Application of telecommunication system "globalstar" for nanosatellite control

One of the key directions of the FSUE "RISDE" activity is the development of on-board and ground-based electronic equipment intended for rocketry involving the devices for satellite control. The transmitter s developed by the Institute for the first satellites laid the foundation of the future tracking, telemetry & command systems (TT&C) and the integrated state ground-based automated complex intended for control the satellites and measurements. In a half a century after launch of the First satellite the new satellite control technology with minor expenditures was experimentally tested and upgraded by the Institute. This experiment was made with using a technological nanosatellite (TNS-O), launched in 2005 from the board of International Space station. The two developed in the FSUE "RISDE" transmitters with total mass of 3.5 kg were installed on the board of the First Earth Satellite launched 50 years ago. Both transmitters operated in the amateur band and radiated signals in e form of a telegraph message. Variations of message rates and intervals between them characterized the temperature and pressure inside the satellite's container. During reception the telegraph signals sounded as the jingles «bip-bip» well known all over the world. In the next following satellites, as well as in Lunar Orbiters the transmitting-receiving equipment of the Institute's development was adopted. No control from the Earth was required for the First satellite, but it proved the possibility of informational exchange between ground stations and satellites. For the purpose of data reception from the first satellites a tracking stations network was originated in our country. Further on basis of this network a ground-based TT&C complex was built for control all the satellites to be launched. In such a way the on-board transmitters of the First Earth Satellite laid the foundation of the future command-measurement systems (tracking-telemetry and command stations - TT&C). The TT&C is the key part of the radio technical satellite control system and designed to provide: satellite flight control by delivery of one-time commands, program and special data to the satellite; TM data reception from the satellite; measurement of the current navigation parameters of satellite motion; verification, correction and phasing of the on-board time scale. The ground component of the TT&C complex belongs to the ground-based automated satellite control complex (so called NAKU). By the time of launching the First Satellite 7 ground TT&C stations were deployed. In succeeding years the hardware configuration, layout and outfit of the TT&C were changed time and again in conformity with requirements to flight support of newly developed automatic and manned spacecraft, as well as automatic interplanetary stations. Ground-and sea-based TT&Cs were also included into the NAKU. Since 1979 the Institute is the leading organization on development of NAKU and the prime developer of more than 80% of systems and means for this complex. In 1999 it was decided to create the Integrated State Ground-based Automated Satellite Control and Measurement Complex (Integrated State NAKU). At present time the Integrated State NAKU is able to provide the control of 180 satellites and assure data ware provision during launch of all types of space vehicles, ballistic missiles and flight of upper stages. Every day the Integrated State NAKU means support the performance of more than 500 control sessions for spacecraft of different purposes [1]. The continuous and varied activity directed to upgrading and further growth of the Integrated State NAKU is being implemented in the FSUE «RISDE». One of the lines of this activity is the introduction of unified cost-efficient means of satellite control, development of recent digital communication and data transmission system with usage of satellite and fiber-optics links. The ways were outlined for the further evolution of NAKU ground infrastructure that will allow the numerical strength of ground means and total number of measurements to be optimized. Toward this end, the new satellite control technologies based on application of space navigation systems, multifunctional relay systems, integration of trajectory and telemetry edges are developed and introduced. In a half a century after launching the First satellite a new experiment focused on bringing to perfection the new satellite control technology was carried out by the Institute. An incitement to pursue this experiment became the new direction of space technology actively progressing now -development of small sized satellites (SSS). This direction is stimulated by the progress in miniaturization of all components and systems of spacecraft, as well as by emerging new opportunities as for the SSS control as for transmission of housekeeping and purposeful data. The miniaturization of satellites and spacecraft, provided that they keep the main individual features, makes it possible not only to reduce the expenditures for their production, orbital injection and operation in the orbit, but also to obtain a number of new important properties, especially in cases when the space constellation should comprise large quantity of SSS. The control of such SSS constellation is a new complicated task, which must be solved bit by bit. It is our opinion, that one of the first steps in this direction should be the test of untraditional technologies of control and data transmission with using existent global telecommunication systems like Internet, cellular networks of GSM, CDMA standards and other low orbit commercial satellite systems GLOBALSTAR, ORBCOMM etc. in condition of the real space flight. If the SSS becomes a subscriber of such a telecommunication system, we will get new possibilities for global (or quasi-global) control with low operational expenses and more high levels of efficiency. The results of these tests present a very important scientific and technical interest. This idea was partly realized in several foreign experimental satellites. The published results needed to be checked and the own experience of practical application of such technologies should be gained. It was also necessary to check in real space flight condition other promising technical solutions and technologies, for example, the technology of data transmission from Earth Remote Sensing instruments, new system of SSS attitude control with using the geomagnetic field and so on. In 2005 the technological nanosatellite (TNS-O No 1) made in the FSUE "RISDE" was manually launched from the board of International Space station [2]. The satellite's weight was 5 kg. The nanosatellite lived in the orbit from 28 of March through 5 of June 2005, i.e. 68 days 20 hours 31 minutes. The useful life of the nanosatellite was restricted by capacity of on-board batteries. On 30 of August 2005 the nanosatellite entered the dense atmospheric layers and ceased to exist. The actual time of its ballistic existence amounted 156 days. The basic principle for control the TNS type satellites is the use of networked and relay methods of automated satellite control by installing the satellite modems for transmitting the command-program information to the nanosatellite through the low orbit communication satellites. The same modem is expected to be used for solving the tasks of telecontrol - transmitting the TM and housekeeping information. In theory, the use of networked (relay) methods of automated satellite control with keeping the appropriate characteristics of employed satellite communication systems makes it possible: 1) to provide the possibility of satellite control in any point of the orbit; 2) to keep up the liaison with the satellite in practically real time scale; 3) to reduce the expenses for satellite control. One of the primary objectives of the TNS-O was the practical refinement of the new satellite control and data transmission technology with usage of existing global telecommunication systems in conditions of real space flight, particularly: check the possibility of satellite control with the use of satellite communication systems of GLOBALSTAR type; refinement of data transmission-reception technology via the up-and down links; obtaining of experimental data characterizing the quality of communication sessions; refinement of the ground-based satellite control stations by using the satellite modems; check of special MCC TNS-O software in condition of the real flight. Toward this end, a modem operating within the GLOBALSTAR system was installed on the board of nanosatellite. Through this modem the integrated on-board informational system for nanosatellite control performed a data exchange with the Mission Control Center: the data from on-board systems were transmitted to the Earth, and command-program information from the Earth was received. Simultaneously with refinement of new technologies for satellite control the soft-and hardware means of low-budget MCC were worked out. The nanosatellite TNS-O control complex (Fig. 1) had in its structure the mission control center MCC TNS-O, which consisted of two automated workstations - MCC-1 (GLOBALSTAR-GS) and MCC-2 (Trunk telephone station - TTS). Both workstations solve similar problems and are fully identical. The MCC-1 (GS) consisting of a "large" notebook (15 inches screen size) and a GSP subscriber's terminal 1620×1 of the GLOBALSTAR system functioned as the core (stationary) MCC and was situated at the FSUE «RISDE» territory. The MCC-2 (TTS) consisting of a "small" notebook (8 inches screen size) and a cellular modem of GSM standard (cellular telephone) functioned as a transferable (mobile) MCC and served as a back up for MCC-1 (GS).