Yuanzheng () is a restartable

upper stage A multistage rocket or step rocket is a launch vehicle that uses two or more rocket ''stages'', each of which contains its own engines and propellant. A ''tandem'' or ''serial'' stage is mounted on top of another stage; a ''parallel'' stage is ...

developed by the

China Academy of Launch Vehicle Technology The China Academy of Launch Vehicle Technology (CALT) is a major state-owned civilian and military space launch vehicle manufacturer in China and one of the major launch service providers in the world. CALT is a subsidiary of the larger China A ...

(CALT) for the

Long March rocket family Long may refer to: Measurement * Long, characteristic of something of great duration * Long, characteristic of something of great length * Longitude (abbreviation: long.), a geographic coordinate * Longa (music), note value in early music mens ...

. The Yuanzheng stage enables the Chinese

launch vehicle A launch vehicle or carrier rocket is a rocket designed to carry a payload ( spacecraft or satellites) from the Earth's surface to outer space. Most launch vehicles operate from a launch pads, supported by a launch control center and ...

s to deploy payloads directly to high-energy orbits such as

medium Earth orbit A medium Earth orbit (MEO) is an Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between above sea level.

(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 The BeiDou Navigation Satellite System (BDS; ) is a Chinese satellite navigation system. It consists of two separate satellite constellations. The first BeiDou system, officially called the BeiDou Satellite Navigation Experimental System and ...

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 An apogee kick motor (AKM) is a rocket motor that is regularly employed on artificial satellites to provide the final impulse to change the trajectory from the transfer orbit into its final (most commonly circular) orbit. For a satellite la ...

. Yuanzheng has a thrust of with a

specific impulse Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse is ...

of 315.5 seconds. It uses the storable

hypergolic A hypergolic propellant is a rocket propellant combination used in a rocket engine, whose components spontaneously ignite when they come into contact with each other. The two propellant components usually consist of a fuel and an oxidizer. T ...

propellants

unsymmetrical dimethylhydrazine Unsymmetrical dimethylhydrazine (UDMH; 1,1-dimethylhydrazine, НДМГ or codenamed Geptil) is a chemical compound with the formula H2NN(CH3)2 that is used as a rocket propellant. It is a colorless liquid, with a sharp, fishy, ammonia-like smell ...

(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 The Long March 3B (, ''Chang Zheng 3B''), also known as the CZ-3B and LM-3B, is a Chinese orbital launch vehicle. Introduced in 1996, it is launched from Launch Area 2 and 3 at the Xichang Satellite Launch Center in Sichuan. A three-stage rock ...

and 3C, YZ-1A for

Long March 7 , stages = {{plainlist, * CZ-7: Two * CZ-7A: Three {{cite web, url=https://www.space.com/china-space-program-new-long-march-rockets.html, last=Jones, first=Andrew, title=China prepares to launch new rockets as part of push to boost spac ...

, YZ-1S for

Long March 2C The Long March 2C (LM-2C), also known as the Chang Zheng 2C (CZ-2C), is a Chinese orbital launch vehicle, part of the Long March 2 rocket family. Developed and manufactured by the China Academy of Launch Vehicle Technology (CALT), the Long Ma ...

, YZ-2 for

Long March 5 Long March 5 (LM-5; zh, s=长征五号 , p=Chángzhēng wǔ hào), or Changzheng 5 (CZ-5), and also by its nickname "''Pang-Wu''" (胖五, "''Fat-Five''"), is a Chinese heavy-lift launch vehicle developed by the China Academy of Launch Vehic ...

, and YZ-3 for

Long March 2D The Long March 2D (), also known as the Chang Zheng 2D, CZ-2D and LM-2D, is a Chinese two-stage orbital carrier rocket mainly used for launching LEO and SSO satellites. It is manufactured by the Shanghai Academy of Spaceflight Technology ( ...

Models

History

Yuanzheng was presented in a 2013 paper and performed its first mission on 30 May 2015. The debut flight of the

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

(YZ-2) in 2016,

(YZ-1S) and

(YZ-3) in 2018.

Versions

Currently, there is known to be five versions: * Yuanzheng-1 (AKA YZ-1) (): Initial version used with the

Long March 3 The Long March 3 (), also known as the Changzheng 3, CZ-3 and LM-3, was a Chinese orbital carrier rocket design. They were all launched from Launch Area 3 at the Xichang Satellite Launch Center. It was a three-stage rocket, and was mostly used ...

. 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

. 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

. * Yuanzheng-2 (AKA YZ-2) (): New version used with the

upper stage. * Yuanzheng-3 (AKA YZ-3) (): New version used with the

References

{{DEFAULTSORT:Yuanzheng-1 Rocket stages