Description: Publication date: January 2017 Source: Planetary and Space Science, Volume 135

Description: Publication date: Available online 30 December 2016 Source: Planetary and Space Science Author(s): D. Koschny, E. Drolshagen, S. Drolshagen, J. Kretschmer, T. Ott, G. Drolshagen, B. Poppe We have developed a new method to determine flux densities of meteoroids using optical double-station meteor observations. It is based on the assumption that the velocity distribution is constant for all mass bins. By comparing the observed velocity distribution with a model distribution we determine de-biasing factors to correct for meteors too slow to emit a detectable amount of light. We use this method to correct a dataset of about 20000 double-station meteoroids detected over a period of about 3.5 years with the Canary Island Long-Baseline Observatory (CILBO). The resulting cumulative flux density has a slope comparable to the model of Grün et al. (1985). The largest uncertainty is the luminous efficiency. Depending on which values for the luminous efficiency are assumed, the mass estimate deviates by about one to 1.5 orders of magnitude. Using the luminous efficiencies derived by Weryk et al. (2013) results in an excellent agreement of our data with the Grün data.

Description: Publication date: Available online 24 December 2016 Source: Planetary and Space Science Author(s): Adrien Deliège, Thomas Kleyntssens, Samuel Nicolay This work examines the scaling properties of Mars topography through a wavelet-based formalism. We conduct exhaustive one-dimensional (both longitudinal and latitudinal) and two-dimensional studies based on Mars Orbiter Laser Altimeter (MOLA) data using the multifractal formalism called Wavelet Leaders Method (WLM). This approach shows that a scale break occurs at approximately 15 km, giving two scaling regimes in both 1D and 2D cases. At small scales, these topographic profiles mostly display a monofractal behavior while a switch to multifractality is observed in several areas at larger scales. The scaling exponents extracted from this framework tend to be greater at small scales. In the 1D context, these observations are in agreement with previous works and thus suggest that the WLM is well-suited for examining scaling properties of topographic fields. Moreover, the 2D analysis is the first such complete study to our knowledge. It gives both a local and global insight on the scaling regimes of the surface of Mars and allows to exhibit the link between the scaling exponents and several famous features of the Martian topography. These results may be used as a solid basis for further investigations of the scaling laws of the Red planet and show that the WLM could be used to perform systematic analyses of the surface roughness of other celestial bodies.

Description: Publication date: Available online 23 December 2016 Source: Planetary and Space Science Author(s): Tadeusz Jan Jopek, Małgorzata Bronikowska Probability of coincidental clustering among orbits of comets, asteroids and meteoroids depends on many factors like: the size of the orbital sample searched for clusters or the size of the identified group, it is different for groups of 2,3,4,… members. Probability of coincidental clustering is assessed by the numerical simulation, therefore, it depends also on the method used for the synthetic orbits generation. We have tested the impact of some of these factors. For a given size of the orbital sample we have assessed probability of random pairing among several orbital populations of different sizes. We have found how these probabilities vary with the size of the orbital samples. Finally, keeping fixed size of the orbital sample we have shown that the probability of random pairing can be significantly different for the orbital samples obtained by different observation techniques. Also for the user convenience we have obtained several formulae which, for given size of the orbital sample can be used to calculate the similarity threshold corresponding to the small value of the probability of coincidental similarity among two orbits.

Description: Publication date: Available online 22 December 2016 Source: Planetary and Space Science Author(s): José M. Madiedo This work analyzes a meteor spectroscopy survey called SMART (Spectroscopy of Meteoroids in the Atmosphere by means of Robotic Technologies), which is being conducted since 2006. In total, 55 spectrographs have been deployed at 10 different locations in Spain with the aim to obtain information about the chemical nature of meteoroids ablating in the atmosphere. The main improvements in the hardware and the software developed in the framework of this project are described, and some results obtained by these automatic devices are also discussed.

