Articles de revues : « Lunar orientation »

1

Dacke, Marie, Marcus J. Byrne, Clarke H. Scholtz et Eric J. Warrant. « Lunar orientation in a beetle ». Proceedings of the Royal Society of London. Series B : Biological Sciences 271, n^o 1537 (22 février 2004) : 361–65. http://dx.doi.org/10.1098/rspb.2003.2594.

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Burov, Alexander A., Anna D. Guerman et Ivan I. Kosenko. « Tether orientation control for lunar elevator ». Celestial Mechanics and Dynamical Astronomy 120, n^o 3 (4 octobre 2014) : 337–47. http://dx.doi.org/10.1007/s10569-014-9579-y.

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Proctor, D. W. « THE ANALYTICAL ORIENTATION OF A LUNAR MODEL ». Photogrammetric Record 6, n^o 31 (26 août 2006) : 49–58. http://dx.doi.org/10.1111/j.1477-9730.1968.tb00913.x.

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Williams, James G., XX Newhall et Jean O. Dickey. « Lunar moments, tides, orientation, and coordinate frames ». Planetary and Space Science 44, n^o 10 (octobre 1996) : 1077–80. http://dx.doi.org/10.1016/0032-0633(95)00154-9.

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Lohmann, K., et A. Willows. « Lunar-modulated geomagnetic orientation by a marine mollusk ». Science 235, n^o 4786 (16 janvier 1987) : 331–34. http://dx.doi.org/10.1126/science.3798115.

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Utreja, Lajpat R. « Lunar Environment ». Applied Mechanics Reviews 46, n^o 6 (1 juin 1993) : 278–84. http://dx.doi.org/10.1115/1.3120356.

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As one of the key elements of the Space Exploration Initiative, the Moon provides a waypoint for scientific exploration and travel to Mars. The Moon’s stable ground in the vacuum of space is an ideal platform for astronomical observatories. Conditions on the Moon are similar to what human beings will face on other planets, so it is a natural test bed to prepare for a manned mission to Mars. A knowledge of the lunar environment is therefore important before undertaking any missions of construction, operations, and habitation on the lunar surface. The purpose of this paper is to review and assemble information on the lunar environment so that engineers and scientists can refer to this as they begin lunar-based engineering studies. The lunar environment is categorized into three major elements: lunar physical constants, lunar atmosphere, and lunar surface. The description of lunar size, orientation, period of rotation, and lunar month are all treated as part of lunar physical constants. Lunar atmosphere includes gas composition, pressure and density, solar flux and radiation, micrometeorite flux, and lunar dust. The geophysical and geochemical properties are provided as lunar surface characteristics. The geophysical properties include terrain characteristics, topography and surface tremors; soil and rock characteristics; mechanical, thermal, electrical, magnetic, and optical properties. The chemical composition of the regolith and rocks are described in geochemical properties.

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Clark, Torin K., Alexander J. Stimpson, Laurence R. Young, Charles M. Oman, Alan Natapoff et Kevin R. Duda. « Human Spatial Orientation Perception During Simulated Lunar Landing Motions ». Journal of Spacecraft and Rockets 51, n^o 1 (janvier 2014) : 267–80. http://dx.doi.org/10.2514/1.a32493.

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Noda, H., K. Heki et H. Hanada. « In situ Lunar Orientation Measurement (ILOM) : Simulation of observation ». Advances in Space Research 42, n^o 2 (juillet 2008) : 358–62. http://dx.doi.org/10.1016/j.asr.2007.01.025.

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Clark, Torin K., Laurence R. Young, Alexander J. Stimpson, Kevin R. Duda et Charles M. Oman. « Numerical simulation of human orientation perception during lunar landing ». Acta Astronautica 69, n^o 7-8 (septembre 2011) : 420–28. http://dx.doi.org/10.1016/j.actaastro.2011.04.016.

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Yang, Peng, Li Xie et Jilin Liu. « Simultaneous celestial positioning and orientation for the lunar rover ». Aerospace Science and Technology 34 (avril 2014) : 45–54. http://dx.doi.org/10.1016/j.ast.2011.07.003.

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Scott, Douglas. « The Solar Lunar Orientations of the Orkney-Cromarty and Clava Cairns ». Journal of Skyscape Archaeology 2, n^o 1 (1 juillet 2016) : 45–66. http://dx.doi.org/10.1558/jsa.v2i1.30036.

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This paper outlines the background to earlier studies of the orientation of the OrkneyCromarty (OC) passage cairns and the Clava passage and ring cairns, and details the outcome of a new and comprehensive survey carried out by the author over recent years. The paper sets out evidence of orientations in both sets of cairns to the eight divisions of the year and tests whether the alignments were observable. The results were compared to see if the Clava cairns had been influenced by the older OC cairns. Other solar and/or lunar aligned monuments are also briefly examined, as is relevant folklore.

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Cresci, Alessandro, Caroline M. Durif, Claire B. Paris, Cameron R. S. Thompson, Steven Shema, Anne Berit Skiftesvik et Howard I. Browman. « The relationship between the moon cycle and the orientation of glass eels ( Anguilla anguilla ) at sea ». Royal Society Open Science 6, n^o 10 (octobre 2019) : 190812. http://dx.doi.org/10.1098/rsos.190812.

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Links between the lunar cycle and the life cycle (migration patterns, locomotor activity, pulses in recruitment) of the European eel ( Anguilla anguilla ) are well documented. In this study, we hypothesized that the orientation of glass eels at sea is related to the lunar cycle. The European eel hatches in the Sargasso Sea and migrates across the Atlantic Ocean towards Europe. Upon reaching the continental shelf, the larvae metamorphose into glass eels and migrate up the estuaries, where some individuals colonize freshwater habitats. How glass eels navigate pelagic waters is still an open question. We tested the orientation of 203 glass eels in a transparent circular arena that was drifting in situ during the daytime, in the coastal Norwegian North Sea, during different lunar phases. The glass eels swimming at sea oriented towards the azimuth of the moon at new moon, when the moon rose above the horizon and was invisible but not during the other moon phases. These results suggest that glass eels could use the moon position for orientation at sea and that the detection mechanism involved is not visual. We hypothesize a possible detection mechanism based on global-scale lunar disturbances in electrical fields and discuss the implications of lunar-related orientation for the recruitment of glass eels to estuaries. This behaviour could help glass eels to reach the European coasts during their marine migration.

