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The high-resolution panchromatic stereo camera Terrain Mapping Camera-2 (TMC-2) on-board the Indian Chandrayaan-2 mission sends images of the lunar surface at 5 m resolution with a low to high sun-angle from an altitude of 100 km. These images help identify subtle topographic variations and enable mapping of low-elevation landforms, one of which is a prominent ~220 km long wrinkle ridge called the Dorsa Geikie (DG) lying within Mare Fecunditatis. The favourable resolution of TMC-2 images and the digital elevation models provide opportunities for a detailed structural study of the DG and to reveal crustal shortening, cumulative contractional strain and palaeostress regime responsible for thrust faulting for the first time. The time of deformation and formation of dorsa is also estimated for a holistic spatio-temporal understanding of deformation. This study presents initial analysis of the data received from TMC-2, and the accuracy of the results are likely to improve as the ingredients get amended and evolved in future.

From the 2000s onwards, unprecedented space missions have brought about a wealth of novel investigations on the different aspects of space geomechanics. Such aspects are related to the exploratory activities such as drilling, sampling, coring, water extraction, anchoring, etc. So far, a whole range of constitutive research projects on the plate tectonics, morphology, volcanic activities and volatile content of planetary bodies have been implemented. Furthermore, various laboratory experiments on extraterrestrial samples and their artificial terrestrial simulants are continually conducted to obtain the physical and mechanical properties of the corresponding specimens. Today, with the space boom being steered by diverse space agencies, the incorporation of geomechanics into space exploration appreciably appears much needed. The primary objective of this article is to collate and integrate the up-to-date investigations related to the geomechanical applications in space technologies. Emphasis is given to the new and future applications such as planetary drilling and water extraction. The main impetus is to provide a comprehensive reference for geoscience scientists and astronauts to quickly become acquainted with the cutting-edge advancements in the area of space geomechanics. Moreover, this research study also elaborates on the operational constraints in space geomechanics which necessitate further scientific investigations.

Orbital data from the MESSENGER spacecraft show that a significant portion of Mercury's northern hemisphere is covered by smooth plains, which are interpreted to be flood volcanic material and/or impact melt. The smooth plains show pervasive tectonic structures and encompass a broad raised bulge of uncertain geophysical interpretation. In this work, we focus on the mapping of all the morphostructures within the northern smooth plains, aiming at providing a useful dataset for further studies about the mapped area. The structural map is obtained through a twofold process: first with an automatic mapping, using an algorithm to identify all the lineaments from a DEM; and second with a visual inspection and classification of the results of the algorithm in a GIS environment. The final maps are drafted at two different scales, 1:300,000 and 1:600,000. With this approach, we mapped and characterized more than fifty thousand lines marking scarps on the surface, creating a database with several morphometric attributes for each of the identified scarps (e.g. length, azimuth, and height), which can be used for geostatistical study of smooth plains tectonics. Our structural map reveals that: (i) the area is broadly dominated by wrinkle ridges, ghost crater assemblages of lineaments, and scarps related to impact crater processes (e.g. radial faults, secondary crater chains, ejecta emplacement) and that (ii) the amount of strain was not evenly accommodated throughout the northern smooth plains.

We present a 1:4,000,000 scale map of tectonic landforms in Chryse Planitia and Arabia Terra, on either side of Mars' dichotomy. Our study area is a ∼3 million km 2 region, transitional between Mars' highlands and lowlands including Oxia Planum, the landing site of the ExoMars rover. Using a structural mapping approach, we digitised all kilometre-scale tectonic structures at a scale of 1:50,000 using high-resolution data (∼6 m/pixel). Although this region is represented as sparsely tectonised on global tectonic maps, we find evidence of widespread tectonic shortening structures across the region. The shortening structures have a dominant N-S orientation and occur in all globally identified geological units. The structural map contributes to a broader understanding of the geological history of the region and Mars' wider tectonic history.

The main purpose of this work is to illustrate a methodology for mapping (identification and delineation) mounds and mountains on the lunar surface. In doing so, a precise meaning is given to positive relief in relation to a local base level which is specific to each mapped feature. The procedure is useful for mapping very shallow volcanic domes and cones, shallow wrinkle ridges and any other positive relief as shown in different test sites. The mapping of lunar mountains has allowed their sizes to be determined and compared with mountains on Earth which are defined using the same methodology. This paper reveals which is the mightiest mountain on the Moon and, by comparison to two emblematic Earth mountains (Mount Everest and Mount Kilimanjaro), it is shown that lunar mountains are mightier than Earth mountains despite the fact that they are more rounded and do not have the steep slopes of mountains on Earth. When comparing their slopes, the mean slopes inside circles of 3 km radius around the summits are, respectively, 39º, 26º and 12º for Mount Everest, Mount Kilimanjaro and the mightiest lunar mountain. It is also shown that significant mountains on the Moon, in the form of volcanic cones, crater central peaks and mighty mountains, have the form of a three-sided pyramid. Given the DEM spatial resolution, the procedure is able to map any mound, which is illustrated by identifying very shallow volcanic domes and volcanic cones. Central crater peaks are also interesting mountains of medium altitude that may reach several thousand metres. The identification and delineation of mountains on the Moon is illustrated by using the LOLA digital elevation model but the methodology is completely general and the only limitation is the spatial resolution of the digital elevation model used to define the scale of the positive reliefs that can be identified and delineated.

The presence of polygonal-shaped craters, i.e., craters with complete or incomplete polygonal rims along with circular or elliptical outlines, on the surface of celestial bodies has been known for nearly a century. However, many investigations on their distribution and formation have not been carried out, until recently. Scientists have proposed that the polygonal shapes of the crater rims owe their origin to the pre-existing structurally weak planes like faults/fractures in the area adjacent to the impact. The present study area is the southern part of Margaritifer Terra, Mars; a mid-Noachian terrain, which has craters of different morphologies, including the polygonal impact craters (PICs). The study focuses on the reason for the development of PICs by identification and mapping of a population of 50 selected polygonal craters along with morphotectonic features namely grabens, wrinkle ridges, and lobate scarps. The analysis of orientations of the straight segments of polygonal crater rims shows marked resemblance with orientations of these morphotectonic features conforming to their control on the rim geometries. Research highlights Structural mapping of the southern Margaritifer Terra region, Mars. Generating rose diagrams and line graphs for the orientation of the straight edges of polygonal craters and the morphotectonic features within the southern Margaritifer Terra region. Conducting statistical F-test to find out the bearing of weak planes on the formation of PICs. Finding out the presence of buried weak planes by comparing the rose diagrams and spike graphs.

The present study area involves part of a deformed coalesced fan located along the Himalayan Frontal Thrust (HFT) on the east of river Tista near the India-Bhutan border. The area is marked by two spectacular E-W trending south-sloping scarps namely the Matiali (ca. 60 m) and Chalsa (ca. 90 m) Scarps and a north-sloping E-W trending Thaljhora (ca. 80 m) Scarp. Our work comprises of a comparative study of geomorphology and geologic history in the adjacent interfluves of Jaldhaka-Gathia and Neora-Murti rivers to understand the tectonic history of the area. We mapped the Jaldhaka-Gathia river interfluve at a 1:25,000 scale and report a hitherto unidentified northerly sloping small scarp of ca. 5m height named the Nagrakata Scarp. This scarp was identified using satellite images, DEMs, and total station survey. We interpret that the two north-sloping, E-W trending scarps (Thaljhora and Nagrakata Scarps) are manifestations of steep limbs of anticlines over blind south-dipping back thrusts. Together they form a wrinkle-ridge pair behind the north-dipping HFT, which is manifested by south-sloping Chalsa Scarp. We propose a plausible geomorphic model interpreting that deformation along the small fan in the Jaldhaka-Gathia interfluves is younger compared to fan deposition and deformation in the adjacent Mal-Murti interfluve. The most recent geomorphology of the Jaldhaka-Gathia interfluve is controlled by tectonism associated with the thrust below the Nagrakata Scarp where the youngest deformation episode is recorded to at around ∼6 ka and is likely related to motion on a splay off of the thrust beneath the Thaljhora Scarp.

