Yuanzheng () is a restartable upper stage developed by the China Academy of Launch Vehicle Technology (CALT) for the Long March rocket family.
The Yuanzheng stage enables the Chinese launch vehicles to deploy payloads directly to high-energy orbits such as medium Earth orbit (MEO) and geosynchronous orbit (GSO). Since the Long March third stage cannot restart, it cannot circularize a GSO or GEO orbit from a geosyncronous transfer orbit (GTO). With its restart capability, Yuanzheng has enabled the deployment of satellite pairs for the BeiDou Navigation Satellite System in MEO and communications satellites in GSO. This eliminates the need for the spacecraft to include a liquid apogee engine or an apogee kick motor.
Yuanzheng has a thrust of with a specific impulse of 315.5 seconds. It uses the storable hypergolic propellants unsymmetrical dimethylhydrazine (UDMH) and dinitrogen tetroxide (), and can perform at least two burns within its rated life of 6.5 hours, sufficient to reach the transfer orbit apogee, and perform the circularization burn from there.
Operational variants are designated YZ-1 for Long March 3B and 3C, YZ-1A for Long March 7, YZ-1S for Long March 2C, YZ-2 for Long March 5, and YZ-3 for Long March 2D.
Versions Currently, there is known to be five versions: Yuanzheng-1 (AKA YZ-1) (): Initial version used with the Long March 3. It could perform missions of 6.5 hours, make two ignitions, perform one spacecraft deployment operation. Yuanzheng-1A (AKA YZ-1A) (): Improved version used with the Long March 7. Improved version with mission life extended to 48hs, capability to perform at least 9 ignitions and ability to do 7 different separation events. It also includes improved thermal control system, guidance algorithms and orbit planning for multiple payload deployment missions. It will be used as the base system for future deep space propulsion stages, space tugs and orbital servicing and debris removal spacecraft. Yuanzheng-1S (AKA YZ-1S) (): Improved version used with the Long March 2C. Yuanzheng-2 (AKA YZ-2) (): New version used with the Long March 5 upper stage. Yuanzheng-3 (AKA YZ-3) (): New version used with the Long March 2D.
History Yuanzheng was presented in a 2013 paper and performed its first mission on 30 May 2015. The debut flight of the Long March 7 in 2016 included an improved version called Yuanzheng-1A that can flexibly deploy multiple payloads into various target orbits. Further variants were later deployed for Long March 5 (YZ-2) in 2016, Long March 2C (YZ-1S) and Long March 2D (YZ-3) in 2018.
Flight No.Date (UTC)Carrier RocketStage ModelSerial numberLaunch siteMissionResult 1 2015-03-3013:52 Long March 3C YZ-1 Y1 Xichang BDS I1-S 2 2015-07-2512:29 Long March 3B YZ-1 Y2 Xichang BDS M1-S / BDS M2-S 3 2016-02-0107:29 Long March 3C YZ-1 Y3 Xichang BDS M3-S 4 2016-06-2512:00 Long March 7 YZ-1A Y1 Wenchang Inaugural Mission 5 2016-11-312:43 Long March 5 YZ-2 Y1 Wenchang Inaugural Mission 6 2017-11-511:45 Long March 3B YZ-1 Y4 Xichang BDS-3 M1BDS-3 M2 7 2018-01-1123:18 Long March 3B YZ-1 Y5 Xichang BDS-3 M7BDS-3 M8 8 2018-02-1205:03 Long March 3B YZ-1 Y6 Xichang BDS-3 M3BDS-3 M4 9 2018-03-2917:56 Long March 3B YZ-1 Y7 Xichang BDS-3 M9BDS-3 M10 10 2018-07-2901:48 Long March 3B YZ-1 Y8 Xichang BDS-3 M5BDS-3 M6 11 2018-08-2423:52 Long March 3B YZ-1 Y9 Xichang BDS-3 M11BDS-3 M12 12 2018-09-1914:07 Long March 3B YZ-1 Y10 Xichang BDS-3 M13BDS-3 M14 13 2018-10-0902:43 Long March 2C YZ-1S Y1 Jiuquan Yaogan 32A, 32B 14 2018-10-1504:23 Long March 3B YZ-1 Y11 Xichang BDS-3 M15BDS-3 M16 15 2018-11-1818:00 Long March 3B YZ-1 Y12 Xichang BDS-3 M17BDS-3 M18 16 2018-12-2908:00 Long March 2D YZ-3 Y1 Jiuquan Yunhai-2 01, 02, 03, 04, 05, 06Hongyan-1 17 2019-09-2221:10 Long March 3B/E YZ-1 Y13 Xichang BDS-3 M23BDS-3 M24 18 2019-11-2300:55 Long March 3B/E YZ-1 Y14 Xichang BeiDou-3 M21BeiDou-3 M22 19 2019-12-1607:22 Long March 3B/E YZ-1 Y15 Xichang BeiDou-3 M19 BeiDou-3 M20 20 2021-08-2411:15 Long March 2C YZ-1S Y2 Jiuquan RSW-01RSW-02unknown payload 21 2021-11-0307:43 Long March 2C YZ-1S Y4 Jiuquan Yaogan 32-02A, 32-02B 22 2022-05-2010:30 Long March 2C YZ-1S Y5 Jiuquan LEO Test Sat 1/2Digui Tongxin Weixing 23 2023-07-0911:00 Long March 2C YZ-1S Y3 Jiuquan Hulianwang Jishu Shiyan 1AHulianwang Jishu Shiyan 1B 24 2023-11-1603:55 Long March 2C YZ-1S Y9 Jiuquan Haiyang-3A 25 2023-11-2310:00 Long March 2D YZ-3 Y2 Xichang Hulianwang Jishu Shiyan 2AHulianwang Jishu Shiyan 2BHulianwang Jishu Shiyan 2C 26 2023-12-2603:26 Long March 3B/E YZ-1 Y16 Xichang BeiDou-3 M25 BeiDou-3 M26 27 2023-12-3000:13 Long March 2C YZ-1S Y17 Jiuquan Hulianwang Jishu Shiyan 4AHulianwang Jishu Shiyan 4BHulianwang Jishu Shiyan 4C 28 2024-03-1312:51 Long March 2C YZ-1S Y18 Xichang DRO-ADRO-B 29 2024-03-2105:27 Long March 2D YZ-3 Y3 Jiuquan Yunhai-2 Group 02 30 2024-09-1901:14 Long March 3B/E YZ-1 Y17 Xichang BeiDou-3 M27 BeiDou-3 M28 31 2024-12-1207:17 Long March 2D YZ-3 Y5 Jiuquan Gaosu Jiguang Zuanshi Xingzuo Shiyan Xitong (High-speed Laser Diamond Constellation Experimental System) × 5 32 2024-12-1610:00 Long March 5B YZ-2 Y2 Wenchang Hulianwang × 10 (SatNet LEO Group 01) 33 2025-04-2820:10 Long March 5B YZ-2 Y3 Wenchang Hulianwang × 10 (SatNet LEO Group 03) 34 2025-08-1306:43 Long March 5B YZ-2 Y4 Wenchang Hulianwang × 10 (SatNet LEO Group 08)
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