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ISSN 0010 9525, Cosmic Research, 2014, Vol. 52, No. 5, pp. 326331. © Pleiades Publishing, Ltd., 2014. Original Russian Text © V.V. Khartov, A.E. Shirshakov, M.I. Artyukhov, Yu.V. Kazakevich, A.Z. Vorob'ev, A.I. Kalashnikov, A.V. Pogodin, E.N. Filippova, S.V. Komovkin, 2014, published in Kosmicheskie Issledovaniya, 2014, Vol. 52, No. 5, pp. 360365.

Features of RadioAstron Mission Control
V. V. Khartov, A. E. Shirshakov, M. I. Artyukhov, Yu. V. Kazakevich, A. Z. Vorob'ev, A. I. Kalashnikov, A. V. Pogodin, E. N. Filippova, and S. V. Komovkin
Lavochkin NPO (Science and Production Corporation), Khimki, Moscow oblast , 141400 Russia e mail: aka@laspace.ru
Received December 16, 2013

Abstract--Support means of the Spektr R spacecraft flight and features of the Mission Control Center oper ation and spacecraft control are considered. Software for scheduling and preparing sessions of controlling and simulating for the spacecraft operation are considered. The problems of ballistic navigation support of the spacecraft flight are presented. Ground spacecraft control segment and software for analyzing and imaging telemetric information are considered. DOI: 10.1134/S0010952514050062

INTRODUCTION The operation of the RadioAstron space observa tory is based on the implementation of the method of Very Long Baseline Interferometry (VLBI) using the space radio telescope created at Lavochkin Research and Production Association connected with the Earth by a high data rate radio channel. The structure of spaceground radio interferometer includes the Mis sion Control Center of the Spektr R spacecraft flight (MCC SR based on MCC of Lavochkin Association), the Science Experiment Scheduling Center (SESC based on Astro Space Center of Lebedev Physical Institute, ASC LPI), Science Data Processing Centers in ASC LPI and Space Research Institute RAS (IKI), Ballistic Center (BC based on Keldysh Institute of Applied Mathematics, KIAM), network of ground stations of Ground Control Segment, GCS (Kobalt R using the TNA 1500 antenna (Special Research Bureau of Moscow Energy Institute, SRB MEI) in Medvezhyi Ozera near Moscow and Klen D using the largest in Russia antenna system P 2500 near Ussuriysk), network of Ground Tracking Stations (GTS) in Pushchino based on the RT 22 antenna (ASC LPI) and the Green Bank observatory (USA), ground radio telescopes, interested research centers, and individual researchers. Due to the high performance demonstrated by the created scientific instrument, the ground space inter ferometer, currently, in the project, in addition to the Russian radio telescope in Kalyazin, the numerous foreign radio telescopes, including the largest radio telescopes in the world, are included. The need for the early long term scheduling of its participation is an important feature of the RadioAstron mission. Organizing elements of the mission are MCC SR providing scheduling the spacecraft and GCS opera tion, as well as SESC providing scientific program

scheduling, operation of ground radio telescopes and GTS. The general control is the Main Operational Control Group (MOCG) headed by the Lavochkin Association and uniting together specialists from enterprises of scientific and technical cooperation, including the developers of onboard spacecraft systems. ORGANIZATION OF THE SPEKTR R SPACECRAFT CONTROL The feature of the operational organization of the space ground radio interferometer and MOCG ser vices is the need for synchronous interaction of a large number of different elements of the mission, some of which (ground radio telescopes, control stations, etc.) are actively used in other programs. Experience in spacecraft operation for scientific investigation shows that the main criteria for the effec tiveness of scientific programs are as follows: the amount of time for scientific research in a defined cal endar period and the efficiency and reliability of the MCC staff at the urgent change of the observation pro gram or operation modes of scientific equipment [2]. These parameters are achieved by the choice of an optimal control scheme, the construction of appropri ate scheduling technology, the implementation of the program for scientific observations and communica tion sessions, the development of hardware and soft ware support, coordinated technologies of communica tion sessions and scientific observations, and the opti mal construction of a ground control complex (GCC). Spacecraft control in flight is performed by special ists at the Lavochkin Association who participate at all stages of the project from designing systems to space craft ground tests. During the flight control of the Spektr R spacecraft, MOCG solves the following main problems: organizing the coordination of inter action of all elements of the ground segment, schedul

