Other
Scientific paper
Jan 1999
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1999nvm..conf...12f&link_type=abstract
Workshop on New Views of the Moon 2: Understanding the Moon Through the Integration of Diverse Datasets, p. 12
Other
Abundance, Deposits, Moon, Volcanology, Lunar Composition, Lunar Crust, Lunar Geology, Lunar Soil, Clementine Spacecraft, Imaging Spectrometers, Spectrum Analysis
Scientific paper
Lunar pyroclastic deposits represent a style of volcanism different from that responsible for the flood basalts that fill the mare basins. As volatile-coated, primitive materials originating deep (about 400 km) within the Moon, these products of explosive volcanic eruptions are also important as probes of mantle composition and as a potential resource for future settlers. While many of the lunar pyroclastic deposits are spatially restricted and relatively small in size, they are easily resolvable at the spatial scale (about 100 m/pixel) of the Clementine UV-VIS camera. Recent studies confirm previous results indicating that these deposits are not compositionally uniform, and suggest that further analyses can help to identify possible genetic relationships among lunar pyroclastic deposits, characterize their juvenile components, and clarify their relationships to nearby maria. Among the juvenile materials from sampled lunar pyroclastic deposits are the orange glass and devitrified black beads found in the Taurus-Littrow Valley and the green glass found by Apollo 15. Recent studies suggest that deposits dominated by materials such as these may represent end members in the observed compositional variations among the lunar pyroclastic deposits. Here we present preliminary results of analyses focused on the use of the Clementine UV-VIS data for characterizing the composition and distribution of juvenile pyroclastic materials. Our test case for detailed mapping of a lunar pyroclastic deposit is that of the Apollo 17 landing site in the Taurus-Littrow (TL) Valley. Although black beads dominate the observed spectral reflectance at this site, sample data show that the pyroclastic eruption changed character, producing first orange glass and then black beads. To assess the compositional variability of this deposit, especially our ability to distinguish the orange glasses, we apply techniques based on spectral mixture analysis to detect materials at subpixel scales. The low albedo and subdued absorption features of the Taurus-Littrow deposit make this a challenging task. In recent years, several subpixel detection techniques have been developed for use with terrestrial airborne imaging spectrometer data. A technique that is functionally equivalent to spectral mixture analysis, the orthogonal subspace projection (OSP) technique is used for the simulations presented here. In OSP, a target spectrum is projected onto a subspace that is orthogonal to a set of background spectra. In this process, the response from the background spectra are nulled and that of the target is maximized. For the TL site, the spectra used for the simulation included three laboratory-measured sample spectra convolved to the five UV/VIS bandpasses, and two spectra extracted from UV-VIS data over the TL Valley. The target spectrum was the orange soil sample 74220 from the Shorty Crater rim. "Background" spectra were from samples 74221 (a gray soil found near the orange soil) and 75111 (a dark mare soil). From the UV/VIS data, additional background spectra were obtained at the mare/highland interface and from the "crater cluster" area in the TL Valley. In the simulation, the background spectra were randomly mixed in each of 100 samples with 0.1% Gaussian noise added. For samples 20,40, 60, and 80, the orange soil target was added in abundances of 90, 80, 60, and 40%. The 100-sample set was then reduced via OSP. For this example, the orange soil was detectable only at the 90 and 80% abundance levels. It was found that the addition of higher noise levels (about 1%), made the orange glass undetectable even at the 90% level. However, using background materials more representative of the highlands made the orange soil detectable at lower abundances. These results suggest that we should be able to map the distribution of juvenile pyroclastic materials, such as the orange glasses, using the Clementine UV-VIS data and subpixel analysis techniques such as spectral mixture analysis and foreground background analysis. Given the low albedo of these materials, a high fill factor will be required on a per pixel basis in order to achieve that mapping; however, observations made by others, including orbital observations by the Apollo 17 astronauts, have indicated that these abundances are met for several pyroclastic deposits. The production of such maps will help to constrain the dynamics of pyroclastic eruptions on the Moon by providing information on die type, relative quantity, and distribution of juvenile volcanic materials. (Additional information is contained in original.)
Farrand William H.
Gaddis Lisa R.
No associations
LandOfFree
Subpixel Detection of Pyroclastic Materials in Clementine Ultra Violet-Visible Data does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Subpixel Detection of Pyroclastic Materials in Clementine Ultra Violet-Visible Data, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Subpixel Detection of Pyroclastic Materials in Clementine Ultra Violet-Visible Data will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1276471