Gullies and Bedrock in Nirgal Vallis
Gullies and Bedrock in Nirgal Vallis
ESP_020087_1515  Science Theme: Mass Wasting Processes
The gullies in this image are within the valley wall of an ancient channel—Nirgal Vallis—a testament to flowing water in Mars’ ancient past. However, the formation of gullies are still the subject of much debate with respect to their formation: “wet” vs. “dry” or even “dry” with the aid of some lubricating fluid.

Gullies most commonly form in the steep walls of simple craters. Gullies are common even in cold arctic deserts on Earth (e.g., the Haughton impact structure on Devon Island). This suggests that these provocative features can form on a mostly dry Mars that is only sporadically wet.

Regardless, these features bear a remarkable resemblance to flowers, including the blossom, petals, stem, and roots. Can you see it too?

Written by: Livio Tornabene and Kayle Hansen (narration: Tre Gibbs)  (11 February 2015)

This is a stereo pair with ESP_019810_1515.
Acquisition date
08 November 2010

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
256.4 km (159.3 miles)

Original image scale range
27.0 cm/pixel (with 1 x 1 binning) so objects ~81 cm across are resolved

Map projected scale
25 cm/pixel and North is up

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Phase angle

Solar incidence angle
63°, with the Sun about 27° above the horizon

Solar longitude
177.7°, Northern Summer

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North azimuth:  97°
Sub-solar azimuth:  25.3°
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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.