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  Image: Geographic Location Direction Photo #: ISS020-E-26195 Date: Jul. 2009
Geographic Region: CHAD
Feature: AOROUNGA IMPACT CRATER, YARDANGS

Ordering information for space photography
 
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  Aorounga Impact Crater, Chad

Aorounga Impact Crater is located in the Sahara Desert, in north-central Chad, and is one of the best preserved impact structures in the world. The crater is thought to be middle or upper Devonian to lower Mississippian (approximately 345–370 million years old) based on the age of the sedimentary rocks deformed by the impact. Spaceborne Imaging Radar (SIR) data collected in 1994 suggests that Aorounga is one of a set of three craters formed by the same impact event. The other two suggested impact structures are buried by sand deposits.

The concentric ring structure of the Aorounga crater—renamed Aorounga South in the multiple-crater interpretation of SIR data—is clearly visible in this detailed astronaut photograph. The central highland, or peak, of the crater is surrounded by a small sand-filled trough; this in turn is surrounded by a larger circular trough. Linear rock ridges alternating with light orange sand deposits cross the image from upper left to lower right; these are called yardangs by geomorphologists. Yardangs form by wind erosion of exposed rock layers in a unidirectional wind field. The wind blows from the northeast at Aorounga, and sand dunes formed between the yardangs are actively migrating to the southwest.
 
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Images: All Available Images Low-Resolution 272k
Mission: ISS020  
Roll - Frame: E - 26195
Geographical Name: CHAD  
Features: AOROUNGA IMPACT CRATER, YARDANGS  
Center Lat x Lon: 19.1N x 19.2E
Film Exposure:   N=Normal exposure, U=Under exposed, O=Over exposed, F=out of Focus
Percentage of Cloud Cover-CLDP: 10
 
Camera: N3
 
Camera Tilt: 42   LO=Low Oblique, HO=High Oblique, NV=Near Vertical
Camera Focal Length: 800  
 
Nadir to Photo Center Direction: SW   The direction from the nadir to the center point, N=North, S=South, E=East, W=West
Stereo?:   Y=Yes there is an adjacent picture of the same area, N=No there isn't
Orbit Number: 1198  
 
Date: 20090725   YYYYMMDD
Time: 105733   GMT HHMMSS
Nadir Lat: 21.5N  
Latitude of suborbital point of spacecraft
Nadir Lon: 20.7E  
Longitude of suborbital point of spacecraft
Sun Azimuth: 242   Clockwise angle in degrees from north to the sun measured at the nadir point
Space Craft Altitude: 187   nautical miles
Sun Elevation: 86   Angle in degrees between the horizon and the sun, measured at the nadir point
Land Views: CRATER, DESERT, EROSION  
Water Views:  
Atmosphere Views:  
Man Made Views:  
City Views:  
Photo is not associated with any sequences


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