As part of the Earth System Science Pathfinder small-satellite program, NASA
has selected a new space mission proposal led by NASA’s Goddard Space Flight
Center in Greenbelt, Md., that will yield fresh insight into how oceans
affect and respond to climate change — knowledge that will help better life
here on Earth.

The mission, named Aquarius, promises to explore the saltiness of the seas
in order to understand how the massive natural exchanges of water between
the ocean, atmosphere and sea ice influence the ocean circulation, our
climate, and our weather.

“Aquarius will provide the first-ever global maps of salt concentration on
the ocean surface, a key area of scientific uncertainty in the oceans’
capacity to store and transport heat, which in turn affects Earth’s climate
and the water cycle,” said Dr. Ghassem Asrar, Associate Administrator for
Earth Science at NASA Headquarters, Washington.

The Aquarius mission will be led by principal investigator Dr. Chester J.
Koblinsky of Goddard. Goddard will build and calibrate the highly accurate
radiometers that are crucial for the detection of ocean salinity and will
manage the mission after launch and provide the science data center. The
project is managed by NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

NASA will partner with the Argentine space program on the Aquarius mission,
building on a successful long- standing relationship between NASA and
Argentina. In all, over 17 universities and corporate and international
partners will be involved in the Aquarius mission.

Aquarius is named after the Water Bearer constellation, because of its
objective to explore the role of the water cycle in ocean circulation and
climate. Aquarius will launch in 2007 and will orbit the Earth for at least
three years, repeating its global pattern every 8 days. Within two months,
Aquarius will collect as many sea surface salinity measurements as the
entire 125-year historical record from ships and buoys, and provide the
first measurements over the 25 percent of the ocean where no previous
observations have been made.

“About 80 percent of atmosphere-water exchange occurs over the oceans,” says
Koblinsky. “These exchanges are important to weather and climate prediction,
but are poorly understood.”

According to Koblinsky, patterns of ocean surface salt concentration result
from many factors: fresh water exchange between the ocean and the atmosphere
(evaporation or precipitation), input from rivers and ground water, melting
and freezing of polar ice, ocean currents and mixing.

“Global salinity measurements will allow us to closely monitor these
processes for the first time, he says. “Global observations of sea surface
salinity will also advance our understanding of ocean circulation and,
perhaps, allow us to minimize the impacts of large-scale natural events in
the future.”

Because fresh water is light and floats on the surface, while salty water is
heavy and sinks, Koblinsky says changes in salt concentration at the ocean
surface affect the weight of surface waters. At high latitudes, melting sea
ice, increased precipitation, and/or river inputs will make surface waters
less salty.

“This density change could diminish the overturning ocean circulation, which
brings warm water poleward on the surface to replace the sinking water,” he
says. “This would restrict the ocean-atmosphere heat pump that normally
warms the atmosphere, leading to possible dramatic changes in climate.”

In the tropics, increased precipitation can lead to fresh surface layers on
the ocean, which heat up, and modify the energy exchange with the
atmosphere, affecting El Nino and Monsoon processes.

NASA will fund up to $175 million for each of the two selected missions. The
selected missions will have approximately nine months to refine their
proposals to mitigate risk before mission development is fully underway.

NASA issued an Announcement of Opportunity and initially received 18
proposals, six of which were selected for detailed assessment, with two now
moving on toward final implementation.

NASA conducts Earth science research to better understand and protect our
home planet. Through the examination of Earth, we are developing the
technologies and scientific knowledge needed to explore the universe while
bettering life on our home planet.