[Show abstract][Hide abstract] ABSTRACT: Lunar volcanic cones are more numerous than previously recognized. Cones 1-2 km in diameter in nearside maria formed from basaltic cinder, spatter, and/or lava.
[Show abstract][Hide abstract] ABSTRACT: We use LROC NAC images and DTMs and LROC WAC multispectral data to study lunar red spots in the Cognitum/Procellarum region, focusing on the Herigonius feature.
[Show abstract][Hide abstract] ABSTRACT: The volcanic domes, cones, sinuous rilles, and pyroclastic deposits of
the Marius Hills region of the Moon (~13.4°N, 304.6°E) represent
a significant episode of magmatic activity at or near the lunar surface
that is still poorly understood. Comparisons between LROC NAC block
populations, Mini-RF data, and Diviner-derived rock abundances confirm
that blocky lava flows comprise the domes of the Marius Hills. 8
µm features measured by Diviner indicate that the domes are not
rich in silica and are not significantly different than surrounding mare
materials. LROC observations indicate that some of the dome-building
lava flows originated directly from volcanic cones. Many of the cones
are C-shaped, while others are irregularly shaped, and local topography
and lava eruptions affect cone shape. In general, the cones are
morphologically similar to terrestrial cinder and lava cones and are
composed of varying amounts of cinder, spatter, and lava. Many of the
cones are found in local groupings or alignments. The wide range of
volcanic features, from broad low domes to steep cones, represents a
range of variable eruption conditions. Complex morphologies and variable
layering show that eruption conditions were variable over the plateau.
Journal of Geophysical Research Atmospheres 04/2013; 118(4):615-634. · 3.44 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Introduction and Background: Understanding the occurrence, compositional range, volumetric and spa-tial extent, and timing of emplacement, of the Moon's crustal materials is important for constraining theories of lunar origin, thermal models of the lunar crust, and geologic evolution. Because they represent strong geo-chemical departures from primordial compositions, the presence and extent of Si-rich rocks on a planetary surface are indicators of internal processing, and are petrologic anomalies on the Moon. Figure 1a. WAC mosaic of Lassell Massif complex and surrounding region. 1b shows WAC VIS color using bands centered at 689, 415, and 321 nm. Note strong red (blue absorption) spot in the southern half of the Lassell Massif; and embayment of mare deposits, establishing relative timing of emplacement. Suspect cone feature is indicated as SC. Asterisk marks ancillary depression.
[Show abstract][Hide abstract] ABSTRACT: New measurements of the optical constants of Fe metal reveal important
differences between Fe protected from the atmosphere and exposed Fe.
Rapid oxidation not apparent to the eye may affect the reflectance of ET
materials measured in the lab.
Meteoritics and Planetary Science Supplement. 09/2012;
[Show abstract][Hide abstract] ABSTRACT: The Lunar Reconnaissance Orbiter Camera (LROC) imaged the landing sites and spacecraft from the Soviet Union's Luna robotic sample return program (Luna 16, 20, and 24) allowing their locations to be determined with unprecedented precision and, more importantly, for the geologic context of the landing sites to be firmly established. Uncertainties in the position of the landing sites are now 25 m (or better), as opposed to kilometers prior to LROC observations. Because of the past uncertainty of the locations, as well as the fact that two of the Luna missions were conducted at night, the geologic context of the samples was only poorly known. LROC images reveal that the Luna 24 sample was collected on the rim of a small impact crater, providing an explanation for the compositional and maturity discrepancy that has existed for the past three decades between samples and remote sensing of the Mare Crisium surface. The location of the unsuccessful Luna 23 spacecraft is also determined and the nature of the failure confirmed.
Planetary and Space Science 08/2012; 69(1):76–88. · 2.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Four examples of compositionally evolved nonmare volcanics on the Moon
include the Gruithuisen and Mairan domes, and the Hansteen-Alpha and
Compton-Belkovich sites. Despite morphologic differences, these
volcanics may have common aspects of origin.
[Show abstract][Hide abstract] ABSTRACT: Impact melt flows exterior to Copernican-age craters are observed in high spatial resolution (0.5 m/pixel) images acquired by the Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC). Impact melt is mapped in detail around 15 craters ranging in diameter from 2.4 to 32.5 km. This survey supports previous observations suggesting melt flows often occur at craters whose shape is influenced by topographic variation at the pre-impact site. Impact melt flows are observed around craters as small as 2.4 km in diameter, and preliminary estimates of melt volume suggest melt production at small craters can significantly exceed model predictions. Digital terrain models produced from targeted NAC stereo images are used to examine the three-dimensional properties of flow features and emplacement setting, enabling physical modeling of flow parameters. Qualitative and quantitative observations are consistent with low-viscosity melts heated above their liquidii (superheated) with limited amounts of entrained solids.
[Show abstract][Hide abstract] ABSTRACT: A robust and compelling Mars mission can be designed to meet the 2018
Mars launch window using advanced in-space power and propulsion provides
enormous mission flexibility and enables Mars Sample Return Technology
Demonstrations on the same mission.
[Show abstract][Hide abstract] ABSTRACT: Iron metal is an opaque phase common in planetary materials both as an
igneous mineral and as a space-weathering by-product. In either form,
iron metal has a large influence on the interpretation of ultraviolet,
visible, and near-infrared spectra of planetary surfaces obtained from
Earth- or space-based observatories. Therefore, the optical properties
of iron are a critical input necessary for accurate theoretical
radiative-transfer mixing models for inversion of maturity and mineral
proportions from reflectance spectra. Here we report new measurements of
the optical constants of iron in the ultraviolet, visible, and
near-infrared portions of the electromagnetic spectrum (˜160 to
1700 nm). These values are determined from an iron metal film
vapor-deposited onto a fused silica prism. Optical constant
determination is carried out using an ellipsometer that performs the
measurement within the prism, sensing the side of the metal film
unexposed to the ambient atmosphere. The data we report have important
implications for modeling planetary spectra and for comparison of
laboratory measurements of extraterrestrial samples with remotely sensed
Geophysical Research Letters 05/2012; 39(10):10204-. · 3.98 Impact Factor