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  • Comet 67P/CG Nucleus Composition and Comparison to Other Comets
    Space Sci. Rev. (IF 9.327) Pub Date : 2019-02-14
    Gianrico Filacchione, Olivier Groussin, Clémence Herny, David Kappel, Stefano Mottola, Nilda Oklay, Antoine Pommerol, Ian Wright, Zurine Yoldi, Mauro Ciarniello, Lyuba Moroz, Andrea Raponi

    We review our current knowledge of comet 67P/Churyumov–Gerasimenko nucleus composition as inferred from measurements made by remote sensing and in-situ instruments aboard Rosetta orbiter and Philae lander. Spectrophotometric properties (albedos, color indexes and Hapke parameters) of 67P/CG derived by Rosetta are discussed in the context of other comets previously explored by space missions. Composed of an assemblage made of ices, organic materials and minerals, cometary nuclei exhibit very dark and red surfaces which can be described by means of spectrophotometric quantities and reproduced with laboratory measurements. The presence of surface water and carbon dioxide ices was found by Rosetta to occur at localized sites where the activity driven by solar input, gaseous condensation or exposure of pristine inner layers can maintain these species on the surface. Apart from these specific areas, 67P/CG’s surface appears remarkably uniform in composition with a predominance of organic materials and minerals. The organic compounds contain abundant hydroxyl group and a refractory macromolecular material bearing aliphatic and aromatic hydrocarbons. The mineral components are compatible with a mixture of silicates and fine-grained opaques, including Fe-sulfides, like troilite and pyrrhotite, and ammoniated salts. In the vicinity of the perihelion several active phenomena, including the erosion of surface layers, the localized activity in cliffs, fractures and pits, the collapse of overhangs and walls, the transfer and redeposition of dust, cause the evolution of the different regions of the nucleus by inducing color, composition and texture changes.

  • The Origin and Fate of O 2 $\mbox{O}_{2}$ in Europa’s Ice: An Atmospheric Perspective
    Space Sci. Rev. (IF 9.327) Pub Date : 2019-02-14
    R. E. Johnson, A. V. Oza, F. Leblanc, C. Schmidt, T. A. Nordheim, T. A. Cassidy

    The early prediction and subsequent detection of an \(\mbox{O}_{2}\) atmosphere on Europa, coupled with the discovery that Europa has an ocean under its ice mantle, has made this moon a prime astrobiologic target, soon to be visited by the JUICE and Europa Clipper spacecraft. In spite of the considerable number of observational, modeling, and laboratory efforts, understanding the physics leading to the observed morphology of Europa’s near-surface \(\mbox{O}_{2}\) atmosphere has been problematic. This is the case as the observed emissions depend on the local incident plasma ion flux, the local temperature and composition of the regolith, as well as on the near-surface electron temperature and density. Here we rely heavily on earlier reviews briefly summarizing the observational, laboratory and simulation efforts. Although it is agreed that radiolysis of the surface ice by the incident Jovian plasma is the ultimate source of observed O2, a recent, simple model of thermal desorption from a regolith permeated with \(\mbox{O}_{2}\) has changed the usual paradigm. In that model, the observed orbital dependence of the local source of the near-surface O2 atmosphere is suggested to be due to the release of \(\mbox{O}_{2}\) likely trapped on the ice grains at dangling bonds by the solar flux with a smaller contribution due to direct sputtering. This assumes that Europa’s icy regolith is permeated with trapped \(\mbox{O}_{2}\), which could also affect our understanding of the suggestion that the radiolytic products in Europa’s regolith might be a source of oxidants for its underground ocean.

  • Accretion of Water in Carbonaceous Chondrites: Current Evidence and Implications for the Delivery of Water to Early Earth
    Space Sci. Rev. (IF 9.327) Pub Date : 2019-02-12
    Josep M. Trigo-Rodríguez, Albert Rimola, Safoura Tanbakouei, Victoria Cabedo Soto, Martin Lee

    Protoplanetary disks are dust-rich structures around young stars. The crystalline and amorphous materials contained within these disks are variably thermally processed and accreted to make bodies of a wide range of sizes and compositions, depending on the heliocentric distance of formation. The chondritic meteorites are fragments of relatively small and undifferentiated bodies, and the minerals that they contain carry chemical signatures providing information about the early environment available for planetesimal formation. A current hot topic of debate is the delivery of volatiles to terrestrial planets, understanding that they were built from planetesimals formed under far more reducing conditions than the primordial carbonaceous chondritic bodies. In this review, we describe significant evidence for the accretion of ices and hydrated minerals in the outer protoplanetary disk. In that distant region highly porous and fragile carbon and water-rich transitional asteroids formed, being the parent bodies of the carbonaceous chondrites (CCs). CCs are undifferentiated meteorites that never melted but experienced other physical processes including thermal and aqueous alteration. Recent evidence indicates that few of them have escaped significant alteration, retaining unique features that can be interpreted as evidence of wet accretion. Some examples of carbonaceous chondrite parent body aqueous alteration will be presented. Finally, atomistic interpretations of the first steps leading to water-mediated alteration during the accretion of CCs are provided and discussed. From these new insights into the water retained in CCs we can decipher the pathways of delivery of volatiles to the terrestrial planets.

  • Astrophysics with the Spatially and Spectrally Resolved Sunyaev-Zeldovich Effects
    Space Sci. Rev. (IF 9.327) Pub Date : 2019-02-12
    Tony Mroczkowski, Daisuke Nagai, Kaustuv Basu, Jens Chluba, Jack Sayers, Rémi Adam, Eugene Churazov, Abigail Crites, Luca Di Mascolo, Dominique Eckert, Juan Macias-Perez, Frédéric Mayet, Laurence Perotto, Etienne Pointecouteau, Charles Romero, Florian Ruppin, Evan Scannapieco, John ZuHone

    In recent years, observations of the Sunyaev-Zeldovich (SZ) effect have had significant cosmological implications and have begun to serve as a powerful and independent probe of the warm and hot gas that pervades the Universe. As a few pioneering studies have already shown, SZ observations both complement X-ray observations—the traditional tool for studying the intra-cluster medium—and bring unique capabilities for probing astrophysical processes at high redshifts and out to the low-density regions in the outskirts of galaxy clusters. Advances in SZ observations have largely been driven by developments in centimetre-, millimetre-, and submillimetre-wave instrumentation on ground-based facilities, with notable exceptions including results from the Planck satellite. Here we review the utility of the thermal, kinematic, relativistic, non-thermal, and polarised SZ effects for studies of galaxy clusters and other large scale structures, incorporating the many advances over the past two decades that have impacted SZ theory, simulations, and observations. We also discuss observational results, techniques, and challenges, and aim to give an overview and perspective on emerging opportunities, with the goal of highlighting some of the exciting new directions in this field.

  • Diffuse Radio Emission from Galaxy Clusters
    Space Sci. Rev. (IF 9.327) Pub Date : 2019-02-05
    R. J. van Weeren, F. de Gasperin, H. Akamatsu, M. Brüggen, L. Feretti, H. Kang, A. Stroe, F. Zandanel

    In a growing number of galaxy clusters diffuse extended radio sources have been found. These sources are not directly associated with individual cluster galaxies. The radio emission reveal the presence of cosmic rays and magnetic fields in the intracluster medium (ICM). We classify diffuse cluster radio sources into radio halos, cluster radio shocks (relics), and revived AGN fossil plasma sources. Radio halo sources can be further divided into giant halos, mini-halos, and possible “intermediate” sources. Halos are generally positioned at cluster center and their brightness approximately follows the distribution of the thermal ICM. Cluster radio shocks (relics) are polarized sources mostly found in the cluster’s periphery. They trace merger induced shock waves. Revived fossil plasma sources are characterized by their radio steep-spectra and often irregular morphologies. In this review we give an overview of the properties of diffuse cluster radio sources, with an emphasis on recent observational results. We discuss the resulting implications for the underlying physical acceleration processes that operate in the ICM, the role of relativistic fossil plasma, and the properties of ICM shocks and magnetic fields. We also compile an updated list of diffuse cluster radio sources which will be available on-line (http://galaxyclusters.com). We end this review with a discussion on the detection of diffuse radio emission from the cosmic web.

  • Shocks and Non-thermal Particles in Clusters of Galaxies
    Space Sci. Rev. (IF 9.327) Pub Date : 2019-02-04
    A. M. Bykov, F. Vazza, J. A. Kropotina, K. P. Levenfish, F. B. S. Paerels

    Galaxy clusters grow by gas accretion, mostly from mergers of substructures, which release powerful shock waves into cosmic plasmas and convert a fraction of kinetic energy into thermal energy, amplification of magnetic fields and into the acceleration of energetic particles. The modeling of the radio signature of cosmic shocks, combined with the lack of detected \(\gamma \)-rays from cosmic ray (CR) protons, poses challenges to our understanding of how cosmic rays get accelerated and stored in the intracluster medium. Here we review the injection of CRs by cosmic shocks of different strengths, combining the detailed “microscopic” view of collisionless processes governing the creation of non-thermal distributions of electrons and protons in cluster shocks (based on analytic theory and particle-in-cell simulations), with the “macroscopic” view of the large-scale distribution of cosmic rays, suggested by modern cosmological simulations. Time dependent non-linear kinetic models of particle acceleration by multiple internal shocks with large scale compressible motions of plasma with soft CR spectra containing a noticeable energy density in the super-thermal protons of energies below a few GeV which is difficult to constrain by Fermi observations are discussed. We consider the effect of plasma composition on CR injection and super-thermal particle population in the hot intracluster matter which can be constrained by fine high resolution X-ray spectroscopy of Fe ions.

  • Mars’ Background Free Oscillations
    Space Sci. Rev. (IF 9.327) Pub Date : 2019-01-30
    Y. Nishikawa, P. Lognonné, T. Kawamura, A. Spiga, E. Stutzmann, M. Schimmel, T. Bertrand, F. Forget, K. Kurita

    Observations and inversion of the eigenfrequencies of free oscillations constitute powerful tools to investigate the internal structure of a planet. On Mars, such free oscillations can be excited by atmospheric pressure and wind stresses from the Martian atmosphere, analogous to what occurs on Earth. Over long periods and on a global scale, this phenomenon may continuously excite Mars’ background free oscillations (MBFs), which constitute the so-called Martian hum. However, the source exciting MBFs is related both to the global-scale atmospheric circulation on Mars and to the variations in pressure and wind at the planetary boundary layer, for which no data are available.

