Cosmos 2557

GLONASS-K (Russian: Глобальная навигационная спутниковая система, "Global Navigation Satellite System") is the latest satellite design intended as a part of the Russian GLONASS radio-based satellite navigation system. Developed by ISS Reshetnev (Information Satellite Systems Reshetnev) and first launched on 26 February 2011, it is a substantial improvement of the previous GLONASS-M second-generation satellites, having a longer lifespan and better accuracy. GLONASS-K is the first unpressurised GLONASS satellite — all of its equipments are able to operate in a vacuum. Due to this, the satellite's mass has been substantially reduced: GLONASS-K has a mass of just 935 kg compared to its predecessor GLONASS-M, which had a mass of 1450 kg. The new satellite has an operational lifetime of 10 years, three years longer than that of GLONASS-M and seven years longer than the lifetime of the original GLONASS satellite. It also increased the power supply from GLONASS-M's 1400 watts to 1600 watts. GLONASS-K will transmit additional navigation signals to improve the system's accuracy. Existing FDMA signals, 2 military and 2 civilian, will be transmitted on the L1 and L2 bands, and additional civilian CDMA signals will be transmitted in the L1, L2, L3 and L5 bands.