We report on the bright burst detected by four Interplanetary network (IPN) spacecraft on 2015 April 12. The IPN localization of the source is consistent with the position of the recently discovered ...soft gamma-repeater SGR 1935+2154. From the Konus-Wind (KW) observation, we derive temporal and spectral parameters of the emission, and the burst energetics. The rather long duration of the burst (∼1.7 s) and the large measured energy fluence (∼2.5 × 10−5 erg cm−2) put it in the class of rare ‘intermediate’ soft gamma-repeater (SGR) flares, and this is the first one observed from SGR 1935+2154. A search for quasi-periodic oscillations in the KW light curve yields no statistically significant signal. Of four spectral models tested, optically thin thermal bremsstrahlung and a single blackbody (BB) function can be rejected on statistical grounds; two more complex models, a cutoff power law (CPL) and a sum of two BB functions (2BB), fit the burst spectra well and neither of them may be ruled out by the KW observation. The CPL and 2BB model parameters we report for this bright flare are typical of SGRs; they are also consistent with those obtained from observations of much weaker and shorter SGR 1935+2154 bursts with other instruments. From the distribution of 2BB spectral fit parameters we estimate the SGR 1935+2154 distance to be <10.0 kpc, in agreement with that of the Galactic supernova remnant G57.2+0.8 at 9.1 kpc.
We examine a sample of 2301 gamma-ray bursts, detected by Konus-Wind in the triggered mode between 1994 and 2017 and localized by the interplanetary network (IPN), for evidence of gravitational ...lensing. We utilize all the available gamma-ray burst (GRB) data: time histories, localizations, and energy spectra. We employ common IPN techniques to find and quantify similarities in the light curves of 2,646,150 burst pairs, and for the pairs with significant similarities, we examine their IPN localizations to determine whether they are consistent with a common origin. For pairs that are consistent, we derive and compare energy spectra, and compute a figure of merit that allows us to compare and rank burst pairs. We conduct both a blind search, between all possible burst pairs, and a targeted search, between pairs in which one burst has both a spectroscopic redshift and an identification of an intervening system, as measured by one or more lower spectroscopic redshifts. We identify six pairs in the blind search that could be taken as evidence for lensing, but none are compelling enough to claim a detection with good confidence. No candidates were detected in the targeted search. For our GRB sample, we set an upper limit to the optical depth to lensing of 0.0033, which is comparable to that of optical sources. We conclude that proposed scenarios in which a large fraction of the GRB population is lensed are extremely unlikely.
BepiColombo is a joint mission between the European Space Agency, ESA, and the Japanese Aerospace Exploration Agency, JAXA, to perform a comprehensive exploration of Mercury. Launched on
20
th
...October 2018 from the European spaceport in Kourou, French Guiana, the spacecraft is now en route to Mercury.
Two orbiters have been sent to Mercury and will be put into dedicated, polar orbits around the planet to study the planet and its environment. One orbiter, Mio, is provided by JAXA, and one orbiter, MPO, is provided by ESA. The scientific payload of both spacecraft will provide detailed information necessary to understand the origin and evolution of the planet itself and its surrounding environment. Mercury is the planet closest to the Sun, the only terrestrial planet besides Earth with a self-sustained magnetic field, and the smallest planet in our Solar System. It is a key planet for understanding the evolutionary history of our Solar System and therefore also for the question of how the Earth and our Planetary System were formed.
The scientific objectives focus on a global characterization of Mercury through the investigation of its interior, surface, exosphere, and magnetosphere. In addition, instrumentation onboard BepiColombo will be used to test Einstein’s theory of general relativity. Major effort was put into optimizing the scientific return of the mission by defining a payload such that individual measurements can be interrelated and complement each other.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Possible correlation is studied between Water Equivalent Hydrogen (WEH) in the Martian subsurface, as measured by the DAN (Dynamic Albedo of Neutrons) instrument along the Curiosity traverse, and the ...presence of hydrated minerals on the surface, as seen from the orbit by CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) instrument onboard MRO (Mars Reconnaissance Orbiter). Cross-analysis of the subsurface WEH values from DAN passive measurements with the distribution of hydrated minerals over the surface of Gale crater according to Specialized Browse Product Mosaics is performed for the initial 20 km part of traverse. As a result, we found an increase up to 0.4 wt% of the mean WEH value for the surface areas with the spectral signatures of polyhydrated sulfates. The increase is shown to be higher with the more prominent spectral signature on the surface. Similar WEH increase for the two other types of hydrated minerals, such as monohydrated sulfates and phyllosilicates, was not found for the tested part of the traverse. Polyhydrated sulfates being a part of the sedimentary deposits composing the surface of Gale crater should have considerable thickness that is necessary for the subsurface neutron sensing by DAN measurements.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
The presence of hydrated phases in the soil and near‐surface bedrock of Gale Crater is thought to be direct evidence for water‐rock interaction in the crater in the ancient past. Layered sediments ...over the Gale Crater floor are thought to have formed in past epochs due to sediment transport, accumulation, and cementation through interaction with fluids, and the observed strata of water‐bearing minerals record the history of these episodes. The first data analysis of the Dynamic Albedo of Neutrons (DAN) investigation on board the Curiosity rover is presented for 154 individual points of active mode measurements along 1900 m of the traverse over the first 361 Martian solar days in Gale crater. It is found that a model of constant water content within subsurface should be rejected for practically all tested points, whereas a two‐layer model with different water contents in each layer is supported by the data. A so‐called direct two‐layer model (water content increasing with depth) yields acceptable fits for odometry ranges between 0 and 455 m and beyond 638 m. The mean water (H2O) abundances of the top and bottom layers vary from 1.5 to 1.7 wt % and from 2.2 to 3.3 wt %, respectively, while at some tested spots the water content is estimated to be as high as ~5 wt %. The data for odometry range 455–638 m support an inverse two‐layer model (water content decreasing with depth), with an estimated mean water abundance of 2.1 ± 0.1 wt % and 1.4 ± 0.04 wt % in the top and bottom layers, respectively.
