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ACTUAL PROBLEMS OF AVIATION AND AEROSPACE SYSTEMS
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On the procedure of selecting orbits for spacecrafts

of astrophysical systems

D.V.Kovkov

TsNIIMash

Russia

V.V.Malyshev, A.V.Fedorov

Moscow Aviation Institute (State Technical University)

Russia

The paper submits the procedures of selecting orbit parameters for spacecrafts on high elliptical orbit (HEO) and high circular orbit (HCO) according to a criterion that reflects the required character of orbital constellation evolution without making orbital adjustments. The procedure consists in forming the optimality criterion reflecting the desired character of spacecraft orbit parameter evolution and its minimization with the help of numerical methods of nonlinear programming. Besides, a set of optimization criteria is proposed, which reflects the desired character of constellation orbit parameter evolution or a radio interferometer base; a method to form a generic criterion of optimality is submitted. Using the proposed procedures, solutions of applied problems have been obtained concerning the critical inclination definition, initial conditions of a constant inclination orbit and initial conditions of an orbit with a specified rate of inclination change.

Space research in the field of extra-atmospheric astronomy is directed towards solving the fundamental problems of stars and galaxies, cosmology, power engineering and the nature of gravitation. The main trends of extra-atmospheric astronomy are as follows:

-        research of the Universe evolution early stages;

-        detection of "dark substance" and "dark energy" nature;

-        research of processes in the vicinity of galaxies' nuclei;

-        research of processes of stars and planetary systems formation.

To solve the above-mentioned problems, the space means carrying various scientific instruments are developed and deployed.

Spectr-R spacecraft was launched into orbit in July 2011 to become an element of a gigantic space radio interferometer. Radio telescopes in Kalyazin, Russia (mirror diameter - 64 meters), Evpatoriya, Ukraine (70 m), Goldstone, USA (70 m), Green Bank, USA, Madrid, Spain, etc. are planned to be used as terrestrial elements of the radio interferometer. When using one terrestrial and one space antenna at the maximal distance of Spectr-R radio interferometer to the Earth, its spacing will be about 3×105 km.

A space astrophysical complex normally uses terrestrial and extra-atmospheric instruments, which observe deep space objects in different frequency ranges.

The analysis of global trends of developments in this domain shows that it is a single spacecraft with a terrestrial radio telescope that is usually used.

It is of certain importance to create a method to solve a technical problem of synthesis of a ballistic structure of a radio interferometer space section. The task is to define the number of satellites, their initial orbit parameters and the date of deployment to achieve the maximal efficiency of the complex.

One criterion characterizes an astrophysical complex with a single radio interferometer in outer space. This is a sector of coelosphere observed by the radio interferometer. The optimization means the search for such initial conditions of spacecraft movement for which the radio interferometer's orbit plane, during the active operation, turns, due to the Moon's gravitation, by an angle which provides the maximal criterion value.

This paper submits an approach based on criterion reflecting the desired pattern of change (evolution) of spacecraft orbit parameters, or parameters of relative movement, for example, a radio interferometer's base as a distance between spacecrafts.

A program complex has been designed to solve the problems, formulated in research.

The core of the complex is an applied program, which implements the user interface. It provides the user's access to the services, implemented by a number of modules, namely:

- the module of simulation of the constellation's disturbed motion, which supports the integration of Newton-Cowell equations for each constellation spacecraft at given initial conditions and disturbing factors. A user can choose from the library of four numerical integration methods;

- the initial data preparation module supports the interactive mode, while defining the constellation composition, integration and recording parameters, initial conditions, disturbances composition, etc.;

- the optimization module supports the interactive preparation of initial data for an optimization  problem: composition of unknown parameters, initial approximation, optimality criterion, optimization method and its parameters. There are 7 zero-level algorithms in the library of methods library;

- the base of calculated versions contains the information about all the problems that had been set and solved by a PC user, forming the information sphere for decision making;

- the visualization module displays the simulation results: construction of routes, zones of radio coverage as 2D or 3D images, and also the diagrams plotted by log files and introduction of them into reports prepared using MS Office.