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Pail, Markus, Lukas Landler et Günter Gollmann. « Orientation and navigation in Bufo bufo : a quest for repeatability of arena experiments ». Herpetozoa 33 (14 août 2020) : 139–47. http://dx.doi.org/10.3897/herpetozoa.33.e52854.

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Research on navigation in animals is hampered by conflicting results and failed replications. In order to assess the generality of previous results, male Bufo bufo were collected during their breeding migration and translocated to two testing sites, 2.4 and 2.9 km away, respectively, from their breeding pond in the north of Vienna (Austria). There each toad was tested twice for orientation responses in a circular arena, on the night of collection and four days later. On the first test day, the toads showed significant axial orientation along their individual former migration direction. On the second test day, no significant homeward orientation was detected. Both results accord with findings of previous experiments with toads from another population. We analysed the potential influence of environmental factors (temperature, cloud cover and lunar cycle) on toad orientations using a MANOVA approach. Although cloud cover and lunar cycle had small effects on the second test day, they could not explain the absence of homeward orientation. The absence of homing responses in these tests may be either caused by the absence of navigational capabilities of toads beyond their home ranges, or by inadequacies of the applied method. To resolve this question, tracking of freely moving toads should have greater potential than the use of arena experiments.

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Iz, H., C. Shum et C. Dai. « Polyaxial figures of the Moon from the lunar reconnaissance orbiter laser altimetry and multi-mission synthesis of the lunar shape ». Journal of Geodetic Science 2, n^o 2 (1 janvier 2012) : 107–12. http://dx.doi.org/10.2478/v10156-011-0031-x.

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Polyaxial figures of the Moon from the lunar reconnaissance orbiter laser altimetry and multi-mission synthesis of the lunar shapeLast decade witnessed a plethora of missions to the Moon by China (Chang'E-1 and Chang-E-2), Japan (SELenological and ENgineering Explorer, SELENE), India (Chandrayaan-1) and USA (Lunar Reconnaissance Orbiter), all carried out laser altimetry measurements. This study is a follow up to a series of earlier investigations that produced a number of new models to represent the gross geometric shape of the Moon using Unified Lunar Control 2005, Chang'E-1, and SELENE laser altimetry data using the Lunar Reconnaissance Orbiter laser altimetry measurements. The symmetric and asymmetric polyaxial geometric models derived from Lunar Reconnaissance Orbiter laser altimetry data, namely, three, four and six-axial lunar figure parameters, are compared and contrasted with the corresponding model parameters estimated from the Chang'E-1 and SELENE laser altimetry. All solutions produced geometric shape, orientation parameters, and the parameters of the geometric center of lunar figure with respect to the center of mass of the Moon showing remarkable agreement with each other within 100 m. A combined solution by the fusion of uniformly sampled laser altimetry data from all three missions produced the best estimates for the lunar shape, orientation, and lunar center of figure parameters, and their realistic error estimates.

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Williams, J. G., J. O. Dickey, X. X. Newhall et E. M. Standish. « The Orientation of the Dynamical Reference Frame ». International Astronomical Union Colloquium 127 (1991) : 146–52. http://dx.doi.org/10.1017/s0252921100063703.

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AbstractWe summarize the current status of the JPL ephemerides, focusing on the various data types utilized, especially the impact of the modern ranging data, and the resulting accuracies obtained. The dynamical equinox, as determined from the analysis of Lunar Laser Ranging data, is determined with an accuracy of 5 mas and the obliquity to a 2 mas level in ~1983, the weighted center of data. Knowledge of the lunar and planetary positions with respect to the dynamical equinox degrades to 10 mas at J2000. Twenty years of LLR data allow for the separation of the 18.6 yr nutation terms from the precession constant. The correction to IAU precession is found to be −2.7 ± 0.4 mas/yr, while the 18.6 yr nutation of the pole is 3.0 ± 1.5 mas larger in magnitude than the 1980 IAU series. The necessity of different reference systems and the accurate knowledge of the interconnections between frames is addressed.

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Iz, H., C. Shum, X. Ding et C. Dai. « Orientation of the Geometrically Best fitting Triaxial Lunar Ellipsoid with Respect to the Mean Earth/Polar Axis Reference Frame ». Journal of Geodetic Science 1, n^o 1 (1 mars 2011) : 52–58. http://dx.doi.org/10.2478/v10156-010-0007-2.

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Orientation of the Geometrically Best fitting Triaxial Lunar Ellipsoid with Respect to the Mean Earth/Polar Axis Reference FrameThis study provides new estimates for the orientation of a geometrically best fitting lunar triaxial ellipsoid with respect to the mean Earth/polar axis reference frame calculated from the footprint positions of the Chang'E-1 (CE-1), SELenological and ENgineering Explorer (SELENE) laser altimetry measurements and Unified Lunar Control Networks 2005, (ULCN 2005) station coordinates. The semi-principal axes of the triaxial ellipsoid and the coordinates of its geometric center are also calculated simultaneously. All the estimated parameters from all three data sets are found to be consistent. In particular, the RMS differences of the semi-principal axes of the triaxial ellipsoids and the locations of their geometric centers from solutions with and without modeling Euler angles (orientation of the triaxial ellipsoid) using uniformly distributed laser altimetry (LAL) footprints are 29 and 31 m respectively. The misclosures of all the solutions indicate a better fit for the triaxial ellipsoid to the footprint and station coordinates if the Euler angles are included in the models.

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Yang, Yong-Zhang, Jin-Song Ping, Jian-Guo Yan et Jin-Ling Li. « Influence of the layered Moon and Earth’s orientation on lunar rotation ». Research in Astronomy and Astrophysics 20, n^o 2 (mars 2020) : 019. http://dx.doi.org/10.1088/1674-4527/20/2/19.

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Rozin, P. E., A. V. Simonov et E. S. Gordienko. « Orientation of the Luna-26 Spacecraft by Onboard Algorithms at the Stage of Mapping the Lunar Surface ». Solar System Research 56, n^o 7 (décembre 2022) : 470–75. http://dx.doi.org/10.1134/s0038094622070140.

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Hanada, Hideo, Kosuke Heki, Nobuyuki Kawano, Masatugu Ooe, Tsuneya Tsubokawa, Seiitsu Tsuruta, Toshiaki Ishikawa et al. « Advanced Observations of Lunar Physical Librations and Gravitational Fields in Japanese Lunar Missions in the Near Future ». International Astronomical Union Colloquium 178 (2000) : 623–30. http://dx.doi.org/10.1017/s0252921100061807.

