If NASA ever invents the Space Olympics, it should include events like making coffee in bags, eating lettuce, running a marathon while strapped to a treadmill and playing ping-pong with floating liquids. Astronaut Scott Kelly is already the favorite for a gold medal when it comes to that latter sport.
Kelly is in the midst of a one-year stay on the International Space Station. January 21 marked his 300th day, so he celebrated with a one-person game of ping pong. There were no standard balls in play here, but rather a spherical drop of liquid floating in microgravity.
Kelly employed two paddles with hydrophobic coatings designed to repel water. He squeezed a ball of water out of a silver bag and allowed the ball of liquid to bounce between the paddles, its shape distending with every strike against the hydrophobic surfaces.
The paddles are unusual pieces of equipment made with polycarbonate laser-etched surfaces sprayed with Teflon. You probably know Teflon from its use as a nonstick coating for cooking pans. "The combined effects of surface roughness and non-wettability produce a super-hydrophobic surface capable of preventing water adhesion in dynamic processes," NASA notes. In short: the ball of water bounces off.
The ball doesn't fall apart, thanks in part to the very gentle impact. It's nothing like watching top-level ping pong players going at it on Earth, smashing the white balls at high rates of speed across a net. Kelly follows the blob of water with his eyes and declares, "Neat stuff."
We've seen all sorts of fun water experiments coming from the space station. Astronaut Chris Hadfield wrung out a washcloth in space in 2013 to show how the water clings to hands and other surfaces. And last year, Kelly demonstrated what happens when you add an effervescent tablet to a glob of colored water. Spoiler alert: it's super-cool.