Keeping satellites cool: An interview with Andrea Ferrari
The University of Cambridge’s Andrea Ferrari made headlines this year after successfully testing graphene’s satellite-cooling potential under microgravity conditions. Here, the director of the Cambridge Graphene Centre discusses the ‘ups and downs’ of his investigations, and how space poses a unique set of challenges to new technologies
Andrea, can you give us a bit of backstory to the research you’re working on?
The target for this project is to develop ‘loop heat pipes,’ pumps that function without moving parts, without wear and tear. This makes them ideal to be used in space applications. One part is exposed to high temperatures—for example, the electronics of a satellite—and typically you’ll want to use them to remove heat to the radiators on the outside. We’re placing graphene inside and around the internal metal wick, which has allowed us to increase its thermal conductivity.
This venture is part of the Graphene Flagship; a large European initiative started in 2013 with the aim to take graphene—and its approximately 2000 related materials—from the lab to the factory floor. The project is also the work of our partners: the Free University of Brussels, the Italian National Research Council, and aerospace company Leonardo.
Why take the system aboard a zero-gravity flight?
We did the first tests on the ground and found a significant improvement in performance by adding graphene. Of course, these instruments need to function in zero-G and, firstly, you need to launch them into space. During launch, a satellite experiences forces up to 1.6G, and you don’t want the device to fail. So that’s one thing to check.
The second point is the performance of the loop heat pipe. We wanted to make sure that the performance in the conditions experienced by satellites is not affected by the lack of gravity.
The hope was that the zero-G performance reproduces the performance in the lab—and our preliminary results make us think that we have achieved that.
What benefits could loop heat pipes bring to satellites?
It would remove the need for pumps with mechanical parts entirely. And, of course, thermal management is key for satellites. An issue with the pumps that are being used now is that they don't start up reliably. If you could fully rely on loop heat pipes, this would significantly improve the performance of satellites and also cut costs. And probably extend their lifetime, too. The same would apply to the International Space Station.
But also, in the long term, if we could make this loop heat pipe at a very low cost, you could envisage them in trains, in cars, and so on, on earth. The problem now is the pipes are too expensive.
So, the long-term vision, if you want, is not just space, but if everything works well, this technology could potentially be used on earth.
Did you enjoy flying on the ‘vomit comet’ and experiencing microgravity?
Yes. Every flight a few people are unwell, and there are no toilets on board, so you have to take some precautions. I didn’t experience adverse effects, so I actually liked it very much.
Away from the experiments, there’s a free-float zone where you can enjoy yourself. It’s not easy to float around in zero-G—you try to swim like you’re in the sea, but it has no effect whatsoever. It’s a really great experience; I think people should experience it.
What’s next? And are you looking into any other space applications for graphene?
We need to analyze the data and then get ready for another parabolic fight. After that, if everything works well, the next step would be to test the pipes on a real satellite in space, and then, a couple of years later, to test on the ISS.
We’re investigating more general applications for graphene in aerospace. We’re looking at applications for aircraft, for civilian drones. There’s another group in the flagship that’s looking at solar sails for satellites, investigating how graphene reacts to light in what’s called a drop tower. In a drop tower, your experiment free-falls for about 4.5 seconds of microgravity, but you cannot go inside as a person. It’s technically challenging, and it’s fun.
But certainly less fun than being on the plane.
Read more about Ferrari's research on the University of Cambridge website.
Poster image credit: The Graphene Flagship