Second Series of Experiments on the International Space Station ISS

Bremen, 21th September 2011 - Although the operational procedure and communication channels show a certain routine, the excitement is still clearly felt. The Bremen team from the Center of Applied Space Technology and Microgravity (ZARM) is now operating their second experiment on the International Space Station. ZARM scientists at ground control monitor the installation of the experiment by astronauts and steer the experiment itself via remote control.

The first experiment phase in January 2011 investigated the capillary behavior of fluids under conditions of microgravity. Specifically, the experiments show which parameters influence the flow of a liquid through capillary channels and how this liquid can be protected from gas ingestion - the so-called "choking effect.

This time the channel geometry has been changed and gas bubbles can be injected into the flow. Beside the investigation of the stability of this new channel, the scientists are interested in how the bubbles formed by gas ingestion can be transported back to the surface and thus separated from the liquid again.

The insights gained from the ZARM team may be used, for instance, for the construction of fuel and life support systems used in space. The bubble-free transport of fluids in microgravity is significantly more difficult than it is on Earth. In the tanks of satellites and space vehicles the fuel does not accumulate at the bottom of the tank. Due to the absence of gravity it is free to spread all over the inner tank walls and other components. Therefore, a system of open capillary channels is necessary to transport the fuel to where it is needed. In these open channels, the liquid is bound by capillary forces, which are based on the principle of attraction between the molecules.

The experimental set-up on the ISS is equipped with channel geometries normally used for handling fluids in space. The channels must have at least one free surface in order to be able to collect and bind fluids by capillary forces. The present experimental set-up incorporates a wedge channel. The fluid flowing through this triangular shape develops special flow profiles – and these can help to eliminate gas bubbles from the liquid by transporting them back to the surface.

Info box:

The CCF project is supported by the German Aerospace Center (DLR) and supported by NASA.

The international team consists of:

• Michael Dreyer, Peter Canfield, Przemyslaw MaxBronowicki, Lars Kiewidt of the Center of Applied Space Technology and Microgravity (ZARM)
• And Mark Weislogel, Will Blackmore, Ryan Jenson and Yongkang Chen of Portland State University (PSU)

For further information:
Prof. Dr. Michael Dreyer
michael.dreyer(at)zarm.uni-bremen.de
+49 421 218-4038

For general media requests and photos:
Birgit Kinkeldey
birgit.kinkeldey(at)zarm.uni-bremen.de
+49 421 218-4801