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AbstractIn the SELenological and ENgineering Explorer (SELENE) project which is the Japanese lunar program to be launched in 2003 by the Institute of Space and Astronautical Science (ISAS) and National Space Development Agency of Japan (NASDA), we measure angular distance between a radio transmitter on a relay satellite, that on the Moon and quasars by differential VLBI and determine amplitudes of the physical librations, gravitational harmonic coefficients of the Moon and lunar ephemeris with an accuracy one or two orders higher than before in cooperation with 4-way Doppler measurements and two-way Doppler and ranging measurements using the lunar orbiter and the relay satellite. We are proposing another selenodetic mission, In situ Lunar Orientation Measurement (ILOM) to study lunar rotational dynamics by direct observations of the lunar physical libration from the lunar surface with an accuracy of 1 milliarcsecond in a post-SELENE project which will be launched about three years after SELENE. Year-long trajectories of the stars provide information on various components of the physical librations and we will also try to detect the lunar free librations in order to investigate the lunar mantle and the liquid core.

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Balyshev, M. A., et Yu Yu Koval. « Participation of the Kharkiv Astronomical Observatory and its staff in the Soviet Space Program in 1960-ies ». Kosmìčna nauka ì tehnologìâ 27, n^o 5 (2021) : 86–99. http://dx.doi.org/10.15407/knit2021.05.086.

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The article is devoted to the studying of documentary facts on the history of astronomy of the 1960s. Its purpose is to highlight the events related to the participation of the Kharkiv astronomical observatory in the Soviet space program in a certain period. The chronology of involvement of Kharkiv astronomers in programs on development and functioning of objects «V-67», «Е-7», «Е-8», «L-3», «М-69», creation of artificial Lunodrome, processing of photographic materials, that were obtained by spacecraft «Lunar orbiter 2», «Ranger 7», «Surveyor 1», «Luna-9», «Luna-12», «Luna-13», and «Zond-3» are considered. The directions of scientific research in projects «Altai», «Atlas», «Luks», and others of the Astronomical observatory of O.M. Gorky Kharkiv State University are analyzed. The main tasks that the Kharkiv astronomical observatory carried out in the 1960s were found next: photometric studies of details on the reverse side of the Moon; study of the physical, mechanical, and chemical properties of the lunar soil and its optical properties; photometric analysis of certain areas of the lunar surface; photometric calculations necessary for the design of orientation systems of automatic interplanetary stations; study of the luminosity of the lunar surface. The retro-information resources, which were firstly involved into consideration, provided a chronological sequence of events related to the participation of the University observatory in the development and functioning of artificial space objects during the given period. These resources helped to specify the achievements of Kharkiv astronomers in the Soviet program of space exploration and to prove (or clarify) some little-known facts.

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Stooke, Philip J. « Lunar and planetary cartographic research at the university of western ontario ». CISM journal 45, n^o 1 (avril 1991) : 23–31. http://dx.doi.org/10.1139/geomat-1991-0003.

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Two research projects are in progress at the University of Western Ontario in the area of lunar and planetary cartography. The first addresses a problem unique to space exploration, the mapping of bodies with extremely irregular shapes. Shapes are determined by modifying a triaxial ellipsoid until its limb and terminator reproduce those seen in all available images, given appropriate orientation and lighting. Morphographic map projections are used for maps of such bodies. The second project involves documenting the history of lunar and planetary cartography, supported by bibliographic research and collection of contemporary maps. Part of this work involves identifying very old lunar maps. Possible examples include rock carvings 4500 years old from Knowth, Ireland and sections of medieval mappaemundi.

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Niell, A. E. « Geocentric Terrestrial Reference Frame Accuracy : DSN Spacecraft Tracking and VLBI/Lunar Laser Ranging ». Symposium - International Astronomical Union 128 (1988) : 115–20. http://dx.doi.org/10.1017/s0074180900119370.

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From a combination of 1) the location of McDonald Observatory from Lunar Laser Ranging, 2) relative station locations obtained from Very Long Baseline Interferometry (VLBI) measurements, and 3) a short tie by traditional geodesy, the geocentric coordinates of the 64 m antennas of the NASA/JPL Deep Space Network are obtained with an orientation which is related to the planetary ephemerides and to the celestial radio reference frame. Comparison with the geocentric positions of the same antennas obtained from tracking of interplanetary spacecraft shows that the two methods agree to 20 cm in distance off the spin axis and in relative longitude. The orientation difference of a 1 meter rotation about the spin axis is consistent with the error introduced into the tracking station locations due to an error in the ephemeris of Jupiter.

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Tian, ZhenLiang, et Jack Wisdom. « Vertical angular momentum constraint on lunar formation and orbital history ». Proceedings of the National Academy of Sciences 117, n^o 27 (22 juin 2020) : 15460–64. http://dx.doi.org/10.1073/pnas.2003496117.

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The Moon likely formed in a giant impact that left behind a fast-rotating Earth, but the details are still uncertain. Here, we examine the implications of a constraint that has not been fully exploited: The component of the Earth–Moon system’s angular momentum that is perpendicular to the Earth’s orbital plane is nearly conserved in Earth–Moon history, except for possible intervals when the lunar orbit is in resonance with the Earth’s motion about the Sun. This condition sharply constrains the postimpact Earth orientation and the subsequent lunar orbital history. In particular, the scenario involving an initial high-obliquity Earth cannot produce the present Earth–Moon system. A low-obliquity postimpact Earth followed by the evection limit cycle in orbital evolution remains a possible pathway for producing the present angular momentum and observed lunar composition.

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Martini, M., S. Dell’Agnello, D. Currie, G. O. Delle Monache, R. Vittori, S. Berardi, A. Boni et al. « MOONLIGHT : A NEW LUNAR LASER RANGING RETROREFLECTOR AND THE LUNAR GEODETIC PRECESSION ». Acta Polytechnica 53, A (17 décembre 2013) : 746–49. http://dx.doi.org/10.14311/ap.2013.53.0746.

