Tongue-Shaped Flow Feature in Hellas Planitia
Tongue-Shaped Flow Feature in Hellas Planitia
PSP_002320_1415  Science Theme: Glacial/Periglacial Processes
This image captures a tongue-shaped lobate flow feature along a interior crater wall located in eastern Hellas Planitia.

The flow feature is approximately 5 kilometers long and 1 kilometer wide with a partial double inner ridge and raised outer margin. The flow feature's surface is generally devoid of impact craters and parts of its outer margin have deflected around obstacles.

Similar flow features, though not as distinctively tongue-shaped as this one, are found in many other craters throughout the southern mid-latitudes of Mars.

Recent studies of these flow features have determined a latitudinal dependence to which side of the crater interior these features are formed upon. For this particular flow feature, it has formed on the pole-facing slope. This polar or equatorial-facing preference has implications for the amount of solar isolation these slopes are receiving, which may be a result of recent climate change due to shifts from low to high obliquity.

Although these Martian flow features may have Earth analogs such as rock glaciers, uncertainty remains as to what types of fluvial, glacial and mass-wasting processes are involved in their formation. This particular flow feature was imaged previously by the Mars Orbiter Camera (MOC) onboard NASA's Mars Global Surveyor spacecraft.

Written by: Frank Chuang  (14 February 2007)

This is a stereo pair with PSP_003243_1415.
Acquisition date
24 January 2007

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
252.4 km (156.9 miles)

Original image scale range
25.6 cm/pixel (with 1 x 1 binning) so objects ~77 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
67°, with the Sun about 23° above the horizon

Solar longitude
171.9°, Northern Summer

For non-map projected images
North azimuth:  96°
Sub-solar azimuth:  30.9°
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Black & white is 5 km across; enhanced color about 1 km
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NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.