NASA Sees New Salt in an Ancient Sea
The expansion of massive salt evaporation projects on the Dead Sea are clearly visible in this time series of images taken by Landsat satellites operated by NASA and the U.S. Geological Survey.
This false-color image was captured by the Landsat 1, 4 & 7 satellites.
Jutting out into the sea from the right in all three images is the Lisan Peninsula. In 1989, the expansion of pools to harvest salt resulted in that white-colored peninsula cutting the sea in half and forming a land bridge across the sea.
The intensity of the blue colors within the sea shows the depth of the water. Deep water in the north part of the sea is dark blue. Lighter colored blue is where the water is channeled into pools for harvesting salt. The straight white lines are dams built to break up the sea into 'fields' of salty water.
Over time, these salt evaporation projects sliced the Dead Sea into more and more of these pools. In 2011 the deeper-looking water in the southern part of the sea is due to weekly variations in the amount of water filling the pools, ongoing changes that depend on the current stage of salt harvesting.
On land, the pale pink and sand-colored regions are desert with denser vegetation appearing bright red.
The Dead Sea is so named because its natural salinity discourages the growth of fish, plants and other wildlife. The sea exists because the land has been sinking for millennia due to the continents of Africa and Asia pulling away from each other. This depression makes the lake the lowest surface feature on Earth at about 1,300 feet (nearly 400 meters) below sea level. On a hot dry summer day, the surface of the Dead Sea can drop as much as one inch (two to three centimeters) because of evaporation.
The sea has attracted visitors for thousands of years. Between 1947 and 1956, a series of 972 ancient texts were discovered in caverns near the sea's northeastern shore. These Dead Sea Scrolls were written on papyrus and paper and contained details from the Hebrew Bible and other biblical documents.
The ancient Egyptians also used salts from the Dead Sea for mummification, fertilizers and potash (a potassium-based salt). In the modern age, the sodium chloride and potassium salts culled from the sea are also used in part for water conditioning, road de-icing and by the chemical industry for the manufacturing of polyvinyl chloride (PVC) plastics.
The Landsat 1, 4 and 7 satellites captured this false-color image using light from near-infrared, red and green wavelengths (MSS bands 4, 2, & 1 and TM and ETM+ bands 4, 3, & 2 respectively).
Landsat 1 launched in 1972 and provided scientific data until 1978. In 1982 NASA launched Landsat 4, which ran for 11 years until 1993. Landsat 7 is still up and running; it was launched in 1999. The data from these and other Landsat satellites has been instrumental in increasing our understanding of forest health, storm damage, agricultural trends, urban growth, and many other ongoing changes to our land.
NASA and the U.S. Department of the Interior through the U.S. Geological Survey (USGS) jointly manage Landsat, and the USGS preserves a 40-year archive of Landsat images that is freely available data over the Internet. The next Landsat satellite, now known as the Landsat Data Continuity Mission (LDCM) and later to be called Landsat 8, is scheduled for launch in January 2013.
NASA's Landsat Data Continuity Mission
USGS's Landsat website
NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission.
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