1
|
Feng R, Zhang Y, Liu J, Zhang Y, Li J, Baoyin H. Soft Robotic Perspective and Concept for Planetary Small Body Exploration. Soft Robot 2021; 9:889-899. [PMID: 34939854 DOI: 10.1089/soro.2021.0054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Tens of thousands of planetary small bodies (asteroids, comets, and small moons) are flying beside our Earth with little understanding. Explorers on the surfaces of these bodies, unlike the Lunar or Mars rovers, have only few attempts and no sophisticated solution. Current concerns mainly focus on landing uncertainties and mobility limitations, which soft robots may suitably aid utilizing their compliance and adaptivity. In this study, we present a perspective of designating soft robots for the surface exploration. Based on the lessons from recent space missions and an astronomy survey, we summarize the surface features of typical small bodies and the associated challenges for possible soft robotic design. Different kinds of soft mobile robots are reviewed, whose morphology and locomotion are analyzed for the microgravity, rugged environment. We also propose an alternative to current asteroid hoppers, as a case of applying progress in soft material. Specifically, the structure is a deployable cube whose outer shell is made of shape memory polymer, so that it can achieve morphing and variable stiffness between liftoff and landing phases. Dynamic simulations of the free-fall landing are carried out with a rigid counterpart for comparison. The results show that the soft deployed shell can effectively contribute to dissipating the kinetic energy and attenuating the excessive rebounds.
Collapse
Affiliation(s)
- Ruoyu Feng
- School of Aerospace Engineering, Tsinghua University, Beijing, China
| | - Yu Zhang
- School of Aerospace Engineering, Tsinghua University, Beijing, China
| | - Jinyu Liu
- School of Aerospace Engineering, Tsinghua University, Beijing, China
| | - Yonglong Zhang
- School of Aerospace Engineering, Tsinghua University, Beijing, China
| | - Junfeng Li
- School of Aerospace Engineering, Tsinghua University, Beijing, China
| | - Hexi Baoyin
- School of Aerospace Engineering, Tsinghua University, Beijing, China
| |
Collapse
|
2
|
Kreuzig C, Kargl G, Pommerol A, Knollenberg J, Lethuillier A, Molinski NS, Gilke T, Bischoff D, Feller C, Kührt E, Sierks H, Hänni N, Capelo H, Güttler C, Haack D, Otto K, Kaufmann E, Schweighart M, Macher W, Tiefenbacher P, Gundlach B, Blum J. The CoPhyLab comet-simulation chamber. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:115102. [PMID: 34852535 DOI: 10.1063/5.0057030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 09/15/2021] [Indexed: 06/13/2023]
Abstract
The Comet Physics Laboratory (CoPhyLab) is an international research program to study the physical properties of cometary analog materials under simulated space conditions. The project is dedicated to studying, with the help of multiple instruments and the different expertise and background from the different partners, the physics of comets, including the processes inside cometary nuclei, the activity leading to the ejection of dust and gas, and the sub-surface and surface evolution of cometary nuclei when exposed to solar illumination. CoPhyLab will provide essential information on the formation and evolution of comets and insights into the origins of primitive Solar System bodies. To this end, we constructed a new laboratory that hosts several small-scale experiments and a large-scale comet-simulation chamber (L-Chamber). This chamber has been designed and constructed to host ice-dust samples with a diameter of up to 250 mm and a variable height between 100 and 300 mm. The cometary-analog samples will be kept at temperatures below 120 K and pressures around 10-6 mbar to ensure cometary-like conditions. In total, 14 different scientific instruments are attached to the L-Chamber to study the temporal evolution of the physical properties of the sample under different insolation conditions. Due to the implementation of a scale inside the L-Chamber that can measure weight changes of the samples with high precision, the cooling system is mechanically decoupled from the sample holder and cooling of the samples occurs by radiation only. The constructed chamber allows us to conduct uninterrupted experiments at low temperatures and pressures up to several weeks.
Collapse
Affiliation(s)
- C Kreuzig
- Institut für Geophysik und extraterrestrische Physik (IGeP), TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
| | - G Kargl
- Space Research Institute, Austrian Academy of Science, Schmiedlstraße 6, 8042 Graz, Austria
| | - A Pommerol
- Physics Institute for Space Research and Planetary Science, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
| | - J Knollenberg
- Deutsches Zentrum für Luft- und Raumfahrt, Rutherfordstraße 2, 12489 Berlin-Adlershof, Germany
| | - A Lethuillier
- Institut für Geophysik und extraterrestrische Physik (IGeP), TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
| | - N S Molinski
- Institut für Geophysik und extraterrestrische Physik (IGeP), TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
| | - T Gilke
- Institut für Geophysik und extraterrestrische Physik (IGeP), TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
| | - D Bischoff
- Institut für Geophysik und extraterrestrische Physik (IGeP), TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
| | - C Feller
- Physics Institute for Space Research and Planetary Science, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
| | - E Kührt
- Deutsches Zentrum für Luft- und Raumfahrt, Rutherfordstraße 2, 12489 Berlin-Adlershof, Germany
| | - H Sierks
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - N Hänni
- Physics Institute for Space Research and Planetary Science, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
| | - H Capelo
- Physics Institute for Space Research and Planetary Science, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
| | - C Güttler
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - D Haack
- Deutsches Zentrum für Luft- und Raumfahrt, Rutherfordstraße 2, 12489 Berlin-Adlershof, Germany
| | - K Otto
- Deutsches Zentrum für Luft- und Raumfahrt, Rutherfordstraße 2, 12489 Berlin-Adlershof, Germany
| | - E Kaufmann
- Space Research Institute, Austrian Academy of Science, Schmiedlstraße 6, 8042 Graz, Austria
| | - M Schweighart
- Space Research Institute, Austrian Academy of Science, Schmiedlstraße 6, 8042 Graz, Austria
| | - W Macher
- Space Research Institute, Austrian Academy of Science, Schmiedlstraße 6, 8042 Graz, Austria
| | - P Tiefenbacher
- Space Research Institute, Austrian Academy of Science, Schmiedlstraße 6, 8042 Graz, Austria
| | - B Gundlach
- Institut für Geophysik und extraterrestrische Physik (IGeP), TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
| | - J Blum
- Institut für Geophysik und extraterrestrische Physik (IGeP), TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
| |
Collapse
|
3
|
Sublimation-driven morphogenesis of Zen stones on ice surfaces. Proc Natl Acad Sci U S A 2021; 118:2109107118. [PMID: 34593645 DOI: 10.1073/pnas.2109107118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2021] [Indexed: 11/18/2022] Open
Abstract
In this article, the formation of Zen stones on frozen lakes and the shape of the resulting pedestal are elucidated. Zen stones are natural structures in which a stone, initially resting on an ice surface, ends up balanced atop a narrow ice pedestal. We provide a physical explanation for their formation, sometimes believed to be caused by the melting of the ice. Instead, we show that slow surface sublimation is indeed the physical mechanism responsible for the differential ablation. Far from the stone, the sublimation rate is governed by the diffuse sunlight, while in its vicinity, the shade it creates inhibits the sublimation process. We reproduced the phenomenon in laboratory-scale experiments conducted in a lyophilizer and studied the dynamics of the morphogenesis. In this apparatus, which imposes controlled constant sublimation rate, a variety of model stones consisting of metal disks was used, which allows us to rule out the possible influence of the thermal conduction in the morphogenesis process. Instead, we show that the stone only acts as an umbrella whose shade hinders the sublimation, hence protecting the ice underneath, which leads to the formation of the pedestal. Numerical simulations, in which the local ablation rate of the surface depends solely on the visible portion of the sky, allow us to study the influence of the shape of the stone on the formation of the ice foot. Finally, we show that the far-infrared black-body irradiance of the stone itself leads to the formation of a depression surrounding the pedestal.
