TNS (Technology Nanosatellites)
TNS (Technology Nanosatellites - Tekhnologicesky Nanosputnik or TEKh-42) is a nanosatellite program within the framework of FSUE (Federal State Unitary Enterprise-meaning a `government industry') / RSIDE (Russian Scientific Institute of Space Device Engineering), Moscow, Russia (the Russian abbreviation of FSUE/RSIDE is RNIIKP). The TNS program consists of two spacecraft: TNS-0 and TNS-1 with different experimental payloads. 1) 2) 3) 4)
The objective of TNS-0 is the on-orbit verification of the GlobalStar communication satellite system serviceability; i.e. checkout of the GlobalStar subscribers' equipment for transmission of the command and program information to the satellite and for transmission of the telemetry information from the satellite.
Background: The space segment of the GlobalStar communication system consists of 48 LEO satellites (the repeaters) providing an access of subscribers to the ground exchange stations. The communication services (duplex data transmission at a rate of 9.6 kbit/s) are normally rendered to the ground users through the GlobalStar modem. However, installations of the user's modem on a LEO satellite change considerably the conditions of setting up and supporting a user's communication channel with a satellite repeater. It is obvious, that the communication quality during the arbitrary point of time will be defined by the relative positioning of the TNS-0 and satellites of the GlobalStar system (relative orientation of velocity vectors) which will set a direction of antenna patterns and values of Doppler frequency shift. It is problematic to make an estimate the influence of the given factors on functioning of a communication system in conditions of a ground experiment having insufficient information on the characteristics of the GlobalStar system.
The experimental data acquisition for specifying the interaction model: LEO satellite -GlobalSatar system presents the primary goal of the TNS-0 space experiment. Within the framework of this problem it is necessary: to estimate the relative positioning of the TNS-0 and GlobalStar satellites in conditions of regular and irregular communication, to investigate a probability to set up a communication channel during the prescribed time interval, to define a probability to communicate during the given time, and to estimate a probability of errors when data is being transferred.
The TNS-0 spacecraft is cylindrical (17 cm diameter, 25 cm length) in shape and does not carry any solar cells. The cylinder is shielded by the metal housing that is stripy-enamel colored. The proportion of the white and black coloring area is computed to provide the average satellite temperature of approximately 20ºC. TNS-0 was designed and built at RSIDE. RSIDE is also the owner of TNS-0. The nanosat has a mass of 5 kg. The operational life is planned to be about 3 months before the lithium battery (2 x 18 V, capacity of 10 Ahr) runs out on power.
Figure 1: The TNS-0 nanosat (left) and bare structure (right), image credit: RSIDE
Spacecraft stabilization: TNS-0 is equipped with a passive MACS (Magnetic Attitude Control System) comprising a permanent magnet and soft-magnetic hysteresis rods. This permits an orientation of one spacecraft axis relative to the geomagnetic field; the aim is to prevent chaotic tumbling motions of the nanosat. The passive MACS provides a very simple attitude mode; however, without a reorientation capability during the mission. The advantage of this simple stabilization approach is that there is no need for the installation of sensors, active actuators, or a processor. MACS was provided by the Keldysh Institute of Applied Mathematics of RAS (Russian Academy of Sciences), Moscow. Attitude is being sensed by solar sensors providing a coarse attitude estimate (Ref. 2). 5) 6) 7) 8)
The overall objectives are:
• To confirm the choice of attitude control system parameters
• To determine the actual attitude motion
• To develop an approach for attitude determination using elementary sun-sensors (3 photodiodes)
• To formulate recommendations for the next missions
Figure 2: Conceptual view of the passive MACS (image credit: Keldysh Institute of Applied Mathematics)
Figure 3: Photo of the TNS-0 spacecraft (image credit: RNIIKP)
The TNS-0 nanosat features the following hardware as illustrated in the block diagram of Figure 4:
• A SC (Spacecraft Controller) consisting of a single chip microcontroller (C8051F022) of the Silicon Laboratories Company. The SC structure includes the microcontroller, the real time clock, the linear regulator, RS-232 transceivers, and controlled power supply switches for the external systems. Furthermore, the microcontroller contains a built-in module for analog information acquisition in structure of a set of multiplexers and ADCs. This built-in module provides measurement of: solar and horizon sensor voltage levels (the photodetectors operating in various ranges of a spectrum), the ambient temperature, a voltage level of the power supply battery (+36V and +18V), and the current consumption values of the GlobalStar modem. In addition, the microcontroller contains a built-in UART, providing interaction with the GlobalStar modem. The programmed I/O pins of the microcontroller are intended to control the power supply to the GlobalStar modem, programming of the real time clock and the SCs hardware change over to the power down operation. The microcontroller has a built-in EEPROM (”flash”).
• A set of solar sensors (sensor 1 to -4) and a horizon sensor
• The GlobalStar modem with antenna system
• A power supply consisting of 2 x 18 V lithium battery at a capacity of 10 Ahr
• A radio beacon of the COSPAS-S&RSAT system. The radio beacon of the COSPAS system serves as an independent indicator of proper functioning of the TNS-0 power supply system. The standard signal transmitted from the radio beacon is being acquired by the reception stations of the COSPAS-S&RSAT system. After the power supply system is turned on, the radio beacon of the COSPAS system operates as far as to the full discharge of a half the battery that has been dedicated for its supply (approximately 48 hours).
Figure 4: Block diagram of the TNS-0 spacecraft (image credit: RSIDE)
TNS-0 spacecraft deployment from the ISS:
TNS-0 was deployed manually as a free-flying satellite on March 28, 2005 from the ISS (International Space Station) by the Russian cosmonaut Salizhan Sharipov. He deployed TNS-0 by giving it a push into the the anti-velocity direction of ISS. After the first orbital period of TNS-0 (90 minutes after deployment), the first signals of TNS-0 were received; this meant the nanosatellite was functioning normally.
