The Global Navigation Satellite System (GLONASS) is based on a constellation of active satellites which continuously transmit coded signals in two frequency bands, which can be received by users anywhere on the Earth's surface to identify their position and velocity in real time based on ranging measurements. The system is a counterpart to the United States Global Positioning System (GPS) and both systems share the same principles in the data transmission and positioning methods. GLONASS is managed for the Russian Federation Government by the Russian Space Forces and the system is operated by the Coordination Scientific Information Center (KNITs) of the Ministry of Defense of the Russian Federation.

The operational space segment of GLONASS consists of 21 satellites in 3 orbital planes, with 3 on-orbit spares. The three orbital planes are separated 120 degrees, and the satellites within the same orbit plane by 45 degrees. Each satellite operates in circular 19,100 km orbits at an inclination angle of 64.8 degrees and each satellite completes an orbit in approximately 11 hours 15 minutes. 

The ground control segment of GLONASS is entirely located within former Soviet Union territory. The Ground Control Center and Time Standards is located in Moscow and the telemetry and tracking stations are in St. Petersburg, Ternopol, Eniseisk, Komsomolsk-na-Amure.

The first GLONASS satellites were launched into orbit in 1982. Two Etalon geodetic satellites were also flown in the 19,100 km GLONASS orbit to fully characterise the gravitational field at the planned altitude and inclination. The original plans called for a complete operational system by 1991, but the deployment of the full constellation of satellites was not completed until late 1995 / early 1996. GLONASS was officially declared operational on September 24, 1993 by a decree of the President of the Russian Federation.

Table 1: GLONASS Satellite Slots/Planes

The Russian military identified, in the late 1960s a need for a Satellite Radio Navigation System (SRNS) for use in precision guidance of new generation of ballistic missiles in planning. The existing Tsiklon satellite navigation system required several minutes of observation by the receiving station to fix a position making them unusable for navigation positioning purposes. In 1968 to 1969 research institutes of the Ministry of Defence, Academy of Sciences, and Soviet Navy joined together to establish a single solution for air, land, sea, and space forces. This resulted in a 1970 requirements document that established the requirements for such a system. After further basic research in 1976 a decree was issued by the Soviet Union establishing the Global'naya Navigatsionnaya Sputnikovaya Sistema (GLONASS, Global Navigation Satellite System).

The constellation is currently operating in a degraded mode with only eight satellites fully operationall. A program for the gradual enhancement of the GLONASS constellation is being developed. That plan calls for 12 functioning satellites in 2001.

Work is underway to modernize the system. The Russian Space Forces plan to start flight tests of a new GLONASS-M program which would be launched between now and 2004. The new GLONASS-M satellite will have better signal characteristics as well as a longer design life (7-8 years instead of the current 3 years). In the future, plans are being developed to transition to a low mass third generation GLONASS-K satellites with a guaranteed lifespan of 10 years.