Collapse
|
4
|
Small All-Range Lidar for Asteroid and Comet Core Missions. SENSORS 2021; 21:s21093081. [PMID: 33925157 PMCID: PMC8125798 DOI: 10.3390/s21093081] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/24/2021] [Accepted: 04/26/2021] [Indexed: 11/16/2022]
Abstract
We report the development of a new type of space lidar specifically designed for missions to small planetary bodies for both topographic mapping and support of sample collection or landing. The instrument is designed to have a wide dynamic range with several operation modes for different mission phases. The laser transmitter consists of a fiber laser that is intensity modulated with a return-to-zero pseudo-noise (RZPN) code. The receiver detects the coded pulse-train by correlating the detected signal with the RZPN kernel. Unlike regular pseudo noise (PN) lidars, the RZPN kernel is set to zero outside laser firing windows, which removes most of the background noise over the receiver integration time. This technique enables the use of low peak-power but high pulse-rate lasers, such as fiber lasers, for long-distance ranging without aliasing. The laser power and the internal gain of the detector can both be adjusted to give a wide measurement dynamic range. The laser modulation code pattern can also be reconfigured in orbit to optimize measurements to different measurement environments. The receiver uses a multi-pixel linear mode photon-counting HgCdTe avalanche photodiode (APD) array with near quantum limited sensitivity at near to mid infrared wavelengths where many fiber lasers and diode lasers operate. The instrument is modular and versatile and can be built mostly with components developed by the optical communication industry.
Collapse
|
5
|
Blocks Size Frequency Distribution in the Enceladus Tiger Stripes Area: Implications on Their Formative Processes. UNIVERSE 2021. [DOI: 10.3390/universe7040082] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We study the size frequency distribution of the blocks located in the deeply fractured, geologically active Enceladus South Polar Terrain with the aim to suggest their formative mechanisms. Through the Cassini ISS images, we identify ~17,000 blocks with sizes ranging from ~25 m to 366 m, and located at different distances from the Damascus, Baghdad and Cairo Sulci. On all counts and for both Damascus and Baghdad cases, the power-law fitting curve has an index that is similar to the one obtained on the deeply fractured, actively sublimating Hathor cliff on comet 67P/Churyumov-Gerasimenko, where several non-dislodged blocks are observed. This suggests that as for 67P, sublimation and surface stresses favor similar fractures development in the Enceladus icy matrix, hence resulting in comparable block disaggregation. A steeper power-law index for Cairo counts may suggest a higher degree of fragmentation, which could be the result of localized, stronger tectonic disruption of lithospheric ice. Eventually, we show that the smallest blocks identified are located from tens of m to 20–25 km from the Sulci fissures, while the largest blocks are found closer to the tiger stripes. This result supports the ejection hypothesis mechanism as the possible source of blocks.
Collapse
|
6
|
Uckert K, Parness A, Chanover N, Eshelman EJ, Abcouwer N, Nash J, Detry R, Fuller C, Voelz D, Hull R, Flannery D, Bhartia R, Manatt KS, Abbey WJ, Boston P. Investigating Habitability with an Integrated Rock-Climbing Robot and Astrobiology Instrument Suite. ASTROBIOLOGY 2020; 20:1427-1449. [PMID: 33052709 DOI: 10.1089/ast.2019.2177] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A prototype rover carrying an astrobiology payload was developed and deployed at analog field sites to mature generalized system architectures capable of searching for biosignatures in extreme terrain across the Solar System. Specifically, the four-legged Limbed Excursion Mechanical Utility Robot (LEMUR) 3 climbing robot with microspine grippers carried three instruments: a micro-X-ray fluorescence instrument based on the Mars 2020 mission's Planetary Instrument for X-ray Lithochemistry provided elemental chemistry; a deep-ultraviolet fluorescence instrument based on Mars 2020's Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals mapped organics in bacterial communities on opaque substrates; and a near-infrared acousto-optic tunable filter-based point spectrometer identified minerals and organics in the 1.6-3.6 μm range. The rover also carried a light detection and ranging and a color camera for both science and navigation. Combined, this payload detects astrobiologically important classes of rock components (elements, minerals, and organics) in extreme terrain, which, as demonstrated in this work, can reveal a correlation between textural biosignatures and the organics or elements expected to preserve them in a habitable environment. Across >10 field tests, milestones were achieved in instrument operations, autonomous mobility in extreme terrain, and system integration that can inform future planetary science mission architectures. Contributions include (1) system-level demonstration of mock missions to the vertical exposures of Mars lava tube caves and Mars canyon walls, (2) demonstration of multi-instrument integration into a confocal arrangement with surface scanning capabilities, and (3) demonstration of automated focus stacking algorithms for improved signal-to-noise ratios and reduced operation time.
Collapse
Affiliation(s)
- Kyle Uckert
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Aaron Parness
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Nancy Chanover
- New Mexico State University, Las Cruces, New Mexico, USA
| | - Evan J Eshelman
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Neil Abcouwer
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Jeremy Nash
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Renaud Detry
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Christine Fuller
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - David Voelz
- New Mexico State University, Las Cruces, New Mexico, USA
| | - Robert Hull
- New Mexico State University, Las Cruces, New Mexico, USA
| | - David Flannery
- Queensland University of Technology, Brisbane, Australia
| | | | - Kenneth S Manatt
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - William J Abbey
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Penelope Boston
- NASA Astrobiology Institute, Ames Research Center, Mountain View, California, USA
| |
Collapse
|
7
|
Marschall R, Skorov Y, Zakharov V, Rezac L, Gerig SB, Christou C, Dadzie SK, Migliorini A, Rinaldi G, Agarwal J, Vincent JB, Kappel D. Cometary Comae-Surface Links: The Physics of Gas and Dust from the Surface to a Spacecraft. SPACE SCIENCE REVIEWS 2020; 216:130. [PMID: 33184519 PMCID: PMC7647976 DOI: 10.1007/s11214-020-00744-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 09/28/2020] [Indexed: 06/04/2023]
Abstract
A comet is a highly dynamic object, undergoing a permanent state of change. These changes have to be carefully classified and considered according to their intrinsic temporal and spatial scales. The Rosetta mission has, through its contiguous in-situ and remote sensing coverage of comet 67P/Churyumov-Gerasimenko (hereafter 67P) over the time span of August 2014 to September 2016, monitored the emergence, culmination, and winding down of the gas and dust comae. This provided an unprecedented data set and has spurred a large effort to connect in-situ and remote sensing measurements to the surface. In this review, we address our current understanding of cometary activity and the challenges involved when linking comae data to the surface. We give the current state of research by describing what we know about the physical processes involved from the surface to a few tens of kilometres above it with respect to the gas and dust emission from cometary nuclei. Further, we describe how complex multidimensional cometary gas and dust models have developed from the Halley encounter of 1986 to today. This includes the study of inhomogeneous outgassing and determination of the gas and dust production rates. Additionally, the different approaches used and results obtained to link coma data to the surface will be discussed. We discuss forward and inversion models and we describe the limitations of the respective approaches. The current literature suggests that there does not seem to be a single uniform process behind cometary activity. Rather, activity seems to be the consequence of a variety of erosion processes, including the sublimation of both water ice and more volatile material, but possibly also more exotic processes such as fracture and cliff erosion under thermal and mechanical stress, sub-surface heat storage, and a complex interplay of these processes. Seasons and the nucleus shape are key factors for the distribution and temporal evolution of activity and imply that the heliocentric evolution of activity can be highly individual for every comet, and generalisations can be misleading.
Collapse
Affiliation(s)
- Raphael Marschall
- Southwest Research Institute, 1050 Walnut St, Suite 300, Boulder, CO 80302 USA
- International Space Science Institute (ISSI), Hallerstrasse 6, 3012 Bern, Switzerland
| | - Yuri Skorov
- Institut für Geophysik und extraterrestrische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | | | - Ladislav Rezac
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Selina-Barbara Gerig
- Physikalisches Institut, University of Bern, Sidlerstr. 5, 3012 Bern, Switzerland
- NCCR PlanetS, Sidlerstrasse 5, 3012 Bern, Switzerland
| | - Chariton Christou
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS Scotland UK
| | - S. Kokou Dadzie
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS Scotland UK
| | | | | | - Jessica Agarwal
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Jean-Baptiste Vincent
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstrasse 2, 12489 Berlin, Germany
| | - David Kappel
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstrasse 2, 12489 Berlin, Germany
- Institute of Physics and Astronomy, University of Potsdam, Potsdam-Golm, Germany
| |
Collapse
|
8
|
Rubin M, Engrand C, Snodgrass C, Weissman P, Altwegg K, Busemann H, Morbidelli A, Mumma M. On the Origin and Evolution of the Material in 67P/Churyumov-Gerasimenko. SPACE SCIENCE REVIEWS 2020. [PMID: 32801398 DOI: 10.1007/s11214-019-0625-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Primitive objects like comets hold important information on the material that formed our solar system. Several comets have been visited by spacecraft and many more have been observed through Earth- and space-based telescopes. Still our understanding remains limited. Molecular abundances in comets have been shown to be similar to interstellar ices and thus indicate that common processes and conditions were involved in their formation. The samples returned by the Stardust mission to comet Wild 2 showed that the bulk refractory material was processed by high temperatures in the vicinity of the early sun. The recent Rosetta mission acquired a wealth of new data on the composition of comet 67P/Churyumov-Gerasimenko (hereafter 67P/C-G) and complemented earlier observations of other comets. The isotopic, elemental, and molecular abundances of the volatile, semi-volatile, and refractory phases brought many new insights into the origin and processing of the incorporated material. The emerging picture after Rosetta is that at least part of the volatile material was formed before the solar system and that cometary nuclei agglomerated over a wide range of heliocentric distances, different from where they are found today. Deviations from bulk solar system abundances indicate that the material was not fully homogenized at the location of comet formation, despite the radial mixing implied by the Stardust results. Post-formation evolution of the material might play an important role, which further complicates the picture. This paper discusses these major findings of the Rosetta mission with respect to the origin of the material and puts them in the context of what we know from other comets and solar system objects.
