NASA SSERVI Contributions to Lunar Science and Exploration

NASA's Solar System Exploration Research Virtual Institute (SSERVI) represents a close collaboration between science, technology and exploration that will enable deeper understanding of the Moon and other airless bodies as we move further out of low-Earth orbit. The new Solar System Exploration Research Virtual Institute (SSERVI) will focus on the scientific aspects of exploration as they pertain to the Moon, Near Earth Asteroids (NEAs) and the moons of Mars. The Institute focuses on interdisciplinary, exploration-related science centered around all airless bodies targeted as potential human destinations. Areas of study reported here will represent the broad spectrum of lunar, NEA, and Martian moon sciences encompassing investigations of the surface, interior, exosphere, and near-space environments as well as science uniquely enabled from these bodies. We will provide a detailed look at research being conducted by each of the 9 domestic US teams as well as our 7 international partners. The research profile of the Institute integrates investigations of plasma physics, geology/geochemistry, technology integration, solar system origins/evolution, regolith geotechnical properties, analogues, volatiles, ISRU and exploration potential of the target bodies

Infrared studies of dust grains in infrared reflection nebulae

IR reflection nebulae, regions of dust which are illuminated by nearby embedded sources, were observed in several regions of ongoing star formation. Near IR observation and theoretical modelling of the scattered light form IR reflection nebulae can provide information about the dust grain properties in star forming regions. IR reflection nebulae were modelled as plane parallel slabs assuming isotropically scattering grains. For the grain scattering properties, graphite and silicate grains were used with a power law grain size distribution. Among the free parameters of the model are the stellar luminosity and effective temperature, the optical depth of the nebula, and the extinction by foreground material. The typical results from this model are presented and discussed

Hydrogen Isotopic Substitution Studies of the 2165 Wavenumber (4.62 Micron) "XCN" Feature Produced by Ion Bombardment

The interstellar 4.62 μm absorption band, commonly seen toward embedded protostellar objects, has not yet been unambiguously identified; here we report new results which further elucidate the components of the band carrier, which is often referred to in the literature as the "XCN" band due to previous implications of carbon and nitrogen. If the atmosphere of the early Earth was not overly reducing, as some studies indicate, production of prebiotic molecules containing the cyanogen bond would have been difficult. In that case, CN-bearing molecules, necessary for the origin of life, may have come primarily from extraterrestrial sources, and the interstellar medium may be an important source of those molecules. Laboratory studies show that energetic processing of ice mixtures containing H, C, N, and O atoms readily reproduce a band similar in peak position and profile to that seen in the interstellar spectra. Earlier isotopic labeling experiments clearly identified carbon, nitrogen, and oxygen as active participants of the XCN species. In this paper, results of ion bombardment of CH3OH : N2 and CD3OD : N2 ices are presented. A shift in band position resulting from deuterium substitution demonstrates that hydrogen is also a component of the carrier in the laboratory-produced 4.62 μm band. Irradiation of ices through ion bombardment allows the testing of mixtures which include N2, a possible source of the available nitrogen in dense cloud ices that cannot be probed through UV photolysis experiments

NASA's Solar System Exploration Research Virtual Institute: Building Collaboration Through International Partnerships

The NASA Solar System Exploration Research Virtual Institute (SSERVI) is a virtual institute focused on research at the intersection of science and exploration, training the next generation of lunar scientists, and community development. As part of the SSERVI mission, we act as a hub for opportunities that engage the larger scientific and exploration communities in order to form new interdisciplinary, research-focused collaborations. This talk will describe the international partnership program, research efforts and how we are engaging the international science and exploration communities through workshops, conferences, online seminars and classes, student exchange programs and internships

THE EFFECTS OF ION IRRADIATION ON THE EVOLUTION OF THE CARRIER OF THE 3.4 MICRON INTERSTELLAR ABSORPTION BAND

Carbon grains in the interstellar medium evolve through exposure to UV photons, heat, gas, and cosmic rays. Understanding their formation, evolution, and destruction is an essential component of evaluating the composition of the dust available for newly forming planetary systems. The 3.4 lm absorption band, attributed to the aliphatic C"H stretch vibration, is a useful probe of the degree to which energetic processing affects hydrogenated carbon grains. Here we report on the effects of ion bombardment of two different kinds of nano-size hydrogenated carbon grains with different hydrogen content. Grain samples, both with and without a mantle of H2O ice, were irradiated with 30 keV He + to simulate cosmic-ray processing in both diffuse and dense interstellar medium conditions. The ion fluences ranged between 1:5 � 10 13 and 7:9 � 10 15 ions cm � 2 . Infrared and Raman spectroscopy were used to study the effects of ion irradiation on grains. In both the dense and diffuse interstellar medium simulations, ion bombardment led to a reduction of the 3.4 lm band intensity. To discuss the effects of cosmic-ray irradiation of interstellar hydrogenated carbon materials we adopt the approximation of 1 MeV monoenergetic protons. An estimate of the C"H bond destruction cross section by 1 MeV protons was made based on experiments using 30 keV He + ions and model calculations. In combination with results from our previous studies, which focused on UV irradiation and thermal H atom bombardment, the present results indicate that the C"H bond destruction by fastcolliding charged particles is negligible with respect to that of UV photons in the diffuse ISM. However, in dense cloud regions, cosmic-ray bombardment is the most significant C"H bond destruction mechanism when the optical depth corresponds to values of the visual extinction larger than � 5 mag. The results presented here strengthen the new interpretation of the evolution of the interstellar aliphatic component (i.e., the C"H bonds in the CH2 and CH3 groups) as evidenced by the presence of the 3.4 lm absorption band in the diffuse medium and the absence of such a signature in the dense cloud environment. The evolutionary transformation of carbon grains, induced by H atoms, UV photons, and cosmic rays, indicates that C"H bonds are readily formed, in situ, in the diffuse interstellar medium and are destroyed in the dense cloud environment

The Interstellar Medium toward the Galactic Center Source 2MASS J17470898-2829561

We describe and discuss remarkable infrared spectra, covering key portions of the $2-5$ $\mu$m wavelength interval, of the probable OH/IR supergiant 2MASS J17470898$-$2829561 (2M1747), located in direction of the Sgr B molecular cloud complex within the Central Molecular Zone (CMZ) of the Galaxy. This star was originally singled out for examination based on its suitability for spectroscopy of lines of H$_3^+$ in the CMZ. Analysis of the spectra shows that 2M1747 is deeply embedded within Sgr B1, with A$_V$ $\gtrsim$ 100 mag, making it the only star within Sgr B for which infrared spectra have been obtained at present, and thereby a unique infrared probe of the dense interstellar medium within the CMZ. Despite the high extinction, spectra of 2M1747 reveal a veiled photosphere in the $K$ band and circumstellar gas in the $M$ band, giving clues as to its nature. Its $3.5-4.0$ $\mu$m spectrum contains the strongest absorption lines of H$_3^+$ observed toward any object to date. The $4.5-4.8$ $\mu$m spectrum has impressively deep and wide absorption lines of interstellar CO, most of which arise in dense gas within Sgr B1. The $3-5$ $\mu$m spectrum also contains several solid state absorption features, which are characteristic of both dense and diffuse clouds, and which raise questions about the identifications of some of these features. We discuss the nature of the star, the extinction to it, the extinction law for dust in the CMZ, and the identifications of the various solid-state features and where they are produced along this complex line of sight.Comment: 17 pages, 10 figures; accepted by ApJ 2021 March 1