Estimates of Martian water ranges from a 50 to a 500 m deep planet-wide ocean. No obvious mechanism for the escape of water from the planet has been devised. Jean?s escape of water via the atmosphere is very slow (of the order of 3 m over 5 Gy). Assuming that Mars was formed with approximately the same relative amount of water as the Earth, it must be assumed that a substantial fraction of this water remains on Mars in one form or another. It is commonly believed to be bound as ice in the polar caps and, in the ground, as ice, icy permafrost or even as water. There is also indirect evidence for widespread presence of ice, bearing permafrost and liquid fase of water through the existence of rampart craters, terrain softening, chaotic terrain and thermokarst.

In order to ensure the greatest possible penetration of the electromagnetic waves into the ground the wavelength must be chosen as long as possible.

A main task of the MARSES system is to examine changes in subsurface properties of local areas regolith on Mars surface, and to relate them to optical Images and other remote sensing data in order to understand the nature of different terrain forms.

The responsibility for the development of the MARSES system and for the coordination of the modifications of the MARSES system and its operation will rest with MPICh, with key partners in JPL/NASA , IRE/RAS and IKI/RAS (Russia), CNRS CEPHAG and SA (France) and ESA/SSD (the Netherlands). A brief summary of the questions addressed by MARSES and the measurements which must be made in order to answer them is given in the following table.