scholarly journals Acoustic in-ice positioning in the Enceladus Explorer project

2014 ◽  
Vol 55 (68) ◽  
pp. 253-259 ◽  
Author(s):  
Dmitry Eliseev ◽  
Dirk Heinen ◽  
Klaus Helbing ◽  
Ruth Hoffmann ◽  
Uwe Naumann ◽  
...  
Keyword(s):  
Space Mission ◽  
Positioning System ◽  
Test Scenario ◽  
Full System ◽  
Ice Surface ◽  
Curved Trajectories ◽  
Future Space ◽  
Glacier Ice ◽  
Taylor Glacier ◽  
Acoustic Positioning

AbstractThe Enceladus Explorer project is a preparatory study for a future space mission to Saturn’s moon, Enceladus. Its ultimate goal is to probe liquid-water pockets below the ice surface of Enceladus for signatures of life. A probe could be based on the IceMole concept, which melts curved trajectories through the ice. In the Enceladus Explorer project, a specialized IceMole probe for a terrestrial test scenario is in development. The goal of this exploratory study is to probe water from a liquid crevasse close to Blood Falls at Taylor Glacier, Antarctica. To navigate such a probe it is essential to be able to determine its position and monitor its trajectory. Part of the navigation system is the in-ice acoustic positioning system. For this, the head of the IceMole is equipped with acoustic sensors, which receive signals from synchronized acoustic emitters situated at the ice surface. Based on the measured propagation times, the speed of sound in ice and the positions of the emitters at the surface, the position of the IceMole can be determined by trilateration techniques. Here we present the developed acoustic positioning system, which is designed to track the in-ice melting probe up to distances of 100 m in glacier ice. Results from full-system tests in water and a first field test on Morteratschgletscher, Switzerland, are discussed.

scholarly journals A Whole-Field Interferometric Scheme for Measuring strain and Flow Rates of Glacier and Other Natural Surfaces

1983 ◽  
Vol 29 (103) ◽  
pp. 492-497
Author(s):  
Gary Cloud ◽  
Edgar Conley
Keyword(s):  
Displacement Vector ◽  
Surface Displacement ◽  
Time Lapse ◽  
Speckle Interferometry ◽  
Narrow Beam ◽  
Coherent Light ◽  
Ice Surface ◽  
Glacier Ice ◽  
Fringe Patterns ◽  
Small Overlap

AbstractThe flow of glacier ice is mapped using high-resolution photography and non-coherent-light speckle interferometry. Young’s fringe patterns result when a double-exposed photoplate image of the straining surface is illuminated by a narrow beam of coherent light. Geometry gives a relationship between the ice surface displacement vector and the interference fringe patterns. This displacement vector is corrected for rigid-body (camera) movement and projected onto the ice surface using topological maps. The strain during the time-lapse interval is thus known. Comparison with data acquired by surveying techniques at Nisqually Glacier, Washington, U.S.A., is limited because of small overlap of the surface studied. In the areas for which results can be compared, our experiments yield a flow of 0.6 m/d where conventional methods yield about 0.4 m/d.

Modeling AUV Localization Error in a Long Baseline Acoustic Positioning System

2018 ◽  
Vol 43 (4) ◽  
pp. 955-968 ◽  
Author(s):  
Dugald J. M. Thomson ◽  
Stan E. Dosso ◽  
David R. Barclay
Keyword(s):  
Positioning System ◽  
Localization Error ◽  
Long Baseline ◽  
Acoustic Positioning

scholarly journals Research on the Tunnel Excavated In Urumqi Glacier No. 1, Tianshan Glaciological Station, China

1987 ◽  
Vol 33 (113) ◽  
pp. 99-104 ◽  
Author(s):  
Huang Maohuan ◽  
Wang Zhongxiang
Keyword(s):  
Melting Point ◽  
Shear Strain ◽  
Maximum Shear Strain ◽  
Ice Surface ◽  
Basal Sliding ◽  
Glacier Ice ◽  
Glacier Motion

AbstractA tunnel was excavated in Urumqi Glacier No. 1, at the Tianshan Glaciological Station. Ice temperature, ice displacement, deformation, and basal sliding, etc. were observed at regular intervals. It is shown that the temperature near the glacier bed is close to the melting point and that the largest proportion of the overall glacier motion is within the lowermost ice layers. The glacier ice is in a state of compression. The maximum shear strain increases towards the entrance of the tunnel, corresponding to the change in slope of the ice surface, and also towards the bedrock.

scholarly journals Present dynamics and future prognosis of a slowly surging glacier

2011 ◽  
Vol 5 (1) ◽  
pp. 299-313 ◽  
Author(s):  
G. E. Flowers ◽  
N. Roux ◽  
S. Pimentel ◽  
C. G. Schoof
Keyword(s):  
Mass Balance ◽  
Force Balance ◽  
Surface Velocity ◽  
Internal Dynamic ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Ice Surface ◽  
Glacier Ice ◽  
Glacier Flow ◽  
Negative Balance

