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  Image: Geographic Location Direction Photo #: ISS022-E-15154 Date: Dec. 2009
Geographic Region: NAMIBIA
Feature: NAMIB SAND SEA, SOSSUS VLEI

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  Tsauchab River and Sossus Vlei Lakebed, Namibia

Taken on Christmas Eve of 2009, this image shows the lower 45 kilometers of the Tsauchab River, a famous landmark for Namibians, tourists, and for orbiting astronauts. The Tsauchab River bed is seen jutting into the sea of red dunes near Namibia’s hyper-arid coast. The riverbed ends in a series of light-colored, silty mud holes on the dry lake floor, known locally as Sossus Vlei (“small lake”).

Because of the present arid climate, few people have ever seen the Tsauchab River with flowing water or a lake in Sossus Vlei. In times past, however, the Tsauchab appears to have reached the Atlantic coast, another 55 kilometers farther west. Like several other rivers of the coastal Namib Desert, the Tsauchab brings sediment down from the hinterland to the coastal lowland. This sediment is then blown from the river beds, and over probably tens of millions of years, has accumulated as the red dunes of the impressive Namib Sand Sea.

This astronaut photo shows sand heaped up in numerous star dunes, each of them with long arms extending in several directions. Unlike crescent-shaped barchan dunes, which form in areas where winds generally blow from one direction, star dunes are apparently generated where winds are variable. In this part of the Namib Sand Sea, winds are mainly from the south, but easterly winds, channeled along the Tsauchab valley, provide another component. And warm dry winter winds—similar to the Santa Ana winds of California—blow from the northeast.

These northeasterly winds are likely responsible for the regular dune arms that point into the valley from both sides. These large dunes facing the river valley are promoted as the highest dunes in the world. Although continuous dune slopes allow hikers to ascend to altitudes more than 300 meters above the river bottom, not all of that elevation gain has to be walked; the main base of the dunes lies on a terrace 180 meters above the river.
 
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Images: All Available Images Low-Resolution 244k
Mission: ISS022  
Roll - Frame: E - 15154
Geographical Name: NAMIBIA  
Features: NAMIB SAND SEA, SOSSUS VLEI  
Center Lat x Lon: 24.7S x 15.4E
Film Exposure:   N=Normal exposure, U=Under exposed, O=Over exposed, F=out of Focus
Percentage of Cloud Cover-CLDP: 10
 
Camera: N2
 
Camera Tilt: 32   LO=Low Oblique, HO=High Oblique, NV=Near Vertical
Camera Focal Length: 180  
 
Nadir to Photo Center Direction: S   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: 3592  
 
Date: 20091224   YYYYMMDD
Time: 091712   GMT HHMMSS
Nadir Lat: 22.9S  
Latitude of suborbital point of spacecraft
Nadir Lon: 16.1E  
Longitude of suborbital point of spacecraft
Sun Azimuth: 97   Clockwise angle in degrees from north to the sun measured at the nadir point
Space Craft Altitude: 185   nautical miles
Sun Elevation: 68   Angle in degrees between the horizon and the sun, measured at the nadir point
Land Views: DESERT, DUNE, VALLEY  
Water Views: RIVER, SEDIMENT  
Atmosphere Views:  
Man Made Views:  
City Views:  
Photo is not associated with any sequences


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