The German Mars Society (Mars Society Deutschland e.V. – MSD) was co-founded in 1998 together with the US Mars Society based on the Mars Society Founding Declaration, and was later-on registered in Germany as a non-profit organization. The MSD has 120 members. In addition to the promotion of unmanned and manned Mars exploration in the public, the MSD has engaged in the development of the ARCHIMEDES project, an innovative method to explore the Mars atmosphere using a 10…19 m balloon deployed in Mars orbit. The balloon carries a scientific payload performing measurement during its slow descent to the Mars surface. The ARCHIMEDES mission feasibility will be demonstrated through the MIRIAM project, where a downscaled ARCHIMEDES balloon probe will be exposed in the high Earth atmosphere to aerodynamic conditions similar to the Mars environment. The MIRIAM launch is scheduled for 2018-19.