Collapse
Affiliation(s)
- Martin Rubin
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
| | - Cécile Engrand
- CNRS/IN2P3, IJCLab, Université Paris-Saclay, 91405 Orsay Cedex, France
| | - Colin Snodgrass
- Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, EH9 3HJ UK
| | | | - Kathrin Altwegg
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
| | - Henner Busemann
- Institute of Geochemistry and Petrology, Department of Earth Sciences, ETH Zurich, Zurich, Switzerland
| | | | - Michael Mumma
- NASA Goddard Space Flight Center, 8800 Greenbelt Rd., Greenbelt, 20771 MD USA
| |
Collapse
|
9
|
Telfer MW, Parteli EJR, Radebaugh J, Beyer RA, Bertrand T, Forget F, Nimmo F, Grundy WM, Moore JM, Stern SA, Spencer J, Lauer TR, Earle AM, Binzel RP, Weaver HA, Olkin CB, Young LA, Ennico K, Runyon K, Buie M, Buratti B, Cheng A, Kavelaars JJ, Linscott I, McKinnon WB, Reitsema H, Reuter D, Schenk P, Showalter M, Tyler L. Dunes on Pluto. Science 2018; 360:992-997. [PMID: 29853681 DOI: 10.1126/science.aao2975] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 04/19/2018] [Indexed: 11/02/2022]
Abstract
The surface of Pluto is more geologically diverse and dynamic than had been expected, but the role of its tenuous atmosphere in shaping the landscape remains unclear. We describe observations from the New Horizons spacecraft of regularly spaced, linear ridges whose morphology, distribution, and orientation are consistent with being transverse dunes. These are located close to mountainous regions and are orthogonal to nearby wind streaks. We demonstrate that the wavelength of the dunes (~0.4 to 1 kilometer) is best explained by the deposition of sand-sized (~200 to ~300 micrometer) particles of methane ice in moderate winds (<10 meters per second). The undisturbed morphology of the dunes, and relationships with the underlying convective glacial ice, imply that the dunes have formed in the very recent geological past.
Collapse
Affiliation(s)
- Matt W Telfer
- School of Geography, Earth and Environmental Sciences, Plymouth University, Drake Circus, Plymouth, Devon PL4 8AA, UK.
| | - Eric J R Parteli
- Department of Geosciences, University of Cologne, Pohligstraße 3, 50969 Cologne, Germany
| | - Jani Radebaugh
- Department of Geological Sciences, College of Physical and Mathematical Sciences, Brigham Young University, Provo, UT 84602, USA
| | - Ross A Beyer
- Sagan Center at the SETI Institute, Mountain View, CA 94043, USA.,NASA Ames Research Center, Moffett Field, CA 94035, USA
| | - Tanguy Bertrand
- Laboratoire de Météorologie Dynamique, Université Pierre et Marie Curie, Paris, France
| | - François Forget
- Laboratoire de Météorologie Dynamique, Université Pierre et Marie Curie, Paris, France
| | - Francis Nimmo
- University of California Santa Cruz, Santa Cruz, CA, USA
| | | | | | | | | | - Tod R Lauer
- National Optical Astronomy Observatory, Tucson, AZ 85726, USA
| | - Alissa M Earle
- Department of Earth, Atmosphere, and Planetary Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Richard P Binzel
- Department of Earth, Atmosphere, and Planetary Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Hal A Weaver
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - Cathy B Olkin
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | | | | | - Kirby Runyon
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Levasseur-Regourd AC, Agarwal J, Cottin H, Engrand C, Flynn G, Fulle M, Gombosi T, Langevin Y, Lasue J, Mannel T, Merouane S, Poch O, Thomas N, Westphal A. Cometary Dust. SPACE SCIENCE REVIEWS 2018; 214:64. [PMID: 35095119 PMCID: PMC8793767 DOI: 10.1007/s11214-018-0496-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/16/2018] [Indexed: 05/15/2023]
Abstract
This review presents our understanding of cometary dust at the end of 2017. For decades, insight about the dust ejected by nuclei of comets had stemmed from remote observations from Earth or Earth's orbit, and from flybys, including the samples of dust returned to Earth for laboratory studies by the Stardust return capsule. The long-duration Rosetta mission has recently provided a huge and unique amount of data, obtained using numerous instruments, including innovative dust instruments, over a wide range of distances from the Sun and from the nucleus. The diverse approaches available to study dust in comets, together with the related theoretical and experimental studies, provide evidence of the composition and physical properties of dust particles, e.g., the presence of a large fraction of carbon in macromolecules, and of aggregates on a wide range of scales. The results have opened vivid discussions on the variety of dust-release processes and on the diversity of dust properties in comets, as well as on the formation of cometary dust, and on its presence in the near-Earth interplanetary medium. These discussions stress the significance of future explorations as a way to decipher the formation and evolution of our Solar System.
Collapse
Affiliation(s)
- Anny-Chantal Levasseur-Regourd
- Sorbonne Université; UVSQ; CNRS/INSU; Campus Pierre et Marie Curie, BC 102, 4 place Jussieu, F-75005 Paris, France, Tel.: + 33 144274875,
| | - Jessica Agarwal
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg, 3, D-37077, Göttingen, Germany
| | - Hervé Cottin
- Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, Université Paris-Est Créteil et Université Paris Diderot, Institut Pierre Simon Laplace, 94000 Créteil, France
| | - Cécile Engrand
- Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), CNRS/IN2P3 Université Paris Sud - UMR 8609, Université Paris-Saclay, Bâtiment 104, 91405 Orsay Campus, France
| | - George Flynn
- SUNY-Plattsburgh, 101 Broad St, Plattsburgh, NY 12901, United States
| | - Marco Fulle
- INAF - Osservatorio Astronomico, Via Tiepolo 11, 34143 Trieste Italy
| | - Tamas Gombosi
- Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yves Langevin
- Institut dAstrophysique Spatiale (IAS), CNRS/Université Paris Sud, Bâtiment 121, 91405 Orsay France
| | - Jérémie Lasue
- IRAP, Université de Toulouse, CNRS, UPS, CNES, Toulouse, France
| | - Thurid Mannel
- Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz, Austria; Physics Institute, University of Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Sihane Merouane
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg, 3, D-37077, Göttingen, Germany
| | - Olivier Poch
- Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
| | - Nicolas Thomas
- Physikalisches Institut, Universität Bern, Sidlerstrasse 5, 3012, Bern, Switzerland
| | - Andrew Westphal
- Space Sciences Laboratory, U.C. Berkeley, Berkeley, California 94720-7450 USA
| |
Collapse
|
11
|
Taylor MGGT, Altobelli N, Buratti BJ, Choukroun M. The Rosetta mission orbiter science overview: the comet phase. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2017; 375:rsta.2016.0262. [PMID: 28554981 PMCID: PMC5454230 DOI: 10.1098/rsta.2016.0262] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/07/2017] [Indexed: 05/11/2023]
Abstract
The international Rosetta mission was launched in 2004 and consists of the orbiter spacecraft Rosetta and the lander Philae. The aim of the mission is to map the comet 67P/Churyumov-Gerasimenko by remote sensing, and to examine its environment in situ and its evolution in the inner Solar System. Rosetta was the first spacecraft to rendezvous with and orbit a comet, accompanying it as it passes through the inner Solar System, and to deploy a lander, Philae, and perform in situ science on the comet's surface. The primary goals of the mission were to: characterize the comet's nucleus; examine the chemical, mineralogical and isotopic composition of volatiles and refractories; examine the physical properties and interrelation of volatiles and refractories in a cometary nucleus; study the development of cometary activity and the processes in the surface layer of the nucleus and in the coma; detail the origin of comets, the relationship between cometary and interstellar material and the implications for the origin of the Solar System; and characterize asteroids 2867 Steins and 21 Lutetia. This paper presents a summary of mission operations and science, focusing on the Rosetta orbiter component of the mission during its comet phase, from early 2014 up to September 2016.This article is part of the themed issue 'Cometary science after Rosetta'.
Collapse
Affiliation(s)
| | - N Altobelli
- ESA/ESAC, 28692 Villanueva de la Cañada, Spain
| | - B J Buratti
- JPL/California Institute of Technology, Pasadena, CA 91109, USA
| | - M Choukroun
- JPL/California Institute of Technology, Pasadena, CA 91109, USA
| |
Collapse
|
12
|
Glassmeier KH. Interaction of the solar wind with comets: a Rosetta perspective. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2017; 375:20160256. [PMID: 28554976 PMCID: PMC5454225 DOI: 10.1098/rsta.2016.0256] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/12/2017] [Indexed: 05/25/2023]
Abstract
The Rosetta mission provides an unprecedented possibility to study the interaction of comets with the solar wind. As the spacecraft accompanies comet 67P/Churyumov-Gerasimenko from its very low-activity stage through its perihelion phase, the physics of mass loading is witnessed for various activity levels of the nucleus. While observations at other comets provided snapshots of the interaction region and its various plasma boundaries, Rosetta observations allow a detailed study of the temporal evolution of the innermost cometary magnetosphere. Owing to the short passage time of the solar wind through the interaction region, plasma instabilities such as ring--beam and non-gyrotropic instabilities are of less importance during the early life of the magnetosphere. Large-amplitude ultra-low-frequency (ULF) waves, the 'singing' of the comet, is probably due to a modified ion Weibel instability. This instability drives a cross-field current of implanted cometary ions unstable. The initial pick-up of these ions causes a major deflection of the solar wind protons. Proton deflection, cross-field current and the instability induce a threefold structure of the innermost interaction region with the characteristic Mach cone and Whistler wings as stationary interaction signatures as well as the ULF waves representing the dynamic aspect of the interaction.This article is part of the themed issue 'Cometary science after Rosetta'.
Collapse
Affiliation(s)
- Karl-Heinz Glassmeier
- Institut für Geophysik und extraterrestrische Physik, Technische Universität Braunschweig, Mendelssohnstraße 3, 38116 Braunschweig, Germany
| |
Collapse
|
13
|
|
14
|
El-Maarry MR, Groussin O, Thomas N, Pajola M, Auger AT, Davidsson B, Hu X, Hviid SF, Knollenberg J, Güttler C, Tubiana C, Fornasier S, Feller C, Hasselmann P, Vincent JB, Sierks H, Barbieri C, Lamy P, Rodrigo R, Koschny D, Keller HU, Rickman H, A’Hearn MF, Barucci MA, Bertaux JL, Bertini I, Besse S, Bodewits D, Cremonese G, Da Deppo V, Debei S, De Cecco M, Deller J, Deshapriya JDP, Fulle M, Gutierrez PJ, Hofmann M, Ip WH, Jorda L, Kovacs G, Kramm JR, Kührt E, Küppers M, Lara LM, Lazzarin M, Lin ZY, Lopez Moreno JJ, Marchi S, Marzari F, Mottola S, Naletto G, Oklay N, Pommerol A, Preusker F, Scholten F, Shi X. Surface changes on comet 67P/Churyumov-Gerasimenko suggest a more active past. Science 2017; 355:1392-1395. [DOI: 10.1126/science.aak9384] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 03/06/2017] [Indexed: 11/02/2022]
Affiliation(s)
- M. Ramy El-Maarry
- Physikalisches Institut, Universität Bern, 3012 Bern, Switzerland
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80301, USA
| | - O. Groussin
- Aix Marseille Université, CNRS, Laboratoire d’Astrophysique de Marseille, UMR 7326, 13388 Marseille, France
| | - N. Thomas
- Physikalisches Institut, Universität Bern, 3012 Bern, Switzerland
| | - M. Pajola
- NASA Ames Research Center, Moffett Field, CA 94035, USA
| | - A.-T. Auger
- Aix Marseille Université, CNRS, Laboratoire d’Astrophysique de Marseille, UMR 7326, 13388 Marseille, France
| | - B. Davidsson
- Jet Propulsion Laboratory, Pasadena, CA 91109, USA
| | - X. Hu
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - S. F. Hviid
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - J. Knollenberg
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - C. Güttler
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - C. Tubiana
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - S. Fornasier
- LESIA, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité, UPMC Université Paris 06, Sorbonne Universités, Meudon Principal Cedex 92195, France
| | - C. Feller
- LESIA, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité, UPMC Université Paris 06, Sorbonne Universités, Meudon Principal Cedex 92195, France
| | - P. Hasselmann
- LESIA, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité, UPMC Université Paris 06, Sorbonne Universités, Meudon Principal Cedex 92195, France
| | - J.-B. Vincent
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - H. Sierks
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - C. Barbieri
- Department of Physics and Astronomy, University of Padova, 35122 Padova, Italy
| | - P. Lamy
- Laboratoire d’Astrophysique de Marseille, UMR 7326 CNRS & Université Aix-Marseille, 13388 Marseille Cedex 13, France
| | - R. Rodrigo
- Centro de Astrobiología, Instituto Nacional de Técnica Aeroespacial, 28850 Torrejón de Ardoz, Madrid, Spain
- International Space Science Institute, 3012 Bern, Switzerland
| | - D. Koschny
- Operations Department, European Space Astronomy Centre/ESA, P.O. Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
| | - H. U. Keller
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
- Institut für Geophysik und Extraterrestrische Physik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - H. Rickman
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
- Polish Academy of Sciences, Space Research Center, 00716 Warsaw, Poland
| | - M. F. A’Hearn
- Department of Astronomy, University of Maryland, College Park, MD 20742, USA
| | - M. A. Barucci
- LESIA, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité, UPMC Université Paris 06, Sorbonne Universités, Meudon Principal Cedex 92195, France
| | - J.-L. Bertaux
- Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), CNRS–Université de Versailles Saint-Quentin-en-Yvelines–Institut Pierre Simon Laplace, 78280 Guyancourt, France
| | - I. Bertini
- Department of Physics and Astronomy, University of Padova, 35122 Padova, Italy
| | - S. Besse