Description: Publication date: Available online 21 December 2016 Source: Planetary and Space Science Author(s): Piero D'Incecco, Nils Mueller, Jörn Helbert, Mario D'Amore From 2006 until 2014 the ESA Venus Express probe observed the atmosphere and surface of the Earth's twin planet. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) has provided data that indicate the occurrence of recent volcanic activity on Venus. We selected the eastern flank of Idunn Mons - Imdr Regio's single large volcano – as the study area, since it was identified in VIRTIS data as one of the regions with relatively high values of thermal emissivity at 1 μm wavelength. Using the capabilities of specific techniques developed in the Planetary Emissivity Laboratory group at DLR in Berlin, our study intends to identify location and extent of the sources of such anomalies, thus the lava flows responsible for the relatively high emissivity observed by VIRTIS over the eastern flank of Idunn Mons. We map the lava flow units on the top and eastern flank of Idunn Mons, varying the values of simulated 1 μm emissivity assigned to the mapped units. For each configuration we calculate the total RMS error in comparison with the VIRTIS observations. In the best-fit configuration, the flank lava flows are characterized by high values of 1 μm simulated emissivity. Hence, the lava flow units on the eastern flank on Idunn Mons are likely responsible for the relatively high 1 μm emissivity anomalies observed by VIRTIS. This result is supported by the reconstructed post-eruption stratigraphy, displaying the relative dating of the mapped lava flows, that is independent of the 1 μm emissivity modeling. Values of average microwave emissivity extracted from the lava flow units range around the global mean, which is consistent with dry basalts.

Description: Publication date: Available online 18 December 2016 Source: Planetary and Space Science Author(s): G. Abdellaoui, S. Abe, A. Acheli, J.H. Adams, S. Ahmad, A. Ahriche, J.-N. Albert, D. Allard, G. Alonso, L. Anchordoqui, V. Andreev, A. Anzalone, W. Aouimeur, Y. Arai, N. Arsene, K. Asano, R. Attallah, H. Attoui, M. Ave Pernas, S. Bacholle, M. Bakiri, P. Baragatti, P. Barrillon, S. Bartocci, T. Batsch, J. Bayer, R. Bechini, T. Belenguer, R. Bellotti, A. Belov, K. Belov, B. Benadda, K. Benmessai, A.A. Berlind, M. Bertaina, P.L. Biermann, S. Biktemerova, F. Bisconti, N. Blanc, J. Błȩcki, S. Blin-Bondil, P. Bobik, M. Bogomilov, M. Bonamente, R. Boudaoud, E. Bozzo, M.S. Briggs, A. Bruno, K.S. Caballero, F. Cafagna, D. Campana, J.-N. Capdevielle, F. Capel, A. Caramete, L. Caramete, P. Carlson, R. Caruso, M. Casolino, C. Cassardo, A. Castellina, G. Castellini, C. Catalano, O. Catalano, A. Cellino, M. Chikawa, G. Chiritoi, M.J. Christl, V. Connaughton, L. Conti, G. Cordero, H.J. Crawford, R. Cremonini, S. Csorna, S. Dagoret-Campagne, C. De Donato, C. de la Taille, C. De Santis, L. del Peral, M. Di Martino, T. Djemil, S.A. Djenas, F. Dulucq, M. Dupieux, I. Dutan, A. Ebersoldt, T. Ebisuzaki, R. Engel, J. Eser, K. Fang, F. Fenu, S. Fernández-González, J. Fernández-Soriano, S. Ferrarese, D. Finco, M. Flamini, C. Fornaro, M. Fouka, A. Franceschi, S. Franchini, C. Fuglesang, J. Fujimoto, M. Fukushima, P. Galeotti, E. García-Ortega, G. Garipov, E. Gascón, J. Geary, G. Gelmini, J. Genci, G. Giraudo, M. Gonchar, C. González Alvarado, P. Gorodetzky, F. Guarino, R. Guehaz, A. Guzmán, Y. Hachisu, M. Haiduc, B. Harlov, A. Haungs, J. Hernández Carretero, W. Hidber, K. Higashide, D. Ikeda, H. Ikeda, N. Inoue, S. Inoue, F. Isgrò, Y. Itow, T. Jammer, E. Joven, E.G. Judd, A. Jung, J. Jochum, F. Kajino, T. Kajino, S. Kalli, I. Kaneko, D. Kang, F. Kanouni, Y. Karadzhov, J. Karczmarczyk, M. Karus, K. Katahira, K. Kawai, Y. Kawasaki, A. Kedadra, H. Khales, B.A. Khrenov, Jeong-Sook Kim, Soon-Wook Kim, Sug-Whan Kim, M. Kleifges, P.A. Klimov, D. Kolev, I. Kreykenbohm, K. Kudela, Y. Kurihara, A. Kusenko, E. Kuznetsov, M. Lacombe, C. Lachaud, H. Lahmar, F. Lakhdari, O. Larsson, J. Lee, J. Licandro, H. Lim, L. López Campano, M.C. Maccarone, S. Mackovjak, M. Mahdi, D. Maravilla, L. Marcelli, J.L. Marcos, A. Marini, K. Martens, Y. Martín, O. Martinez, G. Masciantonio, K. Mase, R. Matev, J.N. Matthews, N. Mebarki, G. Medina-Tanco, L. Mehrad, M.A. Mendoza, A. Merino, T. Mernik, J. Meseguer, S. Messaoud, O. Micu, J. Mimouni, H. Miyamoto, Y. Miyazaki, Y. Mizumoto, G. Modestino, A. Monaco, D. Monnier-Ragaigne, J.A. Morales de los Ríos, C. Moretto, V.S. Morozenko, B. Mot, T. Murakami, B. Nadji, M. Nagano, M. Nagata, S. Nagataki, T. Nakamura, T. Napolitano, A. Nardelli, D. Naumov, R. Nava, A. Neronov, K. Nomoto, T. Nonaka, T. Ogawa, S. Ogio, H. Ohmori, A.V. Olinto, P. Orleański, G. Osteria, W. Painter, M.I. Panasyuk, B. Panico, E. Parizot, I.H. Park, H.W. Park, B. Pastircak, T. Patzak, T. Paul, C. Pennypacker, M. Perdichizzi, I. Pérez-Grande, F. Perfetto, T. Peter, P. Picozza, T. Pierog, S. Pindado, L.W. Piotrowski, S. Piraino, L. Placidi, Z. Plebaniak, S. Pliego, A. Pollini, E.M. Popescu, P. Prat, G. Prévôt, H. Prieto, M. Putis, J. Rabanal, A.A. Radu, M. Rahmani, P. Reardon, M. Reyes, M. Rezazadeh, M. Ricci, M.D. Rodríguez Frías, F. Ronga, M. Roth, H. Rothkaehl, G. Roudil, I. Rusinov, M. Rybczyński, M.D. Sabau, G. Sáez Cano, H. Sagawa, Z. Sahnoune, A. Saito, N. Sakaki, M. Sakata, H. Salazar, J.C. Sanchez, J.L. Sánchez, A. Santangelo, L. Santiago Crúz, A. Sanz-Andrés, M. Sanz Palomino, O. Saprykin, F. Sarazin, H. Sato, M. Sato, T. Schanz, H. Schieler, V. Scotti, A. Segreto, S. Selmane, D. Semikoz, M. Serra, S. Sharakin, T. Shibata, H.M. Shimizu, K. Shinozaki, T. Shirahama, G. Siemieniec-Oziȩbło, J. Sledd, K. Słomińska, A. Sobey, I. Stan, T. Sugiyama, D. Supanitsky, M. Suzuki, B. Szabelska, J. Szabelski, H. Tahi, F. Tajima, N. Tajima, T. Tajima, Y. Takahashi, H. Takami, M. Takeda, Y. Takizawa, M.C. Talai, C. Tenzer, O. Tibolla, L. Tkachev, H. Tokuno, T. Tomida, N. Tone, S. Toscano, M. Traïche, R. Tsenov, Y. Tsunesada, K. Tsuno, T. Tymieniecka, Y. Uchihori, M. Unger, O. Vaduvescu, J.F. Valdés-Galicia, P. Vallania, G. Vankova, C. Vigorito, L. Villaseñor, B. Vlcek, P. von Ballmoos, M. Vrabel, S. Wada, J. Watanabe, S. Watanabe, J. Watts Jr., M. Weber, R. Weigand Muñoz, A. Weindl, T.J. Weiler, T. Wibig, L. Wiencke, M. Wille, J. Wilms, Z. Włodarczyk, T. Yamamoto, Y. Yamamoto, J. Yang, H. Yano, I.V. Yashin, D. Yonetoku, S. Yoshida, R. Young, I.S Zgura, M.Yu. Zotov, A. Zuccaro Marchi We summarize the state of the art of a program of UV observations from space of meteor phenomena, a secondary objective of the JEM-EUSO international collaboration. Our preliminary analysis indicates that JEM-EUSO, taking advantage of its large FOV and good sensitivity, should be able to detect meteors down to absolute magnitude close to 7. This means that JEM-EUSO should be able to record a statistically significant flux of meteors, including both sporadic ones, and events produced by different meteor streams. Being unaffected by adverse weather conditions, JEM-EUSO can also be a very important facility for the detection of bright meteors and fireballs, as these events can be detected even in conditions of very high sky background. In the case of bright events, moreover, exhibiting some persistence of the meteor train, preliminary simulations show that it should be possible to exploit the motion of the ISS itself and derive at least a rough 3D reconstruction of the meteor trajectory. Moreover, the observing strategy developed to detect meteors may also be applied to the detection of nuclearites, exotic particles whose existence has been suggested by some theoretical investigations. Nuclearites are expected to move at higher velocities than meteoroids, and to exhibit a wider range of possible trajectories, including particles moving upward after crossing the Earth. Some pilot studies, including the approved Mini-EUSO mission, a precursor of JEM-EUSO, are currently operational or in preparation. We are doing simulations to assess the performance of Mini-EUSO for meteor studies, while a few meteor events have been already detected using the ground-based facility EUSO-TA.

