Examinando por Autor "Pike, W. T."

Mostrando 1 - 2 de 2

Acceso Abierto
A Comodulation Analysis of Atmospheric Energy Injection Into the Ground Motion at InSight, Mars
(Advancing Earth and Space Science AGU, 2021-02-08) Charalambous, C.; Stott, A. E.; Pike, W. T.; McClean, J. B.; Warren, T.; Spiga, A.; Banfield, D.; García, R. F.; Clinton, J.; Stähler, S. C.; Navarro, Sara; Lognonné, P.; Scholz, J. R.; Kawamura, T.; Van Driel, M.; Böse, M.; Ceylan, S.; Khan, A.; Horleston, A.; Orhand Mainsant, G.; Sotomayor, L. M.; Murdoch, N.; Giardini, D.; Banerdt, W. B.; Murdoch, N. [0000-0002-9701-4075]; Lognonne, P. [0000-0002-1014-920X]; Charalambous, C. [0000-0002-9139-3895]; Stott, A. E. [0000-0001-6121-705X]; Spiga, A. [0000-0002-6776-6268]; Stähler, S. [0000-0002-0783-2489]; Scholz, J. R. [0000-0003-1404-2335]; Ceylan, S. [0000-0002-6552-6850]; Khan, A. [0000-0003-4462-3173]; Van Driel, M. [0000-0002-8938-4615]; Horleston, A. [0000-0002-6748-6522]; Giardini, D. [0000-0002-5573-7638]; Banerdt, W. B. [0000-0003-3125-1542]
Seismic observations involve signals that can be easily masked by noise injection. For the NASA Mars lander InSight, the atmosphere is a significant noise contributor, impeding the identification of seismic events for two-thirds of a Martian day. While the noise is below that seen at even the quietest sites on Earth, the amplitude of seismic signals on Mars is also considerably lower, requiring an understanding and quantification of environmental injection at unprecedented levels. Mars’ ground and atmosphere are a continuously coupled seismic system, and although atmospheric functions are of distinct origins, the superposition of these noise contributions is poorly understood, making separation a challenging task. We present a novel method for partitioning the observed signal into seismic and environmental contributions. Atmospheric pressure and wind fluctuations are shown to exhibit temporal cross-frequency coupling across multiple bands, injecting noise that is neither random nor coherent. We investigate this through comodulation, quantifying the synchrony of the seismic motion, wind and pressure signals. By working in the time-frequency domain, we discriminate between the different origins of underlying processes and determine the site's environmental sensitivity. Our method aims to create a virtual vault at InSight's landing site on Mars, shielding the seismometers with effective postprocessing in lieu of a physical vault. This allows us to describe the environmental and seismic signals over a sequence of sols, to quantify the wind and pressure injection and estimate the seismic content of possible marsquakes with a signal-to-noise ratio that can be quantified in terms of environmental independence. Finally, we exploit the relationship between the comodulated signals to identify their sources.
Restringido
Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data
(Nature Research Journals, 2020-02-24) Lognonné, P.; Banerdt, W. B.; Pike, W. T.; Giardini, D.; Christensesn, U.; García, R. F.; Kawamura, T.; Kedar, S.; Knapmeyer Endrun, B.; Margerin, L.; Nimmo, F.; Panning, M.; Tauzin, B.; Scholz, J. R.; Antonangeli, D.; Barkaoui, S.; Beucler, E.; Bissig, F.; Brinkman, N.; Calvet, M.; Ceylan, S.; Charalambous, C.; Davis, P.; Van Driel, M.; Drilleau, M.; Fayon, L.; Joshi, R.; Kenda, B.; Khan, A.; Knapmeyer, M.; Lekic, V.; McClean, J.; Mimoun, D.; Murdoch, N.; Pan, L.; Perrin, C.; Pinot, B.; Pou, L.; Menina, S.; Rodríguez, Sébastien; Schmelzbach, C.; Schmerr, N.; Sollberg, D.; Spiga, A.; Stähler, S.; Stott, A.; Stutzmann, E.; Tharimena, S.; Widmer Schnidrig, R.; Andersson, F.; Ansan, V.; Beghein, C.; Knollenberg, M.; Krasner, S.; krause, C.; Lorenz, R.; Michaut, C.; Myhill, R.; Nissen Meyer, T.; Ten Pierick, J.; Plesa, A. C.; Quantin Nataf, C.; Robertsson, J.; Rochas, L.; Schimmel, M.; Smrekar, S.; Spohn, T.; Teanby, N.; Tromp, J.; Vallade, J.; Verdier, N.; Vrettos, C.; Weber, R.; Banfield, D.; Barrett, E.; Bierwith, M.; Calcutt, S.; Compaire, N.; Johnson, C. L.; Mance, D.; Euchner, F.; Kerjean, L.; Mainsant, G.; Mocquet, A.; Rodríguez Manfredi, J. A.; Pont, G.; Laudet, P.; Nebut, T.; Raucort, S.; Robert, O.; Russell, C. T.; Sylvestre Baron, A.; Tillier, S.; Warren, T.; Wieczorek, Mark A.; Yana, C.; Zweifel, P.; Centre National D'Etudes Spatiales (CNES); Agence Nationale de la Recherche (ANR); Lognonné, P.[0000-0002-1014-920X]; Spiga, A. [0000-0002-6776-6268]; Murdoch, N. [0000-0002-9701-4075]; Fayon, L. [0000-0002-4276-8160]; Knapmeyer, M. [0000-0003-0319-2514]; Tromp, J. [0000-0002-2742-8299]; Perrin, C. [0000-0002-7200-5682]; Schimmel, M. [0000-0003-2601-4462]; Panning, M. P. [0000-0002-2041-3190]; Rodríguez Manfredi, J. [0000-0003-0461-9815]; Pan, L. [0000-0002-8151-2125]; García, R. F. [0000-0003-1460-6663]; Rodríguez, S. [0000-0003-1219-0641]; Sollberger, D. [0000-0001-6408-6681]; Ceylan, S. [0000-0002-6552-6850]; Irving, J. [0000-0002-0866-8246]; Warren, T. [0000-0003-3877-0046]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Mars’s seismic activity and noise have been monitored since January 2019 by the seismometer of the InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) lander. At night, Mars is extremely quiet; seismic noise is about 500 times lower than Earth’s microseismic noise at periods between 4 s and 30 s. The recorded seismic noise increases during the day due to ground deformations induced by convective atmospheric vortices and ground-transferred wind-generated lander noise. Here we constrain properties of the crust beneath InSight, using signals from atmospheric vortices and from the hammering of InSight’s Heat Flow and Physical Properties (HP3) instrument, as well as the three largest Marsquakes detected as of September 2019. From receiver function analysis, we infer that the uppermost 8–11 km of the crust is highly altered and/or fractured. We measure the crustal diffusivity and intrinsic attenuation using multiscattering analysis and find that seismic attenuation is about three times larger than on the Moon, which suggests that the crust contains small amounts of volatiles.