About 10 years ago, I heard about a project to put a rotational rheometer on the International Space Station. The idea was to study the rheological performance of foams in zero g. The idea is that the fluid in between the bubbles will not drain once the effect of gravity is removed. The project has been approved, although I can't tell if the system has flown or experiments have been performed.
At the time, there were two questions I had about the project. First, how do you keep the sample contained in zero g? Fluids don't stay put but instead float around the cabin. At the time I heard about the project, the only sealed cells that were available used mechanical bearings, which reduced the sensitivity of the measurement. Second, as the amount of air is an issue in space, can one use an air bearing instrument? It appears that these and other issues have been addressed, and I look forward to the publications on this project.
Does anyone know who built the rheometer?
(Picture of the rheometer chamber for FOAM.)