Featured image credit: Zheng Taotao/chinadaily.com.cn
Lift Off Time/Launch Window
|April 8, 2021 – 23:01 UTC|
April 9, 2021 – 07:01 BJT
|China National Space Administration (CNSA)|
|China Aerospace Science and Industry Corporation (CASIC)|
|Long March 4B|
|Launch Complex 9, Satellite Launch Center, Xinzhou, China|
|Unknown, up to 2,800 kg (6,200 lbs) to SSO|
Where is/are the satellite(s) going?
|Sun-Synchronous Orbit (SSO) at ~1,450 km, with a 101.65° inclination|
Will they be attempting to recover the first stage?
|No, the Long March family does not support booster recovery|
Where will the first stage land?
|It will crash land over North East China|
Will they be attempting to recover the fairings?
|No, the Long March family does not support fairing recovery|
Are these fairings new?
How’s the weather looking?
|Winds are predicted to be 6.5 km/hr (4 mph). |
Temperature is expected to be 5.5 °C (42 ° F)
The cloud cover is expected to be only 12%.
This will be the:
|– 4th launch of a Long March 4 (any variant) in 2021|
– 1st launch of a Long March 4B in 2021
– 41st launch of a Long March 4B ever
– 29th orbital launch attempt in 2021
Where to watch
|Livestream (if available)|
What does all this mean?
China National Space Administration (CNSA) is launching a payload known as Shiyan-6-03 to a Sun-Synchronous Orbit (SSO). The payload will orbit with an inclination of 101.56°, at an approximate altitude of 1,450 km. The launch is from the Taiyuan Satellite Launch Center in Xinzhou, North East China.
We know nothing at all about what Shiyan-6-03 actually is. There is no public information available as the Shiyan-6 satellites are classified.
We do know that its predecessor, Shiyan-6-02, was launched on a Long March 2D rocket into a different orbit (484 km perigee, 36,000 km apogee) than the one planned for this mission. This suggests that the Shiyan-6 series may be a technology program rather than a set of identical satellites.
What is the Long March 4B?
The Long March 4B is a 3-stage liquid-fueled rocket which has been in service since 1999. It uses hypergolic fuels in all three stages.
The Long March 4B’s first stage is 27.91 m long, with a diameter of 3.35 m. It uses unsymmetrical dimethyl hydrazine (UDMH) for fuel and nitrogen tetroxide (N204) as oxidizer.
It has four engines designated YF-21C. These engines use the Gas Generator combustion cycle. The YF-21 is a designation that refers to a cluster of four YF-20 engines mounted together.
The stage as a whole has thrust of around 2,960 kN (666,000 lbf). Taking all the engines together, they have a combined specific impulse of 2,550 m/s (8,400 ft/s).
The second stage has a length of 10.9 m and a diameter of 3.35 m (the same as the first stage). It also uses UDMH and N2O4 as fuel and oxidiser respectively.
The stage uses a single YF-24C engine. YF-24C is a designation that refers to a module of a YF-22C main engine and a set of YF-23C Vernier thrusters for control. The YF-22 is the high altitude version of the underlying YF-20 engine mentioned for the first stage.
The thrust of the second stage is 742 kN (166,800 lbf). The specific impulse for the stage is 2,942 m/s (9,650 ft/s) for the main propulsion elements and 2,834 m/s (9,300 ft/s) for the Vernier thrusters.
The third stage is 4.79 m tall, and has a diameter of 2.9 m. This stage again uses UDMH and N2O4 as for the two previous stages.
The stage uses a pair of YF-40 engines. Each of these engines is a dual combustion chamber, in which each combustion chamber can gimbal for control authority.
The YF-40 has a thrust of 103 kN (23,000 lbf) and a specific impulse of 303 seconds.