You likely missed the memo, but I’m letting you know now: tonight is a Marangoni night! At least here on the Space Station.
We like to joke that it sounds like some trendy dance party (I wonder.. can you dance in space?), but it’s actually quite the opposite: on Marangoni nights we’re asked not to exercise and to be particularly gentle in pushing off handrails. And we really should stay clear of the Ryutai rack in the Japanese laboratory, where the Marangoni experiment runs: this experimental protocol is very sensitive to G-jitter – call that the small accelerations we impart on the structure – therefore we need to be careful. So, whenever you want a quiet evening being a couch potato, we can say you’re having a Marangoni night!
As the name implies, this investigation is about Marangoni convection. What, convection? Isn’t it true that you don’t have convection in weightlessness? Well, yes, if you mean the natural convection induced by density differences: for example, on Earth hot air rises because it’s less dense than cold air. But not in weightless conditions, because buoyancy is an effect of gravity! However, Marangoni convection happens at the surface of a liquid and is in fact driven by surface tension or, more precisely, by differences in surface tension induced by temperature. Sounds fancy, but if you’ve observed oil in the center of a hot pan moving to the sides, you’ve observed some Marangoni convection.
Space is the perfect place for Marangoni studies: first of all, as we already mentioned, we don’t have density-driven convection to confuse the observations. But you can also do some neat tricks that on Earth wouldn’t be possible: the experiment that is currently running makes use of a liquid bridge that could never be obtained in that size on Earth – it would collapse under its own weight!
Hey, I got so carried away with Marangoni that I didn’t tell you about my day at all. First I spent the morning working with Elena on Spheres, as you can see in the picture. I’ll write more about Spheres in the future for sure, but for now I’ll tell you that we did a test run in preparation of the finals of the ZeroRobotics competition in January. We had a lot of fun and I’m sure we’ll have even more fun when we’ll have the competing student software loaded on the Spheres satellites!
Butch and I also did another session of offset grapples, similar to what we did on Saturday, in preparation of Dragon capture. We even practiced a transition to our backup robotic workstation in the US Lab, to be prepared for a malfunction on capture day.
Futura mission website (Italian): Avamposto42
avamposto42.esa.int
(Trad IT) Traduzione in italiano a cura di +AstronautiCAST qui:
https://www.astronautinews.it/tag/logbook
(Trad FR) Traduction en français par +Anne Cpamoa ici:
https://spacetux.org/cpamoa/category/traductions/logbook-samantha
(Trad ES – Currently not updated) Tradducción en español aquí:
https://www.intervidia.com/category/bitacora
17/12/2014