A number of abstract classes have been designed for the complex: planet, satellite (spacecraft), atmosphere of a planet, planet's time service, gravitation field service, model to predict the movement of a planet (celestial body). The abstract classes serve as an initial point of appropriate specific concepts, such as: the Earth, numerical (tabular) model of the Earth's atmosphere, Earth upper atmosphere, Earth dynamic atmosphere, "planet" Sun, "planet" Moon, model of gravitation potential, non-disturbed movement of a spacecraft, C20-type model of  a disturbed movement, complete Newton-Cowell model of disturbed movement of a spacecraft.

The applied program, developed in Delphi 7, uses the above mentioned classes to create a constellation model capable of interactively applying different Earth gravitational potential models, atmosphere models and models of constellation movement. The program has a user-friendly interface and allows simulation of constellation's movement. The number of satellites in the constellations is limited only by available virtual memory, allocated to the program by the operating system.

When using Newton-Cowell differential equations as spacecraft movement models, it is possible to apply any of 5 numerical methods, proposed by the program (see original full printed paper).

References

1.           D.V.Kovkov, V.V.Malyshev, A.V.Fedorov. The study of the future astrophysical complexes space segment orbits evolution, MAI bulletin, vol. 17, No. 1, 2010, 62-71.

2.           D.V.Kovkov, V.V.Malyshev, A.V.Fedorov. The evolution and stability of the future astrophysical complexes space segment orbits, Cosmonautics and Rocket Production, No.1 (58), 2010, 111-123.

3.           D.V.Kovkov, V.V.Malyshev, A.V.Fedorov. The analysis of stability of space radio interferometer high-apogee orbits, Cosmonautics and Rocket Production, No. 2 (59), 2010, pp. 117-122.

4.           Kovkov D.V. The evolution and stability of the future astrophysical complexes orbits, The reports theses digest of the 15th International Conference "The System Analysis, Control and Navigation", Evpatoriya, Ukraine, 2010, MAI PRINT publishing company, 2010, pp. 66-67.

5.           D.V.Kovkov, V.V.Malyshev, A.V.Fedorov. The study of the stability of high-apogee orbits with the Moon gravitation accounting, The reports theses digest of the 9th International Conference "Aviation and Cosmonautics -2010", Moscow, 2010, St. Petersburg, Print Workshop, 2010,  86.

 

George Vladimirovich Kovkov, First Deputy Director General of FSUE TsNIIMash, sphere of scientific interests: design of space systems.

Veniamin Vasilyevich Malyshev, Honored scientist of the Russian Federation, Doctor of Engineering Sciences, Professor, member of the International Academy of Astronautics, K.E.Tsiolkovsky Academy of Astronautics, International Academy of the Higher School, International Academy of Nonlinear Sciences, member of the Scientific Council of Roscosmos, Chairman of Specialized Doctoral Thesis Committee, Chairman of the organizing committee of the international conference "System Analysis, Control and Navigation", Laureate of the Prize of the Council of Ministers of the USSR, the Prize for the best research works instituted by the Ministry of Higher Education of the USSR, three prizes named after the 25th anniversary of MAI. For his creative contribution to implementation of space programs and projects he was awarded the Medals of Yu.A.Gagarin, academicians N.A.Pilyugin, V.N.Chelomey, and the Badge of S.P.Korolev. He has a patent for invention. For many years he has been a chairman of the session of the scientific council of RAS on the problems of motion control and navigation, and a member of the editorial board of the journal "Izvestiya RAN. Teoriya i sistemy uprav-leniya" (Proceedings of the Russian Academy of Sciences. Theory and systems of control).

Alexander Victorovich Fedorov, Associate Professor of Department No.604 (since 1988), Candidate of Engineering Sciences (1977). Graduated from MAI, Department No.604. Specializes in applied theory of optimal control and development of software for design and control of complex systems. Main fields of research: development of ballistic support for space systems of communication and navigation, development of algorithms and software for statistical analysis of controlled motion, trajectory optimization and motion control, design and control of space systems. Published over 120 scientific and educational works, including: Sputnikoviye systemy monitoringa. Analiz, sintez i upravleniye (Analysis, synthesis and control. Satellite systems for monitoring), MAI, 2000. Laureate of the Prize of the Council of Ministers of the USSR (1989), the Prize of the 25th Anniversary of MAI (1981).



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