image (199 Kb)
Lake serves as a striking visual marker for astronauts orbiting
over North America. A sharp line across its center is caused by
the restriction in water flow from the railroad causeway. The eye-catching
colors of the lake stem from the fact that Great Salt Lake is hypersaline,
typically 3-5 times saltier than the ocean, and the high salinities
support sets of plants and animals that affect the light-absorbing
qualities of the water. North of the causeway salinities are higher,
and the water turns red from the pigments of halophilic bacteria.
In the shallower corners of the lake, earthen dikes mark large salt
evaporation works, which take on the jewel tones of turquoise, russet,
tamber and pearl white.
image shows some of the salt works operated by Great Salt Lake Minerals
and Chemicals Corporation near West Warren, Utah, on the eastern
shore of the lake. Evaporative salt
harvesting at Great Salt Lake is an important source of minerals
for industrial uses. The lake contains an estimated 5 billion tons
of salt, with 2.5 million additional tons washing in each year.
Extraction rates are slightly higher than the amount added to the
lake each year. In addition to sodium chloride, the ponds near West
Warren are used to extract potassium sulfate and magnesium chloride,
which are used to make fertilizers.
astronauts have recorded the decline in lake levels in response
to a regional five-year drought taking both detailed views and broad
views of the entire lake. As lake levels have declined the salt
works have become islands in the middle of a dry lakebed. Seasonal
fluctuations in Great Salt Lake produce annual lows every fall,
but there are significant longer-term fluctuations in lake levels
relating to the climate. Great Salt Lake hit a 22-year low at 4,198
feet in the fall of 2002, and a near-record
low again in October 2003. The lowest level ever recorded was
4,191 feet in 1963, and the highest
levels were 4,212 feet in June 1986 and April 1987. Experimental
scientific forecasts predict that lake levels will begin gradually
increasing again, but the U.S.
Seasonal Drought Outlook indicate only limited improvement from
this snow season because the water deficits are so high.
world, lake levels are and excellent indicator of local climate.
Repeat observations over time allow comparisons and levels rise
and fall in response to droughts and the broader climate patterns
that are linked to droughts.
was provided by the Earth Sciences and Image Analysis Laboratory
at Johnson Space Center. The International Space Station Program supports the laboratory to help astronauts
take pictures of Earth that will be of the greatest value to scientists
and the public, and to make those images freely available on the
Internet. Additional images taken by astronauts and cosmonauts can
be viewed at the NASA/JSC Gateway
to Astronaut Photography of Earth.