China launches Yunhai-1 03

Military weather satellite successfully entered orbit

Long March-2D No. Y76 was launched from Launch Complex No. 94 of the Jiuquan Launch Center

On September 21, 2022, at 07:15 Beijing time (23:15 UTC September 20), Long March-2D (CZ-2D) rocket No. 94 of the Jiuquan Space Launch Center with the Yunhai-1 Military Weather Satellite No. 03 (YH-103). The satellite was successfully placed into a synchronous orbit with an inclination of 98.50°; perigee of 754.2 km, apogee of 775.6 km and period of 100.13 minutes. The satellite "will be used primarily for detecting atmospheric, marine and space environments, disaster prevention and mitigation, and scientific experiments." The mass of YH-1 03 should be around 1,200 kg as the CZ-2D has a capacity of 1,100 to 1,300 kg for this type of 700 km orbit.


Long March-2D

Yunhai-1 are supposed to be military weather satellites, primarily focused on monitoring marine areas. In addition to the name (the ideogram “yun” means “cloud”, and “hai” means “sea”), this interpretation is supported by the presence on board of a dual-band full polarization microwave radiometer, whose antenna normally makes 18 revolutions per minute, which is manifested in the corresponding variations in the brightness of the object. The second known instrument is the Shanghai Institute of Technical Physics' infrared scanning radiometer which was reported to be on the 2nd and 3rd spacecraft.


The first Yunhai-1 was launched on 12 November 2016 and for six years worked at a height of around 783 km with the descending node crossing at 05:30 local time. Numerous corrections were made primarily to compensate for upper atmosphere drag, although in some cases a decrease in orbit was also observed, likely for phasing purposes. A few days ago, between 15 and 17 September, the YH-1 01 dropped from 782.6 to 776.5 km, which could indicate the end of its operational life. YH-1 03 was launched in the same orbital plane. The second was launched on September 25, 2019, and like its predecessor, went into sun-synchronous orbit but with a local descending node time of 07:10. It quickly climbed to a working altitude of 783 km and made a controlled flight, synchronizing its movement with the first satellite of the series.


On March 18, 2021, Yunhai-1 02 was destroyed, resulting in at least twenty-one fragments, according to the US Space Force's 18th Space Control Squadron; to date, the number of debris in the US catalog has increased to 37. After the incident, variations in the spacecraft's brightness ceased, which was recorded in the Multichannel Monitoring Telescope MMT report for results of analyzing photometric information on orbiting space objects. near Earth from October 2021. At the same time, Yunhai-1 No. 02 continues to correct the orbit and it is assumed that the propulsion system and possibly some instruments of the payload are working. Western radio amateurs continue to receive KA signals in the L-band, which confirms the fact of their abnormal operation.


The third Yunhai-1 is the 93rd launched satellite developed by the 509th SAST Institute, including the 12th in 2022. The creation of the spacecraft was carried out for the first time in digital design mode and development support at all stages. As a result, the debug time for ground equipment has been reduced by 60%, the duration of spacecraft power before launch – by 20%, the duration of field tests – by 10%, and the number of test crews has been reduced. by 15%.


The CZ-2D rocket, like the satellite, was developed by the “8th Academy” in Shanghai, officially known as SAST. The developers announced their rapid pre-release preparation, which has reached a record 11 days and can be upgraded to 10 days. It was the 65th launch of the CZ-2D in 30 years of operation of all its variants, starting on August 9, 1992, and the 50th by Jiuquan. It also became the 482nd for all Chinese rockets and the 438th for the Changzheng (Long March) family, including the 168th for SAST-built rockets.


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