Chinese Zhuque-2 fails during first methalox orbital launch attempt

by Adrian Beil

The first attempt to launch an orbital methane rocket was not successful. China’s LandSpace launched the Zhuque-2 rocket at around 08:30 UTC to a Sun-synchronous orbit (SSO) from Jiuquan. The rocket failed to reach the desired orbit, falling short of orbital velocity by about 2 km/s.

From videos posted on Chinese social media, it seems that the rocket performed a nominal first-stage flight and main engine cutoff (MECO). The problem occurred late in the second stage flight, during a handover point between the main engine and the four vernier engines.

The company did not release a statement about the failed attempt. This is further underlining the fact that it failed as late announcements of rocket launches usually indicate bad news in Chinese spaceflight.

In images that spread from the mission control, it was observable that the rocket performed until about five minutes into the flight. At 5 km/s the second stage most likely suffered an issue during a shutdown and failed to accelerate the mission to orbital velocity. This is comparable to the failure that happened to the Zhuque-1 rocket.

At this point in flight, the main engine of the second stage should have shut down, while the four vernier engines would have continued for the final part of the burn. This is similar to Chang Zheng 2 rockets, where a similar profile using vernier engines is used.

Based on the desired thrust profiles, it appeared that the vernier engines did perform nominal until the second stage cutoff, as the thrust profile did not deviate from the planned profile up to that point. With the suspicion that the vernier engines and the second stage main engine have a lot of shared components, one of these shared parts might have failed at SECO, causing an early shutdown of the verniers.

The rocket was initially announced to launch on Dec. 3. After a few days of delay, Harry Stranger confirmed on Dec. 5 that the rocket reached launch Site 96 at the Jiuquan Satellite Launch Center (JSLC). A few days later, the rocket was put into a vertical launch configuration and readied for launch.

The payloads for the maiden launch are a variety of rideshare satellites, including a Jilin Gaofen payload. Unconfirmed reports indicate 14 payloads on the maiden flight of Zhuque-2. With the rocket not reaching orbit, all of the payloads reentered the atmosphere and were lost. They reentered the atmosphere over the Indian ocean. 

While it did not achieve its mission goals, this still makes ZQ-2 the first rocket in the world to make an orbital attempt with methane. Relativity Space and SpaceX are in a contest with the Terran 1 and Starship rockets to get the next shot to reach orbit first.

Zhuque-2 may also still have a chance, as the second and third flight vehicles are already in construction. Another contender for the first orbital methane rocket might be ULA’s Vulcan, which will use the Blue Origin-provided BE-4 methalox engines.

If the vernier engines were indeed the culprit of failure, it might lead to LandSpace forcing an upgrade for the second stage earlier than expected. This update was previously not expected for flight two of the rocket and would delete the need for vernier engines.

The next ZQ-2 rocket in construction. (Credit: LandSpace)

Zhuque-2 (Redbird 2 in English) is a private rocket of the Chinese company LandSpace. It is 49.5 meters tall, with a diameter of 3.35 meters and a mass at liftoff of about 219 tons. 

It aspires to solve the need of China for medium-capacity launch vehicles, especially for SSO. These orbits are often used for optical satellites and are currently served by old Chang Zheng rockets, which are supposed to be phased out over the coming years. ZQ-2 could play a reasonable part in the replacement of these older hypergolic rockets if it manages success in upcoming missions.

It is planned to launch payloads of up to six tons to a low Earth orbit (LEO), and up to four tons to a 500 km SSO. For today’s launch, it is not known how much the rideshare payloads massed.

The first stage is powered by four TQ-12 methalox engines. These engines are the first in China to use methane as a fuel and the first time that methalox engines were used on an orbital attempt of a rocket. It is a gas generator open cycle engine, similar to the SpaceX Merlin engine, although using a different fuel, that produces about 658 kN of thrust at sea level.

ZQ-2 rolling out. (Credit: LandSpace)

This brings the combined thrust of the four engines at liftoff to about 2,632 kN with a specific impulse of 284.5 seconds. The engine was first fully assembled and fired in May 2019, and performed longer firings of 200 seconds in October of the same year. In January 2021, a series of long-duration firing was conducted to ready the engine for assembly into the first stage module. 

In July 2022, LandSpace announced that the 37th TQ-12 engine was produced, with an overall test duration of over 20,000 seconds. Down the line, the company plans to replace the first-stage engine on the rocket with the improved TQ-12A engine. This engine will provide an increased thrust, a 40 s improved specific impulse, and a massively reduced mass. The current engine production rate allows for one rocket launch per month. 

An upgraded TQ-12A on the test stand. (Credit: LandSpace)

In November 2020, the second stage with its one TQ-12 main engine and four vernier engines was fired on the stand successfully. The TQ-11 are smaller vernier engines that together produce about half the thrust of the main engine if all fired with full force at the same time.

For a later upgrade, the rocket will change to the TQ-15A second stage, which will delete the need for vernier engines, which are the suspected culprit for today’s mission failure. It will feature 836 kN of thrust in vacuum, with the ability to move the engine for control during the second stage flight. This will also feature some weight improvements.

The upgraded TQ-15A. (Credit: LandSpace)

In October 2021, the rocket performed a vibration test to evaluate if it could sustain the vibration forces at liftoff and if these forces would have any influence on the rocket during flight.

LandSpace plans to develop further configurations of Zhuque-2 in the future. ZQ-2A would feature a stretched rocket, while ZQ-2B and ZQ-2C would feature additional side boosters to further increase the capacity of the rocket to up to 32 tons to LEO. A timeline for these has not been given.

Down the line, ZQ-2 is planned to become reusable, as the company has demonstrated the restart of TQ-12 engines. The plan is to reuse the rocket for up to 20 reuses. Further details on the timeline of a first recovery are not known yet.

Interestingly, ZQ-2 does not feature a center engine for easy landings and would need to ignite two engines for a symmetrical burn at landing. This would imply significant throttle capabilities of the TQ-12 engine. The TQ-12 engine was successfully restarted on the test stand in 2022.

The launch was conducted from Pad 96 of the JSLC. It is a spaceport that has already featured over 100 launches, including most of the early-generation Chang Zheng (Long March) vehicles. In the past, it also was the host for the company i-space, which launched its sub-orbital rockets from the center. Furthermore, in 2019, the Hyperbola-1 rocket became the first commercial orbital launch that was conducted from a Jiuquan pad.

(Lead image: ZQ-2 flight 1 fully assembled. Credit: LandSpace)

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