Space exploration missions, in particular human and large cargo flights, will require considerable transportation efforts to future destinations such as Moon and Mars. One option to achieve these payload and crew capabilities is through the refuelling of orbital transportation stages. EXPLORE aims at informing the investigation of technologies and processes for these orbital refuelling activities through a microgravity experiment.

While storable propellants are already transferred in orbit (e.g. at ISS), the handling of more efficient cryogenic propellants pose specific challenges. A fuel tank is typically pressurized by a gas which then remains in the tank after depletion. Refuelling activities then have to ensure best filling of the tank without mixture of the liquid and gaseous phase, while keeping the imposed pressure to avoid propellant boil off. This refuelling process shall be reproduced in the EXPLORE experiment to investigate the influence of the filling flow velocity on the propellant flow and final fill level.

EXPLORE uses six transparent test chambers with connected gas reservoirs that will be filled from two central liquid reservoirs. The fuel transfer process is observed visually by a camera and through the recording of pressure and temperature data. The flow velocity profile will be varied for each chamber to identify optimal conditions for maximum chamber filling.

EXPLORE has been initiated by six students of aerospace engineering from the University of Stuttgart and is implemented throughout the year 2010 by them together with a student of electronic and computer engineering. Find out more about the experiment using the menu bar on the left.