- Operations Department, European Space Astronomy Centre/ESA, P.O. Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
| | - D. Bodewits
- Department of Astronomy, University of Maryland, College Park, MD 20742, USA
| | - G. Cremonese
- Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, 35122 Padova, Italy
| | - V. Da Deppo
- Consiglio Nazionale delle Ricerche–Istituto di Fotonica e Nanotecnologie, Unità Organizzativa di Supporto, Padova Luxor, 35131 Padova, Italy
| | - S. Debei
- Department of Industrial Engineering, University of Padova, 35131 Padova, Italy
| | | | - J. Deller
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - J. D. P. Deshapriya
- LESIA, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité, UPMC Université Paris 06, Sorbonne Universités, Meudon Principal Cedex 92195, France
| | - M. Fulle
- INAF, Osservatorio Astronomico di Trieste, 34014 Trieste, Italy
| | - P. J. Gutierrez
- Instituto de Astrofísica de Andalucía (CSIC), c/ Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - M. Hofmann
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - W.-H. Ip
- Graduate Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan
| | - L. Jorda
- Aix Marseille Université, CNRS, Laboratoire d’Astrophysique de Marseille, UMR 7326, 13388 Marseille, France
| | - G. Kovacs
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - J.-R. Kramm
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - E. Kührt
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - M. Küppers
- Operations Department, European Space Astronomy Centre/ESA, P.O. Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
| | - L. M. Lara
- Instituto de Astrofísica de Andalucía (CSIC), c/ Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - M. Lazzarin
- Department of Physics and Astronomy, University of Padova, 35122 Padova, Italy
| | - Z.-Yi Lin
- Graduate Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan
| | - J. J. Lopez Moreno
- Instituto de Astrofísica de Andalucía (CSIC), c/ Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - S. Marchi
- Solar System Exploration Research, Virtual Institute, Southwest Research Institute, Boulder, CO 80302, USA
| | - F. Marzari
- Department of Physics and Astronomy, University of Padova, 35122 Padova, Italy
| | - S. Mottola
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - G. Naletto
- Consiglio Nazionale delle Ricerche–Istituto di Fotonica e Nanotecnologie, Unità Organizzativa di Supporto, Padova Luxor, 35131 Padova, Italy
- Department of Information Engineering, University of Padova, 35131 Padova, Italy
- Centro di Ateneo di Studi ed Attivitá Spaziali “Giuseppe Colombo” (CISAS), University of Padova, 35131 Padova, Italy
| | - N. Oklay
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - A. Pommerol
- Physikalisches Institut, Universität Bern, 3012 Bern, Switzerland
| | - F. Preusker
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - F. Scholten
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - X. Shi
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| |
Collapse
|
15
|
Shinbrot T, Sabuwala T, Siu T, Vivar Lazo M, Chakraborty P. Size Sorting on the Rubble-Pile Asteroid Itokawa. PHYSICAL REVIEW LETTERS 2017; 118:111101. [PMID: 28368621 DOI: 10.1103/physrevlett.118.111101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Indexed: 06/07/2023]
Abstract
Photographs of the asteroid Itokawa reveal unexpectedly strong size segregation between lowlands populated almost entirely by small pebbles and highlands consisting of larger boulders. We propose that this segregation may be caused by a simple and unexplored effect: pebbles accreting onto the asteroid rebound from boulders, but sink into pebbly regions. By number, overwhelmingly more particles on Itokawa are pebbles, and collisions involving these pebbles must unavoidably cause pebbly regions to grow. We carry out experiments and simulations that demonstrate that this mechanism of size sorting based on simple counting of grains produces strong lateral segregation that reliably obeys an analytic formula.
Collapse
Affiliation(s)
- Troy Shinbrot
- Physics Department, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Tapan Sabuwala
- Continuum Physics Unit, Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0495, Japan
| | - Theo Siu
- Physics Department, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Miguel Vivar Lazo
- Physics Department, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Pinaki Chakraborty
- Fluid Mechanics Unit, Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0495, Japan
| |
Collapse
|
16
|
Lämmel M, Dzikowski K, Kroy K, Oger L, Valance A. Grain-scale modeling and splash parametrization for aeolian sand transport. Phys Rev E 2017; 95:022902. [PMID: 28297955 DOI: 10.1103/physreve.95.022902] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Indexed: 11/07/2022]
Abstract
The collision of a spherical grain with a granular bed is commonly parametrized by the splash function, which provides the velocity of the rebounding grain and the velocity distribution and number of ejected grains. Starting from elementary geometric considerations and physical principles, like momentum conservation and energy dissipation in inelastic pair collisions, we derive a rebound parametrization for the collision of a spherical grain with a granular bed. Combined with a recently proposed energy-splitting model [Ho et al., Phys. Rev. E 85, 052301 (2012)PLEEE81539-375510.1103/PhysRevE.85.052301] that predicts how the impact energy is distributed among the bed grains, this yields a coarse-grained but complete characterization of the splash as a function of the impact velocity and the impactor-bed grain-size ratio. The predicted mean values of the rebound angle, total and vertical restitution, ejection speed, and number of ejected grains are in excellent agreement with experimental literature data and with our own discrete-element computer simulations. We extract a set of analytical asymptotic relations for shallow impact geometries, which can readily be used in coarse-grained analytical modeling or computer simulations of geophysical particle-laden flows.