Wrinkle ridges are a common feature in the lunar maria and record subsequent contraction of mare infill. Automatic detection of wrinkle ridges is challenging because the ridges are of irregular shapes and many ridges have been eroded and/or degraded over time. The proposed method consists of the following steps. First, as the slope can reflect the gradient changes of the ridge rims to a certain extent, the slope map is generated and converted to a grayscale (0–255) image. Then the phase symmetry of the slope map is calculated with filter wavelength and filter scales parameters, which reduce the regions into symmetry regions. Next, a regional threshold is applied to limit the ridge candidates. Candidates with values less than the threshold are rejected. Moreover, the images are processed using a series of morphological operations, such as close, open, edge linking and noise removal. Finally, after thresholding the ridge map can be obtained. An experiment was performed using Lunar Reconnaissance Orbiter Camera (LROC) WAC image and topographic data from LOLA, the results demonstrate promising performance with detection percentage from 73 to 90.

Wrinkle ridges are one of the most common structures usually found in lunar mare basalts, and their formations are closely related to the lunar mare. In this paper, wrinkle ridges in Mare Serenitatis were identified and mapped via high-resolution data acquired from SELENE, and a quantitative method was introduced to analyze the degree of central symmetry of the wrinkle ridges distributed in a concentric or radial pattern. Meanwhile, two methods were used to measure the lengths and orientations of wrinkle ridges before calculating their central symmetry value. Based on the mapped wrinkle ridges, we calculated the central symmetry value of the wrinkle ridges for the whole Mare Serenitatis as well as for the four circular ridge systems proposed by a previous study via this method. We also analyzed the factors that would cause discrepancies when calculating the central symmetry value. The results indicate that the method can be used to quantitatively analyze the degree of central symmetry of the linear features that were concentrically or radially oriented and can reflect the stress field characteristics.

A new tectonic model is proposed for the origin of the Tharsis rise on Mars, which occupies ∼25% of the planet. The model invokes initiation of plate subduction by a large impact during the Late Heavy Bombardment at ca. 4.0 Ga. The model explains migration of Tharsis volcanism by slab rollback and the lack of magnetized crust in the bulk of Tharsis by formation of juvenile crust after the Mars dynamo creased to operate. The model also explains (1) the formation of thrust systems as a result of impact-generated crustal thickening (i.e., Thaumasia thrust), retro-arc contraction (i.e., Solis-Lunae fold belt), and plate subduction (Lycus and Ulysses thrusts), (2) the development of dominantly NE-trending grabens and a major east-facing V-shaped conjugate strike-slip system across the Tharsis rise as a result of backarc extension, and (3) crustal thickening of the Tharsis rise as a result of magmatic accretion during protracted construction of arcs above an episodically stalled and thus stationary subducting slab. The model has several implications for the way in which a unified global plate-tectonic network may have been established on early Earth. First, large impacts were common during the Late Heavy Bombardment (ca. 4.2-3.9 Ma), and thus impact-induced plate subduction would have been highly likely in the Hadean period. Such subduction systems must be local in scale and associated only with trench retreat and slab rollback. Localized plate subduction permits other modes of tectonic processes to have occurred simultaneously on early Earth, reconciling conflicting observations for plate-tectonic and non-plate-tectonic processes. Second, the presence of water at the surface of Hadean Earth would have allowed rapid transformation of basaltic crust to eclogite, allowing a sustainable plate subduction process once it started. The Hadean and possibly Archean Earth may only have had localized subduction systems, all characterized by slab rollback and trench retreat. Trench advance and related shallow-angle plate subduction probably did not begin on Earth until Proterozoic time, when a single and united global plate-tectonic network was established. This may have been accomplished by gradual coalescence of formerly independent subduction systems over a significant period of geologic time (>1 b.y.). Incorporation of trench-advance and shallow-angle plate subduction in the Proterozoic may have been induced by complex interactions of multiple subduction systems in a single and kinematically linked global tectonic network. This in turn led to the beginning of the formation of the crustal structures and petrologic assemblages of modern Earth. Based on a simple conductive cooling model, it appears that the most critical factors that control whether plate subduction could have been initiated in a rocky planet during the Late Heavy Bombardment in the inner solar system are its initial crustal thickness and the cooling rate/thickening rate of the lithosphere.