When most people gaze at the stars, they see beauty. Prof Yin-Zhe Ma sees puzzles — vast cosmic mysteries woven into the fabric of space and time. One of the most perplexing of these is the case of the Universe’s missing matter, and he’s made it his mission to find it.

“From the cosmic microwave background, we know that baryons — the building blocks of matter like protons and neutrons — make up about 4.8% of the universe’s total density,” explains Ma, an astrophysicist and full professor at Stellenbosch University. “But when we look around, we can only see 10% of those. The rest are diffuse, hidden in vast webs of gas between galaxies, nearly impossible to detect with traditional methods.”

This cosmic gas exists in a temperature sweet spot that makes it nearly invisible — too cool to emit detectable X-rays, too warm to form stars. But Ma, the recipient of the NSTF-South32 TW Kambule Researcher Award, has not been deterred: “My work is to develop new estimators that extract these invisible signals from vast datasets.”

His approach combines multiple astronomical surveys — galaxy surveys, gravitational lensing and the Sunyaev-Zeldovich effect—– to tease out incredibly weak signals from cosmic data. His breakthrough came when he realised that the Canada-France-Hawaii Telescope Lensing Survey had accumulated enough data to achieve detection when cross-correlated with Planck satellite observations.

“This tells us not just where matter is, but how galaxies form and evolve, and how energy flows through the cosmos,” he explains. “I stand at the ‘edge of discovery’ and always keep both theories and observations in mind to be the first to achieve detection if the data becomes mature.”

Ma’s fascination with the stars began as a child, but it was a fateful lecture at Nanjing University in 2003 by renowned Chinese cosmologist Prof Tan Lu that lit the spark: “He explained dark matter and neutrinos so simply, and I was hooked. I followed him to the bus stop after the talk, full of questions. His wife gave me their home phone number – she could tell I was serious. That night changed everything.”

Now based in South Africa, Ma is building the country’s reputation as a hub for computational astronomy: “Science isn’t mainstream here yet. People come for beautiful scenery, tasty wines, exotic animals — but not for astrophysics. That must change. Our future depends on building scientific capacity.”

He brings the universe down to earth for students and the public alike. “Nobody likes equations, dry concepts or rules, but everyone loves stories,” he says. “I ask them: Where does your gold ring come from? The answer? Neutron star collisions.”

His advice to young scientists? “Build a solid foundation in physics and mathematics. I don’t think they are separate work — they’re part of my life. Do you think my first language is Chinese? Absolutely not! My first language is equations.”

For Ma, the NSTF-South32 Award is more than personal recognition. “It’s a message that science matters in SA. We are not spectators – we are contributors to the global conversation.”

Read the special Mail & Guardian supplement about all the NSTF-South32 Award winners.

For Prof Liza Korsten, her journey as a scientist began not in a sterile lab, but under the open sky, among leaves and fields. As a girl, she was captivated by the natural world, particularly by plants. This curiosity matured into a passion for plant pathology, a niche field that would soon prove vital in tackling one of the most pressing challenges of our time: food security.

“Science became my life’s work, research my passion and mentoring students my mission,” she recalls.

Now recognised with the prestigious NSTF-South32 Lifetime Award, Korsten reflects on a four-decade career that has seen her evolve from a plant pathologist tinkering with fungi to an internationally renowned scientist influencing food policy, championing sustainability and mentoring a new generation of African researchers.

Seeds of curiosity, roots of purpose

Her foundation in microbiology laid the groundwork for breakthroughs in understanding plant-pathogen interactions.

“I always knew I wanted to work with nature,” says Korsten. “Plant pathology became a calling, combining my love of biology with real-world impact. It connected my scientific interest with a moral purpose: to make food safer for everyone.”

Her career began with a groundbreaking contribution: developing South Africa’s first biological control agent for leaf and fruit diseases. At a time when chemical pesticides dominated agriculture, her innovation was a game-changer, offering a safer, environmentally friendly solution that is now standard practice for sustainable farming.

“Today, these products benefit both farmers and consumers,” she says. “But back then, it took courage and conviction to offer something new.”

Food safety from soil to table, lab to land

But she didn’t stop there. As trade and public health demands increased, her focus expanded. “Food safety became central. I realised that ensuring the quality and safety of fresh produce wasn’t just about pathogens, it was about the entire food system, from soil to table.”

This systems-thinking approach positioned her at the forefront of a new kind of science — one that blends microbiology, plant pathology, policy and regulation to address food security in a rapidly changing world, while never losing sight of the farmer on the ground.

Korsten’s expertise has earned her positions on some of the world’s most influential food safety bodies, including the World Health Organisation (WHO), Food and Agricultural Organisation (FAO), Global Food Safety Initiative (GFSI), International Standards Organisation (ISO), and SA’s food security panels. Most recently, she joined the Academy of Science South Africa’s (ASSAf) new Food Safety forum.

“The selection to serve on these international and local forums reflects the international recognition of African science,” she notes. “It demonstrates the impact we have made and the wide recognition we have as South Africans.” Through these roles, she has shaped global food safety policies while ensuring solutions remain locally relevant.

Locally, she co-directed the DSTI-NRF Centre of Excellence in Food Security at the University of Pretoria, built ISO-accredited food safety labs and advised national policy panels. “Safe food is a basic human right, and food security is a moral obligation,” she says.

Embracing change, leading with grit

What makes Korsten’s work unique is her ability to straddle the worlds of high-tech science and practical farming.

“Agriculture is applied by nature,” she says. “Science only matters if it reaches the farmer, the policymaker and the consumer.”

From genome sequencing to postharvest quality apps, her work blends innovation with application.

“Farmers are incredibly resourceful,” she says. “Engaging with them has been humbling — they work the land with inherent knowledge of nature and the many challenges they face daily.”

Among her toughest scientific challenges was tackling Huanglongbing or citrus greening disease, a destructive crop disease caused by a bacterium that defied traditional isolation methods.

“It was frustrating, but shifting to molecular diagnostics was crucial for progress and reflected the importance of adaptation in a rapidly changing science space,” she recalls. “It taught me something essential: adapt or die.”

She turned to molecular diagnostics and PCR, embracing new technologies that would redefine disease detection. Now, as AI and digital agriculture reshape the research landscape again, Korsten is once more at the cutting edge, integrating tools such asTomatoSmart and SmartSpud into postharvest monitoring and quality control.

“These tools will transform how we detect, monitor and prevent contamination,” she says. “We must evolve with them.”

A legacy of leadership

Of all her achievements, Korsten is proudest of her students. She has mentored more than 87 MSc and PhD graduates and about 60 honours students, many of whom now lead scientific projects across Africa.

“Young scientists are our future, so mentorship isn’t a side project — it’s central to how we build a sustainable, resilient science ecosystem,” she says, adding that another priority must be science communication, innovation and policy training. “Publishing isn’t enough anymore. We need to translate knowledge into impact.”

As a leader in the African Academy of Sciences ARISE-SD programme, she supports 600 researchers in 38 countries, building a collaborative African research network. “We’re creating a science community that’s connected, confident and capable.”

Her passion for empowering women in science is equally strong. “We need more women in leadership, in labs, and in policy rooms. Equity in science means stronger, more diverse solutions.”

Impact, recognition, and purpose

Her current focus? Understanding antimicrobial resistance in the water-plant-food nexus, a field that bridges food safety with global health and environmental sustainability.

“Food safety is no longer just about bacteria on a leaf,” she explains. “It’s about how water, climate and chemicals intersect with health.”

Despite her international accolades, including ranking in the top 2% of scientists globally, Korsten remains grounded in her purpose. “Science should improve lives. It’s not just a career. It’s a lifestyle. And it’s fun.”

Her influence spans continents, institutions and generations, but accolades are not what drive her: “The NSTF-South32 Lifetime Award isn’t just for me. It honours every student, farmer, and colleague who’s walked this road with me.”

She believes recognition is essential to spark public interest in science. “Awards show society what’s possible. They inspire young people, attract funding, and remind us that science matters.”

Looking forward

Even after four decades, Korsten’s passion burns brightly. Her next goals include: advancing research on microbiomes and antimicrobial resistance; scaling postharvest innovations to reduce food waste; expanding pan-African scientific collaboration; and mentoring the next generation of changemakers.

Her advice to young researchers is clear: “Tackle problems that matter to society, work across fields to solve complex challenges, and train others with passion to multiply your impact.”

Her vision? A future where science serves society, not just statistics: “That every learner in SA knows where their food comes from, trusts its safety, and sees a scientist behind every nutritious bite.”

Read the special Mail & Guardian supplement about all the NSTF-South32 Award winners.