NASA will launch a scientific instrument into space next month to measure the salt content of the world's oceans, information that could help confirm scientists' suspicions that climate change is accelerating the world's water cycle.

The instrument, Aquarius, will launch June 9 as part of a joint mission between NASA and Argentina's space agency.

Flying aboard the SAC-D satellite, Aquarius will measure ocean salinity, completing a path around the entire globe every seven days. That's welcome news to scientists who have long relied on salinity measurements collected by boat, buoy or plane, methods that don't provide global coverage.

"A sort of grand problem in Earth science is to understand the water cycle -- evaporation from the ocean, clouds, rain, the formation of ice, the runoff from the land back into the sea," said Eric Lindstrom, Aquarius program scientist at NASA. "Ocean salinity turns out to be a pretty useful diagnostic of the big picture."

Aquarius will be able to measure changes in salinity caused by evaporation, rain and snow, and melting sea ice. Its measurements of ocean saltiness will also help scientists understand how changes in salinity affect the deep currents that drive ocean circulation.

A way to measure extremes
Recent studies have suggested that relatively salty portions of the oceans are getting saltier, and areas where water is relatively fresh are getting fresher.

"If we can confirm water cycle acceleration, what this means to us in a practical way is that there are more extremes. There's more water circulating through the atmosphere, more flooding, more drought," Lindstrom said. "I am just really excited about the idea that we can get this data all over the planet and be able to diagnose what's going on with the water cycle."

Gary Lagerloef, a principal investigator on the Aquarius mission, said the instrument can measure minute changes in the ocean's salt content.

"If you take a dash of salt, an eighth of a teaspoon, and you put that in a gallon of water, that's the amount of salinity change Aquarius will be able to observe from month to month over any part of the ocean," said Lagerloef, president of Earth and Space Research, a Seattle-based research institute.

Aquarius is also notable for another reason. It's the first climate satellite NASA has launched since a faulty rocket sent the space agency's Glory probe crashing into the ocean in February. A similar problem doomed the launch of another climate satellite, the Orbiting Carbon Observatory, in 2009.

Two veteran travelers
But there is an important difference between Aquarius and the previous failed launches: It's flying on a Delta II rocket, not the Taurus XL rockets that carried Glory and OCO.

Meanwhile, even though Aquarius isn't set to launch until next month, the instrument is already a world traveler.

NASA built the instrument in the United States but later sent it to Bariloche, Argentina, where crews from Argentina's space agency placed it on the SAC-D satellite framework, which will carry seven other scientific instruments.

Officials then shipped the completed SAC-D, with Aquarius aboard, to Sâo José dos Campos, Brazil, for environmental testing at a Brazilian Space Agency facility.

The probe is now at Vandenberg Air Force Base in Southern California, where Aquarius is set to take flight June 9.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500