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Ocean Color Instrument

PACE's primary sensor, the Ocean Color Instrument (OCI), is a highly advanced optical spectrometer that will be used to measure properties of light over portions of the electromagnetic spectrum. It will enable continuous measurement of light at finer wavelength resolution than previous NASA satellite sensors, extending key system ocean color data records for climate studies.

The color of the ocean is determined by the interaction of sunlight with substances or particles present in seawater such as chlorophyll, a green pigment found in most phytoplankton species. By monitoring global phytoplankton distribution and abundance with unprecedented detail, the OCI will help us to better understand the complex systems that drive ocean ecology.

The OCI is being built at Goddard Space Flight Center. It will consist of a cross-track rotating telescope, thermal radiators, along with half-angle mirror and solar calibration mechanisms. The OCI's tilt will help avoid sun glint and single science detector design will inhibit image striping. Its signal-to-noise ratios will rival or exceed previous ocean color instruments.

The OCI will feature:
  • Cross track, 360° continuous rotating telescope
  • Two slit grating hyperspectral spectrographs (ultraviolet to visible & visible to near-infrared, NIR)
  • Fiber-coupled multiband filter spectrograph (NIR-to shortwave-infrared)
View OCI Webinar »

OCI Heritage

The OCI design is based on a long heritage of NASA technology development and flight programs. Its functionality – rotating telescope (mechanism and timing), charged couple device (CCD) detector, optics – benefits from previous technology development efforts such as Ocean Radiometer for Carbon Assessment (ORCA).

The OCI's operational concept, cross-track rotating telescope / half-angle mirror, system timing, and data processing infrastructure have been successfully used on previous and existing flight missions such as the Coastal Zone Color Scanner (1978 to 1986), Sea-Viewing Wide Field-of-View Sensor or SeaWiFS (1997 to 2010), Suomi National Polar-orbiting Partnership (Visible Infrared Imaging Radiometer Suite or VIIRS), Aqua and Terra (Moderate Resolution Imaging Spectroradiometer or MODIS instrument). In addition, the OCI's avionics (communications, positioning) will use a significantly smaller electronics system developed by the iMUSTANG effort.

OCI Overview
241 kg (531 lb), current best estimate.
275 W, current best estimate.
0.08° along track and 1.42° cross track.
2-day global coverage at 1-km (0.6-mi) resolution.
Hyperspectral radiometry from the ultraviolet (350 nm) to near-infrared (885 nm).
Shortwave (SW) infrared (IR) bands include: 940, 1038, 1250, 1378, 1615, 2130, and 2260 nm.
Total calibration of instrument artifacts <0.5% at top-of-atmosphere.
Ocean Radiometer for Carbon Assessment (ORCA)
ORCA is a prototype of an advanced ocean biology/biogeochemistry satellite sensor. The concept development began in 2000 with the eventual fabrication of a functional bench top instrument completed in 2013. The prototype development was supported by NASA/GSFC with the actual fabrication and testing conducted under two consecutive grants (three years each) funded through the NASA Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP).