News Item

Dual BeiDou launch

China has launched 2 BeiDou 3 satellites to join its operational constellation.

The BeiDou-24 and -25 satellites were launched by a Long March-3B/YZ-1 rocket at 1145 UTC on 5 November from the Xichang Satellite Launch Center. It took ~4 hours to complete the launch phase, which appears to have been successful.

The launch was previously scheduled for July, but was delayed after the partial failure of the previous launch of this type of rocket for the ChinaSat-9A mission - resulting in the satellite being placed in a lower than planned orbit.

Spacecraft 24 and 25 will join the Medium Earth Orbit (MEO) component in this 3rd phase of Beidou. The final global constellation will comprise 27 MEOs (at ~21,500 km inclined at at 55.5ยบ), 5 in geostationary earth orbit (GEO) plus the existing 3 inclined geosynchronous orbit (IGSO) satellites of the current regional system. Global Full Operational Capability (FOC) with 35 spacecraft is scheduled for 2020.

BeiDou Phase III involves the move to a frequency centered at 1,575.42 MHz - the same as the GPS L1 and Galileo E1 civil signals - and the transformation from a quadrature phase shift keying (QPSK) modulation to the multiplexed binary offset carrier (MBOC) modulation of the future GPS L1C and Galileo E1 signals. Hence all 3 systems should be compatible.

The system will be dual-use, based on a civilian service that claims to yield an accuracy of 10 m in position, 0.2 m/s in velocity and 50 ns in time. A military and authorised service would provide higher accuracies.

Further details from the link below . .

  • 05 November 2017
  • RIN

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