scholarly journals MEGANE investigations of Phobos and the Small Body Mapping Tool

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Nancy L. Chabot ◽  
Patrick N. Peplowski ◽  
Carolyn M. Ernst ◽  
Hari Nair ◽  
Michael Lucks ◽  
...  
Keyword(s):  
Elemental Composition ◽  
Gamma Ray ◽  
Small Body ◽  
Three Dimensional ◽  
Irregular Shape ◽  
Neutron Spectroscopy ◽  
Spectroscopy Data ◽  
Body Mapping ◽  
Scientific Investigations ◽  
Mapping Tool

AbstractThe MEGANE instrument onboard the MMX mission will acquire gamma-ray and neutron spectroscopy data of Phobos to determine the elemental composition of the martian moon and provide key constraints on its origin. To produce accurate compositional results, the irregular shape of Phobos and its proximity to Mars must be taken into account during the analysis of MEGANE data. The MEGANE team is adapting the Small Body Mapping Tool (SBMT) to handle gamma-ray and neutron spectroscopy investigations, building on the demonstrated record of success of the SBMT being applied to scientific investigations on other spacecraft missions of irregularly shaped bodies. This is the first application of the SBMT to a gamma-ray and neutron spectroscopy dataset, and the native, three-dimensional foundation of the SBMT is well suited to MEGANE’s needs. In addition, the SBMT will enable comparisons between the MEGANE datasets and other datasets of the martian moons, including data from previous spacecraft missions and MMX’s multi-instrument suite.

Elemental composition of the lunar surface: Analysis of gamma ray spectroscopy data from Lunar Prospector

2006 ◽  
Vol 111 (E12) ◽  
pp. n/a-n/a ◽  
Author(s):  
T. H. Prettyman ◽  
J. J. Hagerty ◽  
R. C. Elphic ◽  
W. C. Feldman ◽  
D. J. Lawrence ◽  
...  
Keyword(s):  
Elemental Composition ◽  
Surface Analysis ◽  
Lunar Surface ◽  
Gamma Ray ◽  
Spectroscopy Data ◽  
Lunar Prospector ◽  
Gamma Ray Spectroscopy

The Global Average Disk-Resolved Photometric Properties of (101955) Bennu

2020 ◽  
Author(s):  
Xiao-Duan Zou ◽  
Jian-Yang Li ◽  
Beth Clark ◽  
Dathon Golish ◽  
Salvatore Ferrone ◽  
...  
Keyword(s):  
Small Body ◽  
Space Science ◽  
Observation Data ◽  
Minor Planets ◽  
Body Mapping ◽  
Sample Return ◽  
Detailed Survey ◽  
Mapping Tool ◽  
Infrared Spectrometer ◽  
Spacecraft Data

