Opportunity Rover - Mission Timeline - 2004 - Landing Site: "Eagle" Crater

Landing Site: "Eagle" Crater

Opportunity landed in Meridiani Planum at 1°57′S 354°28′E / 1.95°S 354.47°E / -1.95; 354.47, about 25 km downrange (east) of its intended target on January 25, 2004 at 05:05. Although Meridiani is a flat plain, without the rock fields seen at previous Mars landing sites, Opportunity rolled into an impact crater 22 meters in diameter, with the rim of the crater approximately 10 meters (32 ft) from the rover. NASA Scientists were so excited about landing in a crater that they called the landing a "hole in one"; however, they were not aiming for the crater (or even knew it existed). Later, the crater was named Eagle crater and the landing site designated "Challenger Memorial Station". This was the darkest landing site ever visited by a spacecraft on Mars. It would be two weeks before Opportunity was able to get a better look at its surroundings.

Scientists were intrigued by the abundance of rock outcrops dispersed throughout the crater, as well as the crater's soil, which appeared to be a mixture of coarse gray grains and fine reddish grains. This sweeping look at the unusual rock outcropping near Opportunity was captured by the rover's panoramic camera. Scientists believe the seemingly layered rocks are either volcanic ash deposits or sediments laid down by wind or water. It was given the name Opportunity Ledge.

Geologists said that the layers—some no thicker than a finger—indicate the rocks likely originated either from sediments carried by water or wind, or from falling volcanic ash. "We should be able to distinguish between those two hypotheses", said Dr. Andrew Knoll of Harvard University, Cambridge, a member of the science team for Opportunity and its twin, Spirit. If the rocks are sedimentary, water is a more likely source than wind, he said.

These layered rocks measure only 10 centimeters (4 inches) tall and are thought to be either volcanic ash deposits or sediments carried by water or wind. The layers are very thin measuring just a few millimeters thick in some cases.