This picture shows Gusev Crater, which is where Spirit landed. The yellow oval, which is 81 km (50 miles) long, shows the area that Spirit should land within. The colors in this picture show how high (or low) the land is. Low places are shown as blue and green. High places are shown as orange and red. Click on image for full size (131K JPEG) Image courtesy NASA.

The first of two Mars Exploration Rovers (MER) landed within Gusev Crater on Mars on January 3, 2004. The robotic rover is named Spirit. Spirit bounced to a halt within an 81 km by 12 km (50 by 7 miles) oval inside the ancient crater. Once settled into its new "home", Spirit began searching for rocks that might show that there used to be water in Gusev Crater.

The MER vehicles are robotic geologists. They are designed to find rocks and soils that might tell us that there once was liquid water at their landing sites on Mars. Gusev Crater formed by the impact of an asteroid three to four billion years ago. There may have been a large lake in Gusev Crater in the distant past. A valley named Ma'adim Vallis is connected to the south side of the crater. Ma'adim Vallis looks like it might have been a river that poured water into the ancient lake. If that is true, the rocks and soil in Gusev Crater should show signs that water was once there. Wet environments are the best places to look for life. That is why scientists want to find places on Mars that were once wet.

Gusev Crater is about 145 km (90 miles) wide. It is about the same size (area) as the state of Connecticut. The other MER rover, Opportunity, is exploring an area on Mars named Meridiani Planum on the opposite side of Mars.