For NASA's Aquarius, Quest for Salt a Global Endeavor

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Feature: 2011-109 April 06, 2011

For NASA's Aquarius, Quest for Salt a Global Endeavor

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-109&cid=release_2011-109

With more than a few stamps on its passport, NASA's Aquarius instrument on the
Argentinian Satélite de Aplicaciones Científicas (SAC)-D spacecraft will soon embark on
its space mission to "taste" Earth's salty ocean.

After a journey of development and assembly through NASA facilities; a technology center
in Bariloche, Argentina; and testing chambers in Brazil, the Aquarius instrument, set to
measure the ocean's surface salinity, recently made the trip from São José dos Campos,
Brazil, to California's Vandenberg Air Force Base for final integration and testing before its
scheduled launch on June 9.

Aquarius will map the concentration of dissolved salt at the ocean's surface, information
that scientists will use to study the ocean's role in the global water cycle and how this is
linked to ocean currents and climate. Sea surface temperature has been monitored by
satellites for decades, but it is both temperature and salinity that determine the density of
the surface waters of the ocean. Aquarius will provide fundamentally new ocean surface
salinity data to give scientists a better understanding of the density-driven circulation; how
it is tied to changes in rainfall and evaporation, or the melting and freezing of ice; and its
effect on climate variability.

"The ocean is essentially Earth's thermostat. It stores most of the heat, and what we need
to understand is how do changes in salinity affect the 3-D circulation of the ocean," said
Gene Feldman, Aquarius Ground System and Mission Operations manager at NASA's
Goddard Space Flight Center, Greenbelt, Md.

The development of the Aquarius mission began more than 10 years ago as a joint effort
between Goddard and NASA's Jet Propulsion Laboratory in Pasadena, Calif. In 2008,
Goddard engineers completed the Aquarius microwave radiometer instrument, which is
the key component for measuring salinity from space.

"The radiometer is the most accurate and stable radiometer built for sensing of Earth from
space. It's a one-of-a-kind instrument," said Shannon Rodriguez-Sanabria, a microwave
communications specialist at Goddard.

JPL built Aquarius' scatterometer instrument, a microwave radar sensor that scans the
ocean's surface to measure the effect wind speed has on the radiometer measurements.
The radiometer and scatterometer instruments, along with a 2.5-by-3-meter (8.25-by-10-
foot) elliptical antenna reflector and many other systems, have been integrated together at
JPL to form the complete Aquarius instrument. Other instruments aboard the SAC-D
spacecraft are contributions from Argentina, France, Canada and Italy.

In June 2009, Aquarius was flown via a U.S. Air Force cargo jet to San Carlos de
Bariloche, Argentina, a destination known for its natural scenery of blue lakes and verdant
mountains, to be integrated with Argentina's SAC-D spacecraft. A year later, the fully
assembled spacecraft and all the instruments now referred to as the "Aquarius/SAC-D
Observatory" were shipped to Brazil. There, engineers began a nine-month campaign of
alignment, electromagnetic, vibration, and thermal vacuum testing to ensure it will survive
the rigors of launch and space.

JPL will manage the Aquarius mission through Aquarius' commissioning phase,
scheduled to last 45 days after launch. Goddard will then manage the Aquarius instrument
operations during the mission. Argentina's Comisión Nacional de Actividades Espaciales
(CONAE) will operate the spacecraft and download all of the data collected by Aquarius
several times per day. Goddard is responsible for producing the Aquarius science data
products. JPL will manage the data archive and distribution to scientists worldwide.

Aquarius will collect data continuously as it flies in a near-polar orbit and circles Earth 14 to
15 times each day. The field of view of the instrument is 390 kilometers (242 miles) wide,
and it will provide a global map every seven days. The data will be compiled to generate
more accurate monthly averages during the mission, which is designed to last a minimum
of three years.

For more information about Aquarius, please visit http://aquarius.nasa.gov/ .

Melissa Quijada
NASA Goddard Space Flight Center

2011-109

-end-

Alan Buis 818-354-0474
Jet Propulsion Laboratory, Pasadena, Calif.
Alan.buis@jpl.nasa.gov

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