You’ve seen how astronauts take out the trash, now watch how water droplets merge onboard the International Space Station. This experiment, designed by scientists from Cornell and Clemson, allowed the team to observe the dynamics of larger water droplets in zero gravity. Four different surfaces were installed on a space station lab table, each with a different texture.
Water droplets typically resemble spherical caps due toe their surface tension exceeding gravity. However, the footage recorded by cameras revealed that a droplet resting on a surface has a portion that touches the air, resulting in an interface. The section that makes contact with the surface creates and edge or contact line, thus confirming the Davis-Hocking model, which is a method to simulate droplets.
NASA astronauts Kathleen Rubins and Michael Hopkins would deposit a single drop of the desired size at a central location on the surface. This drop is near, but not touching, a small porthole pre-drilled into the surface. The astronaut then injected water through the porthole, which collects and essentially grows an adjacent drop. Injection continues until the two drops touch, at which point they coalesce,” said Josh McCraney, Postdoctoral Associate at Cornell University.
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