Successful flight of SOURCE on MASER-11

The MASER-11 sounding rocket was successfully launched from ESRANGE on Thursday, May 15th, 2008, at 06:00. It carried the SOURCE module to a ballistic flight with an altitude of 250 km providing a ballistic phase of 370 s. The module worked well and delivered the desired data.

SOURCE is a benchmark type of experiment on fluid behavior in tanks to test hypotheses and numerical predictions. This experiment is intended to partially fill in the objectives of the ESA MAP project AO-2004-111 (Convective boiling and condensation). The SOURCE experiment will also serve the needs of the COMPERE research group whose mandate is to investigate the behavior of propellants in spacecraft launcher tanks.

The main element of the SOURCE module is a transparent cylindrical container which will be filled with a test liquid (HFE-7000) during the ballistic phase of the sounding rocket. The container has a linear axial temperature distribution which is achieved prior to the launch by heating the upper part. It is pressurized with nitrogen gas at 3 bars.

During and after the filling the cold liquid comes into contact with the hot walls and a thermo-capillary convection sets in. This convection changes the contact angle and deforms the free surface. This phenomenon can only be investigated in zero gravity condition.

After the observation of the free surface evolution and the corresponding heat flux into the liquid the container pressure will be lowered and a heater in the bottom of the tank will be activated. Vapor/gas bubbles nucleate, grow and then partly recondense on the heater. The bubble behavior in microgravity is completely different from that observed on ground condition. Without buoyancy forces, the bubbles remain in the wall vicinity. Experiments are performed at different heater powers and liquid pressures corresponding to subcooled or saturated boiling conditions. Boiling/degasing is also observed during sequences of depressurization. The evolution of the bubble size is followed by visualization. Heat flux transmitted to the liquid and heater temperature are recorded during the different sequences. The heat transfer coefficient can then be estimated.

The results of the tests will be used to validated numerical tools and correlations which are used (and will be used) to design a new cryogenic re-ignitable European upper stage. The long ballistic flight phases require the knowledge of the thermo-hydraulic behavior of the propellant to predict the location of the liquid in the tanks, the temperature distribution in the liquid and gaseous phases, as well as the amount of evaporated liquid and dissolved gas. The compensated gravity conditions during the ballistic flight phases are unique and can not be tested on ground. Tests on a small scale tank within a sounding rocket provide data for the validation of tools. The results of the tests with a storable liquid will be applied on cryogenic propellants using similarity laws and numerical modeling.

We gratefully acknowledge the support by the European Space Agency (ESA), the French Space Agency (CNES) and the German Aerospace Center (DLR).


Dr. Catherine Colin, IMFT, Toulouse
Dr. Michael Dreyer, ZARM, Bremen
Dr. Philipp Behruzi, Astrium ST, Bremen
Jerome Lacapere, Air Liquide, Grenoble

University of Bremen
Am Fallturm
28359 Bremen