Abstract. Glacier surges are a well-known example of an internal dynamic oscillation whose occurrence is not a direct response to the external climate forcing, but whose character (i.e. period, amplitude, mechanism) may depend on the glacier's environmental or climate setting. We examine the dynamics of a small (∼5 km2) valley glacier in Yukon, Canada, where two previous surges have been photographically documented and an unusually slow surge is currently underway. To characterize the dynamics of the present surge, and to speculate on the future of this glacier, we employ a higher-order flowband model of ice dynamics with a regularized Coulomb-friction sliding law in both diagnostic and prognostic simulations. Diagnostic (force balance) calculations capture the measured ice-surface velocity profile only when non-zero basal water pressures are prescribed over the central region of the glacier, coincident with where evidence of the surge has been identified. This leads to sliding accounting for 50–100% of the total surface motion in this region. Prognostic simulations, where the glacier geometry evolves in response to a prescribed surface mass balance, reveal a significant role played by a bedrock ridge beneath the current equilibrium line of the glacier. Ice thickening occurs above the ridge in our simulations, until the net mass balance reaches sufficiently negative values. We suggest that the bedrock ridge may contribute to the propensity for surges in this glacier by promoting the development of the reservoir area during quiescence, and may permit surges to occur under more negative balance conditions than would otherwise be possible. Collectively, these results corroborate our interpretation of the current glacier flow regime as indicative of a slow surge that has been ongoing for some time, and support a relationship between surge incidence or character and the net mass balance. Our results also highlight the importance of glacier bed topography in controlling ice dynamics, as observed in many other glacier systems.

scholarly journals KM3NeT acoustic positioning and detection system

2019 ◽  
Vol 216 ◽  
pp. 02006 ◽  
Author(s):  
Salvatore Viola
Keyword(s):  
Cherenkov Radiation ◽  
Detection System ◽  
Charged Particles ◽  
Positioning System ◽  
Atmospheric Neutrinos ◽  
Neutrino Telescopes ◽  
Strongly Connected ◽  
Radiation Induced ◽  
Better Than ◽  
Acoustic Positioning

In the Mediterranean Sea, the KM3NeT Collaboration is constructing a the deep-sea research infrastructure hosting next generation neutrino telescopes. In the KM3NeT telescopes the Cherenkov radiation induced by the secondary charged particles produced in the interaction of cosmic and atmospheric neutrinos within an effective volume between megaton and several cubic kilometers of water are detected by an array of thousands of photomultipliers. The capability of the telescope to determine the direction of secondary charged particles and to point back to the neutrino source is strongly connected to the accuracy on photomultipliers positions. In KM3NeT, the photomultiplier positions are continuously monitored by an acoustic positioning system, designed by the KM3NeT Collaboration to reach an accuracy of the photomultiplier positions better than 20 cm.

A newly developed low-cost 3D acoustic positioning system: Description and application in a reverberation room

2020 ◽  
Vol 160 ◽  
pp. 107127
Author(s):  
Paolo Guidorzi ◽  
Francesco Pompoli ◽  
Paolo Bonfiglio ◽  
Massimo Garai
Keyword(s):  
Low Cost ◽  
Positioning System ◽  
System Description ◽  
Acoustic Positioning

scholarly journals An elastic model of Phobos’ libration

2020 ◽  
Vol 636 ◽  
pp. A27
Author(s):  
Yongzhang Yang ◽  
Jianguo Yan ◽  
Xi Guo ◽  
Qingbao He ◽  
Jean-Pierre Barriot
Keyword(s):  
Numerical Model ◽  
Gravity Field ◽  
Numerical Integration ◽  
Elastic Properties ◽  
Rotational Motion ◽  
Space Mission ◽  
Elastic Model ◽  
Shape Model ◽  
Future Space ◽  
Least Squares Fit

Context. Study the rotation of a celestial body is an efficient way to infer its interior structure, and then may give information of its origin and evolution. In this study, based on the latest shape model of Phobos from Mars Express (MEX) mission, the polyhedron approximation approach was used to simulate the gravity field of Phobos. Then, the gravity information was combined with the newest geophysical parameters such as GM and k2 to construct the numerical model of Phobos’ rotation. And with an appropriate angles transformation, we got the librational series respect to Martian mean equator of date. Aims. The purpose of this paper is to develop a numerical model of Phobos’ rotational motion that includes the elastic properties of Phobos. The frequencies analysis of the librational angles calculated from the numerical integration results emphasize the relationship between geophysical properties and dynamics of Phobos. This work will also be useful for a future space mission dedicated to Phobos. Methods. Based on the latest shape model of Phobos from MEX mission, we firstly modeled the gravity field of Phobos, then the gravity coefficients were combined with some of the newest geophysical parameters to simulate the rotational motion of Phobos. To investigate how the elastic properties of Phobos affect its librational motion, we adopted various k2 into our numerical integration. Then the analysis was performed by iterating a frequency analysis and linear least-squares fit of Phobos’ physical librations. From this analysis, we identified the influence of k2 on the largest librational amplitude and its phase. Results. We showed the first ten periods of the librational angles and found that they agree well with the previous numerical results which Phobos was treated as a perfectly rigid body. We also found that the maximum amplitudes of the three parameters of libration are also close to the results from a rigid model, which is mainly due to the inclination of Phobos and moments of inertia. The other amplitudes are slightly different, since the physics contained in our model is different to that of a previous study, specifically, the different low-degree gravity coefficients and ephemeris. The libration in longitude τ has the same quadratic term with previous numerical study, which is consistent with the secular acceleration of Phobos falling onto Mars. We investigated the influence of the tidal Love number k2 on Phobos’ rotation and found a detectable amplitude changes (0.0005°) expected in the future space mission on τ, which provided a potential possibility to constrain the k2 of Phobos by observing its rotation. We also studied the influence of Phobos’ orbit accuracy on its libration and suggested a simultaneous integration of orbit and rotation in future work.

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