Which Crater Came First?
NASA/JPL-Caltech/UArizona
Which Crater Came First?
ESP_020190_1690  Science Theme: Impact Processes
This image shows two craters, both approximately the same diameter (not quite 3 kilometers, or about 1.8 miles), but quite different in appearance otherwise.

The slightly smaller crater to the south seems to have a sharper rim and steeper sides than its partner to the north, which also appears to contain more small craters inside it and along its rim. The interior of the northern crater, in particular its south-facing wall, appears to have a similar texture to the ejecta around the southern crater. This is the second image in a stereo pair (the first is ESP_019346_1690), so we have an anaglyph of these craters.

Although it would require a digital terrain model and more analysis to be certain, in the anaglyph it appears that the southern crater has a higher rim and a deeper center than the northern crater. All these signs point to the northern crater being quite a bit older than the southern crater, rather than the two craters forming in the same impact event. For an example of two craters that might have formed at the same time (see ESP_020894_1395).

Compare the similarity of those two craters with the disparate appearance of the ones in this image.

Written by: Nicole Baugh (audio by Tre Gibbs)  (13 June 2012)

This is a stereo pair with ESP_019346_1690.
 
Acquisition date
16 November 2010

Local Mars time
15:47

Latitude (centered)
-11.037°

Longitude (East)
25.882°

Spacecraft altitude
261.1 km (162.3 miles)

Original image scale range
54.6 cm/pixel (with 2 x 2 binning) so objects ~164 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection
Equirectangular

Emission angle
18.0°

Phase angle
39.9°

Solar incidence angle
57°, with the Sun about 33° above the horizon

Solar longitude
182.3°, Northern Autumn

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  13.0°
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HiView

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Black & white is 5 km across; enhanced color about 1 km
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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.