You’ve probably noticed how your mayonnaise separates in the fridge after a while, or how the sunscreen on your bathroom shelf slowly changes its texture. While this might seem like a minor inconvenience, it’s actually part of a bigger mystery involving “soft matter”, a category that includes substances like gels, foams, and colloids.
These materials behave in ways that are hard to predict because their internal structure reorganizes over time. But until now, scientists have had trouble studying these changes in a meaningful way, mostly because of the constant pull of gravity. On Earth, gravity is always working on these substances, making it difficult to observe their natural evolution. So, what happens when gravity isn’t in the picture?
A Groundbreaking Experiment in Space
To answer this question, a team of researchers from the Politecnico di Milano and the Université de Montpellier decided to take their experiment to space. They launched a facility called COLIS aboard the International Space Station (ISS) to study how soft materials behave in microgravity, where gravity’s influence is nearly nonexistent.
For over 25 years, researchers Luca Cipelletti and Roberto Piazza have been collaborating on this project, which aims to uncover how substances like mayonnaise and sunscreens age and restructure in ways we simply can’t see on Earth.
Overview of the COLIS optomechanical system. Credit: Politecnico di Milano
Cutting-Edge Techniques for Soft Matter
The facility on the ISS isn’t just any ordinary lab. It uses some really advanced tools to study these materials. One of the key methods is called dynamic light scattering. In simple terms, this technique shines a laser through the samples and looks for tiny changes in how the light interacts with the material. These shifts, known as speckle patterns, help scientists track how gels, creams, and other soft materials evolve over time.
This is what the researchers aimed to understand with the COLIS experiment, the results of which were published in scientific journals such as EurekaAlert. The initial findings have already taken the team by surprise. They’ve found that gravity affects soft matter much more dramatically than they expected, especially over long periods of time. Roberto Piazza, a key figure in the research, shared his amazement:
“It’s amazing to see how much gravity, so familiar in our daily lives, acts behind the scenes to shape the materials we use every day,” this realization is opening up new doors for improving products that rely on soft materials.
Real-World Applications for Cosmetics, Food, and Medicine
It might sound like a quirky experiment about space and mayonnaise, but this research has serious real-world implications. Think about the products you use every day. These industries all rely on soft materials that need to stay stable over time. If scientists can figure out how these materials behave in space, they could develop better, longer-lasting products on Earth.
The COLIS lab is now studying colloidal nanoparticles, which are perfect for this kind of research. These nanoparticles, suspended in liquids, are particularly sensitive to changes in environmental conditions, making them ideal for studying how materials behave in the absence of gravity.
The findings from this space experiment could lead to more reliable formulations for everything from lotions to medications, as understanding the stability of these materials in microgravity could improve their performance on Earth. The European Space Agency’s “Colloids in Space” program, along with support from Italian and French space agencies, is helping fund this innovative work.