Every day we get more evidence that astronauts are giant nerds. Today you can listen to them ooh and ahh over a basic cornstarch and water experiment, and discuss how it might lead to their destruction at the hands of robot overlords.
Most people with access to youtube or even a few high school science classes under their belt have seen the cornstarch and water on a speaker experiment. Adding cornstarch to water forms a shear thickening, or non-newtonian, fluid. Most fluid will give way when hit by a force. A shear thickening fluid, however, stiffens when it's hit. The harder and quicker it is hit, the stiffer it becomes. This means that, when such a fluid is placed on a speaker with constant vibration sending kicks through it, figures start to form.
This experiment is repeated in many a science classroom, and it rarely gets as appreciative an audience as it does in the International Space Station. Interestingly, this experiment looks in space very much like the ones do on Earth, meaning that gravity has only a slight effect on it. As far as I can tell, the fact that the orbiting space station negates the pull of gravity only allows for a head-like structure to form on the figures made by the vibration. When the demonstration is done on Earth, by the time the figures get too high and spindly, they're pulled back down by gravity. Occasionally bits will break off the whole and fly around, but the figures are arches and towers, without heads. On the ISS long-lived globes on tiny necks form, pushed up by the vibrations through the liquid, and not pulled down again by gravity. As soon as the globe gets too high, though, the vibration is lessened, so the figures can't get very tall.
While it's interesting to see the subtle differences in the experiment, it's way more entertaining to hear the astronauts go full metal geek during the video. In the beginning, they're talking about how the thing looks like an alien virus monster out to get them. By the end, not only is the crew talking about how "absolutely amazing" the whole thing was, they're imagining what it would be like if the goo merged with the ship's robot, called robonaut, and created a Terminator II prototype that would attack them. It's nice to know that going to space doesn't stop making people appreciate the simple things. "Yeah, we're orbiting the Earth, but check out this corn starch!"
Top Image: NASA