Identification of landing sites for rescue helicopters in mountains with use of Geographic Information Systems

Helicopters are often used in mountain rescue both for rescuers moving in the area of accidents and for evacuating victims, but in steep or forested terrain finding a landing place can be problematic. The main aim of this research is to use Digital Elevation Model(DEM) and cartographic database analysis to select locations that can be used as landing site for the rescue helicopters. Methods were based on GIS analysis;both raster and vector data were used for identifying touchdown points for rescue helicopters. Based on DEM data, locations with a low slope gradient were identified;topographic vector data were used for identifying unforested sites. Then buffer zones for buildings and power lines were excluded, and it was checked whether the areas had any topographic features that prevented helicopter landings. The findings were verified on an orthophotomap. In result, GIS analyses have selected 1232 polygons that fulfilled initial criteria. Their verification on orthophotomap has shown that only 55% of them could be potentially used as landing site. Landing sites can be found mainly on side ridges of mountain ranges and in valley beds, when those on ridges are most important in this research. The greatest difficulties and methodological challenges are posed by: identification of sites having a shape which prevents landing, the obsolescence of data due to environment dynamics, the presence of features that are not shown on maps but prevent helicopter landings. A map of landing sites is a very useful tool to conduct rescue operations, but each use of a given landing site requires both in-field and numerical verification. The analysis demonstrated that GIS toolsare useful in pre-planning of rescue missions, and also showed that such data must be kept up-to-date and in-field verification is needed continuously, the more so as it plays an important role in ensuring the safety of rescuers and victims.

Illumination and regolith temperature at China's next candidate lunar landing site Shackleton crater

This study focuses on the illumination and temperature at China’s next lunar candidate landing site Shackleton crater.We used the NASA’s SPICE system to evaluate the terrain obscuration effect on real-time illumination;the resulting illumination map resembles previous studies,validating the methodologies used in our study.In addition,we estimated an accumulated illumination map for the period of likely rover movement.The map indicates the illuminated inner wall of the Shackleton crater is close to 27%of the whole,meaning that the rover will likely receive solar radiation during its movement.Using the real-time illumination and the distributed 1-D thermal diffusion model,we continuously evaluated the regolith temperature for more than 20 years to stabilize the temperature,and selected the temperature of the end time as the initial value used in a thermal study set for July 20,2023 and May 8,2027.Our results indicate the temperature in the permanent shadow region remains nearly constant,thus validating the stability of our estimated initial temperature.Our results also indicate that the surface temperature is more sensitive to transient illumination,but the subsurface temperature is more likely to be associated with the accumulated illumination.This difference indirectly implies that the conductivity of the lunar regolith is inefficient.The locations receiving more solar radiation show a temperature larger than the threshold(~112 K)of ice stability.The permanently shadowed regions can be as cold as 25 K,and such extreme coldness is a hazard to the rover.There are suitable temperature locations which have a warm surface but cold subsurface to preserve water ice.To further ensure normal rover movement,we provided a map of suitable temperature sites and found that these locations exist not only in the Shackleton crater’s inner wall,but also outside the crater.We suggested four trade-off sampling sites with suitable temperatures and gradual slopes.

Landing site positioning and descent trajectory reconstruction of Tianwen-1 on Mars

Tianwen-1(TW-1)is the first Chinese interplanetary mission to have accomplished orbiting,landing,and patrolling in a single exploration of Mars.After safe landing,it is essential to reconstruct the descent trajectory and determine the landing site of the lander.For this purpose,we processed descent images of the TW-1 optical obstacle-avoidance sensor(OOAS)and digital orthophoto map(DOM)of the landing area using our proposed hybrid-matching method,in which the landing process is divided into two parts.In the first,crater matching is used to obtain the geometric transformations between the OOAS images and DOM to calculate the position of the lander.In the second,feature matching is applied to compute the position of the lander.We calculated the landing site of TW-1 to be 109.9259◦E,25.0659◦N with a positional accuracy of 1.56 m and reconstructed the landing trajectory with a horizontal root mean squared error of 1.79 m.These results will facilitate the analyses of the obstacle-avoidance system and optimize the control strategy in the follow-up planetary-exploration missions.

Medical transportation and the contribution of air medical evacuation in isolated mountainous areas of Greece-Case study,Municipality of Agrafa

In every emergency medical situation,access to emergency medical services is an inalienable right of any citizen.The average acceptable time to provide first aid assistance is 60 minutes.In this paper,the possibility of using helicopters for air travel in mountainous areas was examined for the first time for all of Greece and especially for a mountainous and isolated area such as the Municipality of Agrafa.Initially,the time distance-virtual distance,from the hospitals was calculated at the national level of Greece,with an acceptable first contact time of 60 minutes(golden hour),i.e.,less than two hours from the nearest hospital to the incident and back to the hospital and the relevant conclusions are drawn.Then,the case study of Municipality of Agrafa,one of the most mountainous areas in Greece,was examined.The time distance of the settlements from the nearest primary health point,namely the Primary Health Centre(PHC)of West Fragkista,was calculated and the transportation by ground means was compared with the corresponding time by flying means,to investigate the contribution of air transportation or not,of the timely arrival of the patients in the appropriate health structure.Finally,possible helicopter landing locations were identified,using a geographic information system to facilitate the process of air medical transportation in the Municipality of Agrafa.

基于LESA综合评价模型的耕地质量定级方法

为准确掌握耕地生产效益水平,进一步满足当前国土管理需要,对耕地质量定级方法进行了研究。选取河南省固始县为研究对象,以LESA综合评价模型为基础,结合耕地质量等别更新成果及相关土地提质工程成果,综合分析评定了耕地质量级别,并以耕地产能为依据验证了定级结果。结果表明:基于LESA综合评价体系,固始县的耕地分为6-13级,级别越高,耕地质量越好。其中,9-13级的耕地自然条件较优,地块规则,利于机械耕作;6-8级的耕地自然质量水平较差,集中连片程度低,耕作较为不便。根据耕地产能对定级结果可靠性进行验证,定级结果符合实际产出。基于LESA综合评价模型的耕地质量定级方法不仅继承和沿用了耕地分等成果,还通过选取工程指标体现了高标准基本农田建设成效,突破原有规程法定级结果仅在县域内可比的限制,为耕地定级方法体系研究提供参考。

Geospatial technologies for Chang’e-3 and Chang’e-4 lunar rover missions

This paper presents a brief overview of the geospatial technologies developed and applied in Chang’e-3 and Chang’e-4 lunar rover missions.Photogrammetric mapping techniques were used to produce topographic products of the landing site with meter level resolution using orbital images before landing,and to produce centimeter-resolution topographic products in near real-time after landing.Visual positioning techniques were used to determine the locations of the two landers using descent images and orbital basemaps immediately after landing.During surface operations,visual-positioning-based rover localization was performed routinely at each waypoint using Navcam images.The topographic analysis and rover localization results directly supported waypoint-to-waypoint path planning,science target selection and scientific investigations.A GIS-based digital cartography system was also developed to support rover teleoperation.