  • SEIS: Insight’s Seismic Experiment for Internal Structure of Mars
    Space Sci. Rev. (IF 9.327) Pub Date : 2019-01-28
    P. Lognonné, W. B. Banerdt, D. Giardini, W. T. Pike, U. Christensen, P. Laudet, S. de Raucourt, P. Zweifel, S. Calcutt, M. Bierwirth, K. J. Hurst, F. Ijpelaan, J. W. Umland, R. Llorca-Cejudo, S. A. Larson, R. F. Garcia, S. Kedar, B. Knapmeyer-Endrun, D. Mimoun, A. Mocquet, M. P. Panning, R. C. Weber, A. Sylvestre-Baron, G. Pont, N. Verdier, L. Kerjean, L. J. Facto, V. Gharakanian, J. E. Feldman, T. L. Hoffman, D. B. Klein, K. Klein, N. P. Onufer, J. Paredes-Garcia, M. P. Petkov, J. R. Willis, S. E. Smrekar, M. Drilleau, T. Gabsi, T. Nebut, O. Robert, S. Tillier, C. Moreau, M. Parise, G. Aveni, S. Ben Charef, Y. Bennour, T. Camus, P. A. Dandonneau, C. Desfoux, B. Lecomte, O. Pot, P. Revuz, D. Mance, J. tenPierick, N. E. Bowles, C. Charalambous, A. K. Delahunty, J. Hurley, R. Irshad, Huafeng Liu, A. G. Mukherjee, I. M. Standley, A. E. Stott, J. Temple, T. Warren, M. Eberhardt, A. Kramer, W. Kühne, E.-P. Miettinen, M. Monecke, C. Aicardi, M. André, J. Baroukh, A. Borrien, A. Bouisset, P. Boutte, K. Brethomé, C. Brysbaert, T. Carlier, M. Deleuze, J. M. Desmarres, D. Dilhan, C. Doucet, D. Faye, N. Faye-Refalo, R. Gonzalez, C. Imbert, C. Larigauderie, E. Locatelli, L. Luno, J.-R. Meyer, F. Mialhe, J. M. Mouret, M. Nonon, Y. Pahn, A. Paillet, P. Pasquier, G. Perez, R. Perez, L. Perrin, B. Pouilloux, A. Rosak, I. Savin de Larclause, J. Sicre, M. Sodki, N. Toulemont, B. Vella, C. Yana, F. Alibay, O. M. Avalos, M. A. Balzer, P. Bhandari, E. Blanco, B. D. Bone, J. C. Bousman, P. Bruneau, F. J. Calef, R. J. Calvet, S. A. D’Agostino, G. de los Santos, R. G. Deen, R. W. Denise, J. Ervin, N. W. Ferraro, H. E. Gengl, F. Grinblat, D. Hernandez, M. Hetzel, M. E. Johnson, L. Khachikyan, J. Y. Lin, S. M. Madzunkov, S. L. Marshall, I. G. Mikellides, E. A. Miller, W. Raff, J. E. Singer, C. M. Sunday, J. F. Villalvazo, M. C. Wallace, D. Banfield, J. A. Rodriguez-Manfredi, C. T. Russell, A. Trebi-Ollennu, J. N. Maki, E. Beucler, M. Böse, C. Bonjour, J. L. Berenguer, S. Ceylan, J. Clinton, V. Conejero, I. Daubar, V. Dehant, P. Delage, F. Euchner, I. Estève, L. Fayon, L. Ferraioli, C. L. Johnson, J. Gagnepain-Beyneix, M. Golombek, A. Khan, T. Kawamura, B. Kenda, P. Labrot, N. Murdoch, C. Pardo, C. Perrin, L. Pou, A. Sauron, D. Savoie, S. Stähler, E. Stutzmann, N. A. Teanby, J. Tromp, M. van Driel, M. Wieczorek, R. Widmer-Schnidrig, J. Wookey

    By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight will deploy onto Mars’ surface the SEIS (Seismic Experiment for Internal Structure) instrument; a six-axes seismometer equipped with both a long-period three-axes Very Broad Band (VBB) instrument and a three-axes short-period (SP) instrument. These six sensors will cover a broad range of the seismic bandwidth, from 0.01 Hz to 50 Hz, with possible extension to longer periods. Data will be transmitted in the form of three continuous VBB components at 2 sample per second (sps), an estimation of the short period energy content from the SP at 1 sps and a continuous compound VBB/SP vertical axis at 10 sps. The continuous streams will be augmented by requested event data with sample rates from 20 to 100 sps. SEIS will improve upon the existing resolution of Viking’s Mars seismic monitoring by a factor of \(\sim 2500\) at 1 Hz and \(\sim 200\,000\) at 0.1 Hz. An additional major improvement is that, contrary to Viking, the seismometers will be deployed via a robotic arm directly onto Mars’ surface and will be protected against temperature and wind by highly efficient thermal and wind shielding. Based on existing knowledge of Mars, it is reasonable to infer a moment magnitude detection threshold of \(M_{{w}} \sim 3\) at \(40^{\circ}\) epicentral distance and a potential to detect several tens of quakes and about five impacts per year. In this paper, we first describe the science goals of the experiment and the rationale used to define its requirements. We then provide a detailed description of the hardware, from the sensors to the deployment system and associated performance, including transfer functions of the seismic sensors and temperature sensors. We conclude by describing the experiment ground segment, including data processing services, outreach and education networks and provide a description of the format to be used for future data distribution.

  • Circumplanetary Dust Populations
    Space Sci. Rev. (IF 9.327) Pub Date : 2019-01-28
    Frank Spahn, Manuel Sachse, Martin Seiß, Hsiang-Wen Hsu, Sascha Kempf, Mihály Horányi

    We summarize the current state of observations of circumplanetary dust populations, including both dilute and dense rings and tori around the giant planets, ejecta clouds engulfing airless moons, and rings around smaller planetary bodies throughout the Solar System. We also discuss the theoretical models that enable these observations to be understood in terms of the sources, sinks and transport of various dust populations. The dynamics and resulting transport of the particles can be quite complex, due to the fact that their motion is influenced by neutral and plasma drag, radiation pressure, and electromagnetic forces—all in addition to gravity. The relative importance of these forces depends on the environment, as well as the makeup and size of the particles. Possible dust sources include the generation of ejecta particles by impacts, active volcanoes and geysers, and the capture of exogenous particles. Possible dust sinks include collisions with moons, rings, or the central planet, erosion due to sublimation and sputtering, even ejection and escape from the circumplanetary environment.

  • Geologic Constraints on Early Mars Climate
    Space Sci. Rev. (IF 9.327) Pub Date : 2019-01-24
    Edwin S. Kite

    Early Mars climate research has well-defined goals (MEPAG 2018). Achieving these goals requires geologists and climate modelers to coordinate. Coordination is easier if results are expressed in terms of well-defined parameters. Key parameters include the following quantitative geologic constraints. (1) Cumulative post-3.4 Ga precipitation-sourced water runoff in some places exceeded \(1~\mbox{km}\) column. (2) There is no single Early Mars climate problem: the traces of ≥2 river-forming periods are seen. Relative to rivers that formed earlier in Mars history, rivers that formed later in Mars history are found preferentially at lower elevations, and show a stronger dependence on latitude. (3) The duration of the longest individual river-forming climate was \({>}(10^{2}\mbox{--}10^{3})~\mbox{yr}\), based on paleolake hydrology. (4) Peak runoff production was \({>}0.1~\mbox{mm}/\mbox{hr}\). However, (5) peak runoff production was intermittent, sustained (in a given catchment) for only <10% of the duration of river-forming climates. (6) The cumulative number of wet years during the valley-network-forming period was \({>}10^{5}~\mbox{yr}\). (7) Post-Noachian light-toned, layered sedimentary rocks took \({>}10^{7}~\mbox{yr}\) to accumulate. However, (8) an “average” place on Mars saw water for \({<}10^{7}~\mbox{yr}\) after the Noachian, suggesting that the river-forming climates were interspersed with long globally-dry intervals. (9) Geologic proxies for Early Mars atmospheric pressure indicate pressure was not less than 0.012 bar but not much more than 1 bar. A truth table of these geologic constraints versus currently published climate models shows that the late persistence of river-forming climates, combined with the long duration of individual lake-forming climates, is a challenge for most models.

  • The Space Physics Environment Data Analysis System (SPEDAS)
    Space Sci. Rev. (IF 9.327) Pub Date : 2019-01-22
    V. Angelopoulos, P. Cruce, A. Drozdov, E. W. Grimes, N. Hatzigeorgiu, D. A. King, D. Larson, J. W. Lewis, J. M. McTiernan, D. A. Roberts, C. L. Russell, T. Hori, Y. Kasahara, A. Kumamoto, A. Matsuoka, Y. Miyashita, Y. Miyoshi, I. Shinohara, M. Teramoto, J. B. Faden, A. J. Halford, M. McCarthy, R. M. Millan, J. G. Sample, D. M. Smith, L. A. Woodger, A. Masson, A. A. Narock, K. Asamura, T. F. Chang, C.-Y. Chiang, Y. Kazama, K. Keika, S. Matsuda, T. Segawa, K. Seki, M. Shoji, S. W. Y. Tam, N. Umemura, B.-J. Wang, S.-Y. Wang, R. Redmon, J. V. Rodriguez, H. J. Singer, J. Vandegriff, S. Abe, M. Nose, A. Shinbori, Y.-M. Tanaka, S. UeNo, L. Andersson, P. Dunn, C. Fowler, J. S. Halekas, T. Hara, Y. Harada, C. O. Lee, R. Lillis, D. L. Mitchell, M. R. Argall, K. Bromund, J. L. Burch, I. J. Cohen, M. Galloy, B. Giles, A. N. Jaynes, O. Le Contel, M. Oka, T. D. Phan, B. M. Walsh, J. Westlake, F. D. Wilder, S. D. Bale, R. Livi, M. Pulupa, P. Whittlesey, A. DeWolfe, B. Harter, E. Lucas, U. Auster, J. W. Bonnell, C. M. Cully, E. Donovan, R. E. Ergun, H. U. Frey, B. Jackel, A. Keiling, H. Korth, J. P. McFadden, Y. Nishimura, F. Plaschke, P. Robert, D. L. Turner, J. M. Weygand, R. M. Candey, R. C. Johnson, T. Kovalick, M. H. Liu, R. E. McGuire, A. Breneman, K. Kersten, P. Schroeder

    With the advent of the Heliophysics/Geospace System Observatory (H/GSO), a complement of multi-spacecraft missions and ground-based observatories to study the space environment, data retrieval, analysis, and visualization of space physics data can be daunting. The Space Physics Environment Data Analysis System (SPEDAS), a grass-roots software development platform (www.spedas.org), is now officially supported by NASA Heliophysics as part of its data environment infrastructure. It serves more than a dozen space missions and ground observatories and can integrate the full complement of past and upcoming space physics missions with minimal resources, following clear, simple, and well-proven guidelines. Free, modular and configurable to the needs of individual missions, it works in both command-line (ideal for experienced users) and Graphical User Interface (GUI) mode (reducing the learning curve for first-time users). Both options have “crib-sheets,” user-command sequences in ASCII format that can facilitate record-and-repeat actions, especially for complex operations and plotting. Crib-sheets enhance scientific interactions, as users can move rapidly and accurately from exchanges of technical information on data processing to efficient discussions regarding data interpretation and science. SPEDAS can readily query and ingest all International Solar Terrestrial Physics (ISTP)-compatible products from the Space Physics Data Facility (SPDF), enabling access to a vast collection of historic and current mission data. The planned incorporation of Heliophysics Application Programmer’s Interface (HAPI) standards will facilitate data ingestion from distributed datasets that adhere to these standards. Although SPEDAS is currently Interactive Data Language (IDL)-based (and interfaces to Java-based tools such as Autoplot), efforts are under-way to expand it further to work with python (first as an interface tool and potentially even receiving an under-the-hood replacement). We review the SPEDAS development history, goals, and current implementation. We explain its “modes of use” with examples geared for users and outline its technical implementation and requirements with software developers in mind. We also describe SPEDAS personnel and software management, interfaces with other organizations, resources and support structure available to the community, and future development plans.

  • ExoMars Atmospheric Mars Entry and Landing Investigations and Analysis (AMELIA)
    Space Sci. Rev. (IF 9.327) Pub Date : 2019-01-17
    Francesca Ferri, Özgür Karatekin, Stephen R. Lewis, François Forget, Alessio Aboudan, Giacomo Colombatti, Carlo Bettanini, Stefano Debei, Bart Van Hove, Veronique Dehant, Ari-Matti Harri, Mark Leese, Teemu Mäkinen, Ehouarn Millour, Ingo Muller-Wodarg, Gian Gabriele Ori, Andrea Pacifici, Sebastien Paris, Manish Patel, Mark Schoenenberger, Jeffrey Herath, Tero Siili, Aymeric Spiga, Tetsuya Tokano, Martin Towner, Paul Withers, Sami Asmar, Dirk Plettemeier

    The entry, descent and landing of Schiaparelli, the ExoMars Entry, descent and landing Demonstrator Module (EDM), offered a rare (once-per-mission) opportunity for in situ investigations of the martian environment over a wide altitude range. The aim of the ExoMars AMELIA experiment was to exploit the Entry, Descent and Landing System (EDLS) engineering measurements for scientific investigations of Mars’ atmosphere and surface. Here we present the simulations, modelling and the planned investigations prior to the Entry, Descent and Landing (EDL) event that took place on 19th October 2016. Despite the unfortunate conclusion of the Schiaparelli mission, flight data recorded during the entry and the descent until the loss of signal, have been recovered. These flight data, although limited and affected by transmission interruptions and malfunctions, are essential for investigating the anomaly and validating the EDL operation, but can also contribute towards the partial achievement of AMELIA science objectives.

  • The Physics of Galaxy Cluster Outskirts
    Space Sci. Rev. (IF 9.327) Pub Date : 2019-01-02
    Stephen Walker, Aurora Simionescu, Daisuke Nagai, Nobuhiro Okabe, Dominique Eckert, Tony Mroczkowski, Hiroki Akamatsu, Stefano Ettori, Vittorio Ghirardini

    As the largest virialized structures in the universe, galaxy clusters continue to grow and accrete matter from the cosmic web. Due to the low gas density in the outskirts of clusters, measurements are very challenging, requiring extremely sensitive telescopes across the entire electromagnetic spectrum. Observations using X-rays, the Sunyaev–Zeldovich effect, and weak lensing and galaxy distributions from the optical band, have over the last decade helped to unravel this exciting new frontier of cluster astrophysics, where the infall and virialization of matter takes place. Here, we review the current state of the art in our observational and theoretical understanding of cluster outskirts, and discuss future prospects for exploration using newly planned and proposed observatories.

  • High Precision SEIS Calibration for the InSight Mission and Its Applications
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-12-19
    L. Pou, D. Mimoun, P. Lognonne, R. F. Garcia, O. Karatekin, M. Nonon-Latapie, R. Llorca-Cejudo

    Part of the InSight mission, the SEIS instrument (Seismic Experiment for Interior Structures), is planned to arrive on Mars in November 2018. In order to prepare its future recordings on the red planet, special attention was directed towards calibrating the seismometer in-situ on the Martian surface. Besides relative calibrations, we studied the possibility of actively calibrating the two kinds of seismometers onboard SEIS, the Very Broad Band seismometers (VBB) and the Short Period seismometers (SP) and extended the analysis towards a possible absolute calibration. For that purpose, we developed additional noise models at low frequency and elaborate on how they will be sensed by the seismic sensors from long-period data recorded by the seismometer. Such work will improve SEIS capabilities to unveil the inner structure of Mars by checking SEIS well-being and with applications such as gravimetry with the main Phobos tide. The current calibration procedure is planned to take one hour to calibrate the VBB sensors using the SP sensors, and determine the VBB gain with an accuracy of 0.4%, good enough to resolve the state of the Martian core.

  • Optical-Performance Testing of the Laser RetroReflector for InSight
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-12-17
    Luca Porcelli, Mattia Tibuzzi, Chiara Mondaini, Lorenzo Salvatori, Marco Muccino, Matteo Petrassi, Luca Ioppi, Simone Dell’Agnello, Orlando Luongo, Giovanni Delle Monache, Giuseppe Bianco, Roberto Vittori, Raffaele Mugnuolo

    In the framework of the scientific activities foreseen by the NASA, ASI and INFN agreement for the InSight Mars lander mission (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport), we characterized the optical performance of the LaRRI instrument (Laser RetroReflector for InSight), through two sets of in-air solar-thermo-optical tests carried out at the SCF_Lab (Satellite/lunar/GNSS laser ranging/altimetry and cube/microsat Characterization Facilities Laboratory) of INFN–LNF in Frascati, Italy. The in-air tests consisted of optical and thermal measurements carried out by: (1) varying LaRRI’s bulk temperature (without solar illumination); (2) illuminating LaRRI with a solar spectrum; in both cases, LaRRI was interrogated with a laser at varying incidence angles w.r.t. its surface. This paper describes the tests and their results, which provide a first characterization of LaRRI’s optical and thermal behaviour in approximate Mars surface conditions.

  • Determining True North on Mars by Using a Sundial on InSight
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-12-17
    D. Savoie, A. Richard, M. Goutaudier, N. P. Onufer, M. C. Wallace, D. Mimoun, K. Hurst, N. Verdier, P. Lognonné, J. N. Maki, B. Banerdt

    In this work, we demonstrate the possibility to determine the true North direction on Mars by using a gnomon on the InSight mission. The Sun local coordinates are computed using the analytical solution VSOP87 for the planetary ephemeris. The Sun position in the sky induce specific gnomon shadow orientation and length that can be read on a target. By comparing the images of the shadow with the expected position of the Sun, we can determine the true North direction with an accuracy up to \(1^{\circ }\), well within the seismic requirement of \(5^{\circ }\), even if the lander position or the gnomon verticality are not accurate. To achieve this result, we determine the best periods of observation during the SEIS deployment phase in December 2018. A total period of 5 hours has been identified on mornings and evenings on Mars, during which the impact of errors on position and verticality on the true North direction are minimised.

  • Pre-mission InSights on the Interior of Mars
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-12-17
    Suzanne E. Smrekar, Philippe Lognonné, Tilman Spohn, W. Bruce Banerdt, Doris Breuer, Ulrich Christensen, Véronique Dehant, Mélanie Drilleau, William Folkner, Nobuaki Fuji, Raphael F. Garcia, Domenico Giardini, Matthew Golombek, Matthias Grott, Tamara Gudkova, Catherine Johnson, Amir Khan, Benoit Langlais, Anna Mittelholz, Antoine Mocquet, Robert Myhill, Mark Panning, Clément Perrin, Tom Pike, Ana-Catalina Plesa, Attilio Rivoldini, Henri Samuel, Simon C. Stähler, Martin van Driel, Tim Van Hoolst, Olivier Verhoeven, Renee Weber, Mark Wieczorek

    The Interior exploration using Seismic Investigations, Geodesy, and Heat Transport (InSight) Mission will focus on Mars’ interior structure and evolution. The basic structure of crust, mantle, and core form soon after accretion. Understanding the early differentiation process on Mars and how it relates to bulk composition is key to improving our understanding of this process on rocky bodies in our solar system, as well as in other solar systems. Current knowledge of differentiation derives largely from the layers observed via seismology on the Moon. However, the Moon’s much smaller diameter make it a poor analog with respect to interior pressure and phase changes. In this paper we review the current knowledge of the thickness of the crust, the diameter and state of the core, seismic attenuation, heat flow, and interior composition. InSight will conduct the first seismic and heat flow measurements of Mars, as well as more precise geodesy. These data reduce uncertainty in crustal thickness, core size and state, heat flow, seismic activity and meteorite impact rates by a factor of \(3\mbox{--}10\times\) relative to previous estimates. Based on modeling of seismic wave propagation, we can further constrain interior temperature, composition, and the location of phase changes. By combining heat flow and a well constrained value of crustal thickness, we can estimate the distribution of heat producing elements between the crust and mantle. All of these quantities are key inputs to models of interior convection and thermal evolution that predict the processes that control subsurface temperature, rates of volcanism, plume distribution and stability, and convective state. Collectively these factors offer strong controls on the overall evolution of the geology and habitability of Mars.

  • Hot Atmospheres, Cold Gas, AGN Feedback and the Evolution of Early Type Galaxies: A Topical Perspective
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-12-17
    N. Werner, B. R. McNamara, E. Churazov, E. Scannapieco

    Most galaxies comparable to or larger than the mass of the Milky Way host hot, X-ray emitting atmospheres, and many such galaxies are radio sources. Hot atmospheres and radio jets and lobes are the ingredients of radio-mechanical active galactic nucleus (AGN) feedback. While a consensus has emerged that such feedback suppresses cooling of hot cluster atmospheres, less attention has been paid to massive galaxies where similar mechanisms are at play. Observation indicates that the atmospheres of elliptical and S0 galaxies were accreted externally during the process of galaxy assembly and augmented significantly by stellar mass loss. Their atmospheres have entropy and cooling time profiles that are remarkably similar to those of central cluster galaxies. About half display filamentary or disky nebulae of cool and cold gas, much of which has likely cooled from the hot atmospheres. We review the observational and theoretical perspectives on thermal instabilities in galactic atmospheres and the evidence that AGN heating is able to roughly balance the atmospheric cooling. Such heating and cooling may be regulating star formation in all massive spheroids at late times.

  • InSight Auxiliary Payload Sensor Suite (APSS)
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-12-17
    D. Banfield, J. A. Rodriguez-Manfredi, C. T. Russell, K. M. Rowe, D. Leneman, H. R. Lai, P. R. Cruce, J. D. Means, C. L. Johnson, A. Mittelholz, S. P. Joy, P. J. Chi, I. G. Mikellides, S. Carpenter, S. Navarro, E. Sebastian, J. Gomez-Elvira, J. Torres, L. Mora, V. Peinado, A. Lepinette, The TWINS Team, K. Hurst, P. Lognonné, S. E. Smrekar, W. B. Banerdt

    NASA’s InSight mission to Mars will measure seismic signals to determine the planet’s interior structure. These highly sensitive seismometers are susceptible to corruption of their measurements by environmental changes. Magnetic fields, atmosphere pressure changes, and local winds can all induce apparent changes in the seismic records that are not due to propagating ground motions. Thus, InSight carries a set of sensors called the Auxiliary Payload Sensor Suite (APSS) which includes a magnetometer, an atmospheric pressure sensor, and a pair of wind and air temperature sensors. In the case of the magnetometer, knowledge of the amplitude of the fluctuating magnetic field at the InSight lander will allow the separation of seismic signals from potentially interfering magnetic signals of either natural or spacecraft origin. To acquire such data, a triaxial fluxgate magnetometer was installed on the deck of the lander to obtain magnetic records at the same cadence as the seismometer. Similarly, a highly sensitive pressure sensor is carried by InSight to enable the removal of local ground-surface tilts due to advecting pressure perturbations. Finally, the local winds (speed and direction) and air temperature are estimated using a hot-film wind sensor with heritage from REMS on the Curiosity rover. When winds are too high, seismic signals can be ignored or discounted. Herein we describe the APSS sensor suite, the test programs for its components, and the possible additional science investigations it enables.

  • Impact-Seismic Investigations of the InSight Mission
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-12-06
    Ingrid Daubar, Philippe Lognonné, Nicholas A. Teanby, Katarina Miljkovic, Jennifer Stevanović, Jeremie Vaubaillon, Balthasar Kenda, Taichi Kawamura, John Clinton, Antoine Lucas, Melanie Drilleau, Charles Yana, Gareth S. Collins, Don Banfield, Matthew Golombek, Sharon Kedar, Nicholas Schmerr, Raphael Garcia, Sebastien Rodriguez, Tamara Gudkova, Stephane May, Maria Banks, Justin Maki, Eleanor Sansom, Foivos Karakostas, Mark Panning, Nobuaki Fuji, James Wookey, Martin van Driel, Mark Lemmon, Veronique Ansan, Maren Böse, Simon Stähler, Hiroo Kanamori, James Richardson, Suzanne Smrekar, W. Bruce Banerdt

    Impact investigations will be an important aspect of the InSight mission. One of the scientific goals of the mission is a measurement of the current impact rate at Mars. Impacts will additionally inform the major goal of investigating the interior structure of Mars.