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ing the spacecraft control operation in order to per form scientific observations, organizing and imple menting communication sessions with the spacecraft, an analysis of operation of the onboard spacecraft sys tem, MCC and other elements of the ground segment, ballistic and navigation flight support, and receiving scientific information from the spacecraft by ground tracking stations and transferring it to the interested organizations for further processing. The control of the Spektr R spacecraft is imple mented by the closed scheme conventionally shown in Fig. 1. The technology of the Spektr R spacecraft control takes into account the following requirements charac teristic for this mission: using network structures in the ground control segment of the spacecraft, means of flight scheduling and controlling united by a common network; integrated project scheduling, when the operational result of the scheduling program for the previous stage is used to schedule the next stage of the program (in the pre approved forms); using the com mon typical constructions at all stages of scheduling as basic elements (typical session program, units, typical arrays of spacecraft control systems); the automation of the process for the technological cycle of the space craft control (forming long term program of opera tions with the spacecraft, forming command program information (CPI) and scheduling control session, process of the session implementation); providing automatic receiving telemetry (TM) streams, process ing and controlling all TM parameters and conducting an automated online analysis of the TM information in MCC L; the automation of the analysis of the state of onboard systems and the spacecraft as a whole according the results of secondary processing the TM data up to the level of NORM/NON NORM in order to detect promptly at an early stage the danger ous trends in the operation of the onboard systems and to form recommendations to remove emergency situ
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ations arising on the spacecraft; application of mathe matical simulation, means of data processing and visual imaging the simulation results in the problems of testing the programs of the spacecraft control and the problems of an analysis of system functioning using the TM data to improve the reliability of control; a possibility to adapt program algorithm support (PAS) of the spacecraft control in flight to the chang ing conditions for operation of the scientific equip ment and service systems; using when spacecraft con trolling the working documentation and hardware and software for scheduling, preparation and implementa tion of the communication sessions processed when performing ground complex spacecraft tests. The main stages of the technology cycle of the mis sion control are: scheduling, implementation, and post session data processing. Scheduling the mission operation has a three level structure. Long term sci entific scheduling (for the period up to one year) is the first, top level. It includes collecting applications for scientific experiment implementation, evaluating their realizability, compiling a list of priority sources and compiling the research program, determining the compromise sequence of operations with the space craft to implement the program of scientific observa tions in view of all interested sides and all factors affecting the program implementation (ballistic restrictions, restrictions in the operation of the space craft systems and ground means). At this stage, an esti mate of the realizability of the program of scientific observations is performed. Medium term (one month) scheduling details the program of the space craft operation, confirms operating the GCC means and a network of ground radio telescopes, specifies the observation times of investigated sources and deter mines times of the session for laser ranging, regions for SRT and the Plazma F complex operations, times of control sessions in view of zones of visibility and dis tance taking into account functional restrictions on

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ground and onboard means, possibilities of pointing to the ground tracking stations with the narrow beam antenna, providing energy and thermal balance, etc. Operational scheduling (for one day) includes testing CPI and the program of checking for the prsence of errors in spacecraft operation on the imitating and modeling bench for compliance with the given pro gram during the control session. Specially developed software is used for the sched ule that is intended to form the code commands for the spacecraft control, compile arrays of flight tasks (FT), edit control commands and FT modes, compile com munication sessions, and to check applications and communication session for the temporal and struc tural CPI restrictions. The implementation of these problems in automatic and semi automatic modes allowed us to exclude errors in program formation, increase the efficiency of solving the scheduling prob lems and control reliability, and to reduce the total time of preparation of the control session. The com plex of scheduling programs is constructed by the modular principle and includes the editor of the pro gramming session, the editor of FT compiling, the editor of code commands, the editor of control com mands with the parameters, the editor of arrays of dig ital information, the generator of CPI arrays, and the module of the application formed for spacecraft oper ations. Each editor has an intuitive interface and pow erful editing means controlled for the correctness of the input information and protection against errors introduced by the operator. To check the programs for the session and for spacecraft operation in the autonomous mode, we use the imitating and modeling bench on which we per form the integrated (from session to session) mathe matical simulating of the spacecraft operation, the result of which is protocol for simulation and the spacecraft TM information. If necessary, for physical simulation, we use a complex bench made by the developer of the Onboard Control Complex (OCC), Moscow Experimental Design Bureau Mars. When processing the protocol of simulation, the verification is performed in the automatic mode. To illustrate the simulation results, the time diagram of the flight out put in the text and graphic view. This scheme of the scheduling organization allows us to use the spacecraft resources the most efficiently. The implementation of the communication session includes transmitting to the spacecraft the command and program information, as well as the operational control and an analysis of the technical state of the spacecraft system. To ensure the high reliability of control and transmission of radio commands to the spacecraft the special control means, means of verify ing and confirming the command transmission have been developed. Methods of implementing communi cation session support for the transmission of radio commands in automatic and manual mode allow us to visually image receipts of transmitted commands and

