server with PHP and mySQL extensions, which allows using it in local and remote access mode. The described technique is applied to the of spacecraft charging analysis on a GEO and HEO under various conditions: in the eclipse and in the sunlight, slow or fast rotation spacecraft in sunlight, movement of a shadow on a surface spacecraft, and also at time variation of plasma parameters. The results of spacecraft charging calculation are presented.

This report presents some examples of a computer simulation of spacecraft interaction with space environment. We analysed a set data on electron and ion fluxes measured in 1991 1994 on geostationary satellite GORIZONT-35. The influence of spacecraft eclipse and device eclipse by solar-cell panel on spacecraft charging was investigated. A simple method was developed for an estimation of spacecraft potentials in LEO. Effects of various particle flux impact and spacecraft orientation are discussed. A computer engineering model for a calculation of space radiation is presented. This model is used as a client/server model with WWW interface, including spacecraft model description and results representation based on the virtual reality markup language.