Dark streaks, everywhere! Many Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images of the middle latitudes of the northern and southern hemispheres of Mars show wild patterns of criss-crossing dark streaks. Many of these streaks are straight and narrow, others exhibit curly arcs, twists, and loops. They often cross over hills, run straight across dunes and ripples, and go through fields of house-sized boulders. The example shown above was acquired in the last three months. The picture is illuminated by sunlight from the upper left. It shows dark streaks on the rippled flats of Argyre Planitia and covers an area 3 km by 5 km (1.9 by 3.1 miles) at a latitude of 51°S.

For many months the MOC science team was seeing streaks such as these, but were uncertain how they formed. One speculation was that they might result from the passage of dust devils. Each dust devil would leave a dark streak by removing bright dust from the terrain in its path, revealing a darker surface underneath. An image described by the MOC team in July 1998 showed examples of streaks that were, at the time, speculated to be caused by dust devils.

Photo Credit: NASA/JPL/Malin Space Science Systems