Greyscale footage shows how vapour condenses on the ground (left) and on the International Space Station (right). The footage is sped up five times – the whole clip took around one minute in real time.
On Earth the liquid accumulates at the foot of the fin, whereas in microgravity the liquid spreads across the entire surface as a thin film.
The black layer on the surface of the fin shows the thickness of the moisture layer. On Earth, the liquid film is very thin. In space, without gravity’s pull, this film becomes thicker.
For the first time, a European experiment is looking at the shape liquid films take on cooled surfaces aboard the International Space Station. A fin-shaped metal is in the spotlight for scientists to better observe condensation, liquid drainage and vapour convection.
The Condensation on Fins experiment is pioneering heat transfer tests in orbit to study the role of capillary pressure – the force that pulls liquids through tiny spaces, like water climbing up a paper towel – and condensation, all without gravity getting in the way.
The two pointy fingers on each side are part of the experiment as reference objects for calibration. During every run, the condensed liquid drawn by the sponge and pump is re-evaporated in a closed loop. A high-precision interferometer records the temperature and vapour concentration changes around the fin, as well as tracking the liquid film’s thickness.
From dew at dawn to a foggy mirror after a shower, condensation is part of our daily lives on Earth. In space, microgravity alters how heat flows through gases and liquids, a potential enemy for spacecraft electronics needing to cool down in extreme environments.
Whilst this is fundamental physics research to refine mathematical models, the results will have practical applications, such as cooling electronics in smartphones and computers, and optimising industrial coating processes on our planet.
Space missions could also benefit from more efficient heat exchangers to maintain electronics and life support systems at the right temperature.
More information about this experiment.