If selected for a NASA flight mission, the Ocean Radiometer for Carbon Assessment (ORCA) instrument will study microscopic phytoplankton, the 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.
The ORCA prototype has a scanning telescope designed to sweep across 2,000 kilometers (1,243 miles) of ocean at a time. The technology collects light reflected from the sea surface that then passes through a series of mirrors, optical filters, gratings, and lenses. The components direct the light onto an array of detectors that cover the full range of wavelengths.
Instead of observing a handful of discrete bands at specific wavelengths reflected off the ocean, ORCA measures a range of bands, from 350 nanometers to 900 nanometers at five-nanometer resolution. The sensor will see the entire rainbow, including the color gradations of green that fade into blue. In addition to the hyperspectral bands, the instrument has three short-wave infrared bands that measure specific wavelengths between 1200 and 2200 nanometers for atmospheric applications.
The NASA researchers will use ORCA to obtain more accurate measurements of chlorophyll concentrations, the size of a phytoplankton bloom, and how much carbon it holds. Detecting chlorophyll in various wavelengths also will allow the team to distinguish between types of phytoplankton. Suspended sediments in coastal regions could also be detected by the instrument.
Also: Learn about a Ultra-Low-Maintenance Portable Ocean Power Station.