Drops in Space

Two of my favourite fluidics videos are made by Don Petit, a scientist and astronaut who performs experiments on the International Space Station (ISS). I first came across Don at the NZ Institute of Physics meeting in Christchurch (2009) where he wowed the audience with tales of trying to do science in space. Of course, there are many research groups around the world who compete to have experiments performed in orbit, and Don has to execute these, but the experiments in this video were actually carried out in his spare time. They involve waves, bubbles and a chemical reaction in a football-sized sphere of water.

In a more recent experiment, a droplet ‘orbits’ a charged teflon knitting needle. I’ve put ‘orbits’ in inverted commas because an astrophysics colleague reckons the orbit can’t be stable. Is that right? What if the needle was superhydrophobic, so that a drop rebounded elastically from the needle when it came into contact?

The thing about droplets in space is that because there is little gravity, surface tension becomes very important. It’s nice to be able to see surface tension in action so clearly, because it is also important in nanofluidics and microfluidics.