Special issue of Planetary of Space Science Planet Mars II: A new image of Planet Mars

The international workshop ‘‘Planet Mars II’’ which took place at the Centre de Physique in Les Houches (France) on May 23–June 1, 2005, led to vivid and fruitful discussions about the new results which have recently come out of the Mars Global Surveyor, Mars Odyssey, Exploration Rovers and Mars Express space missions. Following the first workshop which took place on April 28–May 9, 2003 (Encrenaz and Sotin, 2004), about 50 scientists of all horizons listened to tutorials and exchanged latest results concerning all aspects of the planet’s physics, chemistry, geology and environment: internal structure, gravity field, magnetic field, surface morphology, cratering and mineralogy; atmospheric composition and escape; past climate of Mars and obliquity effects; search for past or present traces of life. These discussions demonstrated that our understanding of Mars’ evolution and, in particular, the question of the water cycle over its history has been quite modified by the recent results of the Mars Exploration Rovers and Mars Express.