Description: Publication date: Available online 18 December 2016 Source: Planetary and Space Science Author(s): Xiao-Ping Lu, Wing-Huen Ip, Xiang-Jie Huang, Hai-Bin Zhao Based on the special shape first introduced by Alberto Cellino, which consists of eight ellipsoidal octants with the constraint that adjacent octants must have two identical semi-axes, an efficient algorithm to derive the physical parameters, such as the rotational period, pole orientation, and overall shape from either lightcurves or sparse photometric data of asteroids, is developed by Lu et al. and named as ‘Cellinoid’ shape model. For thoroughly investigating the relationship between the morphology of the synthetic lightcurves generated by the Cellinoid shape and its six semi-axes as well as rotational period and pole, the numerical tests are implemented to compare the synthetic lightcurves generated by three Cellinoid models with different parameters in this article. Furthermore, from the synthetic lightcurves generated by two convex shape models of (6) Hebe and (4179) Toutatis, the inverse process based on Cellinoid shape model is applied to search the best-fit parameters. Especially, for better simulating the real observations, the synthetic lightcurves are generated under the orbit limit of the two asteroids. By comparing the results derived from synthetic lightcurves observed in one apparition and multiple apparitions, the performance of Cellinoid shape model is confirmed and the suggestions for observations are presented. Finally, the whole process is also applied to real observed lightcurves of (433) Eros and the derived results are consistent with the known results.

