Standing in his office at the Shanghai Institute of Ceramics, Zhang Minghui reaches into a nearby cupboard and takes out a handful of small glass beads.

“It took me over a decade to develop them,” he says, showing them off. The size of miniature pearls, they are a concentrated form of rare earth elements. As hard as diamonds, they shine nearly as bright in the lab’s cold light.

Although still in an early stage of development, Zhang says the beads could power the future of satellite communications. If they can be mass-produced, they could wind up in your smartphone camera — or even on jewelry shelves.

But as impressive as these tiny marbles are, they’re not the reason I made the journey to the institute’s leafy campus in downtown Shanghai. But Zhang’s other major achievement is far harder to show off: It’s currently about 250 miles above our heads, in low-earth orbit aboard China’s Tiangong space station.

There, taikonauts are using a furnace of Zhang’s design to conduct zero-gravity experiments on futuristic materials, including new alloys capable of withstanding the temperatures of lift off, that could reshape the way humans reach the stars.

As far as Zhang is concerned, however, there’s little difference between the beads in his hand and the metals being smelted hundreds of kilometers over our heads. “That’s how materials are,” he tells Sixth Tone, a glimmer of excitement flashing across his face. “Big or small, they can be changed in a million different ways.”

1.

Zhang Minghui was born in 1987 in a rural village on the outskirts of the eastern Chinese city of Nanchang, roughly 400 miles southwest of Shanghai. Even today, getting to college from the countryside can be a challenge, and in the late 1990s, Zhang’s fellow villagers were far more interested in starting businesses or getting jobs in the country’s booming factories than fighting for a spot in China’s ultra-competitive universities. Zhang recalls how many of his classmates left their hometown for the coast in search of work as soon as they reached their early teens.

But the Zhang family was an exception. Zhang’s uncle, his father’s younger brother, was the only university student in the entire village at the time, and his diploma was a source of pride for the whole family. “My parents have always been very concerned about my studies, ever since I was young,” Zhang says. “Our meals were usually just rice and some pickled vegetables, but they never hesitated to buy study materials for me.”

Zhang repaid his parents’ faith by coming first in every major exam before winning admission to Jinxian No.1 Middle School, one of the best secondary schools in his home province of Jiangxi. But the pressure to succeed caught up with him days before he was set to take the college entrance exam.

Three days before the test, he began to feel ill. After two days of intravenous drips, Zhang entered the exam hall in a daze. He scored far below expectations, dashing his hopes of getting into the prestigious Tsinghua University in Beijing.

Rather than retake the exam the following year — a common choice in China’s high-stakes education system — Zhang enrolled in the materials science and engineering program at the less distinguished Nanchang University.

There, freed from the weight of expectations for the first time since entering middle school, Zhang hit his stride. After excelling as an undergrad, he was admitted to the Chinese Academy of Sciences’ Shanghai Institute of Ceramics as a postgraduate in 2009. Working under Liu Yan, a researcher at the institute who specializes in practical applications of glass and ceramics, Zhang began to study containerless materials processing — a method of manipulating substances in suspension to produce new types of glass.

In theory, containerless technologies create a zero-interface environment, allowing researchers to create materials without crystallization from contact with the surrounding vessel walls. Think of it like cooking an egg suspended over an open flame: Absent a pan, there’s nothing for the yolk and white to stick to.

Although containerless materials processing was not new — scientists in Japan, the United States, and France had already developed many applications for the technology by the late 2000s — Zhang was one of the first researchers in China to explore the field. The start-up process was slow, but after a gradual process of trial and error, Zhang began construction of a device that could levitate and stabilize materials. Then he got a call that would change his career.

2.

In 2012, Zhang’s doctoral advisor, Liu, was given an important task: to develop a high-temperature experimental furnace for Tiangong-2, China’s first laboratory in space.

Like many designs associated with the Chinese space program, the device was given a codename based on traditional mythology: the “Bagua Furnace,” a reference to the eight trigrams of Taoist cosmology.

With a launch date set for 2016, Liu quickly recruited Zhang to his three-person design team. “We had little experience, so there were a lot of problems at the beginning of the project,” Zhang recalls.

To start, none of them had built anything capable of withstanding the forces of a rocket launch before. “Our equipment had to pass a seismic test because the rocket launch’s impact is so large,” says Zhang. “The equipment we made was often shaken to pieces immediately after we put it on the vibration table.”

In 2014, the team delivered the Bagua Furnace and Zhang received a doctorate for his work on containlerless technologies. Almost immediately, Zhang was recruited for another, even more ambitious space project: designing and building one of eight experimental cabinets bound for the Mengtian laboratory module of the Tiangong space station.

This was a far more complicated prospect than the Bagua Furnace, not least because, unlike Tiangong-2, which was a temporary space lab launched as a proof of concept, Mengtian was expected to be operational for a full decade.

More importantly, while the Bagua Furnace needed to reach temperatures of 900 degrees Celsius, the new high-temperature materials cabinet Zhang was tasked with building had to be able to heat up to 1,600 degrees Celsius.

“Heating is crucial in material science,” Zhang says. “That’s why those of us who work in materials research like to call ourselves ‘furnace workers.’ But furnaces are very energy-intensive, and energy is very precious in space.”

In 2022, shortly before Mengtian was launched, Zhang’s team delivered their design. Resembling a double-door refrigerator, it houses some of the most sophisticated science equipment ever sent into orbit. The cabinet can process 16 samples automatically, using multiple heating modes and incorporating X-ray imaging to observe materials as they melt and solidify in microgravity. And all materials are sealed inside sample boxes, meaning the astronauts only need to open a door, insert samples, and close it again, while the experiments are run automatically or by ground control.

On Oct. 31, 2022, Zhang sat on a viewing platform near the Wenchang launch site in China’s southern island province of Hainan. At exactly 3:37 p.m., he watched as a Long March rocket carrying the Mengtian Experiment Module — and with it, his creation — lifted off into the sky.

3.

For the first time in a decade, Zhang found himself at a loose end. Now, he’s finally getting back to the research he had begun in the early 2010s: the development of new glass materials.

Although he has grown used to an engineering role, Zhang says he prefers to think of himself as a researcher: “The mindset of scientific research and engineering is different. Engineering involves using existing knowledge to make products, focusing on reliability and accuracy, while scientific research is about exploring new knowledge, focusing on innovation.”

Of course, the two directions are not mutually exclusive, and in many cases they can reinforce one another. If anything, Zhang says his experience in engineering design has given his scientific research a more application-oriented focus than other researchers. “If I just had a scientific research mindset, then when I make optical glass, I’ll just want it to have good optical properties. But now I also want it to have good mechanical properties, because that would lead to better applications.”

For instance, Zhang’s team has found a new way to refine rare earths using containerless technologies, allowing them to produce glass spheres with a refractive index and hardness comparable to diamonds. According to Zhang, in addition to applications such as satellite communications, the resulting glass can also be used as a lens for smartphones, enabling superior wide-angle photography.

“And of course, they can also be used as high-end imitation diamonds,” Zhang adds with a smile.

(Header image: Glass samples made through containerless materials processing techniques developed by Zhang’s team, Shanghai, Oct. 23, 2024. Wu Huiyuan/Sixth Tone)