Featured image credit: SAST
Lift Off Time | September 26, 2022 – 20:50 UTC September 27, 2022 – 04:50 BJT |
|---|---|
Mission Name | Shiyan 16A/B & Shiyan 17 |
Launch Provider | China Aerospace Science and Technology Corporation (CASC) |
Customer | China Academy of Launch Vehicle Technology — CALT Shanghai Academy of Spaceflight Technology — SAST |
Rocket | Long March 6 (CZ-6) |
Launch Location | LC-16, Taiyuan Satellite Launch Center, China |
Payload mass | Unknown |
Where did the satellites go? | Circular ~510 km Sun-Synchronous Orbit (SSO) at 97.45 degrees inclination |
Did they attempt to recover the first stage? | No, this is not a capability of the Long March 6 |
Where did the first stage land? | It crashed in the north eastern region of China |
Did they attempt to recover the fairings? | No, this is not a capability of the Long March 6 |
Were these fairings new? | Yes |
This was the: | – 11th launch of the Long March 6 (any variant) – 125th orbital launch attempt of 2022 |
Where to re-watch | Unofficial replay |
How Did it Go?
On September 26, 2022 at 20:50 UTC a Long March 6 was launched by CASC from the Launch Complex 16 belonging to the Taiyuan Satellite Launch Center, located in Shanxi, China. Transporting three satellites — two Shiyan 16 (A and B) and a Shiyan 17 — the rocket went through all of the flight’s milestones and achieved the targeted Sun-synchronous orbit at approximately 510 km in altitude and 97.45 degrees of inclination. All three payloads were then deployed as expected, and the mission was afterward reported a complete success.
What Are The Shiyan Payloads?
China’s aerospace industry has a number of prolific programs aimed at improving applied technologies in this field. Shiyan satellites are a series of spacecraft which certainly play a role in the mentioned search for progress. This particular 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 16 A/B And 17
Not a lot has been disclosed about these payloads, in resonance with all that is explained in the previous paragraphs. Official reports state that these microsatellites have been developed by CALT and by SAST, respectively. These spacecraft will be mainly used in the fields of land surveying, urban planning, and disaster prevention and mitigation. This mission set a record regarding turnaround for CASC’s Eighth Academy — another way of mentioning SAST — since it last sent spacecraft to space.
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 recent past.
| Date | Launch Vehicle | Mission Name |
| April 8, 2021 – 23:01 UTC | Long March 4B | Shiyan 6-03 |
| November 24, 2021 – 23:41:00 UTC | Kuaizhou-1A | Shiyan 11 |
| December 23, 2021 – 10:12 UTC | Long March 7A | Shiyan 12-01 & 02 |
| January 17, 2022 – 02:35 UTC | Long March 2D | Shiyan 13 |
| September 24, 2022 – 22:55 UTC | Kuaizhou-1A | Shiyan 14 & 17 |
What Is The Long March 6?
Long March 6 Yao 9
Yao indicates the vehicle’s serial number, meaning this Long March 6 was the ninth of its kind. For this flight, the rocket saw an increase in its payload fairing size, becoming 2.9 m in diameter. Additionally, a high-altitude wind upgrade now allows the rocket to better adapt to changes in these atmospheric currents. On the side of ground operations, there have also been adjustments to kerosene filling procedures. As a result, this task can now be accomplished in a swifter and safer manner.
A Brief History Of The New Long Marches
Like many other programs in the spaceflight world, the Chinese space program builds up on heritage knowledge and hardware from the defense sector. Examples of this are the veteran rockets in the family, namely the Long March 2, 3, and 4 — these still have active variants — which derive from the Dong Feng 5 intercontinental ballistic missiles (ICBM).
After decades in service, these hypergolics-propelled launch vehicles are finally, though slowly, heading for retirement. In their stead, a program was delineated to develop and manufacture a new generation of rockets purely conceived with only space applications in mind. The enterprise was assigned to the China Academy of Launch Vehicle Technology (CALT).
Aiming to develop flexible launchers, utilizing more advanced technologies, avoiding the use of highly toxic propellants, and following modularization criteria, the Long March 5 (LM-5) was envisaged, and a series of supplementary vehicles: the Long March 6, 7, and 8. Through the implementation of stages in three basic diameters — 5 m (16.4 ft), 3.35 m (11.0 ft), and 2.25 m (7.4 ft) — housing liquid-fed engines specifically developed for this plan, the newcomers were brought forth.
Description Of The Long March 6
As it typically is the case with the Chinese launchers, its name is actually Chang Zheng, which translates to Long March and from it originates the abbreviated form CZ — LM, in English. Because it is the sixth in the family, it adds the number “6” to the end of all these different ways of referring to it. As a launch vehicle, it is a liquid-fueled small-lift rocket developed initially by CALT, then by the Shanghai Academy of Spaceflight Technology (SAST), a subsidiary of the Chinese CASC. This launcher was mainly developed for Sun-synchronous orbits (SSO), although it has also launched to low-Earth orbit (LEO).
Due to performance issues, the initial plans of making this rocket’s first stage with a 2.25 m diameter had to be modified. This is why the lowest part of the rocket is bulkier than the rest, using the next up standard diameter: 3.35 m. After its development started in 2008, the Long March 6 first flew on September 19, 2015.
Assembly, payload integration, and transportation to the launch site are all carried out horizontally. The vehicle is then erected in the pad.
| Characteristic | Value |
|---|---|
| Amount of stages | 3 |
| Length [m] | 29.30 |
| Maximum diameter [m] | 3.35 |
| Fairing length [m] | 6.15 |
| Fairing diameter [m] | 2.60 |
| Lift-off mass [kg] | 103,000 |
| Empty mass [kg] | ~9,020 |
| Mass to LEO [kg] | 1,500 |
| Mass to SSO [kg] | 1,080 |
Stages Of The Long March 6
First
Only one YF-100 engine powers the first stage, which is an oxygen-rich staged combustion cycle engine. It features a specific impulse of 300 s (sea level) and 335 s (vacuum). To ensure enough pressure in the LOx tank, autogenous pressurization is implemented. While the nozzle gimbals, roll control is achieved by redirecting the preburners’ exhaust gasses.
Second
Again, a single YF-115 engine powers the Long March 6’s second stage, featuring a specific impulse of 341.5 s. Being related through its development to the already mentioned YF-100, this smaller engine runs also oxygen-rich and works under a staged combustion cycle. Autogenous pressurization is once more used in the LOx tank. Roll and attitude control is obtained through the third’s stage corresponding system.
Third
There has been some lack of clarity regarding what this third stage was like, but the strongest evidence suggest it is a kick stage for precise orbit injection with an engine running on hypergolic propellants, and relight capabilities.
The following table allows for a fast understanding of the Long March 6’s stages, supplementing the general specifications of the rocket.
| Stage Number | Length [m] | Diameter [m] | Propellant Mass [kg] | Amount of Engines | Engine Name | Propellants | Thrust* [kN] |
| 1 | 13.43 | 3.35 | 76,000 | 1 | YF-100 | RP-1/LOx | ~1,200 |
| 2 | 5.52 | 2.25 | 15,000 | 4 | YF-115 | RP-1/LOx | ~180.0 |
| 3 | 0.79 | 2.25 | Unknown | 1 | Unknown | UDMH/N2O4 | 6.5 |
*Thrust of the stage as a whole.
