Berlin Reflectance Spectral Library (BRSL)

The Berlin Reflectance Spectral Library (BRSL) provides a collection of reflectance spectra between 0.3 and 17 µm. It was originally dedicated to support space missions to small solar system bodies. Meanwhile the library includes selections of biconical reflectance spectra for spectral data analysis of other planetary bodies as well. The library provides reference spectra of well-characterized terrestrial analogue materials and meteorites for interpretation of remote sensing reflectance spectra of planetary surfaces. We introduce the BRSL, summarize the data available, and access to use them for further relevant applications

Laboratory Measurements of Synthetic Pyroxenes and their Mixtures with Iron Sulfides as Inorganic Refractory Analogues for Rosetta/VIRTIS' Surface Composition Analysis of 67P/CG

The Visible and InfraRed Thermal Imaging Spectrometer VIRTIS on board Rosetta provided 0.25-5.1 µm spectra of 67P/CG's surface (Capaccioni et al., 2015). Thermally corrected reflectance spectra display a low albedo of 0.06 at 0.65 µm, different red VIS and IR spectral slopes, and a broad 3.2 µm band. This absorption feature is due to refractory surface constituents attributed to organic components, but other refractory constituents influence albedo and spectral slopes. Possible contributions of inorganic components to spectral characteristics and spectral variations across the surface should be understood based on laboratory studies and spectral modeling. Although a wide range of silicate compositions was found in "cometary" anhydrous IDPs and cometary dust, Mg-rich crystalline mafic minerals are dominant silicate components. A large fraction of silicate grains are Fe-free enstatites and forsterites that are not found in terrestrial rocks but can be synthesized in order to provide a basis for laboratory studies and comparison with VIRTIS data. We report the results of the synthesis, analyses, and spectral reflectance measurements of Fe-free low-Ca pyroxenes (ortho- and clinoenstatites). These minerals are generally very bright and almost spectrally featureless. However, even trace amounts of Fe-ions produce a significant decrease in the near-UV reflectance and hence can contribute to slope variations. Iron sulfides (troilite, pyrrhotite) are among the most plausible phases responsible for the low reflectance of 67P's surface from the VIS to the NIR. The darkening efficiency of these opaque phases is strongly particle-size dependent. Here we present a series of reflectance spectra of fine-grained synthetic enstatite powders mixed in various proportions with iron sulfide powders. The influence of dark sulfides on reflectance in the near-UV to near-IR spectral ranges is investigated. This study can contribute to understand the shape of reflectance spectra of 67P's surface at different spectral ranges. Implications for the VIRTIS data analysis are discussed

Теорія та практика менеджменту безпеки

У збірнику подано тези доповідей та виступів учасників Міжнародної науково-практичної конференції, присвяченої питанням теорії менеджменту безпеки, безпеки особистості, прикладним аспектам забезпечення соціальної, екологічної, економічної безпеки підприємств, питанням механізму забезпечення соціоекологоекономічної безпеки регіону, проблемам забезпечення національної безпеки

Spaceborne VIR spectroscopy of small planetary bodies and inherent clues to their composition: a review and discussions of future requirements

The possibility to study small bodies in the planetary system by means of flybys, orbital observations, and sample return by space missions has potentiated our knowledge about them. Compared to differentiated objects, whose materials have been greatly altered during the evolution of the solar system, they belong to those objects which allow the determination of the state of matter of the early planetary system. Depending on the heliocentric distance of their origin and their further development they exhibit different pristine compositions that include minerals, ices, and organics. Space missions such as Rosetta to comet 67P/Churyumov-Gerasimenko, Hayabusa2 operating at 162173 Ryugu, and Osiris-REx exploring 101955 Bennu have delivered and are delivering comprehensive data including Visible and Infrared/VIR (i.e. Visible and Near-Infrared/VNIR and Mid-Infrared/MIR) spectral information. However, the compositional analysis from VIR spectra is not straightforward. Dark and fine-grained materials influence the spectral properties considerably. Comparative laboratory investigations of analog materials and spectro-photometric modeling form the basis for a data analysis related to the respective planetary body. This paper summarizes selected results of these studies and discusses the scientific and instrumental requirements for future spaceborne VIR spectral studies of minor bodies like Comet Interceptor, AIDA, MMX, Lucy and further planned missions in the solar system

Interpretation of VIRTIS/Rosetta surface spectra of comet 67P from laboratory reflectance measurements of cometary analogues, including iron sulfides

The Rosetta spacecraft has been orbiting the comet 67P from August 2014 to September 2016 with the aim to understand better the activity, the evolution and the surface processes of the nucleus. The VIRTIS spectrometer [1] has acquired reflectance spectra from two channels: VIRTIS-M, an imaging-spectrometer, ranging from 0.25 μm to 5.1 μm with ~2 nm and ~10 nm resolution (resp. in the VIS and IR) and VIRTIS-H, a point spectrometer ranging from 1.9 μm to 5.1 μm with a ~10 times higher spectral resolution than VIRTIS-M. The goal of this study is to reproduce the spectral behavior of the surface as observed by VIRTIS in the range 0.4 μm - 2.7 μm. For this purpose, we measured reflectance spectra of cometary analogs produced in the lab from iron sulphides, coal and silicates

Laboratory spectral reflectance studies aimed at providing clues to composition of refractory phases of comet 67P/CG's nucleus

We present 0.3-5 micron reflectance spectra of well-characterized powdered crystalline materials (Fe-sulfides, Mg-silicates), natural complex hydrocarbons and their mixtures that can serve as spectral analogues of comet 67P/CG's refractory phases. We study the ability of Fe-sulfides to suppress absorption bands of other cometary refractory components and to affect spectral slopes and reflectance values of the 67P/CG surface at different wavelengths from the near-UV to the IR. We investigate the evolution of organic absorption bands as a function of sulfide content in the mixtures and the possibility for detection of individual C-H stretching bands in reflectance spectra of 67P/CG

Geometric preprocessing for Rosetta/VIRTIS-M measurements of comet 67P/C-G

Following earlier surface spectrophotometric analyses of Rosetta/VIRTIS-M measurements of comet 67P/Churyumov-Gerasimenko (hereafter 67P), we refine the instrument's geometric registration model and spatial consistency of the radiometric calibration. For this purpose we compare measured 67P nucleus images from the entire mission to corresponding photometric simulations and determine an optical distortion map between them. The refinements will allow us to improve the retrieval of physical and compositional surface properties of the comet's nucleus

Spectral Characterization of Carboxylic Acids, Amino Acids and Ammonium Salts as the Carriers of 3.2 µm Band of Comet 67P/Churyumov-Gerasimenko

The VIRTIS instrument (Visible InfraRed Thermal Imaging Spectrometer) aboard of the Rosetta spacecraft has collected hyperspectral images of the surface of comet 67P in the 0.4-5 μm range. It revealed a broad feature centered at 3.2 μm in the reflectance spectra of comet 67P/CG, which might be consistent with the presence of semi-volatile organics, also possibly detected by the COSAC and PTOLEMY instruments [1-4]. Carboxylic acids have been proposed as candidates as these molecules in the liquid form display a broad absorption band that fit that of the 3.2 μm band and carboxylic acids are also the main component in the soluble organic fraction in primitive meteorites, with several tens of carboxylic, dicarboxylic and hydroxylated acids identified so far [5]. In this study, we have focused on the experimental spectral characterization of the carriers of the band at ~ 3.2 μm with particular attention to amino acid and carboxylic acids whose spectral properties in the solid state are poorly known, as well as to the ammonium ion