GLONASS launch on Proton LV at Baikonur Launch Site
Builders Notes: Russian GLONASS at the Stage of Active Implementation
Modernized GLONASS-M satellite (left), A GLONASS-M satellite design (right)
The Russian Federation is well into a 10-year program of implementing a modernized GLONASS satellite navigation system. Four new-generation GLONASS-M satellites are now on orbit, and deployment of a 24-satellite constellation is under way. Engineering leaders at the agency responsible for designing the system discuss current efforts and describe GLONASS-M improvements .
On December 25, 2005, from the Baikonur Launch Site, there were three launched three navigation satellites belonging to the GLONASS system: one GLONASS satellite (the last of the first generation) and two new GLONASS-M satellites (see photo, above left).
This launch ensured the possibility of completing the flight tests for the modernized GLONASS system and performing the direct navigation determination using four GLONASS-M satellites simultaneously (two of these GLONASS-M satellites were launched earlier in 2003 and 2004).
Today, the orbital GLONASS constellation includes 16 satellites (12 GLONASS satellites and 4 GLONASS-M satellites). This article discusses the planned modernization of the GLONASS satellite navigation system with particular emphasis on the improved design of GLONASS-M satellites.
A New Commitment
When Russia faced new economical conditions in the 1990s, the financing for the space industry was reduced leading to the orbital GLONASS constellation reduction and decrease of its effectiveness.
Bearing in mind that the Space Navigation System GLONASS is a part of the national patrimony of Russia, in 2001 the president of Russian and the government of the Russian Federation ratified the policy directives setting out the intent to conclusively preserve and develop this navigation system. The Federal Target Program “Global navigation system” is one of these documents.
This program has been developed to be completed for the decade (from 2002 to 2011). During this period certain research and development activities shall be performed, including the ground experimental development for the prospective navigation spacecraft as well as flight and design tests; the ground control segment for the navigation system shall be modernized; the orbital constellation with the nominal number of satellites (24) shall be replenished.
The GLONASS system is being modernized based on the following main conditions:
• qualitative improvement of radio-navigation signal (introduction of the third frequency, increase in message rate, addition of new information into a navigation signal, etc), shift in the frequency bands keeping the possibility to work for the current existing users of the GLONASS system
With the preceding conditions implemented, there is kept the orbital configuration established earlier (three planes, with eight satellites in each plane), the orbital parameters (Н=19,400 km, i=64.8°, е=0) and the quantity of satellites in the nominal constellation (24 satellites). This enables the GLONASS operators to maintain the principles and methods of ballistic support of the satellite constellation and to provide the high-accuracy ephemeris.
New Generation Satellites
1) upgraded navigation radio signal
A GLONASS-М satellite can be injected into orbit by a cluster launch (three satellites by a single launch vehicle — see photo at the top of this article) from the Baikour Launch Site (using Proton LV and Breeze-M Booster) or by a single satellite launch from Plesetsk Launch Site using Soyuz-2 LV and Fregat Booster.
Due to the fact that on board a GLONASS-M satellite there is a great amount of mission equipment units operating in the open space environment, the satellite design represents the intermediate stage between pressurized and non-pressurized design. In the nominal mode, the satellite longitudinal axis is continuously maintained pointed to the Earth, with accuracy of 0.5°, the satellite lateral axis is kept in the Sun-satellite-Earth plane with accuracy of ~0.5°, solar array axes are oriented towards the Sun with the accuracy of 2°. The orientation is provided by electrical wheels, periodically unloaded by electromagnets.
The propulsion subsystem being a single component thruster subsystem based on the catalytic thermal hydrazine separation method provides the possibility to form control torques within the initial orientation modes of the satellite, and to generate pulses for orbit correction. The orbit correction is performed after the satellite has been injected into orbit, while drifting to the designated orbital slot. High accuracy of the initial correction of orbital parameters allows keeping the satellite within the specified station limits (±5° latitude argument) without need for further corrections during the remaining lifetime.
An electric power subsystem based on nickel-hydrogen batteries and silicon solar arrays (30m2 area) provides electric power supply for onboard equipment of continuous stable voltage of 27+1-2 V and the power of up to 1400W, continuously in eclipse and illuminated orbit arcs. The onboard control subsystem based on an onboard digital computer provides data exchange between the equipment via MIL-STD-1553-B buses and performs the functions of control, diagnostic, intersatellite ranging data processing, calculation and generation of ephemeris time data.
For figures, graphs, and images, please download the PDF of the article, above.
Vladimir A. Bartenev is deputy designer general at the Federal State Unitary Enterprise (FSUE) Scientific and Production Company of Applied Mechanics “M. F. Reshetnev” (NPO Prikladnoi Mekhaniki” named after Academician M. F. Reshetnev, Zheleznogorsk, Russia). He holds a doctor of sciences degree in engineering and is a professor and head of the mechanics and control processes department at Krasnoyarsk State University. Professor Bartenev is a recipient of the USSR Council of Ministry and Russian Federation state prizes and has been awarded both USSR and Russian Federation orders. Professor Bartenev participated in many Russian and international space projects, such as MOLNIYA, EXPRESS, and SESAT communications satellites, the project of the second-generation Russian Global Navigation System based on both GLONASS and GLONASS-M satellites, GALILEO, etc. His list of publications includes more than 100 items.
Viktor E. Kosenko is head of the Design Department at FSUE “Scientific and Production Company of Applied Mechanics named after Academician M. F. Reshetnev.” He has been awarded both USSR and Russian Federation orders. Kosenko has participated in projects of the space-based geodetic system based on the GEO-IK satellite, the first-generation Russian satellite navigation system based on TSIKADA satellites, the Russian Global Navigation System based on both GLONASS and GLONASS-M satellites, and GALILEO.
Viktor E. Chebotarev is chief engineer and designer at FSUE “Scientific and Production Company of Applied Mechanics named after Academician M. F. Reshetnev.” He holds a doctor of philosophy degree and is an associated professor. Dr. Chebotarev has received both USSR and Russian Federation orders. He participated in projects of the first-generation Russian satellite navigation system based on TSIKADA satellites and the Russian global navigation system based on both GLONASS and GLONASS-M satellites.
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