Flux (Phi) Probe Experiment - Time resolved Measurement of Atomic Oxygen (FIPEX) is a system which is able to distinguish and measure molecular and atomic oxygen at very low ambient pressures. It is based on solid oxide electrolyte micro-sensors, developed by Technical University of Dresden (TU Dresden) in Germany. The scientific objectives of the experiment FIPEX mounted on the International Space Station (ISS) are in summary:

• Measurement of atomic oxygen flux in low earth orbit over a long period of time.
• Investigation of ISS contamination in thrusting periods and during proximity operations of the logistic vehicles. This experiment would give a time resolved determination of the contamination of satellite structures in space.
• Investigation of the behaviour of the ceramic solid electrolyte and the different electrode coatings during exposure to the space environment.