Examinando por Autor "Murdoch, N."

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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.
Acceso Abierto
A Study of Daytime Convective Vortices and Turbulence in the Martian Planetary Boundary Layer Based on Half-a-Year of InSight Atmospheric Measurements and Large-Eddy Simulations
(American Geophysical Union: Advancing Earth and Space Science, 2021-01-12) Spiga, A.; Murdoch, N.; Lorenz, R.; Forget, F.; Newman, C. E.; Rodríguez, Sébastien; Pla García, J.; Viúdez Moreiras, Daniel; Banfield, D.; Perrin, C.; Mueller, N. T.; Lemmon, M. T.; Millour, E.; Banerdt, W. B.; Agencia Estatal de Investigación (AEI); Spiga, A. [0000-0002-6776-6268]; Murdoch, N. [0000-0002-9701-4075]; Lorenz, R. [0000-0001-8528-4644]; Forget, F. [0000-0002-3262-4366]; Newman, C. [0000-0001-9990-8817]; Rodríguez, S. [0000-0003-1219-0641]; Pla García, J. [0000-0002-8047-3937]; Viúdez Moreiras, D. [0000-0001-8442-3788]; Perrin, C. [0000-0002-7200-5682]; Mueller, N. T. [0000-0001-9229-8921]; Lemmon, M. [0000-0002-4504-5136]; Millour, E. [0000-0003-4808-9203]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Studying the atmospheric planetary boundary layer (PBL) is crucial to understand the climate of a planet. The meteorological measurements by the instruments onboard InSight at a latitude of 4.5°N make a unique rich data set to study the active turbulent dynamics of the daytime PBL on Mars. Here we use the high-sensitivity continuous pressure, wind, and temperature measurements in the first 400 sols of InSight operations (from northern late winter to midsummer) to analyze wind gusts, convective cells, and vortices in Mars’ daytime PBL. We compare InSight measurements to turbulence-resolving large-eddy simulations (LES). The daytime PBL turbulence at the InSight landing site is very active, with clearly identified signatures of convective cells and a vast population of 6,000 recorded vortex encounters, adequately represented by a power law with a 3.4 exponent. While the daily variability of vortex encounters at InSight can be explained by the statistical nature of turbulence, the seasonal variability is positively correlated with ambient wind speed, which is supported by LES. However, wind gustiness is positively correlated to surface temperature rather than ambient wind speed and sensible heat flux, confirming the radiative control of the daytime Martian PBL; and fewer convective vortices are forming in LES when the background wind is doubled. Thus, the long-term seasonal variability of vortex encounters at the InSight landing site is mainly controlled by the advection of convective vortices by ambient wind speed. Typical tracks followed by vortices forming in the LES show a similar distribution in direction and length as orbital imagery.
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.
Restringido
Initial results from the InSight mission on Mars
(Nature Research Journals, 2020-02-24) Banerdt, W. B.; Smrekar, S.; Banfield, D.; Giardini, D.; Golombek, M.; Johnson, C. L.; Lognonné, P.; Spiga, A.; Spohn, T.; Perrin, C.; Stähler, S.; Antonangeli, D.; Asmar, S.; Beghein, C.; Bowles, N.; Bozdag, E.; Chi, P.; Christensesn, U.; Clinton, J.; Collins, G. S.; Daubar, I.; Dehant, V.; Drilleau, M.; Fillingim, M.; Folkner, W.; García, R. F.; Garvin, J. B.; Grant, J.; Grott, M.; Grygorczuk, J.; Hudson, T.; Irving, J. C. E.; Kargl, G.; Kawamura, T.; Kedar, S.; King, S.; Knapmeyer Endrun, B.; Knapmeyer, M.; Lemmon, M. T.; Lorenz, R.; Maki, Justin N.; Margerin, L.; McLennan, S. M.; Michaut, C.; Mimoun, D.; Mittelholz, A.; Mocquet, A.; Morgan, P.; Mueller, N. T.; Murdoch, N.; Nagihara, S.; Newman, C. E.; Nimmo, F.; Panning, M.; Thomas Pike, W.; Plesa, A. C.; Rodríguez, Sébastien; Rodríguez Manfredi, J. A.; Russell, C. T.; Chmerr, N.; Siegler, M.; Stanley, S.; Stutzmann, E.; Teanby, N.; Tromp, J.; Van Driel, M.; Warner, N.; Weber, R.; Wieczorek, Mark A.; Agence Nationale de la Recherche (ANR); Swiss National Science Foundation (SNSF); Tromp, J. [0000-0002-2742-8299]; Rodríguez, S. [0000-0003-1219-0641]; Lognonné, P. [0000-0002-1014-920X]; Perrin, C. [0000-0002-7200-5682]; Murdoch, N. [0000-0002-9701-4075]; Knapmeyer, M. [0000-0003-0319-2514]; Rodríguez Manfredi, J. A. [0000-0003-0461-9815]; Spiga, A. [0000-0002-6776-6268]; Panning, M. P. [0000-0002-2041-3190]; García, R. [0000-0003-1460-6663]; Johnson, C. [0000-0001-6084-0149]; Stutzmann, E. [0000-0002-4348-7475]; Knapmeyer-Endrun, B. [0000-0003-3309-6785]; Schmerr, N. [0000-0002-3256-1262]; Irving, J. C. E. [0000-0002-0866-8246]; Morgan, P. [0000-0001-8714-4178]; Mueller, N. [0000-0001-9229-8921]; Pike, W. [0000-0002-7660-6231]; Kawamura, T. [0000-0001-5246-5561]; Clinton, J. [0000-0001-8626-2703]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