digital data arrays. Methods of TM data analysis allow us to perform the complex operational control of the spacecraft state using several generalized display forms. When implementing the planned operational program, all service information on the spacecraft state is promptly processed and controlled in MCC SR; the access of SESC is ensured in the online mode. Information exchange is performed using a spe cially organized project network for data transmission, as well as public communication channels. Access to the common information space of the project for each participant is determined according to the agreed upon regulations. Post session data processing con sists of the detailed analysis of the technical state of the spacecraft onboard systems and the refinement of the parameters of the spacecraft mathematical model according the results of processing the protocol of the session implementation. A detailed analysis is also carried out using specially designed software. Developed methods of controlling and scheduling certainly will be reflected in future projects of Lavoch kin Association, such as astrophysical spacecraft of the Spektr series, meteorological spacecraft of Elektro L and Arktika series designed on the basis of the Naviga tor space platform. BALLISTIC AND NAVIGATION FLIGHT SUPPORT When preparing to control of the Spektr R space craft flight, the concept of the maximum automation of solving the problems of Ballistic and Navigation Support (BNS) was accepted. This approach allows one to reduce the possibility of errors permitted due to the human factor and increase the productivity of the BNS duty operators. Ballistic and navigation support of the Spektr R spacecraft flight solves the following problems: the determination of the spacecraft motion parameters (in order to ensure the spacecraft control and connect sci entific experiments); the calculation of target indica tions for ground control stations and ground tracking stations; determination of orbit parts, where it is pos sible to perform laser ranging in view of functional restriction of laser ranging stations; the calculation of the spacecraft orientation parameters (in view of func tional restrictions on the spacecraft orientation) to provide scientific observations, to perform laser rang ing and to provide the spacecraft thermal mode; checking the possibility of the implementation by the spacecraft of the scientific observational program pre pared by ASC; the calculation of reference ballistic information to schedule operations with the spacecraft and the spacecraft control (the prediction of the spacecraft orbit parameters, calculation of shadow intervals, radio visibility zones, etc.); and the prepara tion of the ballistic data to support operations of the onboard control complex for subsequent transfer to
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FEATURES OF RADIOASTRON MISSION CONTROL Max Planck Institute World Radio telescopes Public network ASC/IKI ASC correlator Ussuriisk GS
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MCC L software Project network MCC L software GTS Green Bank PRAO Ballistic center KIAM MCC L software MCC Lavochkin Association

Content of scientific segment: Receiving Scheduling Processing Service Interaction Archiving Distribution Systematization Demonstration

Fig. 2.

the spacecraft in an array of command and program information. FLIGHT INFORMATION SUPPORT Connecting technical elements of the ground seg ment are the transfer data network, specially designed and public, as well as technologies related with them. In this case, elements of unified software of MCC L, which carry system creating properties (Fig. 2), are at the intersection of the project network and objects of the ground segment. The technological decision making center, as well as a place of the acquisition and processing of the telemetry data from the spacecraft is the Mission Con trol Center Spektr R (MCC SR). The scheme shown in Fig. 2 does not consider spe cial cases of connecting remote researchers or test technologies of joint transfer via ground communica tion channels of scientific and technological informa tion without sharing (the version of using the station in the United States). GTS stations can also have inde pendent access to the public network to receive infor mation about scheduling, as well as to receive scientific information in SESC/SDPC from the spacecraft. The gateway between the public and project network is pro vided with the means directly connected to a major hub of traffic exchange MSK IX. The favorable geographi cal location of SDPC and SESC promotes to this. Flexible use of special and public networks enables the presence of basic differentiation mechanisms for
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access and data protection, as well as ensures the mechanisms of the necessary quality of network ser vices (QoS). The project has no direct transparent IP routing between networks for all users, and this scheme (access to project network resources from a public network) is used as a reserve to perform emer gency operations or to use functions for IP telephony and video conferencing by MCC L. The standard scheme of the information exchange is an excess at the application level to the special SDPC servers for the MCC applications, as well as unidirectional exchange with typified forms. Using cloud technologies in the project network allows us to organize an access to the information by expanding the boundaries of the cloud according to common infrastructure rules without modifications of the software and agreement of any individual interac tion protocols between organizations. The presence of this environment also improves the efficiency of the use in the framework of ground segment of systems for IP telephony with the numbering plan of MCC L. Scientific information obtained from the space craft by ground tracking stations during the observa tion sessions has autonomous timing and does not require the mode of real time scale when transferring in SESC for correlation processing. In this case, the technological information, which is involved in mak ing decisions for the spacecraft control, i.e., informa tionally forms the so called control circuit, should be transferred and available for automated processing and an analysis as soon as possible in quasi real time. Soft

