China launches resupply mission, lands space plane, and readies methane rocket

by Adrian Beil

China plans to continue its ongoing supply chain for the Tiangong Space Station (TSS) by launching the Tianzhou-6 mission. The launch occurred at 13:25 UTC on May 10 and lofted a Tianzhou capsule on top of a Chang Zheng 7 (Long March 7).

The preparation for this mission began in late April. The Tianzhou-6 capsule was rolled to the fueling and encapsulation building to support final preparations before stacking on top of the rocket. At this stage, China Aerospace Science and Technology Corporation (CASC) also stated that the capsule allows for 20% more payloads than previous Tianzhou capsules. This increases the internal volume from 18 cubic meters to 22.5 cubic meters.

This capsule can deliver about 7.4 metric tons of supplies, including 70kg of fruits, to the Tiangong Space Station.

Besides the vitamin delivery, more science is expected to fly on this mission, as it will support the next crew rotation on Tiangong. No details about the science of this mission, its purpose, and the operation schedule have been released by CASC as of now.

On May 7, it was confirmed that the rocket and capsule were stacked and transported to the launch pad at the Wenchang Space Launch Site in China. 

About Tiangong

The “Palace in the Sky,” or in Chinese, “Tiangong Space Station,” is one of the two space stations currently in orbit around the Earth, next to the International Space Station (ISS). It has about 25% of the mass of the ISS since the science expansions Mengtian and Wentian were installed. The typical orbit of the TSS is between 381 and 385km in altitude, with an orbital inclination of around 41.47 degrees.

The Tianzhou-6 spacecraft. (Credit: CASC)

The TSS project started with the launch of the Tianhe core module in April 2021. By 2022, both science modules were launched. All these expansions were carried out by Chang Zheng 7s bigger brother, Chang Zheng 5 — the currently biggest rocket in the Chinese fleet.

Down the line, China also plans to launch the Xuntian Chinese Survey Space Telescope (CSST). This was planned for late 2023 for a long time, but it slipped to late 2024 a few months ago. The telescope will operate close to Tiangong and occasionally allow spacewalks and docking to repair and upgrade the telescope. Its main mission will be surveying 40% of the night sky with a resolution of 2.6 gigapixels. 

About the current astronauts

The current crew that will support the docking of Tianzhou-6 is the crew of the Shenzhou-15 mission. Commander Fei Junlong, Operator Deng Qingming, and System Operator Zhang Lu are scheduled to be on the station until May 2023, when they will hand over to the Shenzhou-16 rotation and leave shortly after the new crew has docked.

The crew of Shenzhou-15. L.: Fei Junlong / M: Deng Qingming / R: Zhang Lu. (Credit: CASC)

The new crew rotation has not been named yet, which is typical for the Shenzhou missions. Usually, the announcement of the astronauts comes a few weeks before the launch.

About the rocket

The launch vehicle for this mission is the mighty Chang Zheng 7, one of the most powerful rockets in the Chinese fleet. It is exclusively launched from the Wenchang Space Launch Site, which is the most modern launch complex in China. The port opened in 2016 to support the next generation of Chinese rockets, including 5 and 7. Down the line, it will probably also support the bigger new rockets of China, such as the Chang Zheng 10.

Chang Zheng 7 in the VAB. (Credit: CASC)

Chang Zheng 7 can support up to 13,500 kg into low Earth orbit (LEO) and up to 7,000 kg into GTO. It stands 53.1 meters tall at liftoff, with a common Chinese rocket diameter of 3.35 meters on the main body. The four side-mounted liquid boosters are 2.25 meters in diameter each. 

Six YF-100 engines running on RP-1 kerosene and liquid oxygen support the first-stage flight. Each engine produces 1,200 kN at a specific impulse of 300 seconds. The rocket has 7,200 kN of thrust at liftoff, similar to the SpaceX Falcon 9 rocket.

The boosters separated at T+2:56, leaving the first stage in charge for roughly 14 more seconds before it also separated. 

At that point, the second stage of the rocket took over. The four YF-115 engines provide a combined power of 706 kN. They can operate at a specific impulse of 341.5 seconds in a vacuum burned for about seven minutes to perform the insertion of Tianzhou. The fairing exposed the cargo spacecraft to the vacuum of space 25 seconds after stage separation.

With the capsule in free flight, it will use its onboard propulsion to close the gap to Tiangong and dock hours later. A specific timeline has not been provided.

About the Chinese spaceplane

After 276 days in orbit, the Chinese spaceplane touched down on a runway at the Jiuquan Satellite Launch Center in China. This was confirmed by Chinese state media hours later. 

The initial liftoff of the mission was on August 4, with multiple orbit changes and ejected objects throughout the mission. Similar to the X-37B of the United Space Space Force, the missions surrounding this plane are usually very secretive, and few details are given.

The size and mass of the spaceplane was never confirmed. However, it is estimated to have a wingspan of about eight meters, a length of 12 meters, and a mass in the ballpark of 12 metric tons. 

The spaceplane has been active since December 2007, when it conducted drop tests before initial suborbital flights in 2011. It was launched on a Chang Zheng 2F in September 2020 to carry out its first mission. This was the second launch of the spacecraft to an orbital trajectory. It is primarily used by the People’s Liberation Army (PLA) and the China National Space Administration (CNSA).

About ZhuQue-2

China’s first methane-based rocket, ZhuQue-2, is getting ready for its second attempt to reach orbit. After the maiden flight failed in the last stages, the rocket company confirmed that the second rocket was fully assembled and stacked, which points to a very imminent second flight of the potential first methane-based rocket in the world to reach orbit.

On the maiden flight, a LOX pump low-pressure outer casting for the second stage vernier engine broke under the impact of the stage shutdown. These verniers are designed to function as a third stage. LandSpace has reinforced the parts in question and conducted ground testing to verify the problem on the LOX inlet pipe.

Harry Stranger spotted a potential rocket on the LandSpace pad LC-96 just days ago. This could be the rocket or the pathfinder that LandSpace used to check the launch infrastructure before the flight.

(Lead image: Chang Zheng 7 rolling out. Credit: CMS)

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