Winds remained light, with occasional flurries of blowing dust. As the Sun set in a clear sky, temperatures started to plummet, and another day was over at the Carl Sagan Memorial Station, on the surface of the planet Mars. Over the last few weeks we have been obtaining some of the most spectacular views of the Martian surface that we've ever had. However, a second look showed some dramatic differences. On the horizon we see two hills that show signs of water erosion.
Similar signs are visible among some of the foreground rocks and structures.
Many millions of years ago, this area was the site of a great river, winding slowly down to a long lost ocean. The hills also show signs of layering. On Earth this suggests the presence of sedimentary rocks, which are produced when sediments on the beds of oceans, lakes and rivers are compressed over millions of years. Sojourner, the Mars rover, a small, wheeled vehicle, has been exploring the area round the Lander. It was designed to work for a week.