ABSTRACT The most recent comprehensive database of Martian impact craters was the result of the work of impact crater scientists (S.J. Robbins and B.M. Hynek) who carefully examined the available high-resolution imagery of Mars. Building on this previous work, we present the result of an alternative approach involving 56 planetary scientists and trained students. A web platform was designed for this purpose. All impact craters larger than 1 km in diameter were classified according to a simplified classification scheme, recording the primary or secondary nature of the crater, and the morphology of the ejecta (single, double, or multiple layered ejecta rampart sinuous [LERS], or low-aspect-ratio layer ejecta [LARLE]). In total, 8445 LERS craters, 24,530 partially buried craters, 55,309 secondary craters, and 288,155 craters in the category “standard” were identified. Our assessment differs for 8145 entries in the original database compiled by Robbins and Hynek, which are not considered to be impact structures. In this work, ~39,000 secondary craters have been associated with 108 primary craters. Coupled to the existing database, the database we propose here offers a complementary way to investigate the geological history of Mars. More specifically, the completion of layered ejecta crater morphologies down to 1 km and the connection established between secondary and primary impact crater sources will allow the implementation of statistical studies to reveal the spatial and temporal evolution of the impacted material characteristics. Thanks to the simplified classification we performed here, this version of the database can be easily used as a training data set for crater identification algorithms based on machine-learning techniques with the aim to identify smaller impact craters and to automatically define their morphological characteristics. Since it is not possible to confirm an impact structure from remote-sensing data alone, any Martian impact database at this stage remains subjective, and its assessment must be facilitated. The interface we developed for this participative project can be directly used for this purpose and for continuous updates and improvements of this work, in particular, with the latest high-resolution imagery releases such as the CTX global mosaic by J.L. Dickson and others, but also as a platform for building specific databases of craters or any other structures located in a particular region of interest.

Abstract This article describes an attempt to map snow cover accurately from other land covers using Moderate Resolution Imaging Spectrometer (MODIS) data of 500 m spatial resolution. The workflow includes reflectance modelling, computing snow-cover fraction (SCF) and establishing an empirical relationship between the SCF and normalized difference snow index (NDSI) to map snow cover at operational level. Regression relationships have been developed between the SCF derived from the linear mixture model (LMM) and snow obtained from the NDSI based on two criteria, namely: SCF greater than 0.0 and SCF greater than 0.1. The best regression equation has been selected by examining respective graph plots using statistical measures of mean absolute error, correlation coefficient, root mean square error (RMSE) and uncertainty analysis. The results have been validated against the actual SCF obtained from a high-resolution 15 m Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) visible and near infrared (VNIR) scene and covering a substantial range of snow cover of the same area. The selected regression model SCF = 0.25 + 0.35 × NDSI has been tested on other areas and validation efforts show that the pixel-level SCF relationship provides useful results as measured in independent tests against actual SCF obtained from ASTER scene.

Abstract Geology has influenced military commanders and the outcome of military operations since ancient times. Terrain evaluation was developed in the 1960s and has benefited greatly from recent developments in GIS (geographic information systems). Peacekeeping operations are increasingly becoming a component of armed forces workload. Geologic support based on terrain evaluation principles was provided to the UN and NATO during peacekeeping and humanitarian relief operations in Bosnia Herzegovina. This included assessments of slope stability, seismic hazard, flood risk, groundwater potential, and construction materials. The role of the geologist advising military commanders during peace support operations essentially becomes a hybrid of those roles of military geologists and conventional civilian engineering geologists. As ever, training in the engineering operations of the “client” is essential to delivering a successful product—usually defined as an approximate answer within a very limited time frame rather than a “good” answer late.

Abstract Eigenvector analysis of a topographic landform reveals a directional fabric consisting of surface roughness or slope, organization or fabric strength, and preferred orientation. This analysis uses a digital elevation model (DEM) to compute slope and aspect at all points in a region and uses those values to define the normal surface. Standard techniques contour the distributions, extract eigenvectors and eigenvalues from the matrix of the sum of cross products of the directional cosines, and compute eigenvalue ratios. The terrain fabric at a point depends on the size of the region used for the computation and reveals different scales over which directional fabrics operate. With large-scale DEMs, the directional fabric varies in a systematic manner and proves relatively insensitive to the horizontal resolution of the DEM or its quality and creation method. Quantitative measurement of terrain fabric belongs in all studies of terrain analysis and geomorphometry.

