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 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.

The astrobiological case for renewed robotic and human exploration of the Moon

2006 ◽  
Vol 5 (3) ◽  
pp. 191-197 ◽  
Author(s):  
I.A. Crawford
Keyword(s):  
Lunar Exploration ◽  
The Moon ◽  
Impact Cratering ◽  
Early Atmosphere ◽  
The Earth ◽  
The Galaxy ◽  
The Origin Of Life ◽  
Human Exploration ◽  
The Impact

An ambitious programme of lunar exploration will reveal much of astrobiological interest. Examples include: (i) better characterization of the impact cratering rate in the Earth–Moon system, with implications for understanding the possible ‘impact frustration’ of the origin of life; (ii) preservation of ancient meteorites blasted off Earth, Mars and Venus, which may preserve evidence of the early surface environments of these planets, as well as constraining models of lithopanspermia; (iii) preservation of samples of the Earth's early atmosphere not otherwise available; (iv) preservation of cometary volatiles and organics in permanently shadowed polar craters, which would help elucidate the importance of these sources in ‘seeding’ the terrestrial planets with pre-biotic materials; and (v) possible preservation of extraterrestrial artefacts on the lunar surface, which may permit limits to be placed on the prevalence of technological civilizations in the Galaxy. Much of this valuable information is likely to be buried below the present surface (e.g. in palaeoregolith deposits) and will require a considerable amount of geological fieldwork to retrieve. This would be greatly facilitated by a renewed human presence on the Moon, and may be wholly impractical otherwise. In the longer term, such lunar operations would pave the way for the human exploration of Mars, which may also be expected to yield astrobiological discoveries not otherwise obtainable.

scholarly journals Three-Dimensional Model of the Moon with Semantic Information of Craters Based on Chang’e Data

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 959
Author(s):  
Yunfan Lu ◽  
Yifan Hu ◽  
Jun Xiao ◽  
Lupeng Liu ◽  
Long Zhang ◽  
...  
Keyword(s):  
Reference Frame ◽  
3D Model ◽  
Semantic Information ◽  
Three Dimensional ◽  
Impact Craters ◽  
Detection Methods ◽  
The Moon ◽  
Three Dimensional Model ◽  
Data Set ◽  
The Impact

China’s Chang’e lunar exploration project obtains digital orthophoto image (DOM) and digital elevation model (DEM) data covering the whole Moon, which are critical to lunar research. The DOM data have three resolutions (i.e., 7, 20 and 50 m), while the DEM has two resolutions (i.e., 20 and 50 m). Analysis and research on these image data effectively help humans to understand the Moon. In addition, impact craters are considered the most basic feature of the Moon’s surface. Statistics regarding the size and distribution of impact craters are essential for lunar geology. In existing works, however, the lunar surface has been reconstructed less accurately, and there is insufficient semantic information regarding the craters. In order to build a three-dimensional (3D) model of the Moon with crater information using Chang‘e data in the Chang‘e reference frame, we propose a four-step framework. First, software is implemented to annotate the lunar impact craters from Chang’e data by complying with our existing study on an auxiliary annotation method and open-source software LabelMe. Second, auxiliary annotation software is adopted to annotate six segments in the Chang’e data for an overall 25,250 impact crater targets. The existing but inaccurate craters are combined with our labeled data to generate a larger dataset of craters. This data set is analyzed and compared with the common detection data. Third, deep learning detection methods are employed to detect impact craters. To address the problem attributed to the resolution of Chang’e data being too high, a quadtree decomposition is conducted. Lastly, a geographic information system is used to map the DEM data to 3D space and annotate the semantic information of the impact craters. In brief, a 3D model of the Moon with crater information is implemented based on Chang’e data in the Chang‘e reference frame, which is of high significance.

Updated statistics for crater clusters on Mars

2021 ◽  
Author(s):  
Tanja Neidhart ◽  
Katarina Miljković ◽  
Eleanor K. Sansom ◽  
Ingrid J. Daubar ◽  
Gareth S. Collins ◽  
...  
Keyword(s):  
Full Range ◽  
Impact Craters ◽  
Effective Diameter ◽  
Impact Cratering ◽  
Seismic Detection ◽  
Bright Surface ◽  
Uppermost Layer ◽  
Cluster Properties ◽  
Current Impact ◽  
The Impact

<p>An increasing number of newly formed impact craters on Mars have been detected in the last 15 years. These small craters are normally identified via dark spots in lower resolution images that formed during the impact process, presumably through the removal or disturbance of bright surface material [1]. Later higher resolution images revealed single craters or crater clusters, which form when impactors fragment in the atmosphere, within those halos [1,2]. Due to this detection method, most of the new impact sites found are in dusty regions, which imposes an observational bias [3]. Newly formed clusters consist of two to thousands of individual craters and can be tightly clustered or spread out over hundreds of meters [2]. Since the InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission landed on Mars in 2018 [4], the search for newly formed impact craters has become even more important, because identifying impacts in seismic signals could provide further constraints on both the atmospheric and solid-body effects of impact cratering process on Mars, as well as help place further constraints on the properties of the uppermost layer of the crust. As one of InSight’s mission goals is to estimate the current impact rate on Mars, the seismic detection of impacts is also crucial [4].</p> <p>The aim of this new study is to describe the properties of the complete catalog of known newly formed craters on Mars and examine correlations between different crater cluster properties. We investigated 559 crater clusters and 493 single craters detected between 2008 and 2020 using 25 cm/px HiRISE images. The locations and diameters were noted for each single crater, as well as for every individual crater within a cluster down to 1 m diameter. This was done using ArcMap (ArcGIS) software with the three-point method of the CraterTools add-in [5]. We describe the cluster characteristics, such as the number of craters within a cluster, largest crater in a cluster, cluster effective diameter, cluster dispersion, elevation of the impact sites, and the variation in sizes of craters within a cluster.</p> <p>More than half of the new impact sites form as clusters. We did not find any differences between the spatial distribution of single and crater clusters across Mars. The mapped crater clusters from this study consist of 2 to 2334 individual craters. More than half of all clusters (58%) consist of 10 craters or less. Crater clusters containing more than 100 craters are rare. With regard to the sizes of craters within crater clusters, we found that for highly populated clusters, the majority of craters are very small, and clusters with few craters have a tendency for craters that are more equal in size. Clusters having large effective diameters contain more equally sized craters. Our results show the full range of parameter spaces that are possible for cluster properties, which can help validate theoretical atmospheric fragmentation models.</p> <p><strong>References:</strong></p> <p>[1] Malin M. C. et al. (2006) Science, 314, 1573-1577.</p> <p>[2] Daubar I. J. et al. (2019) JGR, 124, 958-969.</p> <p>[3] Daubar I. J. et al. (2013) Icarus, 225, 506-516.</p> <p>[4] Banerdt B. W. et al. (2020) Nature, 13, 183-189.</p> <p>[5] Kneissl T. et al. (2011) Planet. Space Sci., 59, 1243-1254.</p>

2. The Moon

2015 ◽  
pp. 17-45
Author(s):  
David A. Rothery
Keyword(s):  
Solar System ◽  
Impact Craters ◽  
Lunar Exploration ◽  
The Moon ◽  
Virtual Absence ◽  
Rock Samples ◽  
The Face ◽  
The Impact

The Earth’s Moon is the fifth largest moon in our Solar System and is made almost entirely of rock. The virtual absence of an atmosphere leads to a very large day–night range of temperature at the Moon’s surface of about 270°C. ‘The Moon’ outlines the phases, orbit, and rotation of the Moon and goes on to describe the face of the Moon seen from Earth and the farside of the Moon first observed in 1959 from the Soviet probe Luna 3. The impact craters observed on the Moon are explained, and the results of lunar exploration and dating of rock samples brought back are described, but what are the Moon’s origins?

Fluctuation of recent large impact craters rate on Mars from automatic crater detection

2020 ◽  
Author(s):  
Anthony Lagain ◽  
Misha Kreslavsky ◽  
Gretchen Benedix ◽  
David Baratoux ◽  
Phil Bland ◽  
...  
Keyword(s):  
Impact Crater ◽  
Impact Craters ◽  
Asteroid Belt ◽  
Large Impact ◽  
The Moon ◽  
Crater Detection ◽  
Impact Flux ◽  
Ejecta Blanket ◽  
The Impact ◽  
Latitudinal Band

<p>Knowledge of collision rates through time and space is essential because meteoritic impact crater counting is the only way to determine the ages of surface geological units and processes on the solid bodies of our Solar System. All chronology models assume a constant size distribution of impactors and an exponential decay of the impact flux between 4 Ga and 2.5 Ga before the present followed by a constant rate over the last 2.5 Ga. These two assumptions are challenged by recent evidence for an increase of the impact flux on the Moon and the Earth and probably on Mars associated with a decoupling between the flux of small and large impactors over the last billion years. Here, using the results of an automatic crater detection algorithm, we investigate the evolution of the rate of formation of large impact craters (Dc ≥ 20km) on Mars and thus infer the evolution of the flux of large impactors (Di > 5km) from the size-frequency distribution of small craters superposed to the ejecta blankets of large ones.</p><p>The dating of large impact craters on Mars is limited by several factors such as the degradation of ejecta blankets and the retention rate of small craters superposed to their ejecta. We therefore focused on craters ≥20km in diameter exhibiting an ejecta blanket according to the crater database and located on a latitudinal band between ±35°. We then selected those whom their ejecta are not affected by volcanic/tectonic processes or by the formation of another large nearby impact crater. The final set includes 590 impact craters.</p><p>If one can argue the impact flux cannot be fully recorded for the last 4Ga due to resurfacing processes erasing progressively the ejecta blanket and large craters themselves, Hesperian and Noachian terrains within the 35° latitudinal band should nevertheless have retained all D≥20km craters over a portion of the Amazonian period. The CSFD of craters younger than 600Ma (113 craters) superposed to these terrains is consistent with the 600Ma isochron, supporting the fact that the entire population of craters ≥20km formed over the last 600 million years on this portion of the Martian surface has been counted completely. We therefore focused on the analysis of the impact rate evolution over this range of time from this crater sub-sample.</p><p>The formation of large impact craters is not homogeneously distributed over the time range investigated here. Our data suggest an inconsistency between the flux used to date each crater and the rate inferred from these datings, thus implying that the small and large body impact fluxes are decoupled from one another. We note also sharp peaks centered around 480, 280 and 100Ma. Preliminary statistical test show that 280Ma peak is marginally significant whereas the two others are too small to be statistically significant. This pattern would be consistent with other independent arguments for increased rate with similar intensity and timing on the Moon and Mars for which the causes are probably collisions and potentially formation of asteroid families within the main asteroid belt.</p>

Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

1962 ◽  
Vol 14 ◽  
pp. 415-418
Author(s):  
K. P. Stanyukovich ◽  
V. A. Bronshten
Keyword(s):  
Explosive Charge ◽  
The Moon ◽  
Meteorite Impacts ◽  
The Earth ◽  
Lunar Craters ◽  
The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

Thematic maps in the scientific studies of the moon

2019 ◽  
Vol 943 (1) ◽  
pp. 68-75
Author(s):  
S.G. Pugacheva ◽  
E.A. Feoktistova ◽  
V.V. Shevchenko
Keyword(s):  
Natural Resources ◽  
Thermal Inertia ◽  
High Growth ◽  
Lunar Soil ◽  
Nature Management ◽  
The Moon ◽  
Surface Cooling ◽  
Laser Altimeters ◽  
Space Infrastructure ◽  
The Impact

The article presents the results of astrophysical studies of the Moon’s reflected and intrinsic radiation. We studied the intensity of the Moon’s infrared radiation and, thus, carried out a detailed research of the brightness temperature of the Moon’s visible disc, estimated the thermal inertia of the coating substance by the rate of its surface cooling, and the degree of the lunar soil fragmentation. Polarimetric, colorimetric and spectrophotometric measurements of the reflected radiation intensity were carried out at different wavelengths. In the article, we present maps prepared based on our measurement results. We conducted theresearch of the unique South Pole – Aitken basin (SPA). The altitude profiles of the Apollo-11 and Zond-8 spacecrafts and the data of laser altimeters of the Apollo-16 and Apollo-15 spacecrafts were used as the main material. Basing upon this data we prepared a hypsometric map of SPA-basing global relief structure. A surface topography map of the Moon’s Southern Hemisphere is given in the article. The topography model of the SPA topography surface shows displacement centers of the altitude topographic rims from the central rim. Basing upon the detailed study of the basin’s topography as well as its “depth-diameter” ratio we suggest that the basin originated from the impact of a giant cometary body from the Orta Cloud. In our works, we consider the Moon as a part of the Earth’s space infrastructure. High growth rates of the Earth’s population, irrational nature management will cause deterioration of scarce natural resources in the near future. In our article, we present maps of the natural resources on the Moon pointing out the most promising regions of thorium, iron, and titanium. Probably in 20 or 40 years a critical mining level of gold, diamonds, zinc, platinum and other vital rocks and metals will be missing on the Earth.

scholarly journals Changing landscapes: Gay men in the west and northwest of Ireland

Sexualities ◽  
2020 ◽  
pp. 136346072098169
Author(s):  
Aidan McKearney
Keyword(s):  
Gay Men ◽  
Social Rights ◽  
Irish Society ◽  
Recent Past ◽  
Same Sex ◽  
Lgbt People ◽  
The Many ◽  
Northwest Region ◽  
The Impact ◽  
Insight Into

This article focuses on the experiences of gay men in the rural west and northwest region of Ireland, during a period of transformational social and political change in Irish society. These changes have helped facilitate new forms of LGBTQI visibility, and local radicalism in the region. Same-sex weddings, establishment of rural LGBT groups and marching under an LGBT banner at St Patricks Day parades would have been unthinkable in the recent past; but they are now becoming a reality. The men report continuing challenges in their lives as gay men in the nonmetropolitan space, but the emergence of new visibility, voice and cultural acceptance of LGBT people is helping change their lived experiences. The study demonstrates the impact of local activist LGBT citizens. Through their testimonies we can gain an insight into the many, varied and interwoven factors that have interplayed to create the conditions necessary for the men to: increasingly define themselves as gay to greater numbers of people in their localities; to embrace greater visibility and eschew strategies of silence; and aspire to a host of legal, political, cultural and social rights including same-sex marriage. Organic forms of visibility and local radicalism have emerged in the region and through an analysis of their testimonies we can see how the men continue to be transformed by an ever-changing landscape.

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