Collapse
Affiliation(s)
- Marc Lämmel
- Institut für Theoretische Physik, Universität Leipzig, Postfach 100920, 04009 Leipzig, Germany
| | - Kamil Dzikowski
- Institut für Theoretische Physik, Universität Leipzig, Postfach 100920, 04009 Leipzig, Germany
| | - Klaus Kroy
- Institut für Theoretische Physik, Universität Leipzig, Postfach 100920, 04009 Leipzig, Germany
| | - Luc Oger
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes I, 35042 Rennes, France
| | - Alexandre Valance
- Institut de Physique de Rennes, CNRS UMR 6251, Université de Rennes I, 35042 Rennes, France
| |
Collapse
|
17
|
Giant ripples on comet 67P/Churyumov-Gerasimenko sculpted by sunset thermal wind. Proc Natl Acad Sci U S A 2017; 114:2509-2514. [PMID: 28223535 DOI: 10.1073/pnas.1612176114] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Explaining the unexpected presence of dune-like patterns at the surface of the comet 67P/Churyumov-Gerasimenko requires conceptual and quantitative advances in the understanding of surface and outgassing processes. We show here that vapor flow emitted by the comet around its perihelion spreads laterally in a surface layer, due to the strong pressure difference between zones illuminated by sunlight and those in shadow. For such thermal winds to be dense enough to transport grains-10 times greater than previous estimates-outgassing must take place through a surface porous granular layer, and that layer must be composed of grains whose roughness lowers cohesion consistently with contact mechanics. The linear stability analysis of the problem, entirely tested against laboratory experiments, quantitatively predicts the emergence of bedforms in the observed wavelength range and their propagation at the scale of a comet revolution. Although generated by a rarefied atmosphere, they are paradoxically analogous to ripples emerging on granular beds submitted to viscous shear flows. This quantitative agreement shows that our understanding of the coupling between hydrodynamics and sediment transport is able to account for bedform emergence in extreme conditions and provides a reliable tool to predict the erosion and accretion processes controlling the evolution of small solar system bodies.
Collapse
|
18
|
Fornasier S, Mottola S, Keller HU, Barucci MA, Davidsson B, Feller C, Deshapriya JDP, Sierks H, Barbieri C, Lamy PL, Rodrigo R, Koschny D, Rickman H, A’Hearn M, Agarwal J, Bertaux JL, Bertini I, Besse S, Cremonese G, Da Deppo V, Debei S, De Cecco M, Deller J, El-Maarry MR, Fulle M, Groussin O, Gutierrez PJ, Güttler C, Hofmann M, Hviid SF, Ip WH, Jorda L, Knollenberg J, Kovacs G, Kramm R, Kührt E, Küppers M, Lara ML, Lazzarin M, Moreno JJL, Marzari F, Massironi M, Naletto G, Oklay N, Pajola M, Pommerol A, Preusker F, Scholten F, Shi X, Thomas N, Toth I, Tubiana C, Vincent JB. Rosetta’s comet 67P/Churyumov-Gerasimenko sheds its dusty mantle to reveal its icy nature. Science 2016; 354:1566-1570. [DOI: 10.1126/science.aag2671] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 10/27/2016] [Indexed: 11/03/2022]
|
19
|
Lapotre MGA, Ewing RC, Lamb MP, Fischer WW, Grotzinger JP, Rubin DM, Lewis KW, Ballard MJ, Day M, Gupta S, Banham SG, Bridges NT, Des Marais DJ, Fraeman AA, Grant JA, Herkenhoff KE, Ming DW, Mischna MA, Rice MS, Sumner DY, Vasavada AR, Yingst RA. Large wind ripples on Mars: A record of atmospheric evolution. Science 2016; 353:55-8. [DOI: 10.1126/science.aaf3206] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 05/31/2016] [Indexed: 11/03/2022]
Affiliation(s)
- M. G. A. Lapotre
- Division of Geological and Planetary Science, California Institute of Technology, Pasadena, CA 91125, USA
| | - R. C. Ewing
- Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA
| | - M. P. Lamb
- Division of Geological and Planetary Science, California Institute of Technology, Pasadena, CA 91125, USA
| | - W. W. Fischer
- Division of Geological and Planetary Science, California Institute of Technology, Pasadena, CA 91125, USA
| | - J. P. Grotzinger
- Division of Geological and Planetary Science, California Institute of Technology, Pasadena, CA 91125, USA
| | - D. M. Rubin
- Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | - K. W. Lewis
- Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
| | - M. J. Ballard
- Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA
| | - M. Day
- Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - S. Gupta
- Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK
| | - S. G. Banham
- Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK
| | - N. T. Bridges
- Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723, USA
| | | | - A. A. Fraeman
- Division of Geological and Planetary Science, California Institute of Technology, Pasadena, CA 91125, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - J. A. Grant
- National Air and Space Museum, Smithsonian Institution, Washington, DC 20560, USA
| | - K. E. Herkenhoff
- Astrogeology Science Center, U.S. Geological Survey, Flagstaff, AZ 86001-1698, USA
| | - D. W. Ming
- NASA Johnson Space Center, Houston, TX 77058, USA
| | - M. A. Mischna
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - M. S. Rice
- Geology Department, Western Washington University, Bellingham, WA 98225-9080, USA
| | - D. Y. Sumner
- Department of Earth and Planetary Sciences, University of California, Davis, CA 95616, USA
| | - A. R. Vasavada
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - R. A. Yingst
- Planetary Science Institute, Tucson, AZ 85719, USA
| |
Collapse
|
20
|
Fission and reconfiguration of bilobate comets as revealed by 67P/Churyumov-Gerasimenko. Nature 2016; 534:352-5. [PMID: 27281196 DOI: 10.1038/nature17670] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 03/14/2016] [Indexed: 11/08/2022]
Abstract
The solid, central part of a comet--its nucleus--is subject to destructive processes, which cause nuclei to split at a rate of about 0.01 per year per comet. These destructive events are due to a range of possible thermophysical effects; however, the geophysical expressions of these effects are unknown. Separately, over two-thirds of comet nuclei that have been imaged at high resolution show bilobate shapes, including the nucleus of comet 67P/Churyumov-Gerasimenko (67P), visited by the Rosetta spacecraft. Analysis of the Rosetta observations suggests that 67P's components were brought together at low speed after their separate formation. Here, we study the structure and dynamics of 67P's nucleus. We find that sublimation torques have caused the nucleus to spin up in the past to form the large cracks observed on its neck. However, the chaotic evolution of its spin state has so far forestalled its splitting, although it should eventually reach a rapid enough spin rate to do so. Once this occurs, the separated components will be unable to escape each other; they will orbit each other for a time, ultimately undergoing a low-speed merger that will result in a new bilobate configuration. The components of four other imaged bilobate nuclei have volume ratios that are consistent with a similar reconfiguration cycle, pointing to such cycles as a fundamental process in the evolution of short-period comet nuclei. It has been shown that comets were not strong contributors to the so-called late heavy bombardment about 4 billion years ago. The reconfiguration process suggested here would preferentially decimate comet nuclei during migration to the inner solar system, perhaps explaining this lack of a substantial cometary flux.
