Ancient Martian Highlands
The meteorite ALH 84001, where possible traces of martian life have been found, is one of the oldest rocks ever studied The meteorite probably came from one of the oldest regions on Mars.
These ancient parts of Mars, most of its southern hemisphere, are covered with asteroid impact craters, like this area in the bright region of Noachis. This part of Mars is as cratered as the Moon's highlands and is about the same age, more than 4 billion years old.
The biggest crater here is Proctor, named for a nineteenth-century British astronomer. The dark splotches inside Proctor and many other craters are fields of sand dunes. In high-resolution images, these linear dunes look like waves on the ocean, but they actually show how dry and desolate Mars is now.
This image was taken by the Viking 1 orbiter in 1977.