Abstract In warfare military geologists pursue five main categories of work: tactical and strategic terrain analysis, fortifications and tunneling, resource acquisition, defense installations, and field construction and logistics. In peace they train for wartime operations and may be involved in peace-keeping and nation-building exercises. Although many geologists view military geology as a branch of engineering geology, the U.S. military does not include geologists in its force structure and gets geological assistance on an ad hoc basis. The army does, however, include organic terrain teams at division and higher levels to provide routine information for mission planning and execution. The classic dilemma for military geology has been whether support can best be provided by civilian technical-matter experts or by uniformed soldiers who routinely work with the combat units.

Abstract The first recorded use of terrain analysis was in 1813 during the Napoleonic Wars, and in most major military operations since that time, geologic counsel and assessment have played important roles. Intelligent use of the terrain of the battlefield, movement of supplies and personnel, and the procurement of adequate supplies of water and of construction materials all have relied on an understanding and application of geologic principles. During the 19th century, as the value of geologic insight came to be recognized, books on military geology appeared as did basic courses in geology at military academies in the United States and abroad. Beginning in World War I, vital geologic data were placed on increasingly sophisticated specialized terrain maps and used both tactically and strategically. Successful military mining beneath enemy fortifications in World War I required an understanding of subsurface geology, including hydrogeology. And in the 1940s and 1950s, geologic principles were applied on an unprecedented scale to the construction of massive underground installations. Moreover, in the 1950s, these principles, applied in a massive research effort, resulted in the ability to distinguish the release of energy by an underground nuclear test from that produced by a natural seismic event. As weapons and defenses against them continue to evolve, geoscience and geoscientists will play an increasingly important role in military planning and operations in diverse and challenging environments worldwide.

Abstract During World War I the combatants committed the total resources of their nations in this first great total war. This came to include geological expertise. The original use of geologists on the battlefield was to locate potable water supplies; later employments were an outgrowth of the stalemate on the battlefield. Mine warfare quickly developed as the belligerents tried to tunnel under the formidable trench systems. Geologists in uniform provided assistance for these efforts and came to be valued for their professional advice. More uses were quickly found for geologists. Trafficability studies of terrain, predictions of stream and river heights, sources of construction materials, and location of water supplies were important missions. Later, as both sides learned to communicate through ground-loop telephony, ground-conductivity studies became important. By the time the United States entered the war in 1917, mine warfare had been neutralized by countermining, and no further active mine operations were undertaken. The U.S. Army sent 10 geologists (three more were en route on November 11, 1918), a mining regiment, and a water supply regiment of engineers to support the American Expeditionary Force. Most geologic work was in terrain studies and in mapping, water supply, and soil trafficability studies. In the United States, other geologists worked to discover sources of scarce raw materials. American geologists generally were disappointed, however, at the contributions they were able to make to the war effort, whether in France or America.

Abstract On June 24, 1942, the temporary Military Geology Unit of the U.S. Geological Survey was formalized after the U.S. Army Corps of Engineers requested them to prepare terrain intelligence studies to meet wartime priorities. The entire Military Geology Unit wartime roster was 114 professionals, including 88 geologists, 11 soil scientists, and 15 other specialists; 14 were women. Assisting staff (illustrators, typists, photographers, and others) totaled 43. The unit produced 313 studies, including 140 major terrain folios, 42 other major special reports, and 131 minor studies. These reports contain about 5,000 maps, 4,000 photographs and figures, 2,500 large tables, and 140 terrain diagrams. Most products were designed in the beginning for general strategic planning in Washington and later for detailed strategic planning overseas; they utilized graphics and nontechnical, telegraphic-style tabular texts. The Military Geology Unit's principal effort was the preparation of the terrain folios titled Strategic Engineering Studies. They varied somewhat in content and format, but the key components usually were introduction, terrain appreciation, rivers, road and airfield construction, construction materials, and water resources. The folios, produced at an average rate of about one per week and at an average cost of $2,500, were compiled from scientific journals, books, maps, and photographs available in the Washington area by a team of 3 to 8 scientists; 8 to 12 teams might be working concurrently. MGU personnel took great pride in never having missed a delivery deadline. In 1944, 5 Military Geology Unit consultants were sent to Europe and 5-man teams were assigned to the Southwest Pacific Area and to the Central Pacific Area. Each team produced large-scale terrain reports, mostly from aerial photographs, and consulted with engineer units and tactical officers in the field. By the end of the war, a consolidated 20-man team worked in Manila at the headquarters of the Armed Forces Pacific.

Abstract Engineering geologists and hydrogeologists assigned to the 416th Engineer Command (ENCOM) supported the planning and execution of construction and tactical operations during the Gulf War. Military geology applications included locating potential quarry sites for sources of construction aggregate and fill, evaluating terrain features such as sabkhahs to assess cross-country mobility, and developing water sources. Sources of construction aggregate were needed to support sustainment engineering requirements in building and maintaining roads, heliports, and aircraft parking aprons in Saudi Arabia. Technical advice and assistance were provided to host nation forces who supported the production and transportation of aggregate from the source to the stock pile. Terrain analysis contributed to the success of the ground war. Obsolete or inaccurate maps were updated with new satellite images and field reconnaissance. Areas with inadequate terrain data were investigated to document natural as well as man-made obstacles. Coastal sabkhahs were evaluated and tested to determine their effect on mobility. Extensive surficial samples were collected for detailed geologic analysis, and field-expedient methods to improve trafficability were recommended. Military hydrogeologists and engineers worked closely with the Saudi Ministry of Agriculture to design and site new water wells. Several water wells were drilled by military teams to support operations deep in the desert. Satellite images, aerial photographs, maps, existing reports, and field reconnaissance were utilized to evaluate geologic conditions, thorough knowledge of which greatly contributed to the success of the ground war.

Abstract Military geology involves the application of geological science to the decision-making processes required by military command; hence the individual geologist needs to be professionally experienced in applied geology and trained in military staff work and doctrine. The importance of establishing an adequate and relevant database of information is now widely recognized and the trend for its compilation has been toward digital recording in support of the existing paper library information. The provision of geological information together with its interpretation and the means of giving advice are now established components of decision support within headquarters at Corps and Division. Generally the tasks have to be dealt with in emergency situations and so time is very short by comparison with comparable civilian projects. What is primarily required is a rapid assessment of the ground conditions within the context of the prevailing military situation. For the advice to be useful, it has to be presented in a manner compatible with the standard military format and avoiding use of technical jargon. Construction work is required in support of the battle: preparing defenses, supporting an advance and consolidating the new positions. Interaction of these works with the ground and the supply of natural materials, particularly water, requires characterization and management sensitive to the contemporary military operations. Local supplies, even if undamaged, are unlikely to be able to sustain the quantities required by the influx of large numbers of troops. Health risks from poor water, not only due to natural bacteria but also deliberately contaminated from terrorist sabotage or NBC attack, require that suitable supplies be established early in the campaign. Recent actions in the Falkland Islands, the Persian Gulf, and mainland Europe demonstrate how military geology has been used, directly or indirectly, by the British armed forces. The trend throughout the 20th century has been of increased mobility during armed conflict, although the scale of operations has varied enormously.

Abstract The U.S. Army trains soldiers in geology under the guise of related topics. Thus, instructional responsibilities are disjointed. The army considers geologic matters to be the responsibility of Engineer officers. Familiarization of topographic requirements and construction practices, both military and civil, is given in the Engineer Officer Basic Course, with specific concepts included in the Engineer Officer Advanced Course. Officers wanting more depth in topographic matters take the Mapping, Charting, and Geodesy Officers Course that emphasizes terrain analysis. Enlisted personnel have more direct contact with geology. Construction materials specialists and quarry operations specialists receive instruction in rock identification and properties about quarrying and construction. On the topographic side, Basic Terrain Analysis teaches mineral and rock identification—weathering and soils are the targeted tasks. Sergeants learn more advanced geology concepts within an imagery analysis and interpretation block of classes in the Advanced Terrain Analysis Course. Warrant officers, normally selected from the enlisted ranks, provide technical expertise in terrain analysis. Although they receive no formal training, the competitive selection process generally chooses those with the most extensive computer knowledge and field experience in terrain analysis. Geology skills per se are not a criterion. The Topographic Engineering Center provides, when needed, a two-week intensive interdisciplinary imagery analysis and interpretation short course, which is primarily for federal agencies.

Abstract The army moves over, digs in, hides in, and builds on the land. Success in these endeavors relies on information about landform, structure, composition (rock and soil types), nature of the surface (sticky, dusty, hard, soft, etc.), and an evaluation of obstacles, engineering materials, water sources, and potential sites for ambush, defilade, and cover and concealment. Geology looms large. For many world areas, such information is not in the databases nor on maps; yet it is sometimes needed on short notice. The information can be derived from image analysis, and available imagery covers most of the world. Examples of such applications include Thule Air Base, Icecap access routes, Project Sanguine, Southeast Asia trafficability studies, and Operations Desert Shield/Storm. The Remote Sensing Field Guide — Desert , developed by a joint effort between the U.S. Army Topographic Engineering Center (TEC) and the U.S. Geological Survey, was used extensively in Operations Desert Shield/Storm in support of military operations. These materials plus spectral reflectance data are being blended into a hypermedia terrain database to support interactive image analysis between army elements.