Figure 5: Photo of Salizhan Sharipov with the TNS-0 nanosatellite prior to deployment from ISS (image credit: RSIDE)
Prior to this event, TNS-0 was delivered to the space station by the Progress-M 52 as part of the cargo service flight. A Soyuz-U launch vehicle with the unmanned Progress M-52 No. 352 (ISS mission 17P) blasted off from the Baikonur Cosmodrome in Kazakhstan on Feb. 28, 2005. After a two-day flight, the Progress M-52 automatically docked to the aft port of the Zvezda service module of the ISS on March 2, 2005. - It proved too costly to launch the TNS-0 via a carrier rocket, since a separate jettisoning system would have been required. Hence, RNII KP engineers agreed that it would be launched from aboard the space station.
Orbit of TNS-0 at deployment: LEO near-circular orbit, altitude = 350 km x 359 km, inclination = 51.6º, period = 91.6 min. The international flight number is: 2005-007C; name: Tekhnologiya-42 (TEKh-42).
TNS-0 carries a communications package (consisting of two modems, a transceiver, an antenna and a timer) which uses a link to the Globalstar constellation of satellites for contact with the satellite operations center. The antenna system GlobalStar (as a “mushroom”) and the antenna system of COSPAS-S&RSAT (as a stub) are installed on the one butt-end. The special handle is installed on the other butt-end which is intended for launching the satellite by the cosmonaut.
• TNS-0 was deployed from the ISS on March 28, 2005. It passed all in-flight tests successfully. The batteries of satellite had been empty after 4 months of utilizing and it decayed and burnt up in the atmosphere on August 30, 2005. 9)
Figure 6: TNS-0 ground track plotted at 5-minute intervals for Aug. 30, 2005 (image credit: The Aerospace Corp.) 10)
• The experiment worked properly, providing information to evaluate its angular velocity versus time. 11)
• Telemetry was transmitted via the GlobalStar network
• The COSPAS-SARSAT beacon was working for two days in two bands as required
• Accuracy of position determination with the beacon service is about 100 km
• Ground data processing demonstrated the good agreement of prediction and result of the hysteresis damping function regarding the rotational behavior of TNS-0
• At the provided angular velocity, the duration of the transient motion was estimated to last for about 1.5-2 weeks. Actually, TNS-0 was stabilized with respect to the local geomagnetic field within a month.
1) Yu. M. Urlichich, A. S. Selivanov, A. A. Stepanov, “Two Nanosatellites for Space Experiments,” Proceedings of the 5th IAA Symposium on Small Satellites for Earth Observation, April 4-8, 2005, Berlin, Germany, IAA-B5-1403, URL: http://www.dlr.de/iaa.symp/Portaldata/49/Resources/dokumente/archiv5/1403_Urlichich.pdf
2) O. A. Panzyrny, “Hard- and Software of Technological Nanosatellite TNS-0,” Proceedings of the 5th IAA Symposium on Small Satellites for Earth Observation, April 4-8, 2005, Berlin, Germany, IAA-B5-1404, URL: http://www.dlr.de/iaa.symp/Portaldata/49/Resources/dokumente/archiv5/1404_Panzyrny.pdf
3) M. Yu. Ovchinnikov, A. A. Ilyin, N. V. Kupriynova, V. I. Penkov, A. S. Selivanov, “Attitude dynamics of the first Russian nanosatellite TNS-0,” Acta Astronautica, Vol. 61, Issues 1-6, June-August 2007, pp. 277-285, doi:10.1016/j.actaastro.2007.01.006
4) O. Kkromov, O. Panzyrny, “OBC for Technological Nanosatellite Platform,” Proceedings of the 6th IAA Symposium on Small Satellites for Earth Observation, Berlin, Germany, April 23 - 26, 2007
5) M. Yu. Ovchinnikov, A. A. Ilyin, N. V. Kupriynova, V. I. Penkov, S. A. Selivanov, “Attitude Dynamics of the first Russian Nanosatellite TNS-0,” Proceedings of the 57th IAC/IAF/IAA (International Astronautical Congress), Valencia, Spain, Oct. 2-6, 2006, IAC-06-C1.1.06
6) M. Yu. Ovchinnikov, V. I. Penkov, A. A. Ilyin, S. A. Selivanov, “Magnetic Attitude Control Systems of the Nanosatellite TNS Series,” Proceedings of the 5th IAA Symposium on Small Satellites for Earth Observation, April 4-8, 2005, Berlin, Germany, IAA-B5-1201, URL: http://www.dlr.de/iaa.symp/Portaldata/49/Resources/dokumente/archiv5/1201_Ovchinnikov.pdf
7) Information was provided by Michael Ovchinnikov, Keldysh Institute of Applied Mathematics, Moscow, Russia
8) Michael Yu. Ovchinnikov, Andrey A. Baranov, Sergey P. Trofimov, “Development of formation for ionosphere sounding based on two satellites equipped with passive magnetic attitude control system,” Journal of Aerospace Engineering, Sciences and Applications, Jan – April 2011, Vol. III, No 1, URL: http://www.aeroespacial.org.br/jaesa/editions/repository/v03/n01/7-OvchinnikovBaranovTrofimov.pdf
9) A. A. Romanov, Yu. N. Makarov, “Russian technologies of monitoring and remote sensing using nanosatellites,” Proceedings of the 64th International Astronautical Congress (IAC 2013), Beijing, China, Sept. 23-27, 2013, paper: IAC-13.B4.4.9
11) Information provided by M. Yu. Ovchinnikov, Keldysh Institute of Applied Mathematics, Moscow, Russia
The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates.