scholarly journals Candidates for multiple impact craters: popigai and chicxulub as seen by EGM08, a global 5'×5' gravitational model

2010 ◽  
Vol 2 (1) ◽  
pp. 69-103 ◽  
Author(s):  
J. Klokočník ◽  
J. Kostelecký ◽  
I. Pešek ◽  
P. Novák ◽  
C. A. Wagner ◽  
...  
Keyword(s):  
High Spatial Resolution ◽  
Impact Craters ◽  
Stokes Parameters ◽  
Disturbing Potential ◽  
Gravitational Model ◽  
Secondary Crater ◽  
Complete Set ◽  
Multiple Impact ◽  
The Impact ◽  
Main Crater

Abstract. In 2008 the new Earth Gravitational Model (EGM08) was released. It contains a complete set of spherical harmonic coefficients of the Earth's gravitational potential (Stokes parameters) to degree 2190 and order 2159 that can be used for evaluation of various potential quantities with both the unprecedented accuracy and high spatial resolution. Two such quantities, the gravity anomaly and second-order radial derivative of the disturbing potential, were computed over selected areas with known impact craters. The displays of these derivatives for two such sites clearly show not only the strong circular-like features known to be associated with them but also other symmetrical structures which appear to make them multiple impact sites. At Popigai, Siberia, the secondary circular features fall in a line from the primary in the SE direction. At Chicxulub, Yucatán, there appears to be one secondary crater close to the primary in the NE direction, as well as possibly others in the vicinity of the main crater. Gravity information alone is not proof of the impact craters but it is useful in identifying candidate sites for further study, for future examination by geologists and geophysicists.

scholarly journals Candidates for multiple impact craters?: Popigai and Chicxulub as seen by the global high resolution gravitational field model EGM2008

Solid Earth ◽  
2010 ◽  
Vol 1 (1) ◽  
pp. 71-83 ◽  
Author(s):  
J. Klokočník ◽  
J. Kostelecký ◽  
I. Pešek ◽  
P. Novák ◽  
C. A. Wagner ◽  
...  
Keyword(s):  
Field Model ◽  
High Spatial Resolution ◽  
Seismic Profile ◽  
Impact Craters ◽  
Stokes Parameters ◽  
Disturbing Potential ◽  
Complete Set ◽  
Gravity Signal ◽  
Multiple Impact ◽  
Main Crater

Abstract. In 2008 the new Earth Gravitational Model (EGM2008) was released. It contains a complete set of spherical harmonic coefficients of the Earth's gravitational potential (Stokes parameters) to degree 2190 and order 2159 and selected orders to degree 2190, that can be used for evaluation of various potential quantities with both the unprecedented accuracy and high spatial resolution. Two such quantities, the gravity anomaly and second-order radial derivative of the disturbing potential, were computed over selected areas with known impact craters. The displays of these derivatives for two such sites clearly show not only the strong circular-like features known to be associated with them but also other symmetrical structures which appear to make them multiple impact sites. At Popigai, Siberia, the series of circular features fall in a line from the "primary crater" in the southeast (SE) direction. At Chicxulub, Yucatán, there appears to be one more crater close to the "primary" in the northeast (NE) direction, as well as possibly others in the vicinity of the main crater (SW). Gravity information alone is not, however, proof of impact craters but it is useful in identifying candidate sites for further study, for examination by geologists and geophysicists. In the case of Chicxulub, a very recent single seismic profile suggests that a more likely explanation for the observed circular like gravity signal from EGM2008 NE of the "primary" is a pre-impact basin.

scholarly journals The Tharsis mantle source of depleted shergottites revealed by 90 million impact craters

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
A. Lagain ◽  
G. K. Benedix ◽  
K. Servis ◽  
D. Baratoux ◽  
L. S. Doucet ◽  
...  
Keyword(s):  
Thermal Anomaly ◽  
Detection Algorithm ◽  
Impact Craters ◽  
Early History ◽  
Volcanic Province ◽  
Crater Detection ◽  
Depleted Mantle ◽  
History Of ◽  
Secondary Crater ◽  
The Impact

AbstractThe only martian rock samples on Earth are meteorites ejected from the surface of Mars by asteroid impacts. The locations and geological contexts of the launch sites are currently unknown. Determining the impact locations is essential to unravel the relations between the evolution of the martian interior and its surface. Here we adapt a Crater Detection Algorithm that compile a database of 90 million impact craters, allowing to determine the potential launch position of these meteorites through the observation of secondary crater fields. We show that Tooting and 09-000015 craters, both located in the Tharsis volcanic province, are the most likely source of the depleted shergottites ejected 1.1 million year ago. This implies that a major thermal anomaly deeply rooted in the mantle under Tharsis was active over most of the geological history of the planet, and has sampled a depleted mantle, that has retained until recently geochemical signatures of Mars’ early history.

