Long March 3B, Shiyan 10-02, CZ-3B, launch, YF-20, YF-21, YF-25

Shiyan 10 | Long March 3B/E

Liftoff Time
September 27, 2021 – 8:20 UTC | 16:20 BJT
Mission Name
Shiyan 10, an experimental satellite
Launch Provider
(What rocket company launched it?)
China Aerospace Science and Technology Corporation (CASC)
(Who paid for this?)
Given the nature of the payload, probably the Chinese government
Long March 3B/E Y81
Launch Location
LC-3, Xichang Satellite Launch Center, in the Sichuan province, China
Payload mass
Where did the spacecraft go?
Molniya orbit, of about 1480 km by 38,880 km (920 mi by 24,160 mi) at 50.9 degrees inclination; initially: 177 km by 40,104 km (110 mi by 24,925 mi) at 51.04 degrees inclination
Did they attempt to recover the first stage?
No, this is not a capability of the Long March 3B/E
Where did the first stage land?
The boosters of the Long March 3B/E crashed into the mountains of Guangxi
Did they attempt to recover the fairings?
No, this is not a capability of the Long March 3B/E
Were these fairings new?
This was the:
– 93rd orbital launch of 2021
– 36th Chinese launch of 2021
– 33rd launch of 2021 provided by CASC
– 137th mission of the Long March 3 rocket family
– 129th successful mission of the Long March 3 rocket family
– 8th mission in 2021 of a Long March 3 rocket
– 390th launch of a Long March rocket
Where to watch

How Did It Go?

Atop a Long March 3B/E rocket, the China Aerospace Science and Technology Corporation (CASC) launched the secretive Shiyan 10 (SY-10) payload. Xichang Satellite Launch Center’s Launch Complex 3 saw the rocket take to the skies, completing every milestone for the flight. The vehicle deployed the satellite into a transfer orbit, from where it would move using its own propulsion system.

However, many hours after liftoff there was no confirmation of success. The following day, official sources informed that the flight of the rocket had been nominal, as well as the payload’s orbital insertion. In spite of this, the satellite’s condition presented some kind of anomaly during its ride atop the launch vehicle. At this point, there were serious doubts regarding the health of the payload.

Two and a half weeks later, around October 15, Shiyan 10 raised its perigee, contradicting the hypothesis the spacecraft was not operational. Conversely, some rumors claimed the satellite went through a successful recovery process. Months passed, and, between February 28 and March 30, 2022, SY-10 finally moved to its target destination: a Molniya orbit. Such an orbit is a highly elliptical one with a higher apogee than the geostationary one, and relatively high inclination.

Considering the usual Chinese protocols regarding launches, it certainly seems unusual that none of the involved Chinese agencies informed about the success or failure of this mission. Besides the public news of a successful flight, it remains unclear if the satellite became fully operational, in the end.

What Is The Shiyan 10 Payload?

Shiyan Satellites

China’s aerospace industry has a number of prolific programs aimed at improving applied technologies in this field. The Shiyan 10 satellite is indeed part of a series of spacecraft of the same general designation. These certainly play a role in the mentioned search for progress. Particularly, this fact is highlighted by the Chinese word used for their name — Shiyan, or SY for short — which, some experts point out, should be translated as “pilot” or “trial.” However, these satellites are more commonly mentioned as “experiment,” a more widely used translation.

Other series aiming to achieve similar goals are the Shijian, or SJ — best practice, put into practice — and the Chuangxin, or CX — innovation. Both SJ and SY payloads have been contributing for decades now to the China High-resolution Earth Observation System (CHEOS). Apparently, though, a distinction can be made between those last two, as the Shijian sats have favored more radar and infrared payloads. On the other hand, Shiyan have been more focused on Earth-observation satellites.

In order to further differentiate the SY from the SJ, the latter are probably testing, or putting into practice, more mature technologies. These could imply a lower failure ratio, when compared to the Shiyan more experimental spacecraft. Similarly, the Chuangxin might also find themselves in an early condition.

Shiyan 10

Basically nothing has been disclosed about this payload, given the context, but also in resonance with all that is explained in the previous paragraphs. The analysts believe this spacecraft has been developed by SAST. If the hypothesis that Shiyan 10-02 was actually a replica of Shiyan 10, then this can be true. In that case, it is possible to say SY-10 will be mainly used for in-orbit verification of new space technologies, such as space environment monitoring. However, this official statement is contested by analysts who argue the selected Molniya orbit could very well imply uses such as communications, missile warning, and signal intelligence.

Other Shiyan Launches

As previously mentioned, these satellites are part of a larger group of “pilot” payloads. In the following table you can find some other Shiyan spacecraft that were launched in the past.

DateLaunch VehicleMission Name
November 25, 2013 – 2:12 UTCLong March 2DShiyan 5
November 19, 2018 – 23:40 UTCLong March 2DShiyan 6
July 4 – 2020, 23:44 UTCLong March 2DShiyan 6-02
March 11, 2021 – 17:51 UTCLong March 7AShiyan 9
April 8, 2021 – 23:01 UTCLong March 4BShiyan 6-03
List of the previous five Shiyan launches

What Is The Long March 3B?

Despite the Chinese rockets having different heritages, most of China’s orbital launch vehicles use the “Long March” (Chang Zheng) naming scheme. Thus, the Long March 3B is a three-stage rocket, with an optional fourth stage. Four liquid-fueled side boosters stand strapped to the first stage, and the launcher’s maiden flight took place in 1996.

The Long March 3B/E, the enhanced version of the Long March 3B, was first launched in 2007, and has greater Geostationary Transfer Orbit (GTO) payload capacity. The enhanced 3B/E’s have a larger first stage and larger side boosters, compared to the original Long March 3B. As a result, its payload capacity to GTO was increased from 5,100 kg (~11,300 lb) to 5,500 kg (~12,200 lb).

The Long March 3B series features the following sections or stages:

Side Boosters

There are four side boosters that each use one YF-25 engine, which runs on unsymmetrical di-methyl hydrazine (UDMH), the fuel, and nitrogen tetroxide (N2O4), the oxidizer. Although the regular Long March 3B’s side boosters are 15.33 m (50.3 ft) long, the enhanced versions are 16.1 m (52.3 ft) long, producing 740 kN of thrust for both versions. The YF-25 engine has a specific impulse (ISP) of 260 s, and burns for 140 s on the 3B/E variant.

First (Center) Stage

The first stage has four YF-20C engines (this group forms a YF-21C engine), which also use UDMH/N2O4 for propellant. The first stage has an ISP of 260 s and produces 2,960 kN of thrust. In the LM-3B’s case, its length is 23.27 m (76.35 ft) tall, but the 3B/E’s version is 24.76 m (81.23 ft) tall.

Long March 3B/E, launch, APStar-9
Long March 3B/E launch with APStar-9 (Credit: ChinaNews.com)

Second Stage

The second stage is powered by a single YF-22E engine, which is a vacuum-adapted version of the YF-20E. However, a single YF-23C vernier engine with four nozzles provides attitude control, which combined with the main one forms a YF-24E engine. The engine runs on UDMH and N2O4, and produces 742 kN of thrust. The second stage is 12.9 m (42.3 ft) tall and burns for 185 s.

Long March 3, rocket family
The Long March 3 family of rockets (Credit: CGWIC)

Third Stage

The third stage is 12.4 m (40.7 ft) long and two YF-75 engines power it. Unlike the other stages, this stage runs on liquid hydrogen (LH2) and liquid oxygen (LOx).

The third stage will ignite its engine after the second stage is jettisoned, in order to continue to raise the orbital apogee (maximum altitude). Once the target apogee has been achieved, it shuts down. The vehicle will then coast to apogee, where the stage relights and burns to raise the perigee (lowest altitude) of the orbit.

Optional Fourth Stage

The fourth stage runs on UDMH / N2O4, and has a singular YF-50D engine.

Rocket section adapted from Andy Law

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