Engineering topics

Lunsford, Allen W.

Publications and source records attributed to Lunsford, Allen W..

4 records

NASA NTRS2018

In-Flight Calibration and Performance of the OSIRIS-REx Visible and IR Spectrometer (OVIRS)

Performance of the Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) Visible and InfraRed Spectrometer (OVIRS) instrument was validated, showing that it met all science requirements during extensive thermal vacuum ground testing. Preliminary instrument radiometric calibration coefficients and wavelength mapping were also determined before instrument delivery and launch using NIST-traceable sources. One year after launch, Earth flyby data were used to refine the wavelength map by comparing OVIRS spectra with atmospheric models. Near-simultaneous data from other Earth-orbiting satellites were used to cross-calibrate the OVIRS absolute radiometric response, particularly at visible wavelengths. Trending data from internal calibration sources and the Sun show that instrument radiometric performance has been stable to better than 1% in the 18 months since launch.

spectrometer↗

NASA NTRS2018

Landsat 9 TIRS-2 Architecture and Design

TIRS-2 will fly on the LandSat 9. Like TIRS on Landsat 8, TIRS-2 will produce radiometrically calibrated, geo-located thermal image data. USGS is responsible for operational code. TIRS-2 image data will have the same performance characteristics as that of TIRS on Landsat 8 except better in some cases.

Thermal↗

NASA NTRS2011

Spectral Analysis of the Primary Flight Focal Plane Arrays for the Thermal Infrared Sensor

Thermal Infrared Sensor (TIRS) is a (1) New longwave infrared (10 - 12 micron) sensor for the Landsat Data Continuity Mission, (2) 185 km ground swath; 100 meter pixel size on ground, (3) Pushbroom sensor configuration. Issue of Calibration are: (1) Single detector -- only one calibration, (2) Multiple detectors - unique calibration for each detector -- leads to pixel-to-pixel artifacts. Objectives are: (1) Predict extent of residual striping when viewing a uniform blackbody target through various atmospheres, (2) Determine how different spectral shapes affect the derived surface temperature in a realistic synthetic scene.

Montanaro, Matthew↗

NASA NTRS2009

C-12/C-13 Ratio in Ethane on Titan and Implications for Methane's Replenishment

The C-12/C-13 abundance ratio in ethane in the atmosphere of Titan has been measured at 822 cm(sup -1) from high spectral resolution ground-based observations. The value 89(8), coincides with the telluric standard and also agrees with the ratio seen in the outer planets. It is almost identical to the result for ethane on Titan found by the composite infrared spectrometer (CIRS) on Cassini. The C-12/C-13 ratio for ethane is higher than the ratio measured in atmospheric methane by Cassini/Huygens GCMS, 82.3(l), representing an enrichment of C-12 in the ethane that might be explained by a kinetic isotope effect of approximately 1.1 in the formation of methyl radicals. If methane is being continuously resupplied to balance photochemical destruction, then we expect the isotopic composition in the ethane product to equilibrate at close to the same C-12/C-13 ratio as that in the supply. The telluric value of the ratio in ethane then implies that the methane reservoir is primordial.

Jennings, Donald E.↗