Near the Viking 1 Lander on the Chryse Plains of Mars, "Big Joe" stands a silent vigil. This large, often-photographed dark rock has a topping of reddish fine-grained silt that spills down its sides. It is about 2 meters (6.6 feet) long and lies about 8 meters (26 feet) from the spacecraft. The rough texture of the sides shows it to be coarse grained. Big Joe appears to be part of a field of large blocks that has a roughly circular alignment and which may be part of the rim of an ancient degraded crater. Some of the other blocks of the field can be seen to the left, extending out toward the horizon, perhaps 1.5 kilometers (1 mile) away. Drifts of fine-grained material cover the surface to the right and left of Big Joe. The part of the Lander that is visible in the lower left is the cover of the nuclear power supply.