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Fine Lineaments and Their Significance
Published in Gilbert Fielder, Secrets of the Moon, 2021
With the collaboration of P. Rogers of Imperial College, J. Guest, L. Wilson and I, working at the University of London Observatory, had melted basic terrestrial lavas in a furnace and then outgassed them in a vacuum chamber.28 This caused the lavas, releasing their volatile components, to bubble up and form very porous, underdense structures (Fig. 16.2). These were the sort of lavas that I had expected to be present on the surface of the atmosphereless Moon. Using a specially constructed, long-arm goniphotometer (Fig. 16.3), we found that these simulated lunar lavas did not scatter light in the way observed in any part of the Moon's surface. Light scattering functions closer to those of the real lunar rocks were obtained by smashing up the simulated rocks to form a range of particle sizes; just as long-term meteoric impacts might have done. Wilson, who had consulted B. Hapke in the U.S.A., constructed a small proton accelerator as part of his PhD Thesis. He used his accelerator to further damage the particles by proton bombardment, since solar radiation would have damaged rocks exposed on the lunar surface in like fashion. Testing these materials photometrically produced light scattering functions similar to those of the Moon. Following these experiments, I had expected the regolith (lunar soil) to be granular, with a range of particle sizes, and largely structureless.
An analytical approach on the evaluation of stress distribution beneath plain rigid wheels on Tri-1 lunar soil simulant
Published in Alka Mahajan, B.A. Modi, Parul Patel, Technology Drivers: Engine for Growth, 2018
Pala Gireesh Kumar, S. Jayalekshmi
The surface terrain of planets like Mars and the Moon are covered mainly with fine grained, loose soil and sandstone rocks. A rover is required to operate perfectly in an unknown, unpredictable environment with lots of obstacles in order to explore any planetary surface. Designing and controlling a rover to explore these areas is a challenging task. The reason for this is that, the wheels of the rover can easily slip on loose soil, resulting in loss of traction between wheel and ground. This causes mission failures, such as that found in explorations Lunokhod 0 and Spirit 2010. This paper focused on the normal and shear stress distributions produced by a wheel at the wheel-soil interface. Hence, analysis of both normal and tangential/shear stress distributions were carried out for the prediction of wheel performance. A rigid wheel-soil interaction model was used to evaluate the normal and shear stress distribution at the wheel-soil interface on an anorthosite based lunar soil simulant, Tiruchirappalli-1 (TR-1) (Sreenivasulu, 2014), the properties of which are given in Section 2. This corresponds to Apollo16 site characteristics. Plate load tests were carried out on this simulant to yield the cohesion and friction moduli.
Tests of Hypotheses
Published in William M. Mendenhall, Terry L. Sincich, Statistics for Engineering and the Sciences, 2016
William M. Mendenhall, Terry L. Sincich
Study of lunar soil. Meteoritics (March 1995) reported the results of a study of lunar soil evolution. Data were obtained from the Apollo 16 mission to the moon, during which a 62-cm core was extracted from the soil near the landing site. Monomineralic grains of lunar soil were separated out and examined for coating with dust and glass fragments. Each grain was then classified as coated or uncoated. Of interest is the “coat index,” that is, the proportion of grains that are coated. According to soil evolution theory, the coat index will exceed .5 at the top of the core, equal .5 in the middle of the core, and fall below .5 at the bottom of the core. Use the summary data in the accompanying table to test each part of the three-part theory. Use α = .05 for each test.
Terrain-aware traverse planning for a Mars sample return rover
Published in Advanced Robotics, 2021
Other related research proposed to deploy a spectrometer to gather information used in path planning to update local terrain information. The first step is a mapping of geological units (hypothesis), and as the rover gains information about the terrain it can update its route using Bayesian inference [31]. However, a spectrometer is usually time consuming to deploy (about three hours [32]) and could be computationally demanding. A different instrument, easier to implement and deploy, could potentially alleviate this difficulty (e.g. cone penetrometer or shear vane [33]). Instruments have already been utilized to study the geotechnical properties of the regolith, as demonstrated by the Lunakhod rovers and the Apollo missions [34]. Experiments sent to the Moon to retrieve properties of the regolith [35] include a cone penetrometer (to measure bulk density and angle of internal friction [34]) and a cone vane penetrometer (a cone penetrometer with shear vanes) to take measurements of the bearing capacity of the Lunar soil [34]. Similar instruments to what was flown to the Moon have been proposed for future planetary missions to support extensive geotechnical studies [36], such as a percussive dynamic cone penetrometer [35], a low-velocity penetrometer [37] or a Geovane [33]. On Mars, the wheels of the Spirit and Opportunity rovers were used to derive cohesion and angle of internal friction of various soils in an attempt to gain more geotechnical knowledge of the Martian regolith [38].
Estimation of mechanical parameters of Tongji-1 lunar soil simulant based on cone penetration test
Published in European Journal of Environmental and Civil Engineering, 2022
M. J. Jiang, N. Zhang, L. Cui, B. L. Xi, H. Y. Lei, X. X. Wang
The real lunar soil is scarce on the Earth, especially in China, where only 1 g real lunar soil was donated by USA, which was the initial support of our lunar plan and the prototype of the Tongji-1 lunar soil simulant (TJ-1 simulant). Because of the scarcity of the real lunar soil, lunar soil simulants are widely used to simulate the behavior of real lunar soil, e.g. JSC-1 by NASA, FJS-1 in Japan and CAS-1, NAO-1 and TJ-1 simulant in China. In the current study, TJ-1 simulant was used since this simulant has consistent particle size distribution and high shear strength even at high void ratio compared with other lunar soil simulants (Jiang, Li, & Liu, 2011, 2012; Jiang, Li, & Sun, 2012).
Tribological behaviour of textured titanium under abrasive wear
Published in Surface Engineering, 2019
Xingliang Li, Wen Yue, Fei Huang, Jiajie Kang, Lina Zhu, Bin Tian
Simulated lunar soil particles were selected as abrasion medium [34–36]. In order to find some clues between abrasive particle size and texture parameters, two kinds of abrasive particle sizes were selected. One is less than 200 μm and another is larger than 200 μm.