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Planetary Seismology This article was originally published in Treatise on Geophysics, Second Edition, published by Elsevier, and the attached copy is provided by Elsevier for the author's benefit and for the benefit of the author's institution, for non-commercial research and educational use including without limitation use in instruction at your institution, sending it to specific colleagues who you know, and providing a copy to your institution’s administrator. All other uses, reproduction and distribution, including without limitation commercial reprints, selling or licensing copies or access, or posting on open internet sites, your personal or institution’s website or repository, are prohibited. For exceptions, permission may be sought for such use through Elsevier's permissions site at: http://www.elsevier.com/locate/permissionusematerial Lognonné P., and Johnson C.L Planetary Seismology. In: Gerald Schubert (editor-in- chief) Treatise on Geophysics, 2nd edition, Vol 10. Oxford: Elsevier; 2015. p. 65-120. Author's personal copy 10.03 Planetary Seismology P Lognonne´, Universite´ Paris Diderot -Sorbonne Paris Cite´, Institut de Physique du Globe de Paris, Paris, France CL Johnson, University of British Columbia, Vancouver, BC, Canada; Planetary Science Institute, Tucson, AZ, USA ã 2015 Elsevier B.V. All rights reserved. 10.03.1 Introduction 65 10.03.2 Lunar Results 70 10.03.2.1 The Apollo PSE Data 70 10.03.2.2 Seismic-Velocity Structure: Crust and Mantle 72 10.03.2.3 Very Deep Interior 77 10.03.2.4 Mineralogical and Thermal Interpretation of Lunar Seismic Models 78 10.03.3 Seismic Activity of the Moon and Terrestrial Planets 81 10.03.3.1 Internal Seismic Activity 81 10.03.3.2 External Seismic activity: Artificial and Natural Impacts 86 10.03.4 Atmospheric Seismology 90 10.03.4.1 Theoretical Background 90 10.03.4.2 Mars Hum and Martian Atmospheric Sources 94 10.03.4.3 Venus Atmospheric Seismology 96 10.03.4.4 Giant Planets Seismology 99 10.03.5 The New Step: Mars Seismology 103 10.03.5.1 Interior Structure of Mars 103 10.03.5.2 Martian Seismic Noise 105 10.03.5.3 Body-Wave Detection 106 10.03.5.4 Normal Mode Excitation and Tidal Observations 109 10.03.5.5 Surface Waves 111 10.03.6 Concluding Remarks 113 Acknowledgments 114 References 114 10.03.1 Introduction measurements of the core radius of the Moon or Mars; no direct information on the martian mantle structure, including One hundred and twenty five years have passed since Von its discontinuities; no definitive direct measurements of mar- Rebeur-Paschwitz (1889) first detected a remote seismic tian seismic activity; and no direct measurement of the mean event, and almost 70 years have passed since the creation of crustal thickness of Mars. the first mean seismic models of the Earth based on body-wave The use of seismometers in planetary exploration was pro- travel times (Bullen, 1947). As a result, seismology is now posed early in the history of space missions (e.g., Press et al., generally accepted as the geophysical tool best able to 1960). Yet, almost 52 years after the launch of the first seis- determine the internal structure of a planet. Seismology has mometer to a telluric body (Ranger 3, in 1962), planetary and also led to a revolution in Earth science, especially since the small-body seismology has only been successfully studied on advent of three-dimensional (3D) tomographic models of the Earth’s Moon. The Apollo program deployed a network of four Earth’s mantle (e.g., Dziewonski et al., 1977; Woodhouse and seismic stations on the Moon (Latham et al., 1969, 1970a,b, Dziewonski, 1984) that depict major discontinuities in the 1971), as well as the short-lived Apollo 11 seismometer for mantle and reflect convection patterns and lateral variations passive monitoring, and three active seismic experiments were in its temperature or mineralogy. For a complete and extensive conducted during the missions of Apollo 14, 15, 16, and 17 description of seismology as applied to Earth, see volume 1 of (Kovach and Watkins, 1973a; Watkins and Kovach, 1972). The Treatise on Geophysics: Deep Earth Seismology. thirteen other extraterrestrial seismometer experiments that We are a long way from achieving this level of seismological launched successfully never recorded any quakes (see Table 1). knowledge for bodies other than Earth, however, and the These nonyielding lunar missions include the seismometers seismic identification of the Earth’s core, realized by R.D. Old- (Lehner et al., 1962; Press et al., 1960) onboard the 3 Ranger ham one century ago (Oldham, 1906), remains the only exam- lunar probes, which were lost with their missions in the early ple of detecting seismic waves refracted by a planetary core. The 1960s; the seismometer lost with the cancellation of the Apollo situation is similar for the detection of a planet’s normal 13 Moon landing; and the gravimeter onboard the last Apollo modes, with the first successful detection of normal modes 17 mission, which failed to operate despite expectations that it on Earth following the great Chilean Earthquake in 1960 would extend the work of the previous Apollo instruments by (e.g., Benioff et al., 1961). As a consequence (see the other providing long-period (LP) seismic data. Several attempts have chapters of this Treatise), we currently have no precise been made to conduct seismic experiments on Mars. Two Treatise on Geophysics, Second Edition http://dx.doi.org/10.1016/B978-0-444-53802-4.00167-6 65 Treatise on Geophysics, 2nd edition, (2015), vol. 10, pp. 65-120 Author's personal copy 66 Planetary Seismology Table 1 Summary and history of planetary seismology experiments delivered to launch Mission Launch Major mission events Instrument description Seismometer deployment References Ranger 3 1962-01-26 Failure due to the booster. Vertical axis seismometer, Seismometer in a lunar Lehner et al. Moon missed with a free frequency of capsule designed for a (1962) 1 Ranger 4 1962-04-23 Failure of spacecraft central 1 Hz (mass: 3.36 kg) 130–160 km hÀ landing. processor. Moon crash Batteries powered for Ranger 5 1962-10-18 Failure in the spacecraft 30 days of operation power system. Moon missed Apollo 11 1969-7-16 Successful installation. Passive seismic experiment Installation performed by Latham et al. Powered by solar panel, (PSE). Triaxis long-period crew. Seismometers were (1969, worked during the first (LP) seismometer and one manually leveled and 1970a,b) lunation and stopped after vertical short-period (SP) oriented with bubble level 21 days seismometer, with and sun compass. A sun Apollo 12 1969-11-14 Successful installation of a resonance periods of 15 protection/thermal shroud Apollo 14 1971-01-31 network of 4 stations. and 1 s, respectively (mass: was covering the Apollo 15 1971-07-26 Except for the Apollo 12 SP 11.5 kg, power: 4.3–7.4 W) instruments. Power was Apollo 16 1972-04-16 seismometer and Apollo delivered by a plutonium 14 vertical LP seismometer, radioisotope thermoelectric all operated until the end of generator for A12–14– September 1977, when all 15–16 were turned off after a command from the Earth. 26.18 active station years of data collected Apollo 13 1970-4-11 Moon landing aborted. No installation of the PSE experiment, but the lunar crash of the Apollo 13 Saturn-IV upper stage was recorded by the A12 PSE Apollo 14 1971-01-31 Successful installation and String of three geophones on Geophones were anchored Watkins and Apollo 16 1972-04-16 operation of the active A-14 and A-16 and on four into the surface by short Kovach Apollo 17 1972-12-07 seismic experiments. geophones on A-17. spikes as they were (1972), Seismic sources were Frequency was 3–250 Hz unreeled from the thumper/ Kovach and thumper devices (A14, A16) geophone assembly Watkins containing 21 (A14) and (1973a,b) 19 (A16) small explosive sources and a rocket grenade launcher with three sources exploding up to 900 m on A16. Eight sources were used containing up to 2722 g of explosive and deployed up to about 2800 m by astronauts on A17 Apollo 17 1972-12-07 Deployment of the Lunar Gravimeter designed for Installation performed by Weber Surface Gravimeter. The gravity-wave detection. crew (1971), gravimeter was unable to Additional LP vertical Tobias 11 operate properly due to an seismic output (10À lunar (1978) error in the design of the g resolution) for free proof mass oscillation detection, with a 16-Hz sampling Viking Lander 1975-08-20 Successful landing but SP instrument, with an The seismometer was Anderson 1 instrument failure undamped natural period of installed on the Lander et al. Viking 1975-09-09 Successful landing and 0.25 s, a mass of 2.2 kg, a platform. No recentering (1977a,b) Lander 2 19 months of nearly size of 12 15 12 cm and was necessary, because   continuous operation. Too a nominal power the 3-axis seismometer high wind sensitivity consumption of 3.5 W had been designed to associated to the elastic function even when tilted recovery of the Viking to up to 23 (Continued) Treatise on Geophysics, 2nd edition, (2015), vol. 10, pp. 65-120 Author's personal copy Planetary Seismology 67 Table 1 (Continued) Mission Launch Major mission events Instrument description Seismometer deployment References landing legs to the loading of the station by pressure fluctuations induced by the wind Phobos 1-2 1988-07-07 Phobos 1 was lost during Instrument onboard the long- Surkov 1988-07-12 transfer to Mars and service lander (1990) Phobos. Contact with Phobos 2 was lost just before the final phase of lander deployment, after Mars orbit insertion Mars 96 1996-11-16 Failure of the block-D LP vertical-axis seismometer Seismometer in the small Lognonne´ Small surface propulsion system in (0.1–4 Hz, 0.405 kg for the surface station.
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