Key Points
First analysis of active neutron data from DAN instrument on board MSL roverEstimations of water distribution along MSL rover traverse by DAN instrumentEstimations of chlorine abundance along MSL rover traverse by DAN instrument
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Some issues of mathematical modeling of wave fields associated with thin-layered objects in a horizontally layered medium are considered. Systems of partial differential equations that correspond to ...the theory of elasticity are used when describing wave propagation processes. As a result, both vertical and horizontal displacement components are obtained; this is important for setting up and analyzing seismic field work with three-component instruments. In addition, in the mathematical statement of the problem, a buried source of the spreading center type is used; this brings the model results closer to the real experiment. The solution of the problem written in spectral form is analyzed; this may turn out to be significant when this solution is used to solve inverse dynamic seismic problems. The paper presents not only the computational features of the proposed scheme for solving the problem but also the study of the resulting wave fields from the point of view of their use in the processing and interpretation of real seismic data.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The description of Dynamic Albedo of Neutrons (DAN) experiment is presented, as a part of the NASA’s Mars Science Laboratory mission onboard the mars rover Curiosity. The instrument DAN includes ...Pulsing Neutron Generator (PNG) producing pulses of 14.1 MeV neutrons for irradiation of subsurface material below the rover, and Detectors and Electronics (DE) unit, which operates the instrument itself and measures the die-away time profiles of epithermal and thermal neutrons following each neutron pulse. It is shown that the DAN investigation will measure a content of hydrogen along the path of the MSL rover, and it will also provide information about a depth distribution of hydrogen at 10–20 regions selected for the detailed studies and sampling analysis.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Hydrogen has been inferred to occur in enhanced concentrations within permanently shadowed regions and, hence, the coldest areas of the lunar poles. The Lunar Crater Observation and Sensing Satellite ...(LCROSS) mission was designed to detect hydrogen-bearing volatiles directly. Neutron flux measurements of the Moon's south polar region from the Lunar Exploration Neutron Detector (LEND) on the Lunar Reconnaissance Orbiter (LRO) spacecraft were used to select the optimal impact site for LCROSS. LEND data show several regions where the epithermal neutron flux from the surface is suppressed, which is indicative of enhanced hydrogen content. These regions are not spatially coincident with permanently shadowed regions of the Moon. The LCROSS impact site inside the Cabeus crater demonstrates the highest hydrogen concentration in the lunar south polar region, corresponding to an estimated content of 0.5 to 4.0% water ice by weight, depending on the thickness of any overlying dry regolith layer. The distribution of hydrogen across the region is consistent with buried water ice from cometary impacts, hydrogen implantation from the solar wind, and/or other as yet unknown sources.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Data gathered with the Dynamic Albedo of Neutron (DAN) instrument onboard rover Curiosity were analyzed for variations in subsurface neutron flux and tested for possible correlation with local ...geological context. A special DAN observation campaign was executed, in which 18 adjacent DAN active measurements were acquired every 0.75–1.0 m to search for the variations of subsurface hydrogen content along a 15 m traverse across geologic contacts between the Sheepbed and Gillespie Lake members of the Yellowknife Bay formation. It was found that several subunits in Sheepbed and Gillespie Lake could be characterized with different depth distributions of water‐equivalent hydrogen (WEH) and different chlorine‐equivalent abundance responsible for the distribution of neutron absorption elements. The variations of the average WEH at the top 60 cm of the subsurface are estimated at up to 2–3%. Chlorine‐equivalent neutron absorption abundances ranged within 0.8–1.5%. The largest difference in WEH and chlorine‐equivalent neutron absorption distribution is found between Sheepbed and Gillespie Lake.
Key Points
DAN special campaign in Yellowknife Bay
DAN local measurements of water and chlorine abundance
Correlation of DAN measurements and geological context
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The following paper presents some results of long-term research on the urgent problem of recycling waste products and their use in road construction. The studied new materials and technologies are ...justified by the developments of Tyumen Industrial University. The aim of this work is to prove the technique, checking the ecological safety of the road materials with the use of waste products. Research techniques and test subjects are quantitative chemical analysis and biological testing of road material samples with waste additives obtained during drilling and oil production. Along with the standard procedures for analyzing the contamination and toxicity of water extracts, the authors have proposed and tested the evaluation of repeated and long-term extractions, imitating the possible environmental impact of waste products. The obtained results showed the environmental safety of the road-building materials based on wastes.
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