China launches L-SAR 01A as new methane rocket nears first launch from Jiuquan

China successfully launched the Gongjian Ludi Tance-1 01A (L-SAR 01A) satellite into a quasi sun-synchronous orbit of 607 kilometers. The 3.2 metric ton satellite was launched at 23:44 UTC on Tuesday, January 25 on a Chang Zheng 4C from the Jiuquan Satellite Launch Center.

The satellite is equipped with an L-band and multi-channel synthetic aperture radar (SAR) payload. It is a civilian satellite that will use a 33 square meter array to survey the Earth after major events such as earthquakes and landslides.

This is comparable to the Argentinian SAOCOM satellites which are also equipped with L-band and a SAR to monitor environmental disasters. L-band brings the advantage of being able to penetrate clouds, rain, and vegetation which makes it easier to monitor the ground. It operates in a frequency range of 1-2 GHz.

This launch was the first of two for this particular project. The L-SAR 01B mission will be launched at a later date.

The Chang Zheng 4C used for the launch is a three-stage orbital rocket for China. It was designed by the Shanghai Academy of Spaceflight Technology (SAST) and has flown 39 times to date, including this mission. It has a payload capacity of 4,200 kg to low Earth orbit (LEO) and 2,800 kg to Sun-synchronous orbit (SSO).

Ludi Tance-1 01A.

Across its lifetime, all but one of the CZ-4C’s launches have been to these two orbits while the rocket has suffered two failures — the first on the Gaofen 10 mission in August 2016 and the second on the Yaogan 33 mission in 2019.

The CZ-4C stands 45.8 meters tall with a diameter of 3.35 meters and a liftoff mass of 250,000 kg. It first flew in April 2006 with the Yaogan 1 mission. Its previous flight to this launch was the Ziyuan I-02E mission in December 2021.

Originally, the CZ-4C was to be named Chang Zheng 4B-II, as it is an upgrade to the Chang Zheng 4 rocket with an improved payload volume and a restartable upper stage for different orbital maneuvers.

The first two stages of the rocket are derived from the Dongfeng 5 intercontinental ballistic missile. Its first stage stands 27.91 meters tall and has a propellant mass of 182,000 kg. It is powered by four YF-21C engines which utilize dinitrogen tetroxide as an oxidizer and unsymmetrical dimethylhydrazine as a fuel. This hypergolic combination is highly toxic and not as efficient as modern rocket fuels such as methane, kerosene, or hydrogen.

The next generation of rockets in the Chang Zheng family all use these rocket fuels instead of the hypergolic mix.

A Chang Zheng 4C launching from Jiuquan. (Credit: China Daily News)

At liftoff, each of the CZ-4C’s first stage engines produces 740.4 kN of thrust, bringing the liftoff thrust of the first stage to 2,961.6 kN. Each engine has a specific impulse of 260 seconds.

After the first stage has done its job, the second stage takes over. It has a length of 10.9 meters with the same diameter as the first stage and is powered by a single YF-22C engine which uses the same fuel combination as the first stage.

It produces a thrust of 742.04 kN and features four YF-23C vernier engines which produce enough thrust to steer the second stage and the payload on their way to orbit.

Together, the combination of these engines is called the YF-24C.

The last stage is slightly smaller than the first two at only 2.9 meters in diameter and 14.79 meters in length. The single YF-20 engine provides 100 kN of thrust and has a specific impulse of 412 seconds. It is responsible for the last burn before the payload reaches its desired orbit.

Today’s launch was conducted from the Jiuquan Satellite Launch Center (JSLC) which opened in 1958 and has since hosted a variety of Chang Zheng family launchers, such as CZ-2/CZ-4 and CZ-11.

Recent news from the Jiuquan region emerged in photographs from the Pleiades-1B Earth surveillance satellite. In the image, a LandSpace ZhuQue-2 (ZQ-2) rocket is visible in two parts (its fairing/second stage and its first stage) next to a hangar at Jiuquan.

This methane-based rocket has the goal of bringing up to 4,000 kg into LEO and 2,000 kg into SSO. It stands 49.5 meters tall, 3.35 meters in diameter, and has a liftoff mass of 216 tons. At liftoff, the four TQ-12 Methalox engines can produce up to 320 tons of thrust. According to CEO Zhang Changwu, the company hopes to produce up to 15 ZQ-2 rockets in 2022, with the first launch still planned for Q1 of the year. 

So far, LandSpace has launched their smaller ZhuQue-1 rocket once in October 2018. However, that launch was not a success, with the third stage having a malfunction before reaching orbital velocity. Currently, it is unclear if there will be the second flight of ZQ-1.

While early ZQ-2 launches have no reuse planned, LandSpace hopes to eventually reuse the first stage. Based on the satellite image, it is unclear if this is a structural pathfinder or a future launch vehicle. Regardless, it signifies progress towards the first flight this year.

(Lead image: A CZ-4C launches the Lude Tance-1 01A mission from Jiuquan.)

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China launches L-SAR 01A as new methane rocket nears first launch from Jiuquan