Aquarius To Measure Ocean Salinity, Improve Climate Modeling

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SEATTLE — NASA launched an international satellite mission June 10 that will measure the ocean’s saltiness from hundreds of kilometers above Earth.

The Aquarius/SAC-D satellite soared into space at 7:20 a.m. local time from Vandenberg Air Force Base in California atop a United Launch Alliance Delta 2 rocket. The launch was scheduled for June 9, but kinks in the rocket’s flight software caused a one-day delay.

Once it settles into orbit, the satellite will record salt levels in oceans around the world with unprecedented precision for the next three years. This information should help researchers better understand global patterns of precipitation, evaporation and ocean circulation — key drivers of Earth’s climate.

“In this mission, NASA is really ready to take an important science and technological leap forward,” Gary Lagerloef, Aquarius principal investigator at Earth and Space Research in Seattle, said in a June 7 prelaunch briefing.

NASA launch director Omar Baez said June 10 that the launch went smoothly and the Aquarius/SAC-D satellite had deployed its solar arrays in orbit. A camera mounted to the satellite’s rocket caught views of the spacecraft flying free in space after its successful liftoff.

“So exciting, and the team is jubilant from what I can see,” Baez said.

The $400 million Aquarius mission will scan Earth’s oceans continuously from 657 kilometers up, creating a global salinity map every seven days.

NASA has spent $287 million for its portion of the mission, which is a partnership between the U.S. and Argentina space agencies with the countries of Brazil, Canada, France and Italy also participating.

Aquarius is one of eight scientific payloads aboard the SAC-D spacecraft. The other instruments will observe fires and volcanoes, map sea ice and collect a wide range of other environmental data.

Aquarius is so sensitive that it can detect saltiness differences of just two parts per 1,000 — the equivalent of a pinch of salt in several liters of water, researchers said.

Even subtle salinity differences can have a big impact on ocean temperature and circulation, which themselves influence Earth’s climate. So mapping out ocean saltiness precisely should help scientists come up with better climate models, researchers said.

The Aquarius/SAC-D mission joins 13 other NASA satellite missions dedicated to studying Earth from above. But its salt-measuring skills will bring a new capability to the fleet.

“The addition of Aquarius to this suite of instruments helps create a more complete picture of our oceans and the impact on the Earth’s climate,” said Eric Ianson, program executive with NASA’s Science Mission Directorate in Washington.

The successful liftoff of Aquarius/SAC-D must have come as a relief for NASA, which recently lost two Earth observing satellites to launch failures. In 2009, the $273 million Orbiting Carbon Observatory (OCO)crashed into the ocean near Antarctica. And in March of this year, the $424 million Glory climate satellite followed OCO into the drink.

Both of those launches used Taurus rockets, provided by Dulles, Va.-based Orbital Sciences Corp. In both cases, the rocket’s nose-cone fairing — a shell-like covering that protects its satellite payload — failed to separate as designed.

Those two failures played no part in going with United Launch Alliance for Aquarius/SAC-D. The decision to use a Delta 2 was made about nine years ago, researchers said.

The Aquarius/SAC-D mission is a collaboration between NASA and Argentina’s space agency, Comision Nacional de Actividades Espaciales (CONAE). CONAE built SAC-D, which stands for Satélite de Aplicaciones Científicas-D.

 

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