Title: The Ocean Radiometer for Carbon Assessment (ORCA) 
Primary Author: McClain, Charles
Organization:NASA Goddard Space Flight Center
Co-Author(s): Leroy Sparr, Mark Wilson, Manuel Quijada, Mike Behrenfeld, Alan Holmes, Brian Martin, Peter Shu, Steve Brown, Bryan Monosmith, Patrick Thompson, Ken Blumenstock, Jim Butler

A design concept for an advanced ocean color radiometer, the Ocean Radiometer for Carbon Assessment (ORCA) has been underway at NASA Goddard Space Flight Center since 2002. In that time, the design has undergone a number of revisions and is now configured to meet all the measurement requirements for the Decadal Survey Aerosol, Cloud, and Ecology (ACE) ocean ecosystem radiometer (OES). Under the Instrument Incubator Program, the ORCA development objectives are fourfold: (1) develop accurate sensor performance requirements and component specifications, (2) finalize the design and fabricate a functional prototype, (3) develop the sensor characterization test specifications and protocols that correspond to the performance requirements, and (4) conduct the component and system level characterizations. Specifically, the prototype has flightlike fore and aft optics and mechanisms, but, due to cost constraints, nonflightlike commercial off-the-shelf (COTS) focal plane detector arrays. COTS arrays cannot handle flight data rates. However, the COTS arrays are adequate for optical alignment and performance testing. The incorporation of flightlike arrays and associated electronics is being proposed in response to the ROSES2010 IIP solicitation. To date, an initial draft document for Objective 1 has been completed, all optical components have been tested, and the prototype is being fabricated and aligned. Complete sensor characterization is scheduled at the National Institute of Standards and Technology (NIST) later this summer. The presentation will review the ORCA performance requirements, the basic design concept, and performance test results to date.