Scientific and technological talents talk about strengthening the country | Rong Xuzheng, deputy chief designer of "Lijian No. 1": A thorough control of the avionics system of "Lijian No. 1"

Rong Xuzheng still remembers that the day he learned that he was admitted to the aerospace research institute was in the winter of 2013. All things in the north were dormant during the winter, but to this day he still believes that it was the most fruitful season in his life over the past twenty years.

Rong Xuzheng said that when he was five or six years old, he watched the launch of the Long March 3A rocket, and the dream of space travel was planted in his heart. This dream continued to grow and finally came true when he graduated with a master's degree. He became an aerospace science and technology worker as he wished, and was responsible for the testing of solid models in a related position for 6 years.

In 2020, Rong Xuzheng switched to the field of "commercial aerospace" and became the system commander of the avionics system and electrical system of the "Lijian-1" launch vehicle, as well as the person in charge of large-scale comprehensive tests. During the two years of development, Rong Xuzheng personally visited every test site and spent many days and nights in the laboratory repeatedly calculating and debugging. He used time as a measure and completed a thorough control of the avionics system of Lijian-1 with perseverance, and was familiar with the technical status, drawings and documents, and test process of each product.

An ongoing reliability verification

Completing the modular innovation of the Lijian-1 avionics system is the main direction of the avionics design team's work. Innovation means that Rong Xuzheng and his team need to verify the reliability of the new avionics system through massive and repeated tests. From March 2020 to July 2022, in nearly three years, under the leadership of Zhu Yongquan, deputy chief designer of the avionics system of the "Lijian-1" launch vehicle, in the laboratory, the process of repeated testing, verification, modification, and retesting was repeated, and large-scale tests such as electromagnetic compatibility tests, comprehensive matching tests, and ignition tests were completed. The team iterated a mature modular system round by round and successfully developed a launch vehicle avionics system that combines measurement and control.

Ensuring that every single component on the rocket operates flawlessly is a systematic and huge project. The team needs to conduct multiple rounds of tests to ensure that every component can be remotely controlled through the system. During the development of Lijian-1, in order to reduce costs as much as possible and speed up the development progress, the team used some single components that have been maturely applied in automotive systems and satellite systems in the system design process. Rong Xuzheng and his team conducted at least one round of tests on each interface to verify its reliability. This comprehensive test lasted for a whole year, and the entire team worked selflessly from day to early morning until the lights in the laboratory were forced to be turned off.

2021 is a year in which the development of the Lijian-1 carrier rocket has made important progress. During this year, the avionics system comprehensive test and matching test in which Rong Xuzheng participated and was responsible successfully passed the review, and the Lijian-1 Yao-1 carrier rocket entered the final assembly stage.

After the fierce battle, Rong Xuzheng achieved overall control of all the details of the avionics system. The design and circuit diagram of each part on the drawing were firmly imprinted in his mind. "The large-scale comprehensive test of the avionics system is one of the most tiring and time-consuming tasks. As the person in charge, I need to look carefully with a magnifying glass and check carefully without any negligence." When he joined the unit, Rong Xuzheng still had black hair. After a year of comprehensive testing, white hair quietly climbed up the temples of this young aerospace scientist in his thirties.

The power of repetition: 4 hours to locate the problem

It took three years to polish a rocket, and solving problems was also a process throughout the design and launch of the Lijian-1 rocket. This rocket involved 151 items, 761 ground tests, 277,300 lines of code, 646 drawings, and more than 850 project documents. The complexity and difficulty of the rocket are indescribable. Before the rocket was launched, no one could be sure that it would win the battle. Until the moment before the launch, the development team always remained on high alert.

On July 25, 2022, two days before the first flight of Lijian-1, the white metal rocket body stood in the Gobi Desert. To ensure the success of the launch, a launch process rehearsal was conducted that morning. With only 4 minutes left before the simulated ignition, Rong Xuzheng found that the sensors on the ground showed that a weak voltage from the rocket was still detected after the ground power supply was disconnected. The circuit problem attracted great attention from the command center, and they decided to troubleshoot immediately. "At that time, my heart tightened as if it was pricked by a needle, but I didn't panic. The problem occurred before the launch, and we were lucky." His rich technical experience helped him quickly locate the problem.

The test team immediately began to look for data sent back by devices at suspected fault points, and completed the sorting and troubleshooting of the entire rocket's avionics system at extreme speed, just four hours after the problem was discovered.

After identifying the problem, Rong Xuzheng, on behalf of the test team, immediately reported to the leaders of the launch authority, explained the principle and mechanism of the problem, and found the manufacturer of the switch on the rocket overnight to complete the verification test. Rong Xuzheng did not sleep that night, and together with the technicians of the switch team, he used the test results to prove his reasoning.

Rong Xuzheng said that he has always maintained a high degree of respect for spaceflight, and that the record of successful launch is extremely valuable, but success is accompanied by huge risks. "Finding problems is the best problem. We can learn lessons from problems, make ourselves and the team more cautious, and avoid and reduce failures to the greatest extent possible."

Someone asked him why he could accurately identify the problem in 4 hours. The ease behind it must be accompanied by a huge amount of repetition. More than 370 days of endless test verification produced a compound interest effect at this time. "I repeated each test many times. This sensitivity comes from a large number of previous tests. Never underestimate the power of repetition. I am familiar with every test process, so many that I can't even count them. Because of the familiarity, I can make quick judgments."

On July 27, the six satellites carried by Lijian-1 were stably sent into orbit with an accuracy of 545 meters. This was the largest solid-fuel carrier rocket in my country at that time and successfully completed its maiden flight mission. Rong Xuzheng was named "Lijian-1 Quality Star". After three years of denial and rebuttal, he finally got a positive answer at this moment.

Today, Lijian-1 is entering a phase of regular high-density launches. Compared with the first flight, the challenges faced by Rong Xuzheng and his team have only increased. "Easy things are not ours. Lijian-1 is undergoing multiple flight tests and verifications to verify the reliability of launch services. This road to success is destined to be difficult." Although they know that the road is long, they will not be defeated by difficulties and will bravely and fearlessly embark on tomorrow's journey. Rong Xuzheng said: "From the bottom of my heart, I want to treat it as a career and do my best for it."

Text: Lan Simin, China Aerospace Science and Technology

Audit expert: Cong Nan from China Aerospace Science and Technology