<p><strong>1.Introduction</strong></p><p>NASA’s OSIRIS-REx (Origins, Spectral Interpretations, Resource Identification, and Security–Regolith Explorer) asteroid sample return mission (Lauretta et al., 2017) began operating in proximity to near-Earth asteroid (101955) Bennu in December 2018. Here we present an analysis of the global photometry of Bennu from measurements by the OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS; Reuter et al., 2018). This instrument is a point spectrometer with a wedged filter design. OVIRS is used for the spectral characterization of the surface of Bennu, with a field of view of 4 mrad and an effective spectral range from 0.4 to 4.3 μm. Our work focuses on OVIRS data acquired from December 9, 2018, to September 26, 2019.</p><p><strong>2.Dataset</strong></p><p>This study comprises the global observation data from Preliminary Survey and the two sub-phases of Detailed Survey, Baseball Diamond (BBD) and Equatorial Stations (EQ) (campaigns described in Lauretta et al., 2017). We use a total of 299,702 calibrated spots. More details about the data selection and calibration are introduced by Zou et al. (submitted).</p><p><strong>3.Photometric analyses</strong></p><p>We model the scattering properties of the surface of Bennu using the Lommel-Seeliger, Minnaert, McEwen, and Akimov photometric models. The best-fit model is a McEwen model with an exponential phase function and an exponential polynomial partition function. We use this model to correct the OVIRS spectra of Bennu to a standard reference viewing and illumination geometry at visible to infrared wavelengths for the purposes of global spectral mapping (<strong>Figure 1</strong>). We derive a bolometric Bond albedo map in which Bennu’s surface values range from 0.021 to 0.027. We find a phase reddening effect of 1.4±0.3 × 10<sup>−4</sup> μm<sup>−1</sup>deg<sup>−1</sup> across the wavelength range 0.48 to 2.5 μm, and our model is effective at removing this phase reddening.</p><p>We compare our OVIRS results to Golish et al. (2020)’s report on the global photometry of Bennu, based on imaging data from the OSIRIS-REx Camera Suite (OCAMS; Rizk et al., 2018). We also compare the results to ground observation and other minor planets including Ryugu.</p><p><strong>Acknowledgements</strong>: This material is based upon work supported by NASA under Contract NNM10AA11C issued through the New Frontiers Program. We are grateful to the entire OSIRIS-REx Team for making the encounter with Bennu possible and the exploration highly successful. X.-D. Zou and J.-Y. Li also acknowledge partial support from the Solar System Exploration Research Virtual Institute 2016 (SSERVI16) Cooperative Agreement (Grant NNH16ZDA001N), SSERVI-TREX to the Planetary Science Institute. M. A. Barucci acknowledges funding support from CNES. </p><p><strong>References</strong></p><p>Bennett, C.A., et al. 2020. A high-resolution global basemap of (101955) Bennu. Icarus. doi: 10.1016/j.icarus.2020.113690.</p><p>Ernst et al., 2018, The Small Body Mapping Tool (SBMT) for Accessing, Visualizing, and Analyzing Spacecraft Data in Three Dimensions, LPSC 49, abstract no. 1043.</p><p>Golish, D.R., et al. 2020. Disk-resolved photometric modeling and properties of asteroid (101955) Bennu. Icarus, doi:10.1016/j.icarus.2020.113724.</p><p>Lauretta, D.S., et al. 2017. OSIRIS-REx: sample return from asteroid (101955) Bennu. Space Science Reviews 212(1-2):925-984.</p><p>Reuter, D.C., et al. 2018. The OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS): spectral maps of the asteroid Bennu. Space Science Reviews 214(2):54.</p><p>Rizk, B., et al. 2018. OCAMS: the OSIRIS-REx Camera Suite. Space Science Reviews 214(1):26.</p><p>Zou et al. (submitted). Photometry of asteroid (101955) Bennu with OVIRS on OSIRIS-REx. Icarus.</p><p><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gepj.ae31f36dd0fe59163482951/sdaolpUECMynit/0202CSPE&app=m&a=0&c=33cc50f2e94b8ae56cd6415c4151e5ac&ct=x&pn=gepj.elif" alt=""></p><p><strong>Figure 1. </strong>A global 3D facet-based map of the photometrically corrected (to 30°, 0°, 30°) OVIRS spots at a wavelength of 0.55 μm. The data are overlain on the OCAMS imaging basemap (Bennett et al., 2020), as viewed in the Small Body Mapping Tool (Ernst et al. 2018). Input spectra were obtained during Detailed Survey EQ3.</p>

Mapping a Duck: Geological Features and Region Definitions on Comet 67P/Churyumov-Gerasimenko

2021 ◽  
Author(s):  
Björn Grieger ◽  
Mireia Leon-Dasi ◽  
Sebastien Besse ◽  
Michael Küppers
Keyword(s):  
Small Body ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Two Dimensional ◽  
Map Projection ◽  
Complete Surface ◽  
Narrow Angle ◽  
Mapping Tool ◽  
Geological Features ◽  
Comet 67P

<p>The data from the Rosetta mission enabled the reconstruction of the shape of comet 67P/Churyumov-Gerasimenko (hereafter 67P) and the identification of the terrains and features forming its surface. The highly irregular  shape of the comet poses a challenge for the depiction of these geological features on two-dimensional maps. Standard global map projections cannot display the complete surface of 67P because different points on the surface can have the same longitude and latitude.  As a consequence, the geological maps published to date are  created on top of comet images, making them dependent on the viewing angle and image coverage and resolution.</p><p>Here, we make use of the recently published Quincuncial Adaptive Closed Kohonen (QuACK) map. It projects the complete surface of 67P unambiguously onto a square. The QuACK map is topologically equivalent to the Peirce quincuncial projection of the world, which makes it  possible to define generalized longitudes and latitudes. These can be used within any global map projection in order to obtain an  unambiguous QuACK version.</p><p>The mapping of geological features is carried out in three dimensions employing the Small Body Mapping Tool (SBMT). We use images from  the OSIRIS Narrow Angle Camera aboard Rosetta which have been projected onto the shape model of the SBMT. The three-dimensional coordinates are then projected onto two-dimensional maps, either in the QuACK map projection or in the QuACK version of  the equidistant cylindrical projection. We present individual maps for 17 of the 26 regions of 67P, mostly located in the northern  hemisphere. The new maps combine features published in previous studies with newly identified features.</p><p>We discuss the distribution of geological features and the characteristics of the regions. In order to align region boundaries with geological features, we propose two modifications of region definitions.</p>

scholarly journals SEARCH FOR NEUTRINO EMISSION FROM GAMMA-RAY SOURCES WITH THE ANTARES TELESCOPE