NASA’s InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) mission landed in Elysium Planitia on Mars on 26 November 2018. It aims to determine the interior structure, composition and thermal state of Mars, as well as constrain present-day seismicity and impact cratering rates. Such information is key to understanding the differentiation and subsequent thermal evolution of Mars, and thus the forces that shape the planet’s surface geology and volatile processes. Here we report an overview of the first ten months of geophysical observations by InSight. As of 30 September 2019, 174 seismic events have been recorded by the lander’s seismometer, including over 20 events of moment magnitude Mw = 3–4. The detections thus far are consistent with tectonic origins, with no impact-induced seismicity yet observed, and indicate a seismically active planet. An assessment of these detections suggests that the frequency of global seismic events below approximately Mw = 3 is similar to that of terrestrial intraplate seismic activity, but there are fewer larger quakes; no quakes exceeding Mw = 4 have been observed. The lander’s other instruments—two cameras, atmospheric pressure, temperature and wind sensors, a magnetometer and a radiometer—have yielded much more than the intended supporting data for seismometer noise characterization: magnetic field measurements indicate a local magnetic field that is ten-times stronger than orbital estimates and meteorological measurements reveal a more dynamic atmosphere than expected, hosting baroclinic and gravity waves and convective vortices. With the mission due to last for an entire Martian year or longer, these results will be built on by further measurements by the InSight lander.
Acceso Abierto
Lander and rover histories of dust accumulation on and removal from solar arrays on Mars
(Elsevier, 2021-11-01) Lorenz, R. D.; Martínez, G. M.; Spiga, A.; Vicente Retortillo, Á.; Newman, C. E.; Murdoch, N.; Forget, F.; Millour, E.; Pierron, T.; National Aeronautics and Space Administration (NASA); Agence Nationale de la Recherche (ANR); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The degradation in electrical output of solar arrays on Mars landers and rovers is reviewed. A loss of 0.2% per Sol is typical, although observed rates of decrease in ‘dust factor’ vary between 0.05% and 2% per Sol. 0.2%/Sol has been observed throughout the first 800 Sols of the ongoing InSight mission, as well as the shorter Mars Pathfinder and Phoenix missions. This rate was also evident for much of the Spirit and Opportunity missions, but the degradation there was episodically reversed by cleaning events due to dust devils and gusts. The enduring success of those rover missions may have given an impression of the long-term viability of solar power on the Martian surface that is not globally-applicable: the occurrence of cleaning events with an operationally-useful frequency seems contingent upon local meteorological circumstances. The conditions for significant cleaning events have apparently not been realized at the InSight landing site, where, notably, dust devils have not been detected in imaging. Optical obscuration by dust deposition and removal has also been observed by ultraviolet sensors on Curiosity, with a similar (but slightly higher) degradation rate. The observations are compared with global circulation model (GCM) results: these predict a geographically somewhat uniform dust deposition rate, while there is some indication that the locations where cleaning events were more frequent may be associated with weaker background winds and a deeper planetary boundary layer. The conventional Dust Devil Activity metric in GCMs does not effectively predict the different dust histories.