scholarly journals Self-Secondaries Formed by Cold Spot Craters on the Moon

2021 ◽  
Vol 13 (6) ◽  
pp. 1087
Author(s):  
Yiren Chang ◽  
Zhiyong Xiao ◽  
Yang Liu ◽  
Jun Cui
Keyword(s):  
Systematic Investigation ◽  
Impact Craters ◽  
Spatial Density ◽  
Cold Spot ◽  
The Moon ◽  
Potential Threat ◽  
Frequency Distributions ◽  
Crater Size ◽  
The Impact ◽  
Density Pattern

Self-secondaries are a population of background secondaries, and they have been observed on top of impact melt and ballistically emplaced ejecta deposits on various planetary bodies. Self-secondaries are formed by impacts of sub-vertically launched ejecta, but the launch mechanism is not confirmed. The potential threat of self-secondaries to the theoretical and applicable reliability of crater chronology has been noted, but not constrained. Hitherto discovered self-secondaries were located around complex impact craters, but their potential existence around simple craters has not been discovered. Here we report the first discovery of self-secondaries around lunar cold spot craters, which are an extremely young population of simple craters formed within the past ~1 million years on the Moon. Self-secondaries are widespread on layers of cascading flow-like ejecta deposits around cold spot craters. The spatial density of self-secondaries dwarfs that of potential primary craters. The spatial distribution of self-secondaries is highly heterogeneous across the ejecta deposits. With respect to the impactor trajectory that formed cold spot craters, self-secondaries formed at the downrange of the ejecta deposits have the largest spatial density, while those at the uprange have the smallest density. This density pattern holds for all cold spot craters that were formed by non-vertical impacts, but self-secondaries do not exhibit other systematic density variations at different radial distances or at other azimuths with respect to the impactor trajectory. Among known mechanics of ejecting materials to the exterior of impact craters, impact spallation is the most likely scenario to account for the required large ejection velocities and angles to form self-secondaries. The production population of self-secondaries is estimated based on the highly diverse crater size-frequency distributions across the ejecta deposits of cold spot craters. For a better understanding of the impact history on the Moon, a systematic investigation for the effect of self-secondaries on lunar crater chronology is required.

scholarly journals The potentially hazardous NEA 2001 BB16

2019 ◽  
Vol 28 (1) ◽  
pp. 180-190
Author(s):  
Ireneusz Wlodarczyk
Keyword(s):  
Mean Value ◽  
Optical Observations ◽  
Uniform Sampling ◽  
The Earth ◽  
22Nd Century ◽  
Lyapunov Time ◽  
Gravitational Model ◽  
Calculated Probability ◽  
Potential Impact ◽  
The Impact

AbstractWe computed the impact solutions of the potentially dangerous Near Earth Asteroid (NEA) 2001 BB16 based on 47 optical observations from January 20.08316 UTC, 2001, through February 09.15740 UTC, 2016, and one radar observation from January 19.90347 UTC, 2016. We used two methods to sample the starting Line of Variation (LOV). First method, called thereafter LOV1, with the uniform sampling of the LOV parameter, out to LOV = 5 computing 3000 virtual asteroids (VAs) on both sides of the LOV, which gives 6001 VAs and propagated their orbits to JD2525000.5 TDT=February 12, 2201. We computed the non-gravitational parameterA2=(34.55±7.38)·10–14 au/d2 for nominal orbit of 2001 BB16 and possible impacts with the Earth until 2201. For potential impact in 2195 we find A2=20.0·10−14 au/d2. With a positive value of A2, 2001 BB16 can be prograde rotator. Moreover, we computed Lyapunov Time (LT) for 2001 BB16, which for all VAs, has a mean value of about 25 y. We showed that impact solutions, including the calculated probability of a possible collision of a 2001 BB16 asteroid with the Earth depends on how to calculate and take into account the appropriate gravitational model, including the number of perturbing massive asteroids. In some complicated cases, it may depend also on the number of clones calculated for a given sigma LOV1. The second method of computing the impact solutions, called thereafter LOV2, is based on a non-uniformly sampling of the LOV. We showed that different methods of sampling the LOV can give different impact solutions, but all computed dates of possible impacts of the asteroid 2001 BB16 with the Earth occur in accordance at the end of the 22nd century.

Transitional impact craters on the Moon: Insight into the effect of target lithology on the impact cratering process

2018 ◽  
Author(s):  
Gordon R. Osinski ◽  
Elizabeth A. Silber ◽  
Jacqueline Clayton ◽  
Richard A. F. Grieve ◽  
Kayle Hansen ◽  
...  
Keyword(s):  
Impact Craters ◽  
The Moon ◽  
Impact Cratering ◽  
The Impact ◽  
Insight Into

scholarly journals Air quality impacts of COVID-19 lockdown measures detected from space using high spatial resolution observations of multiple trace gases from Sentinel-5P/TROPOMI

2021 ◽  
Author(s):  
Pieternel F. Levelt ◽  
Deborah C. Stein Zweers ◽  
Ilse Aben ◽  
Maite Bauwens ◽  
Tobias Borsdorff ◽  
...  
Keyword(s):  
Air Quality ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Trace Gases ◽  
Trace Gas ◽  
Joint Analysis ◽  
Anthropogenic Emissions ◽  
China And India ◽  
Societal Relevance ◽  
The Impact

Abstract. The aim of this paper is two-fold: to provide guidance on how to best interpret TROPOMI trace gas retrievals and to highlight how TROPOMI trace gas data can be used to understand event-based impacts on air quality from regional to city-scales around the globe. For this study, we present the observed changes in the atmospheric column amounts of five trace gases (NO2, SO2, CO, HCHO and CHOCHO) detected by the Sentinel-5P TROPOMI instrument, driven by reductions of anthropogenic emissions due to COVID-19 lockdown measures in 2020. We report clear COVID-19-related decreases in NO2 concentrations on all continents. For megacities, reductions in column amounts of tropospheric NO2 range between 14 % and 63 %. For China and India supported by NO2 observations, where the primary source of anthropogenic SO2 is coal-fired power generation, we were able to detect sector-specific emission changes using the SO2 data. For HCHO and CHOCHO, we consistently observe anthropogenic changes in two-week averaged column amounts over China and India during the early phases of the lockdown periods. That these variations over such a short time scale are detectable from space, is due to the high resolution and improved sensitivity of the TROPOMI instrument. For CO, we observe a small reduction over China which is in concert with the other trace gas reductions observed during lockdown, however large, interannual differences prevent firm conclusions from being drawn. The joint analysis of COVID-19 lockdown-driven reductions in satellite observed trace gas column amounts, using the latest operational and scientific retrieval techniques for five species concomitantly is unprecedented. However, the meteorologically and seasonally driven variability of the five trace gases does not allow for drawing fully quantitative conclusions on the reduction of anthropogenic emissions based on TROPOMI observations alone. We anticipate that in future, the combined use of inverse modelling techniques with the high spatial resolution data from S5P/TROPOMI for all observed trace gases presented here, will yield a significantly improved sector-specific, space-based analysis of the impact of COVID-19 lockdown measures as compared to other existing satellite observations. Such analyses will further enhance the scientific impact and societal relevance of the TROPOMI mission.

scholarly journals Interpreting high spatial resolution line observations of planet-forming disks with gaps and rings: the case of HD 163296

2020 ◽  
Vol 642 ◽  
pp. A165
Author(s):  
Ch. Rab ◽  
I. Kamp ◽  
C. Dominik ◽  
C. Ginski ◽  
G. A. Muro-Arena ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Line Emission ◽  
High Angular Resolution ◽  
Back Side ◽  
Gas Temperature ◽  
Disk Model ◽  
Gas Density ◽  
The Impact ◽  
Gas Properties

Context. Spatially resolved continuum observations of planet-forming disks show prominent ring and gap structures in their dust distribution. However, the picture from gas observations is much less clear and constraints on the radial gas density structure (i.e. gas gaps) remain rare and uncertain. Aims. We want to investigate the importance of thermo-chemical processes for the interpretation of high-spatial-resolution gas observations of planet-forming disks and their impact on the derived gas properties. Methods. We applied the radiation thermo-chemical disk code PRODIMO (PROtoplanetary DIsk MOdel) to model the dust and gas disk of HD 163296 self-consistently, using the DSHARP (Disk Substructure at High Angular Resolution) gas and dust observations. With this model we investigated the impact of dust gaps and gas gaps on the observables and the derived gas properties, considering chemistry, and heating and cooling processes. Results. We find distinct peaks in the radial line intensity profiles of the CO line data of HD 163296 at the location of the dust gaps. Our model indicates that those peaks are not only a consequence of a gas temperature increase within the gaps but are mainly caused by the absorption of line emission from the back side of the disk by the dust rings. For two of the three prominent dust gaps in HD 163296, we find that thermo-chemical effects are negligible for deriving density gradients via measurements of the rotation velocity. However, for the gap with the highest dust depletion, the temperature gradient can be dominant and needs to be considered to derive accurate gas density profiles. Conclusions. Self-consistent gas and dust thermo-chemical modelling in combination with high-quality observations of multiple molecules are necessary to accurately derive gas gap depths and shapes. This is crucial to determine the origin of gaps and rings in planet-forming disks and to improve the mass estimates of forming planets if they are the cause of the gap.

scholarly journals The developement of red mud flood environmental information system and the methodology for the spatial analysis of the degraded area

2015 ◽  
Vol 9 (1) ◽  
pp. 1-11
Author(s):  
Gábor Bakó ◽  
Gábor Kovács ◽  
Zsolt Molnár ◽  
Judit Kirisics ◽  
Eszter Góber ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Spatial Resolution ◽  
Red Mud ◽  
High Spatial Resolution ◽  
Three Dimensional ◽  
Environmental Information ◽  
Evaluation Methodology ◽  
Aerial Photogrammetry ◽  
Impact Area ◽  
The Impact

The red mud disaster occurred on 4th October 2010 in Hungary has raised the necessity of rapid intervention and drew attention to the long-term monitoring of such threat. Both the condition assessment and the change monitoring indispensably required the prompt and detailed spatial survey of the impact area. It was conducted by several research groups - independently - with different recent surveying methods. The high spatial resolution multispectral aerial photogrammetry is the spatially detailed (high resolution) and accurate type of remote sensing. The hyperspectral remote sensing provides more information about material quality of pollutants, with less spatial details and lower spatial accuracy, while LIDAR ensures the three-dimensional shape and terrain models. The article focuses on the high spatial resolution, multispectral electrooptical method and the evaluation methodology of the deriving high spatial resolution ortho image map, presenting the derived environmental information database

Polygonal impact craters reveal a global fracture pattern on Mercury

2021 ◽  
Author(s):  
Isik Su Yazici ◽  
Christian Klimczak
Keyword(s):  
Fracture Pattern ◽  
Impact Craters ◽  
Fault Reactivation ◽  
Space Environment ◽  
Tectonic Activity ◽  
Plan View ◽  
Additional Information ◽  
Global Tectonics ◽  
The Impact ◽  
East West

<div> <div> <div> <p>Mercury’s surface displays a rich history in impact cratering and tectonic activity, which both provide insight into the geological evolution of the innermost planet. Global contraction, the volume decrease of the planet associated with a long, sustained period of cooling, and tidal despinning, the slowing of rotation to lock Mercury in its current 3:2 spin-orbit resonance with the sun, are both thought to have played an important role on the observed systematic variations of preferred orientations of thrust fault-related landforms across the planet. While these landforms show preferred north-south orientations in the equatorial and mid-latitudes, they show random or concentric (east-west) orientations at the poles. Other fractures, such as joints, are likely present on Mercury, too, but their expressions are too subtle to be identified unless they are utilized as crater rims during the emplacement of impact craters. Fracture sets that existed in the bedrock prior to impact are widely accepted to produce crater rims showing straight rim segments that overall result in polygonal plan-view shapes of the impact structures, with perhaps the most prominent example Meteor Crater, Arizona. To test if regional fracture sets actually governed the shape of polygonal impact craters on Mercury, we have rigorously mapped all impact craters with diameters between 20 to 400 km. A total of 7,146 impact craters were mapped using Mercury Surface Space ENvironment GEochemistry and Ranging (MESSENGER) global image and topography datasets. After analyzing the shape, lengths, and orientations of 124,671 rim segments, we assessed if these rim segments contain additional information about systematic tectonic patterns. Our results show a strong preferred east-west orientation of straight crater rims at the poles, while in the mid-latitude and equatorial regions, they only have weak north-south or random orientations. That straight crater rims to show preferred east-west orientation at the poles is consistent with observed fault orientations by previous studies. However, we observe a lack of correlation of straight crater rim orientations and mapped faults at the equatorial and mid-latitudinal regions. These results have implications for and will enable further quantitative investigations of the global tectonics and fault reactivation on Mercury.</p> </div> </div> </div>

scholarly journals Satellite imagery of lengthy territories with complex configuration with the account of attitude and positioning errors

2019 ◽  
Vol 75 ◽  
pp. 01013
Author(s):  
Dmitriy Mozgovoy ◽  
Dmitriy Svinarenko ◽  
Roman Tsarev ◽  
Tatiana Yamskikh
Keyword(s):  
Spatial Resolution ◽  
Satellite Imagery ◽  
High Spatial Resolution ◽  
Program Control ◽  
Complex Configuration ◽  
Positioning Errors ◽  
Satellite Attitude ◽  
The Impact

A method for monitoring attitude and positioning errors when taking satellite imagery of lengthy territories with complex configuration using an ultra-high spatial resolution optical-electronic scanner is described in the article. The results of modeling the system of automatic satellite attitude program control during the process of imagery are presented. Given these results, the impact of attitude and positioning errors during satellite imagery was estimated on the coverage percentage of the territory to be imaged.

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