Exploring Thermal Processing of the Mildly Aqueously Altered Cm2 Eet 96029 Using Sulphide Mineralogy and Carbon Structure [abstract]

No abstract available

Volatile exposures on the 67P/Churyumov-Gerasimenko nucleus

We present the most extensive catalog of exposures of volatiles on the 67P/Churyumov-Gerasimenko nucleus generated from observations acquired with the OSIRIS cameras on board the Rosetta mission. We identified more than 600 volatile exposures on the comet. Bright spots are found isolated on the nucleus or grouped in clusters, usually at the bottom of cliffs, and most of them are small, typically a few square meters or smaller. Several of them are clearly correlated with the cometary activity. We note a number of peculiar exposures of volatiles with negative spectral slope values in the high-resolution post-perihelion images, which we interpret as the presence of large ice grains ($>$ 1000 $\mu$m) or local frosts condensation. We observe a clear difference both in the spectral slope and in the area distributions of the bright spots pre- and post-perihelion, with these last having lower average spectral slope values and a smaller size, with a median surface of 0.7 m$^2$, even if the size difference is mainly due to the higher resolution achieved post-perihelion. The minimum duration of the bright spots shows three clusters: an area-independent cluster dominated by short-lifetime frosts; an area-independent cluster with lifetime of 0.5--2 days, probably associated with the seasonal fallout of dehydrated chunks; and an area-dependent cluster with lifetime longer than 2 days consistent with water-driven erosion of the nucleus. Even if numerous bright spots are detected, the total surface of exposed water ice is less than 0.1% of the total 67P nucleus surface, confirming that the 67P surface is dominated by refractory dark terrains, while exposed ice occupies only a tiny fraction. Moreover, the abundance of volatile exposures is six times less in the small lobe than in the big lobe, adding additional evidence to the hypothesis that comet 67P is composed of two distinct bodies.Comment: 24 pages, 19 Figures; paper accepted for publication in Astron. and Astrophysics on February 202

Overview of the New Horizons Science Payload

The New Horizons mission was launched on 2006 January 19, and the spacecraft is heading for a flyby encounter with the Pluto system in the summer of 2015. The challenges associated with sending a spacecraft to Pluto in less than 10 years and performing an ambitious suite of scientific investigations at such large heliocentric distances (> 32 AU) are formidable and required the development of lightweight, low power, and highly sensitive instruments. This paper provides an overview of the New Horizons science payload, which is comprised of seven instruments. Alice provides spatially resolved ultraviolet spectroscopy. The Ralph instrument has two components: the Multicolor Visible Imaging Camera (MVIC), which performs panchromatic and color imaging, and the Linear Etalon Imaging Spectral Array (LEISA), which provides near-infrared spectroscopic mapping capabilities. The Radio Experiment (REX) is a component of the New Horizons telecommunications system that provides both occultation and radiometry capabilities. The Long Range Reconnaissance Imager (LORRI) provides high sensitivity, high spatial resolution optical imaging capabilities. The Solar Wind at Pluto (SWAP) instrument measures the density and speed of solar wind particles. The Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) measures energetic protons and CNO ions. The Venetia Burney Student Dust Counter (VB-SDC) is used to record dust particle impacts during the cruise phases of the mission.Comment: 17 pages, 4 figures, 1 table; To appear in a special volume of Space Science Reviews on the New Horizons missio

The spectrum of (136199) Eris between 350 and 2350 nm: Results with X-Shooter

X-Shooter is the first second-generation instrument for the ESO-VLT. It as a spectrograph covering the 300 - 2480 nm spectral range at once with a high resolving power. These properties enticed us to observe (136199) Eris during the science verification of the instrument. The target has numerous absorption features in the optical and near-infrared domain which has been observed by different authors, showing differences in their positions and strengths. We attempt at constraining the existence of super-volatiles, e.g., CH4, CO and N2, and in particular try to understand the physical-chemical state of the ices on Eris' surface. We observed Eris in the 300-2480 nm range and compared the newly obtained spectra with those available in the literature. We identified several absorption features, measuring their positions and depth and compare them with those of reflectance of pure methane ice obtained from the optical constants of this ice at 30 K to study shifts in their positions and find a possible explanation for their origin. We identify several absorption bands in the spectrum all consistent with the presence of CH4 ice. We do not identify bands related with N2 or CO. We measured the central wavelengths of the bands and find variable shifts, with respect to the spectrum of pure CH4 at 30 K. Conclusions. Based on these wavelength shifts we confirm the presence of a dilution of CH4 in other ice on the surface of Eris and the presence of pure CH4 spatially segregated. The comparison of the centers and shapes of these bands with previous works suggest that the surface is heterogeneous. The absence of the 2160 nm band of N2 can be explained if the surface temperature is below 35.6 K, the transition temperature between the alpha and beta phases of this ice. Our results, including the reanalysis of data published elsewhere, point to an heterogeneous surface on Eris.Comment: 15 pages, 5 figure

Ultracarbonaceous Antarctic micrometeorites recovered from snow at the Dome C - CONCORDIA station.

第6回極域科学シンポジウム[OA] 南極隕石11月17日（火）　国立国語研究所 2階 講

Pluto's global surface composition through pixel-by-pixel Hapke modeling of New Horizons Ralph/LEISA data

On July 14th 2015, NASA's New Horizons mission gave us an unprecedented detailed view of the Pluto system. The complex compositional diversity of Pluto's encounter hemisphere was revealed by the Ralph/LEISA infrared spectrometer on board of New Horizons. We present compositional maps of Pluto defining the spatial distribution of the abundance and textural properties of the volatiles methane and nitrogen ices and non-volatiles water ice and tholin. These results are obtained by applying a pixel-by-pixel Hapke radiative transfer model to the LEISA scans. Our analysis focuses mainly on the large scale latitudinal variations of methane and nitrogen ices and aims at setting observational constraints to volatile transport models. Specifically, we find three latitudinal bands: the first, enriched in methane, extends from the pole to 55deg N, the second dominated by nitrogen, continues south to 35deg N, and the third, composed again mainly of methane, reaches 20deg N. We demonstrate that the distribution of volatiles across these surface units can be explained by differences in insolation over the past few decades. The latitudinal pattern is broken by Sputnik Planitia, a large reservoir of volatiles, with nitrogen playing the most important role. The physical properties of methane and nitrogen in this region are suggestive of the presence of a cold trap or possible volatile stratification. Furthermore our modeling results point to a possible sublimation transport of nitrogen from the northwest edge of Sputnik Planitia toward the south.Comment: 43 pages, 7 figures; accepted for publication in Icaru