For the Asteroid Day Festival in Luxembourg, four remarkable women came into the RTL City studio, three scientists and one artist, each travelling through heat, early flights, and long journeys because they care deeply about how we explore, understand, and protect ourselves from objects in space.
My guests were Dr Stefania Soldini, Associate Professor in Space Engineering at the University of Liverpool and Director of the new Zero-G AstroLab; Sabina Raducan, planetary scientist at Vrije Universiteit Brussel and the Royal Observatory of Belgium; Professor Kathrin Altwegg, Professor Emeritus in Space Research and Planetology at the University of Bern; and Aura Satz, a London based artist working with film, sound, performance and sculpture.
An asteroid, as Stefania Soldini explained, is a small rocky object that never became a planet. That is exactly why it matters. These bodies preserve information from the birth of the Solar System more than 4.5 billion years ago. They may carry clues about planets, water, and perhaps even how the building blocks of life came to Earth.
Stefania worked at Japan’s Aerospace Exploration Agency, JAXA, on the famous Hayabusa2 mission to asteroid Ryugu. Hayabusa2 is still working and will fly past a new asteroid on 5 July 2026. Sending a spacecraft to a body around one kilometre across, about 100 million kilometres away, with a communication delay of around 40 minutes, is engineering on a scale that is hard to hold in the human mind.
Hayabusa2 collected material twice: once from the surface and once from below it after creating a crater. Those samples were then returned to Earth, giving scientists access to material from a world we could never touch with human hands.
“When you see the object for the first time, you think, oh wow, it’s nothing like we thought it was.” That sentence captures the drama of asteroid exploration. The maths can take you there, the engineering can keep you alive, but the asteroid itself still has the power to surprise you.
From Hayabusa2, we moved to Sabina Raducan and NASA’s DART mission, the Double Asteroid Redirection Test. This was the world’s first real attempt to deflect an asteroid by deliberately crashing a spacecraft into it.
The target was Dimorphos, a tiny moon around 160 metres across, orbiting the larger asteroid Didymos. The spacecraft was moving at more than six kilometres per second and had to find its target autonomously. The main asteroid became visible only about an hour before impact. The actual target appeared only minutes before the spacecraft hit it.“It was a complete success. So we can all feel safe. So far.”
Because DART was destroyed on impact, we still do not know exactly what happened to Dimorphos. Did it leave a crater? Did it reshape the asteroid? How much material was thrown out? How did that ejecta change the momentum of the system?
That is the job of Hera, the European Space Agency mission now on its way to the Didymos system. Both Sabina and Stefania work on Hera, which will inspect the result of DART and help turn a successful test into knowledge we can use if Earth ever needs protecting.“We know the asteroid was not completely destroyed. But we don’t know what the crater looks like. If there even is a crater.”
Professor Kathrin Altwegg then took us from asteroids to comets. A comet, she said with characteristic humour, is cooler than an asteroid in every sense. It is much colder, around minus 240 degrees, and it contains ices preserved from the early Solar System and beyond.
As Principal Investigator for the ROSINA instrument on ESA’s Rosetta mission to comet 67P, Kathrin helped analyse some of the most pristine material we have ever encountered. Rosetta found water, gases, organic molecules and amino acids, the building blocks of life. She was very clear: this is prebiotic material, not life itself. But the implication is enormous.
For Kathrin, cometary science reaches into the great questions: where do we come from, where are we going, and are we alone? She explained that some of the material found in comets is older than our Solar System. If it is universal, then what happened here on Earth could have happened elsewhere.
Her answer on life beyond Earth was characteristically direct: almost certainly yes, but probably microbes rather than life as we are.
Rosetta was also a lesson in human commitment. This was a mission measured in decades: 10 years of planning, 10 years of building, 10 years of cruise through space, two years of measurements, then many more years of data analysis. When I asked how anyone stays committed for that long, her answer was unforgettable.
In 2029, an asteroid called Apophis, around 300 metres across, will pass extremely close to Earth, at roughly the distance of geostationary satellites. Once considered a possible risk, it has now been ruled out as an impact threat. It will not hit Earth.
Still, the conversation gave us an honest and useful way to think about risk. Dinosaur scale impacts are extraordinarily rare. Smaller objects, around 30 metres and under, are usually dealt with by Earth’s atmosphere. The objects that deserve real attention are around 100 metres across: big enough to cause serious local damage, but small enough that we may be able to act.
Kathrin would not offer false comfort for the truly enormous asteroid scenario. Planetary defence is therefore not about panic. It is about seeing early, understanding properly, and acting in time, if we can.
Aura Satz came into the conversation from a different direction. She is not an asteroid scientist, but her work on sirens, sound, and emergency listening felt unexpectedly central to Asteroid Day. Her film Preemptive Listening explores how we hear warnings, how we respond to alarm, and whether emergency signals can do more than frighten us.
Her work asks a question that belongs in planetary defence too: how do we listen to danger before it is too late?“It points to the possibility of survival.”
One of the most encouraging parts of the conversation came when I asked whether there is room in space science for people who are not brilliant mathematicians or engineers. The answer was yes.
There is room for communicators, artists, outreach specialists, technicians, geologists, chemists, programmers, observers, and people who can help translate difficult science into public understanding.
“You don’t have to be very good at mathematics. There are ways around it.” From Stefania and Sabina came advice that applies far beyond space: follow your passion, take opportunities when they come and keep going. In missions that last years or decades, perseverance matters as much as brilliance.
My favourite image came from Kathrin. The next comet mission, Comet Interceptor, is planned for launch in 2028 or 2029. But it will not fly to a known target. It will park in space and wait, sometimes for years, for a brand new comet entering the inner Solar System for the first time.
A spacecraft, waiting patiently in space for a comet that has not yet arrived. A target that does not yet have a name.
“It depends on the patience you have. I told you it’s a fun mission.” So we will keep watching that little parked spacecraft. We will think of these four women, and of everything they have given to science, space engineering, art, and public understanding. Asteroid Day is about rocks in space, yes. But it is also about us: how we listen, how we collaborate, how we imagine the future, and how we learn to defend the only planet we currently call home.
ESA Hera mission overview
Kathrin Altwegg and ESA’s Rosetta mission
Aura Satz
Instagram: @aurasatz
Konschthal Esch, Luxembourg
