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Accession Number N20130003507
Title Integrated OSPREy System, Chapter 8.
Publication Date Jul 2012
Media Count 21p
Personal Author C. R. Booth G. Bernhard J. H. Morrow R. N. Lind S. B. Hooker
Abstract The previous chapters describe the major elements in the radiometers used in an OSPREy system: a microradiometer cluster with necessary modifications to support OSPREy design criteria, a spectrograph, optical collectors (both radiance and irradiance), primary (housing) and secondary (spectrograph) thermal regulation, and accessories like the tracker and shadowband. This chapter describes how these components -- plus housing design, primary and secondary temperature control, and other support electronics--are integrated to make the radiometers used in OSPREy systems. These include radiance and irradiance field sensors, and a similar pair designated as transfer radiometers. The fully integrated system provides an unprecedented capability in a single housing. The spectrograph provides hyperspectral resolution over a subset of the complete spectral range, while the microradiometers provide a larger dynamic range in responsivity, higher sampling speeds, better sensitivity, and sampling across the entire OSPREy spectral range (290-1,670 nm). The two sensor technologies supplement each other. For example, spectrograph data can be used to detect potential degradation of the interference filters used by the microradiometer channels while the microradiometers help to correct dark-current drifts and nonlinearity in spectrograph measurements. The capability of radiance sensors is further enhanced by a nine-position filter wheel and integrated camera. In the standard configuration, the filter wheel permits hyperspectral polarimetric measurements, direct-Sun viewing, stray-light correction, dark current measurements, and a home position. The video camera is used for locating the Sun and verifying the condition of all targets (cloud-free solar and lunar disks, cloud presence in sky data, and sea surface debris or foam detection). The components of each radiance and irradiance sensor type are integrated in a common housing that is environmentally sealed, nitrogen purged, and temperature controlled. Synchronous and asynchronous sampling modes measure the sea, Sun, and sky, across a wide spectral range (UV-SWIR). The OSPREy architecture is modular and scalable, which permits the configuration (sensor inventory) and complexity (sampling redundancy) to be matched with science objectives and resource allocations. The modularity allows the observing system to expand or contract as mission requirements evolve. These measurements support an unprecedented number of current and next-generation satellite missions involving both atmospheric and oceanic data products.
Keywords Design analysis
Dynamic range
Ocean surface
Sky radiation
System effectiveness
Systems engineering
Systems integration
Temperature control

Source Agency National Aeronautics and Space Administration
NTIS Subject Category 48 - Natural Resources & Earth Sciences
Corporate Author Goddard Space Flight Center, Greenbelt, MD.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1318
Contract Number N/A

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