The twenty-two papers contained in this volume have been selected from the Proceedings of the 2nd COSPAR Colloquium. The exploration of planet Mars will be the focal point of the planetary missions in the coming years, so the investigation of the surface and the upper layers of the soil is of primary importance. The major space agencies are actively working to understand the environmental and technical requirements of the planned missions and experiments and it is predicted that the planet will be host to both ground based and atmospheric investigations in the near future.