Description: Publication date: Available online 10 December 2016 Source: Planetary and Space Science Author(s): Alexandra Heffels, Martin Knapmeyer, Jürgen Oberst, Isabel Haase We re-analyzed Apollo 17 Lunar Seismic Profiling Experiment (LSPE) data to improve our knowledge of the subsurface structure of this landing site. We use new geometrically accurate 3-D positions of the seismic equipment deployed by the astronauts, which were previously derived using high-resolution images by Lunar Reconnaissance Orbiter (LRO) in combination with Apollo astronaut photography. These include coordinates of six Explosive Packages (EPs) and four geophone stations. Re-identified P-wave arrival times are used to calculate two- and three-layer seismic velocity models. A strong increase of seismic velocity with depth can be confirmed, in particular, we suggest a more drastic increase than previously thought. For the three-layer model the P-wave velocities were calculated to 285, 580, and 1825 m/s for the uppermost, second, and third layer, respectively, with the boundaries between the layers being at 96 and 773 m depth. When compared with results obtained with previously published coordinates, we find (1) a slightly higher velocity (+ 4 %) for the uppermost layer, and (2) lower P-wave velocities for the second and third layers, representing a decrease of 34 % and 12 % for second and third layer, respectively. Using P-wave arrival time readings of previous studies, we confirm that velocities increase when changing over from old to new coordinates. In the three-layer case, this means using new coordinates alone leads to thinned layers, velocities rise slightly for the uppermost layer and decrease significantly for the layers below.

Description: Publication date: Available online 2 December 2016 Source: Planetary and Space Science Author(s): Navita Sinha, Sudip Nepal, Timothy Kral, Pradeep Kumar Life as we know it requires liquid water and sufficient liquid water is highly unlikely on the surface of present-day Mars. However, according to thermal models there is a possibility of liquid water in the deep subsurface of Mars. Thus, the martian subsurface, where the pressure and temperature is higher, could potentially provide a hospitable environment for a biosphere. Also, methane has been detected in the Mars’ atmosphere. Analogous to Earth’s atmospheric methane, martian methane could also be biological in origin. The carbon and energy sources for methanogenesis in the subsurface of Mars could be available by downwelling of atmospheric CO 2 into the regolith and water-rock reactions such as serpentinization, respectively. Corresponding analogs of the martian subsurface on Earth might be the active sites of serpentinization at depths where methanogenic thermophilic archaea are the dominant species. Methanogens residing in Earth’s hydrothermal environments are usually exposed to a variety of physiological stresses including a wide range of pressures, temperatures, and pHs. Martian geochemical models imply that the pH of probable groundwater varies from 4.96 to 9.13. In this work, we used the thermophilic methanogen, Methanothermobacter wolfeii , which grows optimally at 55 o C. Therefore, a temperature of 55 o C was chosen for these experiments, possibly simulating Mars’ subsurface temperature. A martian geophysical model suggests depth and pressure corresponding to a temperature of 55 o C would be between 1-30 km and 100-3,000 atm respectively. Here, we have simulated Mars deep subsurface pH, pressure, and temperature conditions and have investigated the survivability, growth rate, and morphology of M. wolfeii after exposure to a wide range of pH (5 to 9) and pressure (1 − 1200 atm) at a temperature of 55 o C. Interestingly, in this study we have found that M. wolfeii was able to survive at all the pressures and pHs tested at 55 o C. In order to understand the effect of different pHs and pressures on the metabolic activities of M. wolfeii , we also calculated their growth rate by measuring methane concentration in the headspace gas samples at regular intervals. In acidic conditions, the growth rate (γ) of M. wolfeii increased with the increase in pressure. In neutral and alkaline conditions, the growth rate ( γ) of M. wolfeii initially increased with pressure, but decreased upon further increase of pressure. To investigate the effect of combined pH, pressure, and temperature on the morphology of M. wolfeii , we took phase contrast images of the cells. We did not find any obvious significant alteration in the morphology of M. wolfeii cells. Methanogens, chemolithoautotrophic anaerobic microorganisms, are considered as ideal model microorganisms for Mars. In light of research presented here, we suggest that at least one methanogen, M. wolfeii, could survive in the deep subsurface environment of Mars.