  • The Marsquake Service: Securing Daily Analysis of SEIS Data and Building the Martian Seismicity Catalogue for InSight
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-12-06
    J. Clinton, D. Giardini, M. Böse, S. Ceylan, M. van Driel, F. Euchner, R. F. Garcia, S. Kedar, A. Khan, S. C. Stähler, B. Banerdt, P. Lognonne, E. Beucler, I. Daubar, M. Drilleau, M. Golombek, T. Kawamura, M. Knapmeyer, B. Knapmeyer-Endrun, D. Mimoun, A. Mocquet, M. Panning, C. Perrin, N. A. Teanby

    The InSight mission expects to operate a geophysical observatory on Mars for at least two Earth years from late 2018. InSight includes a seismometer package, SEIS. The Marsquake Service (MQS) is created to provide a first manual review of the seismic data returned from Mars. The MQS will detect, locate, quantify and classify seismic events, whether tectonic or impact in origin. A suite of new and adapted methodologies have been developed to allow location and quantification of seismic events at the global scale using a single station, and a software framework has been developed that supports these methods. This paper describes the expected signals that will be recorded by SEIS, the methods used for their identification and interpretation, and reviews the planned MQS operational procedures. For each seismic event, the MQS will locate events using all available body and surface phases, using the best estimates of the Martian structure, which will become more accurate as more Martian marsquakes are identified and located. The MQS will curate the Mars seismicity catalogue, with all events being relocated to use revised suites of structure models as they are introduced.

  • Dust Emission by Active Moons
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-12-04
    J. K. Hillier, J. Schmidt, H.-W. Hsu, F. Postberg

    In recent decades, volcanic and cryovolcanic activity on moons within the Solar System has been recognised as an important source of cosmic dust. Two moons, Jupiter’s satellite Io and Saturn’s satellite Enceladus, are known to be actively emitting dust into circumplanetary and interplanetary space. A third moon, Europa, shows tantalising hints of activity. Here we review current observations and theories concerning the generation, emission and evolution of cosmic dust arising from these objects.

  • Recent Advancements and Motivations of Simulated Pluto Experiments
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-11-28
    Caitlin J. Ahrens, William M. Grundy, Kathleen E. Mandt, Paul D. Cooper, Orkan M. Umurhan, Vincent F. Chevrier

    This review of Pluto laboratory research presents some of the recent advancements and motivations in our understanding enabled by experimental simulations, the need for experiments to facilitate models, and predictions for future laboratory work. The spacecraft New Horizons at Pluto has given a large amount of scientific data already rising to preliminary results, spanning from the geology to the atmosphere. Different ice mixtures have now been detected, with the main components being nitrogen, methane, and carbon monoxide. Varying geology and atmospheric hazes, however, gives us several questions that need to be addressed to further our understanding. Our review summarizes the complexity of Pluto, the motivations and importance of laboratory simulations critical to understanding the low temperature and pressure environments of icy bodies such as Pluto, and the variability of instrumentation, challenges for research, and how simulations and modeling are complimentary.

  • Inversion of Meteor Rayleigh Waves on Earth and Modeling of Air Coupled Rayleigh Waves on Mars
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-11-27
    Foivos Karakostas, Virgile Rakoto, Philippe Lognonné, Carene Larmat, Ingrid Daubar, Katarina Miljković

    Meteor impacts and/or meteor events generate body and surface seismic waves on the surface of a planet. When meteoroids burst in the atmosphere, they generate shock waves that subsequently convert into acoustic waves in the atmosphere and seismic waves in the ground. This effect can be modeled as the amplitude of Rayleigh and other Spheroidal modes excitation, due to atmospheric/ground coupling effects.

  • Enrichment of the Hot Intracluster Medium: Observations
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-11-27
    F. Mernier, V. Biffi, H. Yamaguchi, P. Medvedev, A. Simionescu, S. Ettori, N. Werner, J. S. Kaastra, J. de Plaa, L. Gu

    Four decades ago, the firm detection of an Fe-K emission feature in the X-ray spectrum of the Perseus cluster revealed the presence of iron in its hot intracluster medium (ICM). With more advanced missions successfully launched over the last 20 years, this discovery has been extended to many other metals and to the hot atmospheres of many other galaxy clusters, groups, and giant elliptical galaxies, as evidence that the elemental bricks of life—synthesized by stars and supernovae—are also found at the largest scales of the Universe. Because the ICM, emitting in X-rays, is in collisional ionisation equilibrium, its elemental abundances can in principle be accurately measured. These abundance measurements, in turn, are valuable to constrain the physics and environmental conditions of the Type Ia and core-collapse supernovae that exploded and enriched the ICM over the entire cluster volume. On the other hand, the spatial distribution of metals across the ICM constitutes a remarkable signature of the chemical history and evolution of clusters, groups, and ellipticals. Here, we summarise the most significant achievements in measuring elemental abundances in the ICM, from the very first attempts up to the era of XMM-Newton, Chandra, and Suzaku and the unprecedented results obtained by Hitomi. We also discuss the current systematic limitations of these measurements and how the future missions XRISM and Athena will further improve our current knowledge of the ICM enrichment.

  • Clouds and Hazes of Venus
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-11-27
    Dmitrij V. Titov, Nikolay I. Ignatiev, Kevin McGouldrick, Valérie Wilquet, Colin F. Wilson

    More than three decades have passed since the publication of the last review of the Venus clouds and hazes. The paper published in 1983 in the Venus book summarized the discoveries and findings of the US Pioneer Venus and a series of Soviet Venera spacecraft (Esposito et al. in Venus, p. 484, 1983). Due to the emphasis on in-situ investigations from descent probes, those missions established the basic features of the Venus cloud system, its vertical structure, composition and microphysical properties. Since then, significant progress in understanding of the Venus clouds has been achieved due to exploitation of new observation techniques onboard Galileo and Messenger flyby spacecraft and Venus Express and Akatsuki orbiters. They included detailed investigation of the mesospheric hazes in solar and stellar occultation geometry applied in the broad spectral range from UV to thermal IR. Imaging spectroscopy in the near-IR transparency “windows” on the night side opened a new and very effective way of sounding the deep atmosphere. This technique together with near-simultaneous UV imaging enabled comprehensive study of the cloud morphology from the cloud top to its deep layers. Venus Express operated from April 2006 until December 2014 and provided a continuous data set characterizing Venus clouds and hazes over a time span of almost 14 Venus years thus enabling a detailed study of temporal and spatial variability. The polar orbit of Venus Express allowed complete latitudinal coverage. These studies are being complemented by JAXA Akatsuki orbiter that began observations in May 2016. This paper reviews the current status of our knowledge of the Venus cloud system focusing mainly on the results acquired after the Venera, Pioneer Venus and Vega missions.

  • Organic Ices in Titan’s Stratosphere
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-11-26
    C. M. Anderson, R. E. Samuelson, D. Nna-Mvondo

    Titan’s stratospheric ice clouds are by far the most complex of any observed in the solar system, with over a dozen organic vapors condensing out to form a suite of pure and co-condensed ices, typically observed at high winter polar latitudes. Once these stratospheric ices are formed, they will diffuse throughout Titan’s lower atmosphere and most will eventually precipitate to the surface, where they are expected to contribute to Titan’s regolith.

  • Ion Composition of the Earth’s Radiation Belts in the Range from 100 keV to 100 MeV / nucleon $100\mbox{ MeV}/\mbox{nucleon}$ : Fifty Years of Research
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-11-23
    Alexander S. Kovtyukh

    Spatial, energy and angular distributions of ion fluxes in the Earth’s radiation belts (ERB) near the equatorial plane, at middle geomagnetic latitudes and at low altitudes are systematically reviewed herein. Distributions of all main ion components, from protons to Fe (including hydrogen and helium isotopes), and their variations under the action of solar and geomagnetic activity are considered. For ions with \(Z\geq 2\) and especially for ions with \(Z \geq 9\), these variations are much more than for protons, and these have no direct connection with the intensity of magnetic storms (\(Z\) is the charge of the atomic nucleus with respect to the charge of the proton). The main physical mechanisms for the generation of ion fluxes in the ERB and the losses of these ions are considered. Solar wind, Solar Cosmic Rays (SCR), Galactic Cosmic Rays (GCR), and Anomalous component of Cosmic Rays (ACR) as sources of ions in the ERB are considered.

  • Enrichment of the Hot Intracluster Medium: Numerical Simulations
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-11-19
    V. Biffi, F. Mernier, P. Medvedev

    The distribution of chemical elements in the hot intracluster medium (ICM) retains valuable information about the enrichment and star formation histories of galaxy clusters, and on the feedback and dynamical processes driving the evolution of the cosmic baryons. In the present study we review the progresses made so far in the modelling of the ICM chemical enrichment in a cosmological context, focusing in particular on cosmological hydrodynamical simulations. We will review the key aspects of embedding chemical evolution models into hydrodynamical simulations, with special attention to the crucial assumptions on the initial stellar mass function, stellar lifetimes and metal yields, and to the numerical limitations of the modelling. At a second stage, we will overview the main simulation results obtained in the last decades and compare them to X-ray observations of the ICM enrichment patterns. In particular, we will discuss how state-of-the-art simulations are able to reproduce the observed radial distribution of metals in the ICM, from the core to the outskirts, the chemical diversity depending on cluster thermo-dynamical properties, the evolution of ICM metallicity and its dependency on the system mass from group to cluster scales. Finally, we will discuss the limitations still present in modern cosmological, chemical, hydrodynamical simulations and the perspectives for improving the theoretical modelling of the ICM enrichment in galaxy clusters in the future.

  • Magnetic Field Amplification in Galaxy Clusters and Its Simulation
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-11-13
    J. Donnert, F. Vazza, M. Brüggen, J. ZuHone

    We review the present theoretical and numerical understanding of magnetic field amplification in cosmic large-scale structure, on length scales of galaxy clusters and beyond. Structure formation drives compression and turbulence, which amplify tiny magnetic seed fields to the microGauss values that are observed in the intracluster medium. This process is intimately connected to the properties of turbulence and the microphysics of the intra-cluster medium. Additional roles are played by merger induced shocks that sweep through the intra-cluster medium and motions induced by sloshing cool cores. The accurate simulation of magnetic field amplification in clusters still poses a serious challenge for simulations of cosmological structure formation. We review the current literature on cosmological simulations that include magnetic fields and outline theoretical as well as numerical challenges.

  • Solar Ultraviolet Bursts
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-11-06
    Peter R. Young, Hui Tian, Hardi Peter, Robert J. Rutten, Chris J. Nelson, Zhenghua Huang, Brigitte Schmieder, Gregal J. M. Vissers, Shin Toriumi, Luc H. M. Rouppe van der Voort, Maria S. Madjarska, Sanja Danilovic, Arkadiusz Berlicki, L. P. Chitta, Mark C. M. Cheung, Chad Madsen, Kevin P. Reardon, Yukio Katsukawa, Petr Heinzel

    The term “ultraviolet (UV) burst” is introduced to describe small, intense, transient brightenings in ultraviolet images of solar active regions. We inventorize their properties and provide a definition based on image sequences in transition-region lines. Coronal signatures are rare, and most bursts are associated with small-scale, canceling opposite-polarity fields in the photosphere that occur in emerging flux regions, moving magnetic features in sunspot moats, and sunspot light bridges. We also compare UV bursts with similar transition-region phenomena found previously in solar ultraviolet spectrometry and with similar phenomena at optical wavelengths, in particular Ellerman bombs. Akin to the latter, UV bursts are probably small-scale magnetic reconnection events occurring in the low atmosphere, at photospheric and/or chromospheric heights. Their intense emission in lines with optically thin formation gives unique diagnostic opportunities for studying the physics of magnetic reconnection in the low solar atmosphere. This paper is a review report from an International Space Science Institute team that met in 2016–2017.

