Well-Preserved Impact Ejecta and Impact Melt-Rich Deposits in Terra Sabaea
Well-Preserved Impact Ejecta and Impact Melt-Rich Deposits in Terra Sabaea
ESP_047735_1610  Science Theme: Impact Processes
This image of a well-preserved unnamed elliptical crater in Terra Sabaea, is illustrative of the complexity of ejecta deposits forming as a by-product of the impact process that shapes much of the surface of Mars.

Here we see a portion of the western ejecta deposits emanating from a 10-kilometer impact crater that occurs within the wall of a larger, 60-kilometer-wide crater. In the central part is a lobe-shaped portion of the ejecta blanket from the smaller crater. The crater is elliptical not because of an angled (oblique) impact, but because it occurred on the steep slopes of the wall of a larger crater. This caused it to be truncated along the slope and elongated perpendicular to the slope. As a result, any impact melt from the smaller crater would have preferentially deposited down slope and towards the floor of the larger crater (towards the west).

Within this deposit, we can see fine-scale morphological features in the form of a dense network of small ridges and pits. These crater-related pitted materials are consistent with volatile-rich impact melt-bearing deposits seen in some of the best-preserved craters on Mars (e.g., Zumba, Zunil, etc.). These deposits formed immediately after the impact event, and their discernible presence relate to the preservation state of the crater. This image is an attempt to visualize the complex formation and emplacement history of these enigmatic deposits formed by this elliptical crater and to understand its degradation history.

Written by: Arya Bina, Elise Harrington, Eric Pilles and Livio Tornabene (audio: Tre Gibbs)  (12 January 2017)
Acquisition date
02 October 2016

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
258.8 km (160.9 miles)

Original image scale range
25.9 cm/pixel (with 1 x 1 binning) so objects ~78 cm across are resolved

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25 cm/pixel and North is up

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Solar incidence angle
46°, with the Sun about 44° above the horizon

Solar longitude
233.7°, Northern Autumn

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North azimuth:  97°
Sub-solar azimuth:  355.1°
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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.