Restringido
The atmosphere of Mars as observed by InSight.
(Nature Research Journals, 2020-02-24) Banfield, D.; Spiga, A.; Newman, C. E.; Forget, F.; Lemmon, M. T.; Lorenz, R.; Murdoch, N.; Viúdez Moreiras, Daniel; Pla García, J.; García, R. F.; Lognonné, P.; Karatekin, Özgür; Perrin, C.; Martire, L.; Teanby, N.; Van Hove, B.; Maki, Justin N.; Kenda, B.; Mueller, N. T.; Rodriguez, Sébastien; Kawamura, T.; McClean, J. B.; Stott, A. E.; Charalambous, C.; Millour, E.; Johnson, C. L.; Mittelholz, A.; Määttänen, A.; Lewis, S. R.; Clinton, J.; Stähler, S. C.; Ceylan, S.; Giardini, D.; Warren, T.; Pike, W. T.; Daubar, I.; Golombek, M.; Rolland, L.; Widmer Schnidrig, R.; Mimoun, D.; Beucler, E.; Jacob, A.; Lucas, A.; Baker, M.; Ansan, V.; Hurst, K.; Mora Sotomayor, L.; Navarro, Sara; Torres, J.; Lepinette, A.; Molina, A.; Marín Jiménez, M.; Gómez Elvira, J.; Peinado, V.; Rodríguez Manfredi, J. A.; Carchic, B. T.; Sackett, S.; Russell, C. T.; Spohn, T.; Smrekar, S. E.; Banerdt, W. B.; Agence Nationale de la Recherche (ANR); Määttänen, A. [0000-0002-7326-8492]; Martire, L. [0000-0002-9402-6150]; Rodríguez Manfredi, J. A. [0000-0003-0461-9815]; Lognonné, P. [0000-0002-1014-920X]; Rodríguez, S. [0000-0003-1219-0641]; Spiga, A. [0000-0002-6776-6268]; Perrin, C. [0000-0002-7200-5682]; Molina, A. [0000-0002-5038-2022]; Rodríguez Manfredi, J. A. [0000-0003-0461-9815]; García, R. [0000-0003-1460-6663]; Murdoch, N. [0000-0002-9701-4075]; Lorenz, R. [0000-0001-8528-4644]; Mittelholz, A. [0000-0002-5603-7334]; Kawamura, T. [0000-0001-5246-5561]; Widmer Schnidrig, R. [0000-0001-9698-2739]; McClean, J. [0000-0002-7863-0120]; Mueller, N. [0000-0001-9229-8921]; Lewis, S. [0000-0001-7237-6494]; Teanby, N. [0000-0003-3108-5775]; Warren, T. [0000-0003-3877-0046]; Milliour, E. [0000-0003-4808-9203]; Lemmon, M. [0000-0002-4504-5136]; Clinton, J. [0000-0001-8626-2703]; Ceylan, S. [0000-0002-6552-6850]; Banfield, D. [0000-0003-2664-0164]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The atmosphere of Mars is thin, although rich in dust aerosols, and covers a dry surface. As such, Mars provides an opportunity to expand our knowledge of atmospheres beyond that attainable from the atmosphere of the Earth. The InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) lander is measuring Mars’s atmosphere with unprecedented continuity, accuracy and sampling frequency. Here we show that InSight unveils new atmospheric phenomena at Mars, especially in the higher-frequency range, and extends our understanding of Mars’s meteorology at all scales. InSight is uniquely sensitive to large-scale and regional weather and obtained detailed in situ coverage of a regional dust storm on Mars. Images have enabled high-altitude wind speeds to be measured and revealed airglow—faint emissions produced by photochemical reactions—in the middle atmosphere. InSight observations show a paradox of aeolian science on Mars: despite having the largest recorded Martian vortex activity and dust-devil tracks close to the lander, no visible dust devils have been seen. Meteorological measurements have produced a catalogue of atmospheric gravity waves, which included bores (soliton-like waves). From these measurements, we have discovered Martian infrasound and unexpected similarities between atmospheric turbulence on Earth and Mars. We suggest that the observations of Mars’s atmosphere by InSight will be key for prediction capabilities and future exploration.