2012 ◽  
Vol 08 ◽  
pp. 307-310
Author(s):  
C. BIGONGIARI
Keyword(s):  
Gamma Ray ◽  
Neutrino Flux ◽  
Three Dimensional ◽  
Effective Area ◽  
High Energy ◽  
Neutrino Telescope ◽  
Neutrino Detector ◽  
Upper Limits ◽  
Cosmic Neutrino ◽  
Promising Source

ANTARES is the first undersea neutrino detector ever built and presently the neutrino telescope with the largest effective area operating in the Northern Hemisphere. A three-dimensional array of photomultiplier tubes detects the Cherenkov light induced by the muons produced in the interaction of high energy neutrinos with the matter surrounding the detector. The detection of astronomical neutrino sources is one of the main goals of ANTARES. The search for point-like neutrino sources with the ANTARES telescope is described and the preliminary results obtained with data collected from 2007 to 2010 are shown. No cosmic neutrino source has been observed and neutrino flux upper limits have been calculated for the most promising source candidates.

scholarly journals Aluminum abundance on the surface of Mercury: Application of a new background-reduction technique for the analysis of gamma-ray spectroscopy data

2012 ◽  
Vol 117 (E12) ◽  
pp. n/a-n/a ◽  
Author(s):  
Patrick N. Peplowski ◽  
Edgar A. Rhodes ◽  
David K. Hamara ◽  
David J. Lawrence ◽  
Larry G. Evans ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Reduction Technique ◽  
Spectroscopy Data ◽  
Background Reduction ◽  
Gamma Ray Spectroscopy

scholarly journals Magnetar formation through a convective dynamo in protoneutron stars

2020 ◽  
Vol 6 (11) ◽  
pp. eaay2732 ◽  
Author(s):  
Raphaël Raynaud ◽  
Jérôme Guilet ◽  
Hans-Thomas Janka ◽  
Thomas Gastine
Keyword(s):  
Gamma Ray ◽  
Magnetic Energy ◽  
Three Dimensional ◽  
Observational Constraints ◽  
Rotation Rates ◽  
Theoretical Support ◽  
Firm Basis ◽  
Protoneutron Stars ◽  
Protoneutron Star ◽  
Three Dimensional Simulations

The release of spin-down energy by a magnetar is a promising scenario to power several classes of extreme explosive transients. However, it lacks a firm basis because magnetar formation still represents a theoretical challenge. Using the first three-dimensional simulations of a convective dynamo based on a protoneutron star interior model, we demonstrate that the required dipolar magnetic field can be consistently generated for sufficiently fast rotation rates. The dynamo instability saturates in the magnetostrophic regime with the magnetic energy exceeding the kinetic energy by a factor of up to 10. Our results are compatible with the observational constraints on galactic magnetar field strength and provide strong theoretical support for millisecond protomagnetar models of gamma-ray burst and superluminous supernova central engines.

scholarly journals Neutron Star Mergers, Disks Around Black Holes, and Gamma-Ray Bursts

1997 ◽  
Vol 163 ◽  
pp. 384-387 ◽  
Author(s):  
H.-Th. Janka ◽  
M. Ruffert
Keyword(s):  
Neutron Stars ◽  
Energy Deposition ◽  
Gamma Ray ◽  
Three Dimensional ◽  
Energy Output ◽  
Central Black Hole ◽  
Order Of Magnitude ◽  
Hydrodynamical Simulations ◽  
Piecewise Parabolic ◽  
Favorable Conditions

AbstractWe have performed three-dimensional hydrodynamical simulations of the coalescence of binary neutron stars taking into account the emission and backreaction of gravitational waves in the Newtonian code based on the “Piecewise Parabolic Method”. The use of the physical equation of state (EOS) of Lattimer & Swesty (1991) allowed us to calculate the production of neutrinos. We evaluated our models for the efficiency of v⊽ annihilation in the surroundings of the coalescing neutron stars. The corresponding energy deposition prior to and during merging turned out to be 2–3 orders of magnitude too small to power a typical γ-ray burst (GRB) with an energy output of ~ (1051/4π) erg/sterad at cosmological distances. Analytical estimates of the subsequent evolution of the disk which possibly surrounds the central black hole showed that even under the most favorable conditions the energy provided by v⊽ → e−e+ → γγ falls short by at least an order of magnitude. We discuss the implications of our results and speculate about possibilities how v⊽ annihilation might still be a viable energy source for GRBs.

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