Salt-Seeking Spacecraft Arrives At Launch Site NASA Instrument Will Measure Ocean Surface Salinity

WASHINGTON -- An international spacecraft that will take NASA's first space-based measurements of ocean surface salinity has arrived at its launch site at Vandenberg Air Force Base in California. The Aquarius/SAC-D mission will provide scientists with a key missing variable in satellite observations of Earth that links ocean circulation, the global balance of freshwater, and climate.

The Aquarius/SAC-D spacecraft left São José dos Campos, Brazil on
March 29. Following final tests, the spacecraft will be attached to a
Delta II rocket for a June 9 launch.

The mission is a collaboration between NASA and Argentina's space
agency, Comisión Nacional de Actividades Espaciales (CONAE), with
participation from Brazil, Canada, France and Italy. Aquarius, the
NASA-built primary instrument on CONAE's SAC-D spacecraft, will map
global changes in the concentration of dissolved salt at the ocean
surface. Measuring salinity is important to understanding how changes
in rainfall, evaporation and the melting or freezing of ice influence
ocean circulation and are linked to climate changes. The three-year
mission will provide new insights into how variations in ocean
surface salinity relate to these fundamental climate processes.

"Just as salt is essential to life as we know it, salinity is crucial
to Earth's climate system," said Aquarius principal investigator Gary
Lagerloef of Earth and Space Research in Seattle. "Very small changes
in salinity can have large-scale effects on ocean circulation and the
way the ocean moderates our climate. These changes are linked to the
movement of water between the ocean, atmosphere and cryosphere."

Aquarius will greatly enhance the quantity of ocean salinity
measurements that have been collected from ships, buoys and floats.
"When combined with data from other sensors that measure sea level,
ocean color, temperature, winds, rainfall and evaporation, Aquarius'
continuous, global salinity data will give scientists a much clearer
picture of how the ocean works, how it is linked to climate and how
it may respond to climate change," Lagerloef said.

Precise salinity measurements from Aquarius will reveal changes in
patterns of global precipitation and evaporation, and show how these
affect ocean circulation. Studies from Aquarius eventually will
improve computer models used to forecast future climate conditions,
including short-term climate events such as El Nino and La Nina.

"The mission continues a long and successful partnership between NASA
and CONAE, and it will provide a new type of ocean observation for
ocean and climate studies," said Amit Sen, Aquarius project manager
at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Aquarius will measure ocean surface salinity by sensing thermal
microwave emissions from the water's surface with a radiometer. When
other environmental factors are equal, these emissions indicate how
salty the surface water is. Because salinity levels in the open ocean
vary by only about five parts per thousand, Aquarius employs new
technologies to detect changes in salinity as small as about two
parts per 10,000, equivalent to about one-eighth of a teaspoon of
salt in a gallon of water.

Flying in a 408-mile high, polar orbit, Aquarius/SAC-D will map the
global ocean once every seven days. Its measurements will be merged
to yield monthly estimates of ocean surface salinity with a spatial
resolution of 93 miles. The data will reveal how salinity changes
over time and from one part of the ocean to another.

Aquarius is a NASA Earth System Science Pathfinder Program mission.
The Aquarius instrument was jointly built by JPL and NASA's Goddard
Space Flight Center in Greenbelt, Md. NASA's Launch Services Program
at the Kennedy Space Center in Florida is managing the launch. JPL
will manage Aquarius through the mission's commissioning phase and
archive mission data. Goddard will manage the mission's operations
phase and process Aquarius science data.

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

For more information on Aquarius, visit:



Source: NASA

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