  • Feedstocks of the Terrestrial Planets
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-11-06
    Richard W. Carlson, Ramon Brasser, Qing-Zhu Yin, Mario Fischer-Gödde, Liping Qin

    The processes of planet formation in our Solar System resulted in a final product of a small number of discreet planets and planetesimals characterized by clear compositional distinctions. A key advance on this subject was provided when nucleosynthetic isotopic variability was discovered between different meteorite groups and the terrestrial planets. This information has now been coupled with theoretical models of planetesimal growth and giant planet migration to better understand the nature of the materials accumulated into the terrestrial planets. First order conclusions include that carbonaceous chondrites appear to contribute a much smaller mass fraction to the terrestrial planets than previously suspected, that gas-driven giant planet migration could have pushed volatile-rich material into the inner Solar System, and that planetesimal formation was occurring on a sufficiently rapid time scale that global melting of asteroid-sized objects was instigated by radioactive decay of 26Al. The isotopic evidence highlights the important role of enstatite chondrites, or something with their mix of nucleosynthetic components, as feedstock for the terrestrial planets. A common degree of depletion of moderately volatile elements in the terrestrial planets points to a mechanism that can effectively separate volatile and refractory elements over a spatial scale the size of the whole inner Solar System. The large variability in iron to silicon ratios between both different meteorite groups and between the terrestrial planets suggests that mechanisms that can segregate iron metal from silicate should be given greater importance in future investigations. Such processes likely include both density separation of small grains in the nebula, but also preferential impact erosion of either the mantle or core from differentiated planets/planetesimals. The latter highlights the important role for giant impacts and collisional erosion during the late stages of planet formation.

  • A Numerical Model of the SEIS Leveling System Transfer Matrix and Resonances: Application to SEIS Rotational Seismology and Dynamic Ground Interaction
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-10-31
    Lucile Fayon, Brigitte Knapmeyer-Endrun, Philippe Lognonné, Marco Bierwirth, Aron Kramer, Pierre Delage, Foivos Karakostas, Sharon Kedar, Naomi Murdoch, Raphael F. Garcia, Nicolas Verdier, Sylvain Tillier, William T. Pike, Ken Hurst, Cédric Schmelzbach, William B. Banerdt

    Both sensors of the SEIS instrument (VBBs and SPs) are mounted on the mechanical leveling system (LVL), which has to ensure a level placement on the Martian ground under currently unknown local conditions, and provide the mechanical coupling of the seismometers to the ground. We developed a simplified analytical model of the LVL structure in order to reproduce its mechanical behavior by predicting its resonances and transfer function. This model is implemented numerically and allows to estimate the effects of the LVL on the data recorded by the VBBs and SPs on Mars. The model is validated through comparison with the horizontal resonances (between 35 and 50 Hz) observed in laboratory measurements. These modes prove to be highly dependent of the ground horizontal stiffness and torque. For this reason, an inversion study is performed and the results are compared with some experimental measurements of the LVL feet’s penetration in a martian regolith analog. This comparison shows that the analytical model can be used to estimate the elastic ground properties of the InSight landing site. Another application consists in modeling the 6 sensors on the LVL at their real positions, also considering their sensitivity axes, to study the performances of the global SEIS instrument in translation and rotation. It is found that the high frequency ground rotation can be measured by SEIS and, when compared to the ground acceleration, can provide ways to estimate the phase velocity of the seismic surface waves at shallow depths. Finally, synthetic data from the active seismic experiment made during the HP3 penetration and SEIS rotation noise are compared and used for an inversion of the Rayleigh phase velocity. This confirms the perspectives for rotational seismology with SEIS which will be developed with the SEIS data acquired during the commissioning phase after landing.

  • Past, Present and Future of Active Radio Frequency Experiments in Space
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-10-30
    A. V. Streltsov, J.-J. Berthelier, A. A. Chernyshov, V. L. Frolov, F. Honary, M. J. Kosch, R. P. McCoy, E. V. Mishin, M. T. Rietveld

    Active ionospheric experiments using high-power, high-frequency transmitters, “heaters”, to study plasma processes in the ionosphere and magnetosphere continue to provide new insights into understanding plasma and geophysical proceses. This review describes the heating facilities, past and present, and discusses scientific results from these facilities and associated space missions. Phenomena that have been observed with these facilities are reviewed along with theoretical explanations that have been proposed or are commonly accepted. Gaps or uncertainties in understanding of heating-initiated phenomena are discussed together with proposed science questions to be addressed in the future. Suggestions for improvements and additions to existing facilities are presented including important satellite missions which are necessary to answer the outstanding questions in this field.

  • Flexible Mode Modelling of the InSight Lander and Consequences for the SEIS Instrument
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-10-24
    N. Murdoch, D. Alazard, B. Knapmeyer-Endrun, N. A. Teanby, R. Myhill

    We present an updated model for estimating the lander mechanical noise on the InSight seismometer SEIS, taking into account the flexible modes of the InSight lander. This new flexible mode model uses the Satellite Dynamics Toolbox to compute the direct and the inverse dynamic model of a satellite composed of a main body fitted with one or several dynamic appendages. Through a detailed study of the sensitivity of our results to key environment parameters we find that the frequencies of the six dominant lander resonant modes increase logarithmically with increasing ground stiffness. On the other hand, the wind strength and the incoming wind angle modify only the signal amplitude but not the frequencies of the resonances. For the baseline parameters chosen for this study, the lander mechanical noise on the SEIS instrument is not expected to exceed the instrument total noise requirements. However, in the case that the lander mechanical noise is observable in the seismic data acquired by SEIS, this may provide a complementary method for studying the ground and wind properties on Mars.

  • Interstellar Mapping and Acceleration Probe (IMAP): A New NASA Mission
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-10-22
    D. J. McComas, E. R. Christian, N. A. Schwadron, N. Fox, J. Westlake, F. Allegrini, D. N. Baker, D. Biesecker, M. Bzowski, G. Clark, C. M. S. Cohen, I. Cohen, M. A. Dayeh, R. Decker, G. A. de Nolfo, M. I. Desai, R. W. Ebert, H. A. Elliott, H. Fahr, P. C. Frisch, H. O. Funsten, S. A. Fuselier, A. Galli, A. B. Galvin, J. Giacalone, M. Gkioulidou, F. Guo, M. Horanyi, P. Isenberg, P. Janzen, L. M. Kistler, K. Korreck, M. A. Kubiak, H. Kucharek, B. A. Larsen, R. A. Leske, N. Lugaz, J. Luhmann, W. Matthaeus, D. Mitchell, E. Moebius, K. Ogasawara, D. B. Reisenfeld, J. D. Richardson, C. T. Russell, J. M. Sokół, H. E. Spence, R. Skoug, Z. Sternovsky, P. Swaczyna, J. R. Szalay, M. Tokumaru, M. E. Wiedenbeck, P. Wurz, G. P. Zank, E. J. Zirnstein

    The Interstellar Mapping and Acceleration Probe (IMAP) is a revolutionary mission that simultaneously investigates two of the most important overarching issues in Heliophysics today: the acceleration of energetic particles and interaction of the solar wind with the local interstellar medium. While seemingly disparate, these are intimately coupled because particles accelerated in the inner heliosphere play critical roles in the outer heliospheric interaction. Selected by NASA in 2018, IMAP is planned to launch in 2024. The IMAP spacecraft is a simple sun-pointed spinner in orbit about the Sun-Earth L1 point. IMAP’s ten instruments provide a complete and synergistic set of observations to simultaneously dissect the particle injection and acceleration processes at 1 AU while remotely probing the global heliospheric interaction and its response to particle populations generated by these processes. In situ at 1 AU, IMAP provides detailed observations of solar wind electrons and ions; suprathermal, pickup, and energetic ions; and the interplanetary magnetic field. For the outer heliosphere interaction, IMAP provides advanced global observations of the remote plasma and energetic ions over a broad energy range via energetic neutral atom imaging, and precise observations of interstellar neutral atoms penetrating the heliosphere. Complementary observations of interstellar dust and the ultraviolet glow of interstellar neutrals further deepen the physical understanding from IMAP. IMAP also continuously broadcasts vital real-time space weather observations. Finally, IMAP engages the broader Heliophysics community through a variety of innovative opportunities. This paper summarizes the IMAP mission at the start of Phase A development.

  • Origin of Molecular Oxygen in Comets: Current Knowledge and Perspectives
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-10-18
    Adrienn Luspay-Kuti, Olivier Mousis, Jonathan I. Lunine, Yves Ellinger, Françoise Pauzat, Ujjwal Raut, Alexis Bouquet, Kathleen E. Mandt, Romain Maggiolo, Thomas Ronnet, Bastien Brugger, Ozge Ozgurel, Stephen A. Fuselier

    The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument onboard the Rosetta spacecraft has measured molecular oxygen (O2) in the coma of comet 67P/Churyumov-Gerasimenko (67P/C-G) in surprisingly high abundances. These measurements mark the first unequivocal detection of O2 in a cometary environment. The large relative abundance of O2 in 67P/C-G despite its high reactivity and low interstellar abundance poses a puzzle for its origin in comet 67P/C-G, and potentially other comets. Since its detection, there have been a number of hypotheses put forward to explain the production and origin of O2 in the comet. These hypotheses cover a wide range of possibilities from various in situ production mechanisms to protosolar nebula and primordial origins. Here, we review the O2 formation mechanisms from the literature, and provide a comprehensive summary of the current state of knowledge of the sources and origin of cometary O2.

  • On the Detectability and Use of Normal Modes for Determining Interior Structure of Mars
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-10-18
    Felix Bissig, Amir Khan, Martin van Driel, Simon C. Stähler, Domenico Giardini, Mark Panning, Mélanie Drilleau, Philippe Lognonné, Tamara V. Gudkova, Vladimir N. Zharkov, Ana-Catalina Plesa, William B. Banerdt

    The InSight mission to Mars is well underway and will be the first mission to acquire seismic data from a planet other than Earth. In order to maximise the science return of the InSight data, a multifaceted approach will be needed that seeks to investigate the seismic data from a series of different frequency windows, including body waves, surface waves, and normal modes. Here, we present a methodology based on globally-averaged models that employs the long-period information encoded in the seismic data by looking for fundamental-mode spheroidal oscillations. From a preliminary analysis of the expected signal-to-noise ratio, we find that normal modes should be detectable during nighttime in the frequency range 5–15 mHz. For improved picking of (fundamental) normal modes, we show first that those are equally spaced between 5–15 mHz and then show how this spectral spacing, obtained through autocorrelation of the Fourier-transformed time series can be further employed to select normal mode peaks more consistently. Based on this set of normal-mode spectral frequencies, we proceed to show how this data set can be inverted for globally-averaged models of interior structure (to a depth of \(\sim 250~\mbox{km}\)), while simultaneously using the resultant synthetically-approximated normal mode peaks to verify the initial peak selection. This procedure can be applied iteratively to produce a “cleaned-up” set of spectral peaks that are ultimately inverted for a “final” interior-structure model. To investigate the effect of three-dimensional (3D) structure on normal mode spectra, we constructed a 3D model of Mars that includes variations in surface and Moho topography and lateral variations in mantle structure and employed this model to compute full 3D waveforms. The resultant time series are converted to spectra and the inter-station variation hereof is compared to the variation in spectra computed using different 1D models. The comparison shows that 3D effects are less significant than the variation incurred by the difference in radial models, which suggests that our 1D approach represents an adequate approximation of the global average structure of Mars.

  • Thermal Properties of Icy Surfaces in the Outer Solar System
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-10-18
    C. Ferrari

    The thermal properties of airless icy surfaces are providing a wealth of information on their regolith structure after eons of space weathering. Numerous observations of the thermal cycles of Jupiter and Saturn icy satellites or Centaurs and TNOs have been acquired in the latest decades thanks to the Galileo and Cassini missions and to the Spitzer and Herschel telescopes. These observations and the latest developments on thermophysical modeling which have been achieved to link the thermal inertia to the regolith structure are reviewed here. Measured thermal inertias of these surfaces covered with water ice are very low, roughly between about 1 and 100 J/m2/K/s1/2. Often interpreted as due to unconsolidated or highly porous regoliths, these low values may result from a composition of amorphous ice or from the roughness of grains defacing contacts in a regolith of normal compaction. Taken together, thermal inertias appear to increase with probed depth and to decrease with heliocentric distance. This latter effect can be easily reproduced if heat transfer is dominated by radiation in pores, despite low temperatures, because the conduction through grains is limited, either due to the presence of amorphous ice or because of the roughness of grains.