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Since the 1970s Lunar Laser Ranging (LLR) to the Apollo Cube Corner Retroreflector (CCR) arrays (developed by the University of Maryland, UMD) supplied almost all significant tests of General Relativity (Alley et al., 1970; Chang et al., 1971; Bender et al.,1973): possible changes in the gravitational constant, gravitational self-energy, weak equivalence principle, geodetic precession, inverse-square force-law. The LNF group, in fact, has just completed a new measurement of the lunar geodetic precession with Apollo array, with accuracy of 9 × 10−3, comparable to the best measurement to date. LLR has also provided significant information on the composition and origin of the moon. This is the only Apollo experiment still in operation. In the 1970s Apollo LLR arrays contributed a negligible fraction of the ranging error budget. Since the ranging capabilities of ground stations improved by more than two orders of magnitude, now, because of the lunar librations, Apollo CCR arrays dominate the error budget. With the project MoonLIGHT (Moon Laser Instrumentation for General relativity High-accuracy Tests), in 2006 INFN-LNF joined UMD in the development and test of a new-generation LLR payload made by a single, large CCR (100mm diameter) unaffected by the effect of librations. With MoonLIGHT CCRs the accuracy of the measurement of the lunar geodetic precession can be improved up to a factor 100 compared to Apollo arrays. From a technological point of view, INFN-LNF built and is operating a new experimental apparatus (Satellite/lunar laser ranging Characterization Facility, SCF) and created a new industry-standard test procedure (SCF-Test) to characterize and model the detailed thermal behavior and the optical performance of CCRs in accurately laboratory-simulated space conditions, for industrial and scientific applications. Our key experimental innovation is the concurrent measurement and modeling of the optical Far Field Diffraction Pattern (FFDP) and the temperature distribution of retroreflector payloads under thermal conditions produced with a close-match solar simulator. The apparatus includes infrared cameras for non-invasive thermometry, thermal control and real-time payload movement to simulate satellite orientation on orbit with respect to solar illumination and laser interrogation beams. These capabilities provide: unique pre-launch performance validation of the space segment of LLR/SLR (Satellite Laser Ranging); retroreflector design optimization to maximize ranging efficiency and signal-to-noise conditions in daylight. Results of the SCF-Test of our CCR payload will be presented. Negotiations are underway to propose our payload and SCF-Test services for precision gravity and lunar science measurements with next robotic lunar landing missions. In particular, a scientific collaboration agreement was signed on Jan. 30, 2012, by D. Currie, S. Dell’Agnello and the Japanese PI team of the LLR instrument of the proposed SELENE-2 mission by JAXA (Registered with INFN Protocol n. 0000242-03/Feb/2012). The agreement foresees that, under no exchange of funds, the Japanese single, large, hollow LLR reflector will be SCF-Tested and that MoonLIGHT will be considered as backup instrument.

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Speyerer, E. J., R. V. Wagner et M. S. Robinson. « GEOMETRIC CALIBRATION OF THE CLEMENTINE UVVIS CAMERA USING IMAGES ACQUIRED BY THE LUNAR RECONNAISSANCE ORBITER ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B4 (14 juin 2016) : 497–501. http://dx.doi.org/10.5194/isprs-archives-xli-b4-497-2016.

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The Clementine UVVIS camera returned over half a million images while in orbit around the Moon in 1994. Since the Clementine mission, our knowledge of lunar topography, gravity, and the location of features on the surface has vastly improved with the success of the Gravity Recovery and Interior Laboratory (GRAIL) mission and ongoing Lunar Reconnaissance Orbiter (LRO) mission. In particular, the Lunar Reconnaissance Orbiter Camera (LROC) has returned over a million images of the Moon since entering orbit in 2009. With the aid of improved ephemeris and on-orbit calibration, the LROC team created a series of precise and accurate global maps. With the updated reference frame, older lunar maps, such as those generated from Clementine UVVIS images, are misaligned making cross-mission analysis difficult. In this study, we use feature-based matching routines to refine and recalibrate the interior and exterior orientation parameters of the Clementine UVVIS camera. After applying these updates and rigorous orthorectification, we are able generate precise and accurate maps from UVVIS images to help support lunar science and future cross-mission investigations.

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Speyerer, E. J., R. V. Wagner et M. S. Robinson. « GEOMETRIC CALIBRATION OF THE CLEMENTINE UVVIS CAMERA USING IMAGES ACQUIRED BY THE LUNAR RECONNAISSANCE ORBITER ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B4 (14 juin 2016) : 497–501. http://dx.doi.org/10.5194/isprsarchives-xli-b4-497-2016.

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The Clementine UVVIS camera returned over half a million images while in orbit around the Moon in 1994. Since the Clementine mission, our knowledge of lunar topography, gravity, and the location of features on the surface has vastly improved with the success of the Gravity Recovery and Interior Laboratory (GRAIL) mission and ongoing Lunar Reconnaissance Orbiter (LRO) mission. In particular, the Lunar Reconnaissance Orbiter Camera (LROC) has returned over a million images of the Moon since entering orbit in 2009. With the aid of improved ephemeris and on-orbit calibration, the LROC team created a series of precise and accurate global maps. With the updated reference frame, older lunar maps, such as those generated from Clementine UVVIS images, are misaligned making cross-mission analysis difficult. In this study, we use feature-based matching routines to refine and recalibrate the interior and exterior orientation parameters of the Clementine UVVIS camera. After applying these updates and rigorous orthorectification, we are able generate precise and accurate maps from UVVIS images to help support lunar science and future cross-mission investigations.

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Zhang, Mingyue, Jürgen Müller, Liliane Biskupek et Vishwa Vijay Singh. « Characteristics of differential lunar laser ranging ». Astronomy & ; Astrophysics 659 (mars 2022) : A148. http://dx.doi.org/10.1051/0004-6361/202142841.

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Context. To obtain more details about the lunar interior, a station at Table Mountain Observatory of JPL will enable a new measurement of lunar laser ranging (LLR), known as differential lunar laser ranging (DLLR). It will provide a novel type of observable, namely, the lunar range difference, which is the difference of two consecutive ranges obtained via a single station swiftly switching between two or more lunar reflectors. This previously unavailable observation will have a very high level of accuracy (about 30 μm), mainly resulting from a reduction in the Earth’s atmospheric error. In addition to the intended improvements for the lunar part, it is expected to contribute to improved relativity tests, for instance, the equivalence principle (EP). Aims. This paper focuses on the simulation and investigation of the characteristics of DLLR. Methods. Using simulated DLLR data, we analyzed and compared the parameter sensitivity, correlation, and accuracy obtained by DLLR with those attained by LLR. Results. The DLLR measurement maintains almost the same sensitivity to certain parameters (called group A) as that of LLR, such as the lunar orientation parameters. For other parameters (called group B), such as station coordinates, it is shown to be less sensitive. However, owing to its extraordinary measurement accuracy, it not only retains nearly the same level of accuracy of group B as LLR, but it also improves the estimation of group A significantly (with the exception of reflector coordinates, due to the DLLR measuring mode). Also, DLLR increases the correlations among the reflectors and between stations and reflectors caused by its constellation. Additionally, we compared different switching intervals with respect to sensitivity and correlation. Large switching intervals are more beneficial for group B and the decorrelation of stations and reflectors. Furthermore, DLLR enhances the accuracy of EP tests.

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Kuo, C. T., Y. T. Tien et K. W. Chiang. « VISUAL-BASED INTEGRATED NAVIGATION SYSTEM APPLIED TO A SIMULATION OF LUNAR MODULE LANDING ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B1-2020 (6 août 2020) : 305–13. http://dx.doi.org/10.5194/isprs-archives-xliii-b1-2020-305-2020.

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Abstract. With the development of space technology, more and more lunar researches are performed by different countries. For the lunar landing mission success, the lunar landing module should equip with advanced Positioning and Orientation System (POS) for the navigation requirements. For the pinpoint landing mission formulated by NASA, a good POS with error less than 100 meters is needed in order to make the lunar module land safely at the exact destination on lunar surface. However, the existing technologies for lunar navigation, such as satellite positioning and star tracker, have poor performance for the navigation requirements. The visual-based positioning technology is an alternative way to make sure a lunar landing module reaches the destination. There are two types of visual-based positioning technology, absolute and relative navigation. The relative navigation system can provide the solution at a higher rate, but the error would accumulate over time. On the contrary, the absolute navigation could provide an initial position or updates of position and attitude for relative navigation. Thus, the integrated navigation system from those two methods can take advantage of both stand-alone systems. On the other hand, the Inertial Navigation System (INS) can help it overcome the disadvantage that the images much closer to the lunar surface are not available. This study shows an integrated navigation system that integrates a visual-based navigation system and an INS, which is implemented in a simulated lunar surface.

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Dickey, J. O., X. X. Newhall et J. G. Williams. « Earth orientation from lunar laser ranging and an error analysis of polar motion services ». Journal of Geophysical Research 90, B11 (1985) : 9353. http://dx.doi.org/10.1029/jb090ib11p09353.

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Brown, Irene L., et L. Richard Mewaldt. « Behavior of Sparrows of the Genus Zonotrichia, in Orientation Cages during the Lunar Cycle ». Zeitschrift für Tierpsychologie 25, n^o 6 (26 avril 2010) : 668–700. http://dx.doi.org/10.1111/j.1439-0310.1968.tb00037.x.

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Neneman, Maciej, Sébastien Wagner, Ludovic Bourg, Laurent Blanot, Marc Bouvet, Stefan Adriaensen et Jens Nieke. « Use of Moon Observations for Characterization of Sentinel-3B Ocean and Land Color Instrument ». Remote Sensing 12, n^o 16 (7 août 2020) : 2543. http://dx.doi.org/10.3390/rs12162543.

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During the commissioning of the Sentinel-3B satellite, a single lunar observation was performed to assess the possible use of the moon for characterization and validation of onboard instruments. The observation was carried out in stable orientation after a roll maneuver, allowing the moon to be imaged by the Earth view of instruments. Data acquired by the Ocean Land Color Instrument (OLCI) allowed inflight verification of stray-light correction (SLC) performed by the Mission Performance Centre (MPC), and assessment of radiometric behavior of instrument in comparison with lunar irradiance models performed in cooperation between European Space Research and Technology Centre (ESTEC) and European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). This paper describes the results of those activities along with the proposed update of stray-light correction developed with the use of lunar data.

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Wan, W., Z. Liu, Y. Wang, M. Peng, K. Di, C. Liu, L. Li et al. « TOPOGRAPHIC MAPPING WITH MANIPULATOR ARM CAMERA IN LUNAR SAMPLE RETURN MISSION ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B3-2020 (21 août 2020) : 1159–63. http://dx.doi.org/10.5194/isprs-archives-xliii-b3-2020-1159-2020.

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Abstract. The topographic mapping of sampling areas, providing basic sampling environment information, is crucial in sample return mission. The fixed monitoring cameras were designed for mapping of sampling areas in fixed effective resolution. In order to perform more detailed topographic analysis of sampling areas, this paper proposed a topographic mapping method based on the sequential sample images captured with the movements of manipulator arm. The tie point matching results and the image exterior orientation parameters obtained from measurements of manipulator arm joints were employed to the weighted bundle adjustment based optimization for the accurate topographic mapping. The simulated images were adopted to validate the effectiveness and accuracy of the proposed method.

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Yano, Taihei, Naoteru Gouda, Yukiyasu Kobayashi, Takuji Tsujimoto, Tadashi Nakajima, Hideo Hanada, Yukitoshi Kan‐ya et al. « CCD Centroiding Experiment for theJapan Astrometry Satellite Mission(JASMINE) andIn Situ Lunar Orientation Measurement(ILOM) ». Publications of the Astronomical Society of the Pacific 116, n^o 821 (juillet 2004) : 667–73. http://dx.doi.org/10.1086/422399.

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Feissel, M., et Yaroslav Yatskiv. « The Contribution of the IERS to Astrophysics and Geodynamics ». Symposium - International Astronomical Union 156 (1993) : 406. http://dx.doi.org/10.1017/s0074180900173619.

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The International Earth Rotation Service (IERS) maintains a celestial reference frame and a terrestrial reference frame based on observations in Very Long Baseline radio Interferometry, Lunar and Satellite Laser Ranging, and Global Positioning System, as well as a time series of the Earth Orientation Parameters in a system that is consistent at the level of 0.001″.

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Standish, E. M. « The Dynamical Reference Frame ». Symposium - International Astronomical Union 166 (1995) : 109–16. http://dx.doi.org/10.1017/s0074180900227939.

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Planetary and lunar ephemerides continue to improve in accuracy as they continue to be adjusted to newer and more accurate observational data. An additional improvement will be that of the orientation of the ephemerides; in the future, the ephemerides produced at JPL will be based upon the reference frame of the radio source catalogues. Recent planetary observations have been made directly with respect to the radio reference frame, and these observations have shown a satisfying degree of absolute accuracy and internal consistency; they enable the automatic orientation of the ephemerides onto the radio reference system during the ephemeris adjustment process.

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Barkin, M. Yu, P. M. Shkapov et Hideo Hanada. « The Physical Librations of the Moon Caused by its Tidal Deformation ». Herald of the Bauman Moscow State Technical University. Series Natural Sciences, n^o 83 (2018) : 4–16. http://dx.doi.org/10.18698/1812-3368-2019-2-4-16.

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The Moon, like Earth, is not completely solid, and experiences deformation changes, for example due to the tides, caused by the gravitational pull of the Earth's orbit in a complex and resonant nature of the motion of the Moon. It is shown that these deformations lead to temporary variations of Moon inertia tensor components and consequently to the variations in the movement of the poles of the Moon, as well as to the variations of axial rotation. The indicated variations module is in the order of 10--12 mas (millisecond of arc). There variations are important for the development of the high-precision theory of lunar physical libration, suitable for modern projects for the reclamation of the Moon, in particular the Japanese project ILOM, which contemplates installing the telescope on the lunar surface and determining its orientation accuracy of the order of 1--0.1 msd, as well as the Russian lunar program, providing the launch of five automatic stations to the Moon in 2019--2024

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G. Wawrzyniak, Geoffrey, et Kathleen C. Howell. « Investigating the Design Space for Solar Sail Trajectories in the Earth-Moon System ». Open Aerospace Engineering Journal 4, n^o 1 (27 octobre 2011) : 26–44. http://dx.doi.org/10.2174/1874146001104010026.

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Solar sailing is an enabling technology for many mission applications. One potential application is the use of a sail as a communications relay for a base at the lunar south pole. A survey of the design space for a solar sail spacecraft that orbits in view of the lunar south pole at all times demonstrates that trajectory options are available for sails with characteristic acceleration values of 1.3 mm/s or higher. Although the current sail technology is presently not at this level, this survey reveals the minimum acceleration values that are required for sail technology to facilitate the lunar south pole application. This information is also useful for potential hybrid solar-sail-low-thrust designs. Other critical metrics for mission design and trajectory selection are also examined, such as body torques that are required to articulate the vehicle orientation, sail pitch angles throughout the orbit, and trajectory characteristics that would impact the design of the lunar base. This analysis and the techniques that support it supply an understanding of the design space for solar sails and their trajectories in the Earth-Moon system.

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Eubanks, T. M., et J. A. Steppe. « The Long Term Stability of VLBI Earth Orientation Measurements ». Symposium - International Astronomical Union 129 (1988) : 369–70. http://dx.doi.org/10.1017/s0074180900135041.

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Tectonic motions will, in general, change the orientation as well as the length of baselines used in Very Long Baseline Interferometry (VLBI), and will thus cause slow divergences between Earth orientation results obtained with different VLBI networks, as well as between VLBI results and those obtained by Satellite Laser Ranging (SLR) and Lunar Laser Ranging (LLR). Such drifts (on the order of a milliarcsecond /year) are inherently interesting as well as being significant in combinations of orientation results from different sources. The geodetic study of tectonic motions is also closely connected to research into the nature and causes of systematic errors in data from the modern techniques of space geodesy. We describe both a special coordinate system found to be of use in the analysis of VLBI data and tectonic motion estimates for a VLBI baseline stretching from California to Australia.

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Ricklefs, Randall L., et Peter J. Shelus. « An analysis of MLRS Near-Real-Time Earth orientation results ». Symposium - International Astronomical Union 128 (1988) : 165–70. http://dx.doi.org/10.1017/s0074180900119448.

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In this paper a comparison is presented between near-real-time earth orientation parameters, produced on-site by the McDonald Laser Ranging System (MLRS) at McDonald Observatory, using observations to the Apollo 15 lunar retroreflector, and those results which are obtained after the fact at the University of Texas at Austin and elsewhere, as well as the results obtained from other techniques. The MLRS data set which is included in this study spans the interval from the commencement of on-site earth orientation solutions at MLRS in February 1985, through the present time, September 1986. This research is supported by the National Aeronautics and Space Administration under Grant NAG5-754 and Contract NAS5-29404 to McDonald Observatory and the University of Texas at Austin from the Goddard Space Flight Center in Greenbelt, Maryland.

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Pasynok, Sergey L., Igor V. Bezmenov, Igor Yu Ignatenko, Efim N. Tcyba et Vladimir E. Zharov. « Improving methods and facilities of Earth’s orientation parameters evaluation in Main metrological center of State service for time, frequency and Earth’s orientation parameters evaluation ». Izmeritel`naya Tekhnika, n^o 5 (2020) : 16–21. http://dx.doi.org/10.32446/0368-1025it.2020-5-16-21.

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The results of improvement of methods and facilities of Earth’s orientation parameters in Main metrological center of State service for time, frequency and Earth’s orientation parameters evaluatio in the last five years are considered. The hardware and software are modernized. As result Main metrological center of State service for time, frequency and Earth’s orientation parameters evaluation has program correlator now, the calculation thechnic was improved, Analysis Center of Main metrological center of State service for time, frequency and Earth’s orientation parameters evaluation was created. The Russian metrological institute of technical physics and radio engineering has satellite laser ranging station of new generation now. This station was created by Institute for precision instrument engineering. The new software for satellite laser ranging processing and lunar laser ranging processing was created. The new sofware of the global navigation satellite systems processing was developed. The software for very long base interferometry data processing and software for combination were modernized. Development of evaluation and predictioning facilities of Earth’s orientation parameters Russian metrological institute of technical physics and radio engineering was provided according to modern international direction. This allowed to provide work of evaluation and predictioning of Earth’s orientation parameters at the high international level.

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Meschini, Enrico, Anna Gagliardo et Floriano Papi. « Lunar orientation in sandhoppers is affected by shifting both the moon phase and the daily clock ». Animal Behaviour 76, n^o 1 (juillet 2008) : 25–35. http://dx.doi.org/10.1016/j.anbehav.2007.12.011.

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А. В., Мальцев,, Тимохин, П. Ю. et Страшнов, Е. В. « Simulation of Virtual Environment for Crewed Lunar Missions ». Успехи кибернетики / Russian Journal of Cybernetics, n^o 4(12) (28 décembre 2022) : 46–53. http://dx.doi.org/10.51790/2712-9942-2022-3-4-06.

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в работе рассматривается задача виртуального моделирования процесса управления пилотируемым космическим кораблем в рамках исследовательских миссий по освоению лунной поверхности, предполагающих выполнение посадки на нее. Данная задача является актуальной ввиду необходимости изучения естественного спутника Земли в ближней и среднесрочной перспективе. Разработанные решения основаны на применении современных технологий виртуальной реальности, когда окружающая человека среда полностью заменяется на виртуальный прототип. Рассматривается предлагаемая для решения поставленной задачи структура системы виртуального окружения, которая включает в себя аппаратный блок, программный комплекс и цифровые модели. Моделирование движения и посадки виртуального прототипа космического корабля осуществляется путем расчета сил тяги реактивных двигателей и основано на синтезе оптимального управления с реализацией критериев быстродействия (для переориентации корабля) и минимального расхода топлива (для торможения корабля). При этом разработанное управление формируется в виде обратной связи по показаниям виртуальных датчиков и обеспечивает стабилизацию, переориентацию, торможение и мягкую посадку космического корабля на поверхность Луны. Моделирование лунной поверхности выполняется на графическом процессоре с использованием детализированных текстур Луны и адаптивной триангуляции сетки высот. Апробация показала адекватность предложенных решений поставленной задаче и их применимость при реализации современных видеотренажеров подготовки космонавтов. we studied the virtual simulation of a crewed spacecraft control for research missions to the Moon’s surface. There is an obvious need to survey the Moon in the short and medium term. The solutions are based on advanced VR: the environment is completely replaced by a virtual one. We proposed an architecture of a virtual environment system consisting of hardware, software, and digital models. The motion and landing of a virtual spacecraft are simulated by estimating the jet engine thrust. The control inputs are optimized for fast response (spacecraft orientation) and min fuel consumption (for deceleration). The control logic is supported with feedback from virtual sensors to stabilize, orient, decelerate, and perform a soft landing on the Moon. The moon’s surface is simulated by a GPU using detailed Moon textures and adaptive triangulation of the terrain grid. The proposed solution is suitable to build video simulators for space crew training.

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Šprajc, Ivan, et Pedro Francisco Sánchez Nava. « Astronomy and Architecture in the Maya Lowlands ». Journal of Skyscape Archaeology 2, n^o 2 (10 février 2017) : 189–215. http://dx.doi.org/10.1558/jsa.30050.

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This article summarises recent systematic research into the use and significance of astronomical orientations in ancient Maya architecture, and shows how by applying a more rigorous methodology to a large number of orientations we were able to detect alignment patterns that shed light on the validity of former hypotheses and provide a basis for novel interpretations. Our measurements and analysis confirm that orientations to the Sun’s position on the horizon, which largely prevail, allowed the use of observational calendars composed of multiples of 13 and 20 days and were also intended to facilitate proper scheduling of agricultural activities. Further, while some buildings recorded Venus extremes, a previously unknown orientation group has been found to refer to major lunar standstill positions. Some important buildings, aside from exhibiting astronomical orientations, are aligned to prominent features of natural or cultural landscape, implying a deliberate selection of these places for their construction. Discussing some relevant contextual evidence, we argue that Maya architectural and urban planning was dictated by a complex set of rules, in which astronomical considerations and their practical uses were embedded in a broader framework of cosmological concepts.

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Yang, Z., et Z. Kang. « ACCURATE REGISTRATION OF THE CHANG’E-1 IIM DATA BASED ON LRO LROC-WAC MOSICA DATA ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W1 (25 juillet 2017) : 191–98. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w1-191-2017.

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In the detection of the moon, the visible and near-infrared reflectance data of the lunar material are important information sources for lunar chemical substances and mineral inversion. The Interferometer Imaging Spectrometer (IIM) aboard the Chang'E-1 lunar orbiter is the first multispectral imaging spectrometer for Chinese lunar missions. In this paper, we use the mosaic image of global moon acquired by the Wide-angle Camera (WAC) of the Lunar Reconnaissance Orbiter Camera (LROC) to realize the accurate registration of Chang'E-1 IIM hyperspectral images. Due to the lack of GCPs, the emphasis of this work is to find a huge number of homologous points. The method proposed in this paper is to obtain several homologous points by manually matching, and then we utilize those points to calculate the initial homography matrix of LROC-WAC image and IIM image. This matrix is used to predict the area on IIM image where homologous points may be located, and the locations of the homologous points are determined by the orientation correlation in frequency domain. Finally we save the parts of homologous points which satisfied the conversion relationship of initial homography matrix to calculate homography matrix again. We use this iterative way to obtain a more accurate location of the homologous points. In this process, we take into account that the geometric deformations of different regions on IIM image are quite different. Therefore, we added image threshold segmentation based on the initial homography matrix in the experiment, and completed the above work of finding the homologous points on the segmented images. The final realization of registration accuracy of IIM images are in 1&ndash;2 pixels (RMSE). This provides a reliable data assurance for the subsequent study of using IIM images to inverse the lunar elements.

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Smith, Joseph P., Frank C. Smith et Karl S. Booksh. « Multivariate Curve Resolution–Alternating Least Squares (MCR-ALS) with Raman Imaging Applied to Lunar Meteorites ». Applied Spectroscopy 72, n^o 3 (11 août 2017) : 404–19. http://dx.doi.org/10.1177/0003702817721715.

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Lunar meteorites provide a more random sampling of the surface of the Moon than do the returned lunar samples, and they provide valuable information to help estimate the chemical composition of the lunar crust, the lunar mantle, and the bulk Moon. As of July 2014, ∼96 lunar meteorites had been documented and ten of these are unbrecciated mare basalts. Using Raman imaging with multivariate curve resolution–alternating least squares (MCR-ALS), we investigated portions of polished thin sections of paired, unbrecciated, mare-basalt lunar meteorites that had been collected from the LaPaz Icefield (LAP) of Antarctica—LAP 02205 and LAP 04841. Polarized light microscopy displays that both meteorites are heterogeneous and consist of polydispersed sized and shaped particles of varying chemical composition. For two distinct probed areas within each meteorite, the individual chemical species and associated chemical maps were elucidated using MCR-ALS applied to Raman hyperspectral images. For LAP 02205, spatially and spectrally resolved clinopyroxene, ilmenite, substrate-adhesive epoxy, and diamond polish were observed within the probed areas. Similarly, for LAP 04841, spatially resolved chemical images with corresponding resolved Raman spectra of clinopyroxene, troilite, a high-temperature polymorph of anorthite, substrate-adhesive epoxy, and diamond polish were generated. In both LAP 02205 and LAP 04841, substrate-adhesive epoxy and diamond polish were more readily observed within fractures/veinlet features. Spectrally diverse clinopyroxenes were resolved in LAP 04841. Factors that allow these resolved clinopyroxenes to be differentiated include crystal orientation, spatially distinct chemical zoning of pyroxene crystals, and/or chemical and molecular composition. The minerals identified using this analytical methodology—clinopyroxene, anorthite, ilmenite, and troilite—are consistent with the results of previous studies of the two meteorites using electron microprobe analysis. To our knowledge, this is the first report of MCR-ALS with Raman imaging used for the investigation of both lunar and other types of meteorites. We have demonstrated the use of multivariate analysis methods, namely MCR-ALS, with Raman imaging to investigate heterogeneous lunar meteorites. Our analytical methodology can be used to elucidate the chemical, molecular, and structural characteristics of phases in a host of complex, heterogeneous geological, geochemical, and extraterrestrial materials.

