NASA Mission Will Observe Earth's Salty Seas For Climate Clues

WASHINGTON -- Final preparations are under way for the June 9 launch
of the international Aquarius/SAC-D observatory. The mission's
primary instrument, Aquarius, will study interactions between ocean
circulation, the water cycle and climate by measuring ocean surface salinity.

Engineers at Vandenberg Air Force Base in California are performing
final tests before mating Aquarius/SAC-D to its Delta II rocket. The
mission is a collaboration between NASA and Argentina's space agency,
Comision Nacional de Actividades Espaciales (CONAE), with
participation from Brazil, Canada, France and Italy. SAC stands for
Satelite de Applicaciones Cientificas.

In addition to Aquarius, the observatory carries seven other
instruments that will collect environmental data for a wide range of
applications, including studies of natural hazards, air quality, land
processes and epidemiology.

The mission will make NASA's first space observations of the
concentration of dissolved salt at the ocean surface. Aquarius'
observations will reveal how salinity variations influence ocean
circulation, trace the path of freshwater around our planet, and help
drive Earth's climate. The ocean surface constantly exchanges water
and heat with Earth's atmosphere. Approximately 80 percent of the
global water cycle that moves freshwater from the ocean to the
atmosphere to the land and back to the ocean happens over the ocean.

Salinity plays a key role in these exchanges. By tracking changes in
ocean surface salinity, Aquarius will monitor variations in the water
cycle caused by evaporation and precipitation over the ocean, river
runoff, the freezing and melting of sea ice. Salinity also makes
seawater denser, causing it to sink, where it becomes part of deep,
interconnected ocean currents. This deep ocean "conveyor belt" moves
water masses and heat from the tropics to the polar regions, helping
to regulate Earth's climate.

"Salinity is the glue that bonds two major components of Earth's
complex climate system: ocean circulation and the global water
cycle," said Aquarius Principal Investigator Gary Lagerloef of Earth
& Space Research in Seattle. "Aquarius will map global variations in
salinity in unprecedented detail, leading to new discoveries that
will improve our ability to predict future climate."

Aquarius will measure salinity by sensing microwave emissions from the
water's surface with a radiometer instrument. These emissions can be
used to indicate the saltiness of the surface water, after accounting
for other environmental factors. Salinity levels in the open ocean
vary by only about five parts per thousand, and small changes are
important. Aquarius uses advanced technologies to detect changes in
salinity as small as about two parts per 10,000, equivalent to a
pinch (about one-eighth of a teaspoon) of salt in a gallon of water.

Aquarius will map the entire open ocean every seven days for at least
three years from 408 miles (657 kilometers) above Earth. Its
measurements will produce monthly estimates of ocean surface salinity
with a spatial resolution of 93 miles (150 kilometers). The data will
reveal how salinity changes over time and from one part of the ocean
to another.

The Aquarius/SAC-D mission continues NASA and CONAE's 17-year
partnership. NASA provided launch vehicles and operations for three
SAC satellite missions and science instruments for two. Aquarius was
built by NASA's Jet Propulsion Laboratory in Pasadena, Calif., and
the agency's Goddard Space Flight Center in Greenbelt, Md. JPL will
manage Aquarius through its commissioning phase and archive mission
data. Goddard will manage Aquarius mission operations and process
science data. NASA's Launch Services Program at the agency's Kennedy
Space Center in Florida is managing the launch.

CONAE is providing the SAC-D spacecraft, an optical camera, a thermal
camera in collaboration with Canada, a microwave radiometer; sensors
from various Argentine institutions and the mission operations center
there. France and Italy are contributing instruments.

For more information about Aquarius/SAC-D, visit:

http://www.nasa.gov/aquarius

http://www.conae.gov.ar/eng/principal.html

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