  • Old-Aged Primary Distance Indicators
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-10-18
    Rachael L. Beaton, Giuseppe Bono, Vittorio Francesco Braga, Massimo Dall’Ora, Giuliana Fiorentino, In Sung Jang, Clara E. Martínez-Vázquez, Noriyuki Matsunaga, Matteo Monelli, Jillian R. Neeley, Maurizio Salaris

    Old-aged stellar distance indicators are present in all Galactic structures (halo, bulge, disk) and in galaxies of all Hubble types and, thus, are immensely powerful tools for understanding our Universe. Here we present a comprehensive review for three primary standard candles from Population II: (i) RR Lyrae type variables (RRL), (ii) type II Cepheid variables (T2C), and (iii) the tip of the red giant branch (TRGB). The discovery and use of these distance indicators is placed in historical context before describing their theoretical foundations and demonstrating their observational applications across multiple wavelengths. The methods used to establish the absolute scale for each standard candle is described with a discussion of the observational systematics. We conclude by looking forward to the suite of new observational facilities anticipated over the next decade; these have both a broader wavelength coverage and larger apertures than current facilities. We anticipate future advancements in our theoretical understanding and observational application of these stellar populations as they apply to the Galactic and extragalactic distance scale.

  • Development of the Primary Sorption Pump for the SEIS Seismometer of the InSight Mission to Mars
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-10-18
    Mihail P. Petkov, Steven M. Jones, Gerald E. Voecks, Kenneth J. Hurst, Olivier Grosjean, Delphine Faye, Guillaume Rioland, Cecily M. Sunday, Emma M. Bradford, William N. Warner, Jerami M. Mennella, Ned W. Ferraro, Manuel Gallegos, David M. Soules, Philippe Lognonné, W. Bruce Banerdt, Jeffrey W. Umland

    We report on the development of a passive sorption pump, capable of maintaining high-vacuum conditions in the InSight seismometer throughout the duration of any extended mission. The adsorber material is a novel zeolite-loaded aerogel (ZLA) composite, which consists of fine zeolite particles homogeneously dispersed throughout a porous silica network. The outgassing species within the SEIS evacuated container were analyzed and the outgassing rate was estimated by different methods. The results were used to optimize the ZLA composition to adsorb the outgassing constituents, dominated by water, while minimizing the SEIS bakeout constraints. The InSight ZLA composite additionally facilitated substantial CO2 adsorption capabilities for risk mitigation against external leaks in Mars atmosphere. To comply with the stringent particle requirements, the ZLA getters were packaged in sealed containers, open to the SEIS interior through \(1~\upmu\mbox{m}\)-size pore filters. Results from experimental validation and verification tests of the packaged getters are presented. The pressure forecast based on these data, corroborated by rudimentary in situ pressure measurements, infer SEIS operational pressures not exceeding \(10^{-5}~\mbox{mbar}\) throughout the mission.

  • X-Ray Spectroscopy of Galaxy Clusters: Beyond the CIE Modeling
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-10-02
    Liyi Gu, Irina Zhuravleva, Eugene Churazov, Frits Paerels, Jelle Kaastra, Hiroya Yamaguchi

    X-ray spectra of galaxy clusters are dominated by the thermal emission from the hot intracluster medium. In some cases, besides the thermal component, spectral models require additional components associated, e.g., with resonant scattering and charge exchange. The latter produces mostly underluminous fine spectral features. Detection of the extra components therefore requires high spectral resolution. The upcoming X-ray missions will provide such high resolution, and will allow spectroscopic diagnostics of clusters beyond the current simple thermal modeling. A representative science case is resonant scattering, which produces spectral distortions of the emission lines from the dominant thermal component. Accounting for the resonant scattering is essential for accurate abundance and gas motion measurements of the ICM. The high resolution spectroscopy might also reveal/corroborate a number of new spectral components, including the excitation by non-thermal electrons, the deviation from ionization equilibrium, and charge exchange from surface of cold gas clouds in clusters. Apart from detecting new features, future high resolution spectroscopy will also enable a much better measurement of the thermal component. Accurate atomic database and appropriate modeling of the thermal spectrum are therefore needed for interpreting the data.

  • Atmospheric Science with InSight
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-10-02
    Aymeric Spiga, Don Banfield, Nicholas A. Teanby, François Forget, Antoine Lucas, Balthasar Kenda, Jose Antonio Rodriguez Manfredi, Rudolf Widmer-Schnidrig, Naomi Murdoch, Mark T. Lemmon, Raphaël F. Garcia, Léo Martire, Özgür Karatekin, Sébastien Le Maistre, Bart Van Hove, Véronique Dehant, Philippe Lognonné, Nils Mueller, Ralph Lorenz, David Mimoun, Sébastien Rodriguez, Éric Beucler, Ingrid Daubar, Matthew P. Golombek, Tanguy Bertrand, Yasuhiro Nishikawa, Ehouarn Millour, Lucie Rolland, Quentin Brissaud, Taichi Kawamura, Antoine Mocquet, Roland Martin, John Clinton, Éléonore Stutzmann, Tilman Spohn, Suzanne Smrekar, William B. Banerdt

    In November 2018, for the first time a dedicated geophysical station, the InSight lander, will be deployed on the surface of Mars. Along with the two main geophysical packages, the Seismic Experiment for Interior Structure (SEIS) and the Heat-Flow and Physical Properties Package (HP3), the InSight lander holds a highly sensitive pressure sensor (PS) and the Temperature and Winds for InSight (TWINS) instrument, both of which (along with the InSight FluxGate (IFG) Magnetometer) form the Auxiliary Sensor Payload Suite (APSS). Associated with the RADiometer (RAD) instrument which will measure the surface brightness temperature, and the Instrument Deployment Camera (IDC) which will be used to quantify atmospheric opacity, this will make InSight capable to act as a meteorological station at the surface of Mars. While probing the internal structure of Mars is the primary scientific goal of the mission, atmospheric science remains a key science objective for InSight. InSight has the potential to provide a more continuous and higher-frequency record of pressure, air temperature and winds at the surface of Mars than previous in situ missions. In the paper, key results from multiscale meteorological modeling, from Global Climate Models to Large-Eddy Simulations, are described as a reference for future studies based on the InSight measurements during operations. We summarize the capabilities of InSight for atmospheric observations, from profiling during Entry, Descent and Landing to surface measurements (pressure, temperature, winds, angular momentum), and the plans for how InSight’s sensors will be used during operations, as well as possible synergies with orbital observations. In a dedicated section, we describe the seismic impact of atmospheric phenomena (from the point of view of both “noise” to be decorrelated from the seismic signal and “signal” to provide information on atmospheric processes). We discuss in this framework Planetary Boundary Layer turbulence, with a focus on convective vortices and dust devils, gravity waves (with idealized modeling), and large-scale circulations. Our paper also presents possible new, exploratory, studies with the InSight instrumentation: surface layer scaling and exploration of the Monin-Obukhov model, aeolian surface changes and saltation / lifing studies, and monitoring of secular pressure changes. The InSight mission will be instrumental in broadening the knowledge of the Martian atmosphere, with a unique set of measurements from the surface of Mars.

  • The OSIRIS-REx Spacecraft and the Touch-and-Go Sample Acquisition Mechanism (TAGSAM)
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-09-20
    E. B. Bierhaus, B. C. Clark, J. W. Harris, K. S. Payne, R. D. Dubisher, D. W. Wurts, R. A. Hund, R. M. Kuhns, T. M. Linn, J. L. Wood, A. J. May, J. P. Dworkin, E. Beshore, D. S. Lauretta, the OSIRIS-REx Team

    The Origins, Spectral-Interpretation, Resource-Identification, Security and Regolith-Explorer (OSIRIS-REx) spacecraft supports all aspects of the mission science objectives, from extensive remote sensing at the asteroid Bennu, to sample collection and return to Earth. In general, the success of planetary missions requires the collection, return, and analysis of data, which in turn depends on the successful operation of instruments and the host spacecraft. In the case of OSIRIS-REx, a sample-return mission, the spacecraft must also support the acquisition, safe stowage, and return of the sample. The target asteroid is Bennu, a B-class near-Earth asteroid roughly 500 m diameter. The Lockheed Martin-designed and developed OSIRIS-REx spacecraft draws significant heritage from previous missions and features the Touch-and-Go-Sample-Acquisition-Mechanism, or TAGSAM, to collect sample from the surface of Bennu. Lockheed Martin developed TAGSAM as a novel, simple way to collect samples on planetary bodies. During short contact with the asteroid surface, TAGSAM releases curation-grade nitrogen gas, mobilizing the surface regolith into a collection chamber. The contact surface of TAGSAM includes “contact pads”, which are present to collect surface grains that have been subject to space weathering. Extensive 1-g laboratory testing, “reduced-gravity” testing (via parabolic flights on an airplane), and analysis demonstrate that TAGSAM will collect asteroid material in nominal conditions, and a variety of off-nominal conditions, such as the presence of large obstacles under the TAGSAM sampling head, or failure in the sampling gas firing. TAGSAM, and the spacecraft support of the instruments, are central to the success of the mission.

  • Presolar Isotopic Signatures in Meteorites and Comets: New Insights from the Rosetta Mission to Comet 67P/Churyumov–Gerasimenko
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-09-06
    Peter Hoppe, Martin Rubin, Kathrin Altwegg

    Comets are considered the most primitive planetary bodies in our Solar System, i.e., they should have best preserved the solid components of the matter from which our Solar System formed. ESA’s recent Rosetta mission to Jupiter family comet 67P/Churyumov–Gerasimenko (67P/CG) has provided a wealth of isotope data which expanded the existing data sets on isotopic compositions of comets considerably. In this paper we review our current knowledge on the isotopic compositions of H, C, N, O, Si, S, Ar, and Xe in primitive Solar System materials studied in terrestrial laboratories and how the Rosetta data acquired with the ROSINA (Rosetta Orbiter Sensor for Ion and Neutral Analysis) and COSIMA (COmetary Secondary Ion Mass Analyzer) mass spectrometer fit into this picture. The H, Si, S, and Xe isotope data of comet 67P/CG suggest that this comet might be particularly primitive and might have preserved large amounts of unprocessed presolar matter. We address the question whether the refractory Si component of 67P/CG contains a presolar isotopic fingerprint from a nearby Type II supernova (SN) and discuss to which extent C and O isotope anomalies originating from presolar grains should be observable in dust from 67P/CG. Finally, we explore whether the isotopic fingerprint of a potential late SN contribution to the formation site of 67P/CG in the solar nebula can be seen in the volatile component of 67P/CG.

