NASA Mars Picture of the Day: Gullies in Nirgal

Mars Global Surveyor Mars Orbiter Camera

MGS MOC Release No. MOC2-535, 5 November 2003

NASA/JPL/Malin Space Science Systems

This is a Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)
narrow angle image of gullies carved into debris on the south-facing
wall of Nirgal Vallis, an ancient martian valley. The gullies were
conduits for sediment that has accumulated at a point where
each channel met the valley floor. The aprons of debris are superposed
upon the large ripple-like dunes, suggesting that the gullies
are younger than these bedforms. Gullies such as these might have been
formed by a liquid, such as water, seeping from the layered bedrock
exposed in the valley wall, or perhaps by mass movement of the
smooth-surfaced debris that covers much of the lower two-thirds
of the valley wall. This picture is located
near 28.6°S, 41.5°W. The image covers
an area 3 km (1.9 mi) across and is illuminated by
sunlight from the upper left.

Malin Space Science Systems and the California Institute of Technology
built the MOC using spare hardware from the Mars Observer mission.
MSSS operates the camera from its facilities in San Diego, California.
The Jet Propulsion Laboratory’s Mars Surveyor Operations Project
operates the Mars Global Surveyor spacecraft with its industrial
partner, Lockheed Martin Astronautics, from facilities in Pasadena,
California and Denver, Colorado.