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Standish, E. M. « Dynamical Reference Frame — Current Relevance and Future Prospects ». International Astronomical Union Colloquium 180 (mars 2000) : 120–26. http://dx.doi.org/10.1017/s025292110000021x.

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AbstractPlanetary and lunar ephemerides are no longer used for the determination of inertial space. Instead, the new fundamental reference frame, the ICRF, is inherently less susceptible to extraneous, non-inertial rotations than would be a dynamical reference frame determined by the ephemerides. Consequently, the ephemerides are now adjusted onto the ICRF, and they are fit to two modern, accurate observational data types: ranging (radar, lunar laser, spacecraft) and VLBI (of spacecraft near planets).The uncertainties remaining in the inner planet ephemerides are on the order of 1 kilometer, both in relative positions between the bodies and in the orientation of the inner system as a whole. The predictive capabilities of the inner planet ephemerides are limited by the uncertainties in the masses of many asteroids. For this reason, future improvements to the ephemerides must await determinations of many asteroid masses. Until then, it will be necessary to constantly update the ephemerides with a continuous supply of observational data.

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Nefedjev, Yu A., A. I. Nefedjeva et N. G. Rizvanov. « METHODS OF DETERMINATION OF THE ORIENTATION OF A SPACE SYSTEM OF COORDINATES ON THE BASIS OF LUNAR OCCULTATIONS ». Astronomical & ; Astrophysical Transactions 22, n^o 4-5 (août 2003) : 633–37. http://dx.doi.org/10.1080/1055679031000124510.

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Di, K., B. Xu, B. Liu, M. Jia et Z. Liu. « GEOPOSITIONING PRECISION ANALYSIS OF MULTIPLE IMAGE TRIANGULATION USING LRO NAC LUNAR IMAGES ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B4 (13 juin 2016) : 369–74. http://dx.doi.org/10.5194/isprs-archives-xli-b4-369-2016.

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This paper presents an empirical analysis of the geopositioning precision of multiple image triangulation using Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) images at the Chang’e-3(CE-3) landing site. Nine LROC NAC images are selected for comparative analysis of geopositioning precision. Rigorous sensor models of the images are established based on collinearity equations with interior and exterior orientation elements retrieved from the corresponding SPICE kernels. Rational polynomial coefficients (RPCs) of each image are derived by least squares fitting using vast number of virtual control points generated according to rigorous sensor models. Experiments of different combinations of images are performed for comparisons. The results demonstrate that the plane coordinates can achieve a precision of 0.54 m to 2.54 m, with a height precision of 0.71 m to 8.16 m when only two images are used for three-dimensional triangulation. There is a general trend that the geopositioning precision, especially the height precision, is improved with the convergent angle of the two images increasing from several degrees to about 50°. However, the image matching precision should also be taken into consideration when choosing image pairs for triangulation. The precisions of using all the 9 images are 0.60 m, 0.50 m, 1.23 m in along-track, cross-track, and height directions, which are better than most combinations of two or more images. However, triangulation with selected fewer images could produce better precision than that using all the images.

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Di, K., B. Xu, B. Liu, M. Jia et Z. Liu. « GEOPOSITIONING PRECISION ANALYSIS OF MULTIPLE IMAGE TRIANGULATION USING LRO NAC LUNAR IMAGES ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B4 (13 juin 2016) : 369–74. http://dx.doi.org/10.5194/isprsarchives-xli-b4-369-2016.

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This paper presents an empirical analysis of the geopositioning precision of multiple image triangulation using Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) images at the Chang’e-3(CE-3) landing site. Nine LROC NAC images are selected for comparative analysis of geopositioning precision. Rigorous sensor models of the images are established based on collinearity equations with interior and exterior orientation elements retrieved from the corresponding SPICE kernels. Rational polynomial coefficients (RPCs) of each image are derived by least squares fitting using vast number of virtual control points generated according to rigorous sensor models. Experiments of different combinations of images are performed for comparisons. The results demonstrate that the plane coordinates can achieve a precision of 0.54 m to 2.54 m, with a height precision of 0.71 m to 8.16 m when only two images are used for three-dimensional triangulation. There is a general trend that the geopositioning precision, especially the height precision, is improved with the convergent angle of the two images increasing from several degrees to about 50°. However, the image matching precision should also be taken into consideration when choosing image pairs for triangulation. The precisions of using all the 9 images are 0.60 m, 0.50 m, 1.23 m in along-track, cross-track, and height directions, which are better than most combinations of two or more images. However, triangulation with selected fewer images could produce better precision than that using all the images.

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el Jundi, Basil, Eric J. Warrant, Marcus J. Byrne, Lana Khaldy, Emily Baird, Jochen Smolka et Marie Dacke. « Neural coding underlying the cue preference for celestial orientation ». Proceedings of the National Academy of Sciences 112, n^o 36 (24 août 2015) : 11395–400. http://dx.doi.org/10.1073/pnas.1501272112.

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Diurnal and nocturnal African dung beetles use celestial cues, such as the sun, the moon, and the polarization pattern, to roll dung balls along straight paths across the savanna. Although nocturnal beetles move in the same manner through the same environment as their diurnal relatives, they do so when light conditions are at least 1 million-fold dimmer. Here, we show, for the first time to our knowledge, that the celestial cue preference differs between nocturnal and diurnal beetles in a manner that reflects their contrasting visual ecologies. We also demonstrate how these cue preferences are reflected in the activity of compass neurons in the brain. At night, polarized skylight is the dominant orientation cue for nocturnal beetles. However, if we coerce them to roll during the day, they instead use a celestial body (the sun) as their primary orientation cue. Diurnal beetles, however, persist in using a celestial body for their compass, day or night. Compass neurons in the central complex of diurnal beetles are tuned only to the sun, whereas the same neurons in the nocturnal species switch exclusively to polarized light at lunar light intensities. Thus, these neurons encode the preferences for particular celestial cues and alter their weighting according to ambient light conditions. This flexible encoding of celestial cue preferences relative to the prevailing visual scenery provides a simple, yet effective, mechanism for enabling visual orientation at any light intensity.

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