  • The Color Cameras on the InSight Lander
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-08-29
    J. N. Maki, M. Golombek, R. Deen, H. Abarca, C. Sorice, T. Goodsall, M. Schwochert, M. Lemmon, A. Trebi-Ollennu, W. B. Banerdt

    The NASA Mars InSight lander was successfully launched from Earth in May 2018 and is scheduled to land on Mars in November 2018. The key objective of the InSight mission is to investigate the interior structure and processes of Mars using a seismometer and heat flow probe that must first be placed onto the Martian surface by a robotic arm. The lander is equipped with two cameras to assist in this instrument deployment task. The Instrument Deployment Camera (IDC) is mounted to the lander robotic arm and will acquire images of the lander and surrounding terrain before, during, and after the instrument deployment activities. The IDC has a field of view (FOV) of \(45^{\circ} \times45^{\circ}\) and an angular resolution of 0.82 mrad/pixel at the center of the image. The Instrument Context Camera (ICC) is mounted to the lander and will acquire wide-angle views of the instrument deployment activities. The ICC has a FOV of \(124^{\circ} \times124^{\circ}\) and an angular FOV of 2.1 mrad/pixel at the center of the image. The IDC and ICC cameras are flight spare engineering cameras from the Mars Science Laboratory (MSL) mission. The InSight project upgraded the inherited cameras from single-channel greyscale to red/green/blue (RGB) color by replacing the detector with a Bayer-pattern version of the same \(1024~\mbox{pixel} \times1024~\mbox{pixel}\) detector. Stereo IDC image pairs, acquired by moving the arm between images, are critical for characterizing the topography of the instrument deployment workspace, a \(4~\mbox{meter} \times 6~\mbox{meter}\) area located in front of the lander. Images from the cameras are processed using software from previous Mars surface missions, with several new image products developed for InSight to support instrument placement activities. This paper provides a brief description of the IDC/ICC hardware and related image processing.

  • A Pre-Landing Assessment of Regolith Properties at the InSight Landing Site
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-08-23
    Paul Morgan, Matthias Grott, Brigitte Knapmeyer-Endrun, Matt Golombek, Pierre Delage, Philippe Lognonné, Sylvain Piqueux, Ingrid Daubar, Naomi Murdoch, Constantinos Charalambous, William T. Pike, Nils Müller, Axel Hagermann, Matt Siegler, Roy Lichtenheldt, Nick Teanby, Sharon Kedar

    This article discusses relevant physical properties of the regolith at the Mars InSight landing site as understood prior to landing of the spacecraft. InSight will land in the northern lowland plains of Mars, close to the equator, where the regolith is estimated to be \(\geq3\mbox{--}5~\mbox{m}\) thick. These investigations of physical properties have relied on data collected from Mars orbital measurements, previously collected lander and rover data, results of studies of data and samples from Apollo lunar missions, laboratory measurements on regolith simulants, and theoretical studies. The investigations include changes in properties with depth and temperature. Mechanical properties investigated include density, grain-size distribution, cohesion, and angle of internal friction. Thermophysical properties include thermal inertia, surface emissivity and albedo, thermal conductivity and diffusivity, and specific heat. Regolith elastic properties not only include parameters that control seismic wave velocities in the immediate vicinity of the Insight lander but also coupling of the lander and other potential noise sources to the InSight broadband seismometer. The related properties include Poisson’s ratio, P- and S-wave velocities, Young’s modulus, and seismic attenuation. Finally, mass diffusivity was investigated to estimate gas movements in the regolith driven by atmospheric pressure changes. Physical properties presented here are all to some degree speculative. However, they form a basis for interpretation of the early data to be returned from the InSight mission.

  • The DREAMS Experiment Onboard the Schiaparelli Module of the ExoMars 2016 Mission: Design, Performances and Expected Results
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-08-20
    F. Esposito, S. Debei, C. Bettanini, C. Molfese, I. Arruego Rodríguez, G. Colombatti, A.-M. Harri, F. Montmessin, C. Wilson, A. Aboudan, P. Schipani, L. Marty, F. J. Álvarez, V. Apestigue, G. Bellucci, J.-J. Berthelier, J. R. Brucato, S. B. Calcutt, S. Chiodini, F. Cortecchia, F. Cozzolino, F. Cucciarrè, N. Deniskina, G. Déprez, G. Di Achille, F. Ferri, F. Forget, G. Franzese, E. Friso, M. Genzer, R. Hassen-Kodja, H. Haukka, M. Hieta, J. J. Jiménez, J.-L. Josset, H. Kahanpää, O. Karatekin, G. Landis, L. Lapauw, R. Lorenz, J. Martinez-Oter, V. Mennella, D. Möhlmann, D. Moirin, R. Molinaro, T. Nikkanen, E. Palomba, M. R. Patel, J.-P. Pommereau, C. I. Popa, S. Rafkin, P. Rannou, N. O. Renno, J. Rivas, W. Schmidt, E. Segato, S. Silvestro, A. Spiga, D. Toledo, R. Trautner, F. Valero, L. Vázquez, F. Vivat, O. Witasse, M. Yela, R. Mugnuolo, E. Marchetti, S. Pirrotta

    The first of the two missions foreseen in the ExoMars program was successfully launched on 14th March 2016. It included the Trace Gas Orbiter and the Schiaparelli Entry descent and landing Demonstrator Module. Schiaparelli hosted the DREAMS instrument suite that was the only scientific payload designed to operate after the touchdown. DREAMS is a meteorological station with the capability of measuring the electric properties of the Martian atmosphere. It was a completely autonomous instrument, relying on its internal battery for the power supply. Even with low resources (mass, energy), DREAMS would be able to perform novel measurements on Mars (atmospheric electric field) and further our understanding of the Martian environment, including the dust cycle. DREAMS sensors were designed to operate in a very dusty environment, because the experiment was designed to operate on Mars during the dust storm season (October 2016 in Meridiani Planum). Unfortunately, the Schiaparelli module failed part of the descent and the landing and crashed onto the surface of Mars. Nevertheless, several seconds before the crash, the module central computer switched the DREAMS instrument on, and sent back housekeeping data indicating that the DREAMS sensors were performing nominally. This article describes the instrument in terms of scientific goals, design, working principle and performances, as well as the results of calibration and field tests. The spare model is mature and available to fly in a future mission.

  • Venus Atmospheric Thermal Structure and Radiative Balance
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-08-13
    Sanjay S. Limaye, Davide Grassi, Arnaud Mahieux, Alessandra Migliorini, Silvia Tellmann, Dmitrij Titov

    From the discovery that Venus has an atmosphere during the 1761 transit by M. Lomonosov to the current exploration of the planet by the Akatsuki orbiter, we continue to learn about the planet’s extreme climate and weather. This chapter attempts to provide a comprehensive but by no means exhaustive review of the results of the atmospheric thermal structure and radiative balance since the earlier works published in Venus and Venus II books from recent spacecraft and Earth based investigations and summarizes the gaps in our current knowledge. There have been no in-situ measurements of the deep Venus atmosphere since the flights of the two VeGa balloons and landers in 1985 (Sagdeev et al., Science 231:1411–1414, 1986). Thus, most of the new information about the atmospheric thermal structure has come from different remote sensing (Earth based and spacecraft) techniques using occultations (solar infrared, stellar ultraviolet and orbiter radio occultations), spectroscopy and microwave, short wave and thermal infrared emissions. The results are restricted to altitudes higher than about 40 km, except for one investigation of the near surface static stability inferred by Meadows and Crisp (J. Geophys. Res. 101:4595–4622, 1996) from 1 \(\upmu\)m observations from Earth. Little information about the lower atmospheric structure is possible below about 40 km altitude from radio occultations due to large bending angles. The gaps in our knowledge include spectral albedo variations over time, vertical variation of the bulk composition of the atmosphere (mean molecular weight), the identity, properties and abundances of absorbers of incident solar radiation in the clouds. The causes of opacity variations in the nightside cloud cover and vertical gradients in the deep atmosphere bulk composition and its impact on static stability are also in need of critical studies. The knowledge gaps and questions about Venus and its atmosphere provide the incentive for obtaining the necessary measurements to understand the planet, which can provide some clues to learn about terrestrial exoplanets.

  • The Rotation and Interior Structure Experiment on the InSight Mission to Mars
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-08-09
    William M. Folkner, Véronique Dehant, Sébastien Le Maistre, Marie Yseboodt, Attilio Rivoldini, Tim Van Hoolst, Sami W. Asmar, Matthew P. Golombek

    The Rotation and Interior Structure Experiment (RISE) on-board the InSight mission will use the lander’s X-band (8 GHz) radio system in combination with tracking stations of the NASA Deep Space Network (DSN) to determine the rotation of Mars. RISE will measure the nutation of the Martian spin axis, detecting for the first time the effect of the liquid core of Mars and providing in turn new constraints on the core radius and density. RISE will also measure changes in the rotation rate of Mars on seasonal time-scales thereby constraining the atmospheric angular momentum budget. Finally, RISE will provide a superb tie between the cartographic and inertial reference frames. This paper describes the RISE scientific objectives and measurements, and provides the expected results of the experiment.

  • Transforming Dust to Planets
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-08-09
    Francis Nimmo, Katherine Kretke, Shigeru Ida, Soko Matsumura, Thorsten Kleine

    We review recent progress in understanding how nebular dust and gas are converted into the planets of the present-day solar system, focusing particularly on the “Grand Tack” and pebble accretion scenarios. The Grand Tack can explain the observed division of the solar system into two different isotopic “flavours”, which are found in both differentiated and undifferentiated meteorites. The isotopic chronology inferred for the development of these two “flavours” is consistent with expectations of gas-giant growth and nebular gas loss timescales. The Grand Tack naturally makes a small Mars and a depleted, dynamically-excited and compositionally mixed asteroid belt (as observed); it builds both Mars and the Earth rapidly, which is consistent with the isotopically-inferred growth timescale of the former, but not the latter. Pebble accretion can explain the rapid required growth of Jupiter and Saturn, and the number of Kuiper Belt binaries, but requires specific assumptions to explain the relatively protracted growth timescale of Earth. Pure pebble accretion cannot explain the mixing observed in the asteroid belt, the fast proto-Earth spin rate, or the tilt of Uranus. No current observation requires pebble accretion to have operated in the inner solar system, but the thermal and compositional consequences of pebble accretion have yet to be explored in detail.

  • Global Non-Potential Magnetic Models of the Solar Corona During the March 2015 Eclipse
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-08-08
    Anthony R. Yeates, Tahar Amari, Ioannis Contopoulos, Xueshang Feng, Duncan H. Mackay, Zoran Mikić, Thomas Wiegelmann, Joseph Hutton, Christopher A. Lowder, Huw Morgan, Gordon Petrie, Laurel A. Rachmeler, Lisa A. Upton, Aurelien Canou, Pierre Chopin, Cooper Downs, Miloslav Druckmüller, Jon A. Linker, Daniel B. Seaton, Tibor Török

    Seven different models are applied to the same problem of simulating the Sun’s coronal magnetic field during the solar eclipse on 2015 March 20. All of the models are non-potential, allowing for free magnetic energy, but the associated electric currents are developed in significantly different ways. This is not a direct comparison of the coronal modelling techniques, in that the different models also use different photospheric boundary conditions, reflecting the range of approaches currently used in the community. Despite the significant differences, the results show broad agreement in the overall magnetic topology. Among those models with significant volume currents in much of the corona, there is general agreement that the ratio of total to potential magnetic energy should be approximately 1.4. However, there are significant differences in the electric current distributions; while static extrapolations are best able to reproduce active regions, they are unable to recover sheared magnetic fields in filament channels using currently available vector magnetogram data. By contrast, time-evolving simulations can recover the filament channel fields at the expense of not matching the observed vector magnetic fields within active regions. We suggest that, at present, the best approach may be a hybrid model using static extrapolations but with additional energization informed by simplified evolution models. This is demonstrated by one of the models.

  • Dust Phenomena Relating to Airless Bodies
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-08-07
    J. R. Szalay, A. R. Poppe, J. Agarwal, D. Britt, I. Belskaya, M. Horányi, T. Nakamura, M. Sachse, F. Spahn

    Airless bodies are directly exposed to ambient plasma and meteoroid fluxes, making them characteristically different from bodies whose dense atmospheres protect their surfaces from such fluxes. Direct exposure to plasma and meteoroids has important consequences for the formation and evolution of planetary surfaces, including altering chemical makeup and optical properties, generating neutral gas and/or dust exospheres, and leading to the generation of circumplanetary and interplanetary dust grain populations. In the past two decades, there have been many advancements in our understanding of airless bodies and their interaction with various dust populations. In this paper, we describe relevant dust phenomena on the surface and in the vicinity of airless bodies over a broad range of scale sizes from \(\sim10^{-3}~\mbox{km}\) to \(\sim10^{3}~\mbox{km}\), with a focus on recent developments in this field.

