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This animation shows, in a simplified way, the operation of SHOOT, the Superfluid Helium On-Orbit Transfer experiment. This apparatus, which flew in the Space Shuttle, demonstrated pumping superfluid helium back and forth between two dewars. Because of the unusual properties of superfluid helium, the pumping was done, not with mechanical pumps, but with porous plugs and heaters. For a nontechnical explanation, see the SHOOT section of the Liquid Helium in Space.
Here is a key to the parts of the diagram. This is a frame from the part of the animation showing the helium being pumped from right to left.
I've drawn this diagram showing the liquid helium sitting in the bottoms of the tanks, as it did when SHOOT was being tested on the ground. That's not the way the liquid helium behaved while it was orbiting in the Space Shuttle.
In orbit, liquids don't stay put in their containers the way they do on the ground. Here on the ground, your coffee, for example, sits quietly in your mug till you get around to drinking it. That's not true in orbit. With no gravity to hold it in your mug, your coffee would float out into the air, in small and large drops, drifting in the air currents. Not what you want to happen to your Royal Kona! That's why astronauts drink liquids out of squeeze bottles.
By the same token, when SHOOT was in orbit, the liquid helium didn't sit in the bottoms of the tanks. Nevertheless, the SHOOT experiment showed that the porous plug system was quite able to acquire the liquid helium and pump it to the other tank. I've shown the helium sitting on the bottoms of the tanks (as it did during ground testing) because it's easier to make a simple diagram that way.Links