19 Sep: China launched a Long March-3B with a Yuanzheng-1 (Expedition-1) upper stage and two backup Beidou-3 navigation satellites (2024-168) from Xichang. The two medium earth orbit (MEO) satellites (BeiDou-3 MEO-27 and MEO-28) are the 59th and 60th of the Beidou family and the fourth and fifth to act as backup satellites for China’s Beidou-3 Navigation Satellite System (BDS-3). They are the final satellites in the Beidou-3 constellation. Launch Video.
– Both satellites reached their intended orbit of 22,192 x 21,530km with an inclination of 55°. The satellites will be used as spares for the existing 24 MEO Beidou-3 satellites as well as for testing new upgraded atomic clock parts and new inter-satellite link terminals for China’s planned Beidou-4 constellation.
– Prior to the 19 Sep launch, the most recent Beidou-3 launch occurred in late-2023 and also sent 2 satellites to MEO. Those satellites were also considered spares.
– Most of the Beidou-3 satellites have been operational for six years. The spare satellites allow for the system to keep operating while older satellites are maintained and managed.
– Beidou is China’s own global navigation satellite system (GNSS) to rival U.S. GPS, Europe’s Galileo and Russia’s GLONASS systems. China completed its construction in mid-2020. See video on Beidou development history.
– China embarked on building the Beidou constellation in 1996 after it suspected two of its three missile tests over Taiwan failed due to their reliance on GPS.
– According to one PLA Colonel at the time: “It was a great shame for the PLA … an unforgettable humiliation.”
– In 1996, China decided to build its own navigation system, to be completed within 25 years. Their goal was to establish truly independent military command and control, and precision missile guidance and tracking.
– Beidou-3 operates in 3 MEO-planes (8 satellites per plane not counting spares), GEO Stationary Orbit (3 satellites) and Inclined GEO Synchronous Orbit (3 satellites). Beidou-3 provides global coverage and offers more accessible and accurate PNT data in the Asia-Pacific region than any other GNSS, including GPS, according to a 2023 report by Harvard’s Belfer Center.
– China is expected to begin launching Beidou-4 satellites to Low Earth Orbit (LEO) as early as 2025.
– With Beidou-4, China aims to build a more ubiquitous, integrated and intelligent PNT system by 2035. China intends for Beidou-4 to be more powerful, secure and reliable, providing services from indoors to outdoors, and from deep sea to deep space.
BeiDou-3 constellation showing MEO-27 and MEO-28, with 28 MEO, 3 GEO, and 3 IGSO satellites (spaceaware.io).
Long March-3B lift off with BeiDou-3 MEO-27 and MEO-28 (@Skyfeather16 via X).
