Argentine spacecraft to map ocean salinity

An Argentine-built spacecraft is set to blast off on 10 June 2011 from Vandenburg Air Force Base in California carrying instrumentation to measure the saltiness of the world’s oceans.

The SAC-D (Satelite de Aplicaciones Cientificas) spacecraft will orbit 657 km above the Earth and use an instrument built by the US National Aeronautics & Space Administration (NASA) to map weekly changes in the levels of brine in the sea.

NASA’s Aquarius instrument consists of three passive microwave radiometers to detect the surface emission that is used to obtain salinity and an active scatterometer to measure the ocean waves that affect the precision of the salinity measurement. While salinity levels in the open ocean are generally 32-37 practical salinity units (psu; roughly equivalent to parts per thousand), the Aquarius sensor will be able to detect changes in salinity as small as 0.2 psu.

Though the amount of salt in the world’s oceans remains mostly unchanged, the brine concentration in the topmost layer varies around the globe. Understanding how brackish the sea surface is will help researchers better predict future climate change and short-term climate phenomena such as El Nino and its alter ego La Nina, which can have profound effects on weather around the world.

It could also provide valuable information for desalination.

Aquarius/SAC-D is designed to measure ocean surface salinity for at least three years, repeating its global pattern every seven days. During its lifetime, the mission will provide monthly maps of global changes in ocean surface salinity with a resolution of 150 km, showing how salinity changes from month-to-month, season-to-season and year-to-year.

The Aquarius/SAC-D observatory is a collaboration between NASA and Argentina’s space agency, Comision Nacional de Actividades Espaciales.