Delivery capability is the best in the world! Tianzhou launches new products, 3 launches in 2 years

In 2023, China officially entered the manned space station application and development stage. As the first spacecraft, Tianzhou-6 is also the first ship of the improved Tianzhou cargo spacecraft , which undertakes the tasks of space station material support, on-orbit support and space science experiments. China's new batches (Tianzhou-6 to Tianzhou-11) of cargo spacecraft present many new features and release more potential, which also indicates that the application prospects in future space station missions will be broader.
▲ Schematic diagram of the Tianzhou-6 cargo spacecraft (provided by the Fifth Academy)

What has been changed?

A set of data shows that the transport capacity of Tianzhou-6 cargo spacecraft has been significantly improved compared with the previous one: the cargo loading space of the sealed cabin has increased from 18.1 cubic meters to 22.5 cubic meters , and the loading capacity has increased from 5.5 tons to 6.7 tons ; the cargo loading capacity of the whole ship has increased from 6.9 tons to 7.4 tons , and the uplink cargo ratio has increased from 0.51 to 0.53 . Although both are "cargo cabin + propulsion cabin" two-cabin configuration, the sealed cabin of Tianzhou-6 has a larger loading space , and the sealed cabin of the rear cone section can be "entered".

Li Zhihui, deputy commander of the Tianzhou-6 cargo spacecraft of the Fifth Academy of China Aerospace Science and Technology Corporation, introduced that the cargo cabin of the Tianzhou cargo spacecraft consists of a front cone section, a column section, and a rear cone section. In the past, in the propulsion cabins of the Tianzhou-1 to Tianzhou-5 spacecraft, the front cone section and the column section were connected to each other as sealed cabins, and the rear cone section was separated by the spherical bottom as a non-sealed cabin. Tianzhou-6 moved the spherical bottom to the lower part of the rear cone section, making all three sections connected . The cargo cabin's sealed cabin has increased its loading space by 4.4 cubic meters , and its loading capacity has increased by 1.2 tons . After docking with the space station, people can directly enter the sealed cabin of the rear cone section, making it more convenient for astronauts to pick up goods. From the perspective of the propulsion cabin, the number of tanks in the propulsion cabin has been reduced from 8 to 4 , and all the instruments and equipment originally installed in the rear cone section of the cargo cabin have been moved to the propulsion cabin. This not only reduces the weight by more than 100 kilograms, but also releases precious loading space for the cargo cabin. The Tianzhou-6 cargo spacecraft carried 280 days of astronaut supplies, platform maintenance spare parts and various test payloads for three people, about 260 items of cargo, 700 kilograms of propellant for the upward flight, and a total weight of about 5.8 tons of transported materials. The improved "Tianzhou" has the largest transport capacity among the world's active cargo spacecrafts and the highest cargo-to-load ratio .

Reduced to 3 times in 2 years

This year is the first year of the space station application and development stage. In a sense, the uplink capability of the Tianzhou cargo spacecraft will enhance the application and development of the space station. From the perspective of mission arrangement, with the improvement of uplink transportation capability, the launch frequency of the new batch of Tianzhou cargo spacecraft has been reduced from 4 launches in 2 years to 3 launches in 2 years, which has improved the comprehensive benefits of the space station project.

Lei Jianyu, chief designer of the cargo spacecraft system of the Fifth Academy of China Aerospace Science and Technology Corporation, introduced that with the upgrading of the fully sealed model represented by Tianzhou-6, the three models of Tianzhou cargo spacecraft, namely fully sealed, semi-sealed and semi-open, and fully open, have more reasonable structures and clearer division of labor : the fully sealed model meets the conventional tasks and daily needs of the space station; the semi-sealed model highlights the transportation capacity of large extravehicular equipment and test payloads, and mainly performs emergency maintenance tasks; the fully open model realizes the overall transportation of ultra-large test payloads, and supports the development of major scientific mission capabilities of the space station. The improved cargo spacecraft not only enhances the conventional cargo transportation capacity, but also provides many convenient conditions for the transportation of special cargo and test payloads such as ultra-standard, large size, and heavy mass, and strict transportation guarantee requirements.

Take the space station electric propulsion xenon bottle assembly transported this time as an example. This assembly weighs about 160 kilograms and is currently the heaviest single piece of cargo transported by a cargo spacecraft to my country's space station. Transporting heavier xenon bottle assemblies can add more "fuel" to the space station. After the cargo spacecraft docks with the space station, the astronauts will remove the xenon bottle and install it outside the Mengtian laboratory cabin during extravehicular activities. 160 kilograms is "very light" in the space environment, but it is not easy to load on the ground. The development team formulated a detailed process plan and designed special in-cabin installation tooling, carried out whole-ship loading and test verification in Beijing, and finally installed it in one step at the launch site.

"One step at a time"

The Tianzhou 6 to 11 cargo spacecraft still adopt the batch development and production mode. Compared with the previous batch of spacecraft, the Tianzhou 6 has undergone major changes. The development team has improved efficiency while ensuring quality and success, and achieved "one-step proof" - that is, from product design, production testing, experiments, to the final flight into space, it is the same spacecraft . "The development team carried out a large number of test and verification work on the ground from component level, single machine level to whole ship level to ensure success with high quality; through digital development and production, as well as batch ordering, large-scale production and other methods to improve efficiency." Li Zhihui said. Localization and independent control of components are the meaning of China's aerospace science and technology to achieve a high level of self-reliance and self-improvement. In the development of the new batch of spacecraft, the development team has solidly promoted the full chain of components, raw materials, and basic electromechanical products. The proportion of domestic models and specifications and the proportion of quantity have increased significantly, and key components have been 100% localized .

In addition, the Tianzhou-6 uses a phased array relay terminal to replace the directional relay terminal, which greatly reduces the manufacturing cycle and cost; the measurement and control system software and hardware are fully upgraded, and automatic navigation is completely dependent on the Beidou system . The team actively implemented the digital aerospace strategy during the development of the spacecraft, carried out full-process digital design, production and simulation testing, and shortened the development cycle of a single spacecraft by 6 months . By redesigning the layout, the number of tanks in the propulsion cabin of the Tianzhou-6 spacecraft was reduced by half. The increase or decrease of equipment is not a simple relocation, but reflects the designer's ingenuity of "making a temple in a snail shell". At the same time, the Tianzhou-6 propulsion cabin achieved a single-cabin mechanical test and a whole-ship mechanical test in one pass, giving full play to the role of digital model simulation as an accelerator on the road to product development.