This article focuses on the first-class award of the 2022 Shanghai Municipal Science and Technology Progress Award for the "Mars Exploration Interplanetary Flight and Orbital Platform Technology" project. The award was presented to Zhu Xinbo, Chu Yingzhi, Xu Liang, Zhang Wei, Wang Wei, Wang Minjian, Zhang Xuguang, Niu Junpo, Du Yang, Wang Jianwei, Xin Sibao, Yang Jin, Yan Kui, Yin Xingfeng, and Yu Miao from the Shanghai Academy of Spaceflight Technology.

In the age of exploration centuries ago, humanity first established connections across continents and oceans, bringing the world together. Deep space exploration serves as a bridge between Earth and extraterrestrial civilizations; from Chang'e's journey to the moon to Kuafu chasing the sun, humanity has never ceased its pursuit of the stars and the sea.

In the vast universe, Mars embodies humanity’s profound aspirations. In July 2020, China’s first Mars exploration mission, the "Tianwen-1" probe, was successfully launched. Over the next several hundred days and nights, the "Tianwen-1" mission accomplished "orbiting, landing, and patrolling" in a single endeavor. The development team behind the Mars orbiter also received the first-class award of the Shanghai Municipal Science and Technology Award in 2022, as the technologies they developed for the orbiter will be utilized in future planetary exploration missions such as "Tianwen-3" and "Tianwen-4."

Overcoming Challenges Across 400 Million Kilometers

Within the "Tianwen-1" mission, orbiting Mars is a crucial phase. The flight path from Earth to Mars covers over 400 million kilometers, and "Tianwen-1" took more than 200 days to complete the journey. In nearly seven months, the successful capture of the probe by Mars was the first major milestone, marking one of the highest technical risks and most critical moments in the Mars exploration mission.

During the probe's journey from Earth to Mars, the opportunity to be captured by Mars’s gravity and enter into orbit occurs only once. At the time of capture, the probe was just 400 kilometers from Mars, and any slight deviation could result in a collision with the planet or cause it to drift away. Thus, the success or failure of the capture became the key determinant of the Mars exploration mission's fate.

Capturing the probe by Mars is only the first hurdle; subsequent challenges include entering an elliptical orbit around Mars, docking for exploration, separating the two spacecraft, relay communication, and planetary remote sensing. Any failure at any link could lead to the failure of the orbiting mission.

To successfully complete the "fire" exploration mission, Zhu Xinbo, the deputy chief designer of the Mars orbiter from the China Aerospace Science and Technology Corporation's Eighth Academy, led a team to develop the Mars orbiter, which was tasked with carrying the landing rover and accomplishing transfer from Earth to Mars, Mars capture, orbital adjustments around Mars, and preliminary area detection; executing separation of the two spacecraft, and providing relay support services; and utilizing scientific payloads for global, comprehensive remote sensing of Mars while in orbit.

From near-Earth to near-Mars, the orbiter had to endure significant temperature fluctuations. In the shadow region around Mars, the probe faced extreme low temperatures of -180℃, posing high demands on the thermal control of onboard products and systems. The R&D team ensured thermal stability through systematic thermal design and power balancing, while the materials used for external products underwent rigorous selection and testing to ensure they could withstand extremely low temperatures.

Typically, satellites orbiting Earth are controlled by ground control centers based on real-time data and task requirements. However, in contrast to Earth satellites, the Mars orbiter faced significant communication delays, with one-way transmission times of over 20 minutes when at its farthest, leading to round-trip communication lags exceeding 40 minutes, preventing immediate intervention by ground commands.

Deep space probes also encounter the unique "solar conjunction" phenomenon, where the probe, Earth, and the Sun are aligned, causing sunlight to interfere with the radio signals between Earth and Mars, leading to communication interruptions. For the Tianwen-1 mission, the longest solar conjunction lasted 30 days. During this period, the orbiter had to "take care of itself," depend on its onboard systems for task management, and rapidly restore contact with the ground after exiting this conjunction.

To address these challenges, the development team created a highly integrated, miniaturized comprehensive electronic system. The orbiter achieved integrated functions for system management, telemetry, thermal control, power distribution, propulsion, mechanism actuation, and data storage, laying a hardware foundation for autonomous management of information. By designing multi-system and multi-mode information integration and autonomous processing methods onboard, the team ensured that primary failures would not disrupt mission execution, and that secondary failures would maintain overall safety, successfully demonstrating the orbiter's capability for autonomous operation in orbit for over 30 days. Equipped with a 2.5-meter large aperture data transmission antenna operating in the X-band, the orbiter tracked and aligned itself with Earth in real-time, transmitting its status and scientific data back to Earth at a maximum speed of 4 Mb/s.

A Decade of Preparation for Mars

Zhu Xinbo, who has been involved in aerospace work for over 20 years, played a key role in the development of the Mars orbiter, overseeing overall design, quality control during system development, and large-scale testing throughout the research process. He feels deeply the uniqueness and challenges of the Mars exploration mission.

"Unlike satellite missions around Earth, deep space exploration missions demand the highest performance standards for the probes, with complex system designs and significant technical challenges." Zhu Xinbo explained that due to the celestial mechanics of Mars and Earth orbiting the Sun, the launch window for Mars probes only opens once every 26 months, with very stringent requirements. Consequently, the Tianwen-1 mission was locked into a July 2020 launch window from the start, leaving no room for delay, which added tremendous pressure to the probe's development timeline.

He and his team began background task validation in 2010, experiencing multiple rounds of plan iterations, and officially initiating plan development work in 2014. Thus, the development of the Mars orbiter spanned three stages: design, initial prototypes, and final models, taking six years to complete. During this period, they overcame numerous obstacles, resulting in the development of the plan verification unit, initial structural units, initial electronic units, and the final model, making the entire R&D process take a full decade.

In July 2020, the "Tianwen-1" probe was successfully launched from the Wenchang Satellite Launch Center in Hainan. The Mars orbiter, developed under Zhu Xinbo's leadership, set off toward Mars, carrying the hopes of the entire nation. He closely monitored the orbiter's status through the telemetry data being transmitted back in real time. Once the orbiter separated from the launch vehicle, "the Mars orbiter executed every step of the operation precisely as designed." In that moment, he was filled with excitement.

Prior to "Tianwen-1," China lacked firsthand Mars exploration data and had to rely on foreign sources. The successful execution of the "Tianwen-1" mission provided an abundance of scientific data for Chinese researchers, leading to numerous scientific breakthroughs.

After approximately 202 days away from Earth, the Mars orbiter approached Mars. That day, the orbiter met expectations and, like a textbook example, successfully completed the Mars capture maneuver, making it the first artificial Mars satellite for China. "The 'Tianwen-1' mission marked the first step in our country's planetary exploration, and we will continue to explore Mars and other celestial bodies in the future," Zhu Xinbo stated, emphasizing that the technology developed for the Mars orbiter will be applied in future deep space exploration missions, such as "Tianwen-3" and "Tianwen-4."

"Deep space exploration is a systematic project that requires collective intelligence and effort." Zhu Xinbo reflected that during the mission development process, it is crucial to leverage national strengths and work together under unified top-level leadership to complete the task. At the same time, meticulous and serious attention to detail is essential for ensuring success. All ground issues represent huge risks in space. Therefore, no small detail in the development process can be overlooked. He also encouraged young people to focus on grounding themselves in basic professional knowledge during their studies, develop systematic viewpoints, continuously learn, gain hands-on experience, keep updating their knowledge, and practice regularly to elevate their comprehensive skills, turning the dream of a strong aerospace nation—a pursuit championed by generations of aerospace workers—into reality.