Microgravity, macro questions: COLIS, twenty years of physics from Earth to space

Roberto Piazza, Professor of Materials Physics at the Politecnico di Milano, has been studying the behaviour of soft materials for over twenty-five years. These are complex systems that change slowly over time, such as gels and colloidal glasses. A facility known as COLIS, developed together with the Université de Montpellier and installed on the International Space Station, has now made it possible to observe these changes without the interference of gravity.

He told us the story of a project that took twenty years to get into orbit.

It all began in 2004, with an Announcement of Opportunity from the European Space Agency. I’d never had anything to do with space, but I decided to give it a try, building European partnerships with the Montpellier group led by Luca Cipelletti, and a Dutch team.

The project came first among those for physics and second overall. It felt like the start of a very fast race. But it was actually a marathon that lasted more than twenty years.

To start with, the Italian funding didn’t come through, and the Italian Space Agency was going through a difficult time. We went ahead doggedly, until new people arrived at the Agency, and we were able to get an initial funding. It wasn’t huge, but it was decisive.

COLIS is an optical facility designed to study complex materials — colloidal gels and glasses, soft materials — in conditions of microgravity.

It’s the size of a suitcase, but inside there are optics, lasers, cameras, and heat control systems. We analyse speckle patterns, tiny variations in the light patterns scattering off the samples; these extremely sensitive signals enable us to understand how the internal structure of the material evolves over time.

In some experiments, we simply observe the scattered light; in others, we use localised thermal manipulation with a laser to see if the microstructure rearranges.

Microgravity gives us a unique advantage: we can observe processes without the continuous — and often invisible — effect of Earth’s gravity.

Because gravity is a silent but constant force.

A gel can look solid when you throw it like a ball, but if you leave it on a table it slowly begins to droop. Some years ago, cosmetic creams showed a tendency to separate over time. This relates to their shelf life. Here too, gravity is slowly but surely having an effect.

We can use centrifuges here on Earth to accelerate these processes, but the mechanisms are not necessarily identical. The central question is:
if we remove gravity, will the processes of reorganisation take place just the same? And how long will they take?

COLIS was designed to answer exactly that.

With enormous patience.

ESA asks for very detailed specifications when working with the industry: every change requires reassessments and new approvals. It’s a rigorous system, but inevitably slow.

The instrumentation was eventually combined with other experiments, including those on the crystallisation of proteins by a Belgian group. This prolonged the timescale even further.

Then there were also logistical problems in space: damaged ships, stranded cargo, crews returning early. Every unforeseen event meant months of waiting.

But COLIS finally arrived on the ISS. And it’s now operational.

We only have preliminary results, because transferring data from the Station is a slow and highly controlled process.

But we’ve already seen something surprising: a sample that takes about two hours to stabilise on Earth, seems to take a whole day when in orbit. That’s massively slower.

And we don’t yet know why. And this gets right to the heart of our research: when the data calls into question something we’ve taken for granted.

The crystallisation of proteins has been a crucial issue for many years; we could only apply diffraction to well-formed crystals to determine the structure of proteins.

However, the context has changed in the meantime. With the use of artificial intelligence — and with Nobel Prize-winning developments — it’s now possible to predict the 3D structure of a protein from its sequence of amino acids.

This doesn’t make these experiments in microgravity futile, but it changes their significance. It shows that research evolves even while it’s underway.

A key role.

We’ve known each other since he did his doctorate in Milan. It was already abundantly clear how brilliant he was — and he was also an exceptionally talented cellist.

Over the years we’ve shared students, periods of working together, projects. I still remember waking up in the States to the sound of his cello as he practiced for hours on end.

Our collaboration is based on real human rapport. And I believe that, for such a long project, mutual trust has been as decisive a factor as scientific expertise.

There are still some remaining slots for experiments on the ISS: for the Belgian group, for Cipelletti and for our team.

It will all depend on the scheduling of the missions and the availability of cargo deliveries. When the hard drive with the data arrives on Earth, it will still take months to complete the checks and make all the information available.

The most exciting part is yet to come: the full analysis.

Yes. As a child, I used to look up at the sky from Lambro Park using a basic telescope. I passed this interest on to my children during summers in Basilicata, identifying the constellations together.

It’s very meaningful for me to know that an instrument resulting from our work is now up there, in orbit.
I’ve never been into space, but a part of me is there.

It reflects my ongoing curiosity, which has never changed.

That research is a living organism.

You can start with a set plan, but then the questions, the equipment, the scientific context all change. You need to be aware of this process of evolution.

I often say to students: the scientist wants to understand the world, the engineer wants to change it. I feel more like a scientist. COLIS has been this: an attempt to understand more profoundly.

And, after twenty years, the journey is still not over.