The Bedrock Riddles of Nili Fossae
NASA/JPL/University of Arizona
The Bedrock Riddles of Nili Fossae
ESP_060064_2005  Science Theme: Geologic Contacts/Stratigraphy
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This image of the Nili Fossae region, to the west of the great Isidis basin, shows layered bedrock with many impact craters.

Nili Fossae is one of the most mineralogically important sites on Mars. Remote observations by the infrared spectrometer onboard MRO (called CRISM) suggest the layers in the ancient craters contain clays, carbonates, and iron oxides, perhaps due to hydrothermal alteration of the crust. However, the impact craters have been degraded by many millions of years of erosion so the original sedimentary, impact ejecta, or lava flows are hard to distinguish.

The bright linear features are sand dunes, also known as “transverse aeolian dunes,” because the wind direction is at ninety degrees to their elongated orientation. This shows that the erosion of Nili Fossae continues to the present day with sand-sized particles broken off from the local rocks mobilized within the dunes.

Written by: John Bridges (audio: Tre Gibbs)  (3 September 2019)

This is a stereo pair with ESP_052389_2005.
 
Acquisition date
20 May 2019

Local Mars time
14:25

Latitude (centered)
20.435°

Longitude (East)
78.083°

Spacecraft altitude
279.7 km (173.8 miles)

Original image scale range
56.6 cm/pixel (with 2 x 2 binning) so objects ~170 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection
Equirectangular

Emission angle
9.5°

Phase angle
45.5°

Solar incidence angle
36°, with the Sun about 54° above the horizon

Solar longitude
27.9°, Northern Spring

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  357.7°
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All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible:
NASA/JPL/University of Arizona

POSTSCRIPT
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.