|NASA Photo ID||ISS047-E-54173|
|Time taken||10:08:34 GMT|
1000 x 659 pixels 540 x 356 pixels 3108 x 2072 pixels 720 x 480 pixels 4928 x 3280 pixels 640 x 426 pixels
|Nikon D4 Electronic Still Camera|
|4928E: 4928 x 3280 pixel CMOS sensor, 36.0mm x 23.9mm, total pixels: 16.6 million, Nikon FX format|
|1000 pixels||659 pixels||No||No||Earth From Space collection||Download Image|
|540 pixels||356 pixels||Yes||No||Earth From Space collection||Download Image|
|3108 pixels||2072 pixels||No||No||NASA's Earth Observatory web site||Download Image|
|720 pixels||480 pixels||Yes||Yes||NASA's Earth Observatory web site||Download Image|
|4928 pixels||3280 pixels||No||No||Download Image|
|640 pixels||426 pixels||No||No||Download Image|
Orbiting over the deserts of Inner Asia, a crew member aboard the International Space Station (ISS) used a 400 mm lens to capture the detail of the unusual mix of desert dunes and dense populations. A major cordon of dunes dominates the view, crossing the image from top right to lower left in this oblique view. The dunes form the shoreline of Bosten Lake in China's far northwest. Even in this desert region, rain and snowfall in the Tien Shan Mountains immediately to the north generate enough water locally for the small (55,000 people) but dense population to be supported. Here the Kaidu River brings mountain water to numerous, close-packed fields, and feeds muddy sediment into the waters of the lake (at image center). Over the centuries, sediments from the Kaidu River have built up the large smooth arable surface of an alluvial fan, now mostly covered with fields (at image right). Other, less prominent fields occupy smaller fans on the other side of the dune cordon (at image top left).
Water from the lake infiltrates under the dunes and evaporates on the other side (at image center left) producing salt flats. Neither the toxic salty soils of these flats nor the dune sands can be used to grow crops. Bosten Lake is a freshwater lake covering an area of about 1,000 km2 (390 sq mi) and one of the largest inland lakes in China which supplies a fish catch for the local populations. The outflow channel of the lake follows the dune margin, where it has been modernized as an engineered canal (see the detailed image, at image top right). Interestingly, a core drilled into the lake bed shows how ephemeral is this water supply: geologists now know that the lake has dried out eleven times in the last 8,500 years.
An image from 1992 shows the entire lake and enclosing dune cordon (STS047-91-52).