By Brian Vastag
Published: 10 June 2011
NASA’s ocean-watching Aquarius sensor soared into space Friday morning on a mission to fill critical gaps in understanding how the Earth’s oceans affect the planet’s climate.
In a key success for NASA’s climate science program, the Aquarius device achieved orbit aboard an Argentine-built satellite, called SAC-D. Two previous Earth-watching NASA craft crashed after launching from the same site, Vandenberg Air Force Base in California.
“Elated would be an understatement,” said Gary Lagerloef, chief scientist for Aquarius, shortly after launch engineers confirmed that the satellite was circling Earth in the proper orbit. “Of course, everyone was really apprehensive.”
In March, NASA’s Glory climate satellite splashed into the South Pacific when its nose cone covering failed to detach. In 2009, the agency’s Orbiting Carbon Observatory suffered the same fate, for the same reason. Both launch failures occurred aboard Taurus rockets, made by Orbital Sciences Corp. of Dulles.
But this time, NASA chose the more reliable Delta II rocket, built by Boeing, which has sent about 150 payloads into orbit, including seven NASA missions to Mars.
Late this summer, Lagerloef, a scientist at the nonprofit Earth and Space Research institute in Seattle, expects Aquarius to begin delivering the most detailed map ever made of the salt content of the world’s oceans. Circling pole-to-pole about 400 miles above the Earth, the device’s three sensors are exquisitely sensitive, sniffing the equivalent of a pinch of salt in a bucket of water. Aquarius senses salinity by bouncing microwaves off the ocean’s surface.
Mapping ocean salinity will provide vital clues to ocean circulation patterns while simultaneously mapping rainfall and evaporation. As rain falls over the ocean, salinity decreases; evaporation increases it.
Buoys and other Earth-bound sensors have already painted a picture of rapidly changing ocean salinity patterns, said Kevin Trenberth, a climate scientist at the National Center for Atmospheric Research in Boulder, Colo., who is not involved in the mission.
These altered rainfall and evaporation patterns are “changing the structure of the ocean, which can have impacts on fisheries and ultimately, climate,” Trenberth said.
The SAC-D spacecraft carrying Aquarius was built by Argentina’s space agency, CONAE. Brazil, Canada, France, and Italy also contributed to the $400 million mission.
In addition to Aquarius, the satellite carries seven other cameras and sensors to monitor forest fires, search for space debris, and make measurements of sea ice.