Without gravity, it's difficult -- if not impossible -- to predict how a liquid will behave. To develop a better understanding of fluids in microgravity, a Capillary Flow Experiment is being conducted onboard the International Space Station.
We now know that if two solid surfaces meet at a narrow-enough angle, fluids in microgravity naturally flow along the join, with no pumping required. As a result of this discovery, Professor of Physics Mark Weislogel of Portland State University and his colleagues have been granted a patent for a Zero Gravity Coffee Cup.
Astronaut Don Pettit, who worked with the Capillary Flow Experiment during his time on board the ISS, helped invent the cup. One side has a sharp interior corner and capillary forces send fluid flowing along the channel and into the drinker's mouth. Pettit said:
As you sip, more fluid keeps coming, and you can enjoy your coffee in a weightless environment -- clear down to the last drop. This may well be what future space colonists use when they want to have a celebration.
Check out the video above to see how the Zero Gravity Cup works.