Status Report

NASA Mars Picture of the Day: Multiple-Event Gully

By SpaceRef Editor
November 24, 2003
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Mars Global Surveyor Mars Orbiter Camera

MGS MOC Release No. MOC2-554, 24 November 2003

NASA/JPL/Malin Space Science Systems

Middle- and polar-latitude gullies are common on crater
and trough walls in the martian southern hemisphere. Some
also occur in the north. One of the controversies surrounding
gullies is whether they involved fluid flow (such as liquid
water) or were formed by dry landsliding processes. The
occurrence of banked and leveed channels in many gullies
argues that they formed by fluid flow. Another question
centers on whether gullies are “one-shot deals” or involved
more than one episode of fluid flow.
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)
image, acquired in November 2003, shows a gully with
an apron, near the center of the frame, that formed
by multiple fluid flows. The apron of debris at the base
of the gully near the center of the picture is not just
one apron, it is three. Three separate aprons formed at
three different times. First, the larger, left-most apron
formed. Later, another event caused fluid to cut through
that apron and create a new one (the middle of the three).
Later, a third event cut both aprons and formed a small,
third one. This image shows the wall of an impact crater
located near 51.3°S, 326.6°W.
The image covers an area 3 km (1.9 mi) wide, 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.

SpaceRef staff editor.