A man in a mask and lab coat next to a model rover.

Zhang Rongqiao with a model of the Zhurong rover at the Beijing Aerospace Control Center.Credit: Xinhua/Shutterstock

In May, China landed a rover on Mars, completing the most difficult stretch of its mission to send an orbiter, lander and rover to the red planet. It was China’s first independent mission to Mars, and made the country only the second, after the United States, to successfully place a rover on the planet.

Zhang Rongqiao, chief designer of the Tianwen-1 mission, featured in Nature’s 10 — a list of ten people who helped to shape science in 2021. In this extended interview, conducted over e-mail, Zhang discusses his thoughts on the mission so far, the progress of the rover — named Zhurong — and what it means for China’s space-research endeavours. Zhang has made numerous appearances in the Chinese press but very rarely speaks to the international media.

What is your role in the mission and how big is the team?

As the programme’s chief designer, I am responsible for engineering development, spacecraft launch and flight control. Once the mission was in flight, I had to keep track of the spacecraft’s status, find the right people to deal with emergencies and ensure that the probe remained in good working condition, so that our rover could successfully land on Mars and achieve its objectives. I am also in charge of coordinating scientific research through exchanges with planetary scientists at home and abroad. Our successes have been thanks to the concerted efforts of thousands of research and development entities and tens of thousands of scientific and technological team members.

Were you confident about sending an orbiter, lander and rover in one mission?

We were fully aware that Mars exploration missions are technically challenging and risky. China is a latecomer to planetary exploration and science, and faced a technological leap compared to international missions. But China has already realized human space flight and lunar exploration, so the technical groundwork was in place to reach Mars.

How have you balanced the engineering and scientific mission goals?

Mars exploration is guided by scientific objectives and propels research forward. Mars missions are fairly difficult — only about half of those with a lander or rover have succeeded — but we still tried to ensure that scientific goals were a priority during planning. We optimized the probe’s flight capabilities, the weight and energy demands of its scientific payloads, and its communication technologies to ensure that we could collect a rich variety and high quality of data during exploration.

How did you feel when you learnt that Zhurong had successfully landed?

When I first saw the telemetry of the landing in the control room, I was overwhelmed. I was moved by the unremitting efforts of the team. I felt grateful for the support coming from all sectors. With every feeling rushing to my heart, I could not help but shed tears.

Red planet against a black background.

Mars, as photographed by China’s Tianwen-1 orbiter in March 2021.Credit: CNSA/Xinhua/Alamy

What has the rover been doing in the past few months?

It has continued to travel to the suspected coastline of an ancient sea and ancient land in the southern part of Utopia Planitia, in Mars’s northern hemisphere, to conduct scientific exploration and find clues to uncover the mystery of the origin and evolution of Mars.

What are the biggest challenges the mission has faced so far?

Our challenge of going to Mars was enormous. For example, there are many unknowns about its surface topography, climate and environment. We do not even know what we do not know about. To equip our rover for an unknown environment, we carried out comprehensive mission planning and testing on Earth. We decided on a suspension system for Zhurong with six independently driven wheels, which enable it to move in unique ways, such as walking like a crab or wriggling like a worm. Because of Mars’s thin atmosphere, we also came up with unique ways of changing the aerodynamic shape of the landing capsule to slow it down and guarantee stability during descent. Sticking to schedule was also a challenge — the launch window only comes once every 26 months, so we would have had to wait for more than 2 years if we had let this one slide by.

If you could go back in time, what would you do differently?

This is China’s first Mars mission, so not everything was done perfectly. We have been self-reflecting, looking for gaps compared with technologies used by other international missions, and checking out any problems in our implementation.

How has the success of the mission changed space science in China?

The successes of Tianwen-1 have presented us with a new opportunity to understand Mars and will greatly promote the development of China’s space science, especially planetary science. We have acquired first-hand data on Mars’s terrain, the composition of surface material, subsurface structures, the magnetic field, meteorology and climate. This will give researchers a foundation for expanding planetary science in China. The China National Space Administration has been actively promoting international exchanges and cooperation with foreign scientists.

Where will China’s space endeavours be a decade from now?

Tianwen-1 is the first step in China’s exploration of the planets, which will be followed by asteroid exploration, a Mars sample-return mission and a fly-by of Jupiter and its moons. Technology developed in our successful missions will contribute to future scientific research.