  • ExoMars 2016 Schiaparelli Module Trajectory and Atmospheric Profiles Reconstruction
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-08-06
    A. Aboudan, G. Colombatti, C. Bettanini, F. Ferri, S. Lewis, B. Van Hove, O. Karatekin, S. Debei

    On 19th October 2016 Schiaparelli module of the ExoMars 2016 mission flew through the Mars atmosphere. After successful entry and descent under parachute, the module failed the last part of the descent and crashed on the Mars surface. Nevertheless the data transmitted in real-time by Schiaparelli during the entry and descent, together with the entry state vector as initial condition, have been used to reconstruct both the trajectory and the profiles of atmospheric density, pressure and temperature along the traversed path.

  • The Heat Flow and Physical Properties Package (HP 3 ) for the InSight Mission
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-08-02
    T. Spohn, M. Grott, S. E. Smrekar, J. Knollenberg, T. L. Hudson, C. Krause, N. Müller, J. Jänchen, A. Börner, T. Wippermann, O. Krömer, R. Lichtenheldt, L. Wisniewski, J. Grygorczuk, M. Fittock, S. Rheershemius, T. Spröwitz, E. Kopp, I. Walter, A. C. Plesa, D. Breuer, P. Morgan, W. B. Banerdt

    The Heat Flow and Physical Properties Package HP3 for the InSight mission will attempt the first measurement of the planetary heat flow of Mars. The data will be taken at the InSight landing site in Elysium planitia (136 ∘E, 5 ∘N) and the uncertainty of the measurement aimed for shall be better than ±5 mW m−2. The package consists of a mechanical hammering device called the “Mole” for penetrating into the regolith, an instrumented tether which the Mole pulls into the ground, a fixed radiometer to determine the surface brightness temperature and an electronic box. The Mole and the tether are housed in a support structure before being deployed. The tether is equipped with 14 platinum resistance temperature sensors to measure temperature differences with a 1-\(\sigma \) uncertainty of 6.5 mK. Depth is determined by a tether length measurement device that monitors the amount of tether extracted from the support structure and a tiltmeter that measures the angle of the Mole axis to the local gravity vector. The Mole includes temperature sensors and heaters to measure the regolith thermal conductivity to better than 3.5% (1-\(\sigma \)) using the Mole as a modified line heat source. The Mole is planned to advance at least 3 m—sufficiently deep to reduce errors from daily surface temperature forcings—and up to 5 m into the martian regolith. After landing, HP3 will be deployed onto the martian surface by a robotic arm after choosing an instrument placement site that minimizes disturbances from shadows caused by the lander and the seismometer. The Mole will then execute hammering cycles, advancing 50 cm into the subsurface at a time, followed by a cooldown period of at least 48 h to allow heat built up during hammering to dissipate. After an equilibrated thermal state has been reached, a thermal conductivity measurement is executed for 24 h. This cycle is repeated until the final depth of 5 m is reached or further progress becomes impossible. The subsequent monitoring phase consists of hourly temperature measurements and lasts until the end of the mission. Model calculations show that the duration of temperature measurement required to sufficiently reduce the error introduced by annual surface temperature forcings is 0.6 martian years for a final depth of 3 m and 0.1 martian years for the target depth of 5 m.

  • Influence of Body Waves, Instrumentation Resonances, and Prior Assumptions on Rayleigh Wave Ellipticity Inversion for Shallow Structure at the InSight Landing Site
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-07-30
    Brigitte Knapmeyer-Endrun, Naomi Murdoch, Balthasar Kenda, Matthew P. Golombek, Martin Knapmeyer, Lars Witte, Nicolas Verdier, Sharon Kedar, Philippe Lognonné, William B. Banerdt

    Based on an updated model of the regolith’s elastic properties, we simulate the ambient vibrations background wavefield recorded by InSight’s Seismic Experiment for Interior Structure (SEIS) on Mars to characterise the influence of the regolith and invert SEIS data for shallow subsurface structure. By approximately scaling the synthetics based on seismic signals of a terrestrial dust devil, we find that the high-frequency atmospheric background wavefield should be above the self-noise of SEIS’s SP sensors, even if the signals are not produced within 100–200 m of the station. We compare horizontal-to-vertical spectral ratios and Rayleigh wave ellipticity curves for a surface-wave based simulation on the one hand with synthetics explicitly considering body waves on the other hand and do not find any striking differences. Inverting the data, we find that the results are insensitive to assumptions on density. By contrast, assumptions on the velocity range in the upper-most layer have a strong influence on the results also at larger depth. Wrong assumptions can lead to results far from the true model in this case. Additional information on the general shape of the curve, i.e. single or dual peak, could help to mitigate this effect, even if it cannot directly be included into the inversion. We find that the ellipticity curves can provide stronger constraints on the minimum thickness and velocity of the second layer of the model than on the maximum values. We also consider the effect of instrumentation resonances caused by the lander flexible modes, solar panels, and the SEIS levelling system. Both the levelling system resonances and the lander flexible modes occur at significantly higher frequencies than the expected structural response, i.e. above 35 Hz and 20 Hz, respectively. While the lander and solar panel resonances might be too weak in amplitude to be recorded by SEIS, the levelling system resonances will show up clearly in horizontal spectra, the H/V and ellipticity curves. They are not removed by trying to extract only Rayleigh-wave dominated parts of the data. However, they can be distinguished from any subsurface response by their exceptionally low damping ratios of 1% or less as determined by random decrement analysis. The same applies to lander-generated signals observed in actual data from a Moon analogue experiment, so we expect this analysis will be useful in identifying instrumentation resonances in SEIS data.

  • InSight Mars Lander Robotics Instrument Deployment System
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-07-30
    A. Trebi-Ollennu, Won Kim, Khaled Ali, Omair Khan, Cristina Sorice, Philip Bailey, Jeffrey Umland, Robert Bonitz, Constance Ciarleglio, Jennifer Knight, Nicolas Haddad, Kerry Klein, Scott Nowak, Daniel Klein, Nicholas Onufer, Kenneth Glazebrook, Brad Kobeissi, Enrique Baez, Felix Sarkissian, Menooa Badalian, Hallie Abarca, Robert G. Deen, Jeng Yen, Steven Myint, Justin Maki, Ali Pourangi, Jonathan Grinblat, Brian Bone, Noah Warner, Jaime Singer, Joan Ervin, Justin Lin

    The InSight Mars Lander is equipped with an Instrument Deployment System (IDS) and science payload with accompanying auxiliary peripherals mounted on the Lander. The InSight science payload includes a seismometer (SEIS) and Wind and Thermal Shield (WTS), heat flow probe (Heat Flow and Physical Properties Package, HP3) and a precision tracking system (RISE) to measure the size and state of the core, mantle and crust of Mars. The InSight flight system is a close copy of the Mars Phoenix Lander and comprises a Lander, cruise stage, heatshield and backshell. The IDS comprises an Instrument Deployment Arm (IDA), scoop, five finger “claw” grapple, motor controller, arm-mounted Instrument Deployment Camera (IDC), lander-mounted Instrument Context Camera (ICC), and control software. IDS is responsible for the first precision robotic instrument placement and release of SEIS and HP3 on a planetary surface that will enable scientists to perform the first comprehensive surface-based geophysical investigation of Mars’ interior structure. This paper describes the design and operations of the Instrument Deployment Systems (IDS), a critical subsystem of the InSight Mars Lander necessary to achieve the primary scientific goals of the mission including robotic arm geology and physical properties (soil mechanics) investigations at the Landing site. In addition, we present test results of flight IDS Verification and Validation activities including thermal characterization and InSight 2017 Assembly, Test, and Launch Operations (ATLO), Deployment Scenario Test at Lockheed Martin, Denver, where all the flight payloads were successfully deployed with a balloon gravity offload fixture to compensate for Mars to Earth gravity.

  • Isolation of Seismic Signal from InSight/SEIS-SP Microseismometer Measurements
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-07-30
    J. Hurley, N. Murdoch, N. A. Teanby, N. Bowles, T. Warren, S. B. Calcutt, D. Mimoun, W. T. Pike

    The InSight mission is due to launch in May 2018, carrying a payload of novel instruments designed and tested to probe the interior of Mars whilst deployed directly on the Martian regolith and partially isolated from the Martian environment by the Wind and Thermal Shield. Central to this payload is the seismometry package SEIS consisting of two seismometers, which is supported by a suite of environmental/meteorological sensors (Temperature and Wind Sensor for InSight TWINS; and Auxiliary Payload Sensor Suite APSS). In this work, an optimal estimations inversion scheme which aims to decorrelate the short-period seismometer (SEIS-SP) signal due to seismic activity alone from the environmental signal and random noise is detailed, and tested on both simulated and Viking data. This scheme also applies a module to identify measurements contaminated by Single Event Phenomena (SEP). This scheme will be deployed as the pre-processing pipeline for all SEIS-SP data prior to release to the scientific community for analysis.

  • Water and Volatile Inventories of Mercury, Venus, the Moon, and Mars
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-07-26
    James P. Greenwood, Shun-ichiro Karato, Kathleen E. Vander Kaaden, Kaveh Pahlevan, Tomohiro Usui

    We review the geochemical observations of water, \(\mbox{D}/\mbox{H}\) and volatile element abundances of the inner Solar System bodies, Mercury, Venus, the Moon, and Mars. We focus primarily on the inventories of water in these bodies, but also consider other volatiles when they can inform us about water. For Mercury, we have no data for internal water, but the reducing nature of the surface of Mercury would suggest that some hydrogen may be retained in its core. We evaluate the current knowledge and understanding of venusian water and volatiles and conclude that the venusian mantle was likely endowed with as much water as Earth of which it retains a small but non-negligible fraction. Estimates of the abundance of the Moon’s internal water vary from Earth-like to one to two orders of magnitude more depleted. Cl, K, and Zn isotope anomalies for lunar samples argue that the giant impact left a unique geochemical fingerprint on the Moon, but not the Earth. For Mars, an early magma ocean likely generated a thick crust; this combined with a lack of crustal recycling mechanisms would have led to early isolation of the Martian mantle from later delivery of water and volatiles from surface reservoirs or late accretion. The abundance estimates of Martian mantle water are similar to those of the terrestrial mantle, suggesting some similarities in the water and volatile inventories for the terrestrial planets and the Moon.

  • Cosmological Distance Indicators
    Space Sci. Rev. (IF 9.327) Pub Date : 2018-07-25
    Sherry H. Suyu, Tzu-Ching Chang, Frédéric Courbin, Teppei Okumura

    We review three distance measurement techniques beyond the local universe: (1) gravitational lens time delays, (2) baryon acoustic oscillation (BAO), and (3) HI intensity mapping. We describe the principles and theory behind each method, the ingredients needed for measuring such distances, the current observational results, and future prospects. Time-delays from strongly lensed quasars currently provide constraints on \(H_{0}\) with \(<4\%\) uncertainty, and with \(1\%\) within reach from ongoing surveys and efforts. Recent exciting discoveries of strongly lensed supernovae hold great promise for time-delay cosmography. BAO features have been detected in redshift surveys up to \(z\lesssim0.8\) with galaxies and \(z\sim2\) with Ly-\(\alpha\) forest, providing precise distance measurements and \(H_{0}\) with \(<2\%\) uncertainty in flat \(\Lambda\)CDM. Future BAO surveys will probe the distance scale with percent-level precision. HI intensity mapping has great potential to map BAO distances at \(z\sim0.8\) and beyond with precisions of a few percent. The next years ahead will be exciting as various cosmological probes reach \(1\%\) uncertainty in determining \(H_{0}\), to assess the current tension in \(H_{0}\) measurements that could indicate new physics.

Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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