Uragan-K or GLONASS-K (originally called Uragan-K) spacecraft are the third generation of GLONASS navigation satellites. These satellites have an increased lifetime of 10 - 12 years, reduced weight of only 935 kg and offer an additional L-Band navigational signal.
GLONASS (Globalnaya Navigationnaya Sputnikovaya Sistema, Global Orbiting Navigation Satellite System) is a Russian space-based navigation system comparable to the American GPS system, which consists of Uragan spacecraft. The operational system contains 21 satellites in 3 orbital planes, with 3 on-orbit spares. GLONASS provides 100 meters accuracy with its C/A (deliberately degraded) signals and 10-20 meter accuracy with its P (military) signals.
The Uragan-K spacecraft are 3-Axis stabilized, nadir pointing with dual solar arrays.
The payload consists of L-Band navigation signals in 25 channels separated by 0.5625 MHz intervals in two frequency bands: 1602.5625 - 1615.5 MHz and 1240 - 1260 MHz. EIRP 25 to 27 dBW. Right hand circular polarized. On-board cesium clocks provide time accuracy to 1000 nanoseconds. A civil reference signal on L2 frequency is to be added after the completion of flight testing of Glonass-M in 2004 to substantially increase the accuracy of navigation relaying on civil signals. A third civil reference signal within the new frequency band of 1164-1215 MHz offered by the Glonass-K1 satellite to enable civil airlines to use satellite-aided positioning as the primary navigation facility.
Besides the GLONASS navigation payload, these satellites carry several hosted payloads:
- a KOSPAS-SARSAT international search-and-rescue transponder
- the SKYaI nuclear detection payload
The two Uragan-K spacecraft were launched from Plesetsk on Soyuz-2-1b Fregat boosters. They were built to be launched in pairs, but as they gained mass during development this was not used.
Originally, only two satellites were to be built, but this series was extended to 13 satellites to be launched until 2023. This series will be gradually replaced with the improved Uragan-K2 (GLONASS-K2) series beginning in late 2019.
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