Collapse
|
21
|
Exposed water ice on the nucleus of comet 67P/Churyumov-Gerasimenko. Nature 2016; 529:368-72. [PMID: 26760209 DOI: 10.1038/nature16190] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Accepted: 10/28/2015] [Indexed: 11/08/2022]
Abstract
Although water vapour is the main species observed in the coma of comet 67P/Churyumov-Gerasimenko and water is the major constituent of cometary nuclei, limited evidence for exposed water-ice regions on the surface of the nucleus has been found so far. The absence of large regions of exposed water ice seems a common finding on the surfaces of many of the comets observed so far. The nucleus of 67P/Churyumov-Gerasimenko appears to be fairly uniformly coated with dark, dehydrated, refractory and organic-rich material. Here we report the identification at infrared wavelengths of water ice on two debris falls in the Imhotep region of the nucleus. The ice has been exposed on the walls of elevated structures and at the base of the walls. A quantitative derivation of the abundance of ice in these regions indicates the presence of millimetre-sized pure water-ice grains, considerably larger than in all previous observations. Although micrometre-sized water-ice grains are the usual result of vapour recondensation in ice-free layers, the occurrence of millimetre-sized grains of pure ice as observed in the Imhotep debris falls is best explained by grain growth by vapour diffusion in ice-rich layers, or by sintering. As a consequence of these processes, the nucleus can develop an extended and complex coating in which the outer dehydrated crust is superimposed on layers enriched in water ice. The stratigraphy observed on 67P/Churyumov-Gerasimenko is therefore the result of evolutionary processes affecting the uppermost metres of the nucleus and does not necessarily require a global layering to have occurred at the time of the comet's formation.
Collapse
|
22
|
Massironi M, Simioni E, Marzari F, Cremonese G, Giacomini L, Pajola M, Jorda L, Naletto G, Lowry S, El-Maarry MR, Preusker F, Scholten F, Sierks H, Barbieri C, Lamy P, Rodrigo R, Koschny D, Rickman H, Keller HU, A'Hearn MF, Agarwal J, Auger AT, Barucci MA, Bertaux JL, Bertini I, Besse S, Bodewits D, Capanna C, Da Deppo V, Davidsson B, Debei S, De Cecco M, Ferri F, Fornasier S, Fulle M, Gaskell R, Groussin O, Gutiérrez PJ, Güttler C, Hviid SF, Ip WH, Knollenberg J, Kovacs G, Kramm R, Kührt E, Küppers M, La Forgia F, Lara LM, Lazzarin M, Lin ZY, Lopez Moreno JJ, Magrin S, Michalik H, Mottola S, Oklay N, Pommerol A, Thomas N, Tubiana C, Vincent JB. Two independent and primitive envelopes of the bilobate nucleus of comet 67P. Nature 2015; 526:402-5. [PMID: 26416730 DOI: 10.1038/nature15511] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 07/10/2015] [Indexed: 11/09/2022]
Abstract
The factors shaping cometary nuclei are still largely unknown, but could be the result of concurrent effects of evolutionary and primordial processes. The peculiar bilobed shape of comet 67P/Churyumov-Gerasimenko may be the result of the fusion of two objects that were once separate or the result of a localized excavation by outgassing at the interface between the two lobes. Here we report that the comet's major lobe is enveloped by a nearly continuous set of strata, up to 650 metres thick, which are independent of an analogous stratified envelope on the minor lobe. Gravity vectors computed for the two lobes separately are closer to perpendicular to the strata than those calculated for the entire nucleus and adjacent to the neck separating the two lobes. Therefore comet 67P/Churyumov-Gerasimenko is an accreted body of two distinct objects with 'onion-like' stratification, which formed before they merged. We conclude that gentle, low-velocity collisions occurred between two fully formed kilometre-sized cometesimals in the early stages of the Solar System. The notable structural similarities between the two lobes of comet 67P/Churyumov-Gerasimenko indicate that the early-forming cometesimals experienced similar primordial stratified accretion, even though they formed independently.
Collapse
Affiliation(s)
- Matteo Massironi
- Dipartimento di Geoscienze, University of Padova, via G. Gradenigo 6, 35131 Padova, Italy.,Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy
| | | | - Francesco Marzari
- University of Padova, Department of Physics and Astronomy, Vicolo dell'Osservatorio 3, 35122 Padova, Italy
| | - Gabriele Cremonese
- INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
| | - Lorenza Giacomini
- Dipartimento di Geoscienze, University of Padova, via G. Gradenigo 6, 35131 Padova, Italy
| | - Maurizio Pajola
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy
| | - Laurent Jorda
- Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille), UMR 7326, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France
| | - Giampiero Naletto
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy.,CNR-IFN UOS Padova LUXOR, via Trasea 7, 35131 Padova, Italy.,Department of Information Engineering, University of Padova, via Gradenigo 6/B, 35131 Padova, Italy
| | - Stephen Lowry
- The University of Kent, School of Physical Sciences, Canterbury, Kent CT2 7NZ, UK
| | | | - Frank Preusker
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany
| | - Frank Scholten
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany
| | - Holger Sierks
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, 37077 Göttingen, Germany
| