The many faces of mars

The geologcial surveys reveal that Mars has experienced a striking diversity of processes and conditions throughout its history. The Opportunity rover headed to the plains of Meridiani, which marked a new phase in humanity's exploration of the solar system. The largest outcrop that Opportunity explored, named Burns Cliff, appeared to be a series of preserved sand dunes that were wetted by surface and ground waters. The TES instrument has discovered that Martian rocks and sands are composed of the volcanic minerals. The climate is dry and cold, yet the Opportunity rover found itself on the floor of an ancient sea, indicating that the climate used to be very different.