IMAGE:From left to right: Gerhard Meister, Bryan Monosmith and Chuck McClain are shown here with the ORCA prototype, which is a strong contender for a NASA Earth science mission. view more

Credit: NASA's Goddard Space Flight Center/Bill Hrybyk

Its name refers to one of the biggest animals in the sea, but ORCA, the Ocean Radiometer for Carbon Assessment instrument, will be observing the smallest.

If selected for a flight mission, ORCA will study microscopic phytoplankton, tiny green plants that float in the upper layer of the ocean and make up the base of the marine food chain.

Conceived in 2001 as the next technological step forward in observing ocean color, the ORCA-development team used funding from Goddard's Internal Research and Development program and NASA's Instrument Incubator Program (IIP) to develop a prototype. Completed in 2014, ORCA now is a contender as the primary instrument on an upcoming Earth science mission.

Should it be chosen, ORCA will take ocean-color monitoring to the next level, helping scientists to more precisely measure marine photosynthesis, which is key to the carbon cycle and the ocean food chain.

Like its predecessors that also measured ocean color, the instrument will observe phytoplankton, which blooms en masse, covering hundreds of square miles of the sea surface at once and leaving a trail that is clearly visible from space. In particular, researchers will observe global changes in ocean color to estimate concentrations of chlorophyll, the pigment plants use for photosynthesis -- the process during which the tiny plants convert energy from the sun and carbon dioxide into organic compounds that support life.

About a fourth of man-made carbon dioxide ends up in the ocean, said Chuck McClain, former ORCA principal investigator with Goddard's Ocean Color Group. "The ocean is a big sink for CO2 and part of that sink involves ocean biology."

ORCA builds on the work Goddard scientists and engineers pioneered in the development of ocean color sensors. Goddard's proof-of-concept -- the Coastal Zone Color Scanner that flew on Nimbus-7 from 1978 to 1986 -- was the first sensor to demonstrate that ocean chlorophyll could be measured from space. NASA's Sea-Viewing Wide Field-of-View Sensor mission, which collected data from 1997 to 2010, was the first flagship mission to routinely observe ocean color for long-term climate research. Currently, researchers employ the Moderate Resolution Imaging Spectroradiometer on NASA's Terra and Aqua spacecraft, and the Visible Infrared Imager Radiometer Suite aboard the Suomi National Polar-orbiting Partnership satellite.

ORCA's Distinguishing Characteristics

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ORCA prototype ready for the open ocean