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ware elements of MCC L on GTS and GCC stations are special user terminations that, as a rule, automati cally provide the execution by the station of the stan dard service functions. The Medvezhyi Ozera GCC station includes the Kobalt R station type of SRB MEI developed specifi cally for the Spektr R project and initially has the nec essary MCC software components of UNIX system in its composition. At the Ussuriisk station, the typical station of the Klen family is used that was designed by OAO RSS (Russian Space Systems), which imple ments its own, less technological, set of exchange functions and MCC software that operates on a sepa rate additional system. When choosing a unified exchange protocol, we perform an analysis of the existing national solutions (including implemented in the same Klen systems, which is the most accepted), as well as foreign proto cols of the CCSDS SLE families, for which Lavochkin Association has its own certified ESA implementa tion. To ensure the exchange of information with the ground tracking stations, the high tech solutions are implemented in it using in the automatic mode, the collection of information and service capabilities of GTS stations and including methods of receiving, decoding, and sharing streams of technological and scientific information from the radio line of high data rate radio complex (HDRRC); methods of filter ing and routing traffic and organizing necessary tunnel interfaces and data encryption; methods for systemiz ing and local archiving the TM session data; sub systems for transferring a data stream using MCC IP protocols; and systems that ensure service func tions, including the organization of running and diag nostics of abnormal situations, states, and statistics for the session; and methods of remote access to the func tions using web interface. In the project, the ballistic center is used according to traditional technology. It is assumed that all ballistic estimates and calculations needed to support the effi ciency of the control circuit are carried out by the ser vice of ballistic and navigation support located at MCC. Therefore, the data exchange with BC is per formed by file oriented forms of exchange with lower efficiency that carry out any software components from MCC, and BC is not provided. These forms are processed and imaged in the corresponding database record at MCC SR. An important point of the MCC software place ment is SDPC IKI/SESC ASC. In the comfort mode, the server for applications specially installed in the ter ritory of scientific organizations enables one to ana lyze and estimate the state of the target equipment. The server is included in the computing cloud of MCC SR and has an access to all necessary informa tion. Using the server is performed with the applica tion of the XDMCP protocol from working places of the research group of ASC LPI and the group of the

Plasma F experiment in IKI RAS. On the server, a part of the standard MCC software is operated, which is associated with the presentation of the processing results of TM information (special software, SS O). The SS O components (the Tsytrus system) are capa ble to image the form in a graphic view on the real state of the instrument with lighting parameters, which exceed some given range. For working specialists of the analysis group at MCC SR, the program complex SS O is fully imple mented; the total number of available in MCC tele metry forms is about 500, in which the results of pro cessing more than 3000 TM parameters from the spacecraft are used. Some of the forms represent the so called "secondary parameters," also known as "generalized judgments," a powerful tool for inte grated express estimates of the state of the spacecraft. In this case, the process of sharing and processing of the TM parameters takes place online on special independent servers. TM information processing servers also automatically prepare special slices of information ready for prompt transfer to third party organizations, in particular to the complex bench of the developer of onboard control complex (OCC), MEDB Mars. Servers for MCC SR applications also have the possibility to run other set of software that performs the functions of scheduling and implementing com munication sessions, as well as many service functions of control and diagnostics, acquisition and imaging of the statistical information implemented with web technologies. A separate group of software is used visual repre sentation. This software includes the so called "main form" and means of 3D representation at all stages of spacecraft flight from the launching phase. These sys tems are performed in the same project manner and admit different versions of using from presentation assemblies and hall sets to complex reductions with automatic change of representation forms. Programs are not entertaining animation; they operate a large set of the data obtained online from the TM information processing servers, as well as visually represent certain sets in the automatic mode that accompany them via a three dimensional scene of the spacecraft in the light of the Sun. CONCLUSIONS The operation of the RadioAstron ground space system continues successfully. From November 2012 to December 2013, 257 control sessions, 885 observa tion sessions, and 28 sessions of the SRT adjustment were performed. The implementation of the planned program of the spacecraft control during this period was 98.9% [3].The system is complemented with new elements; the ground tracking station in Green Bank was introduced and already nominally used. The prep aration of the station in Pretoria for operation has
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begun. There is an accumulation of statistical data on the operation of onboard spacecraft systems in the ses sions of scientific observations that allows us to expand the boundaries in using the spacecraft for scientific research. ACKNOWLEDGMENTS The RadioAstron project is being carried out by the Astro Space Center of Lebedev Physical Institute and Lavochkin Scientific and Production Association under contract with the Russian Space Agency, along with many scientific and technical organizations in Russia and other countries.

REFERENCES
1. Aleksandrov, Yu.A., Babakin, N.G., Babyshkin, V.E., et al., RadioAstron (the Spektr R project): A radio tele scope much larger than the Earth. Ground based seg ment and basic lines of research, Vestnik NPO im.S.A.Lavochkina, 2011, no. 3, pp. 1930. 2. Khartov, V.V., et al., The RadioAstron space mission, Vestnik NPO im. S.A. Lavochkina, 2012, no. 3, p. 5. 3. Kardashev, N.S., Khartov, V.V., et al., RadioAstron: A telescope with a size of 300 000 km: Basic parameters and first results of observations, Astron. Zh., 2013, vol. 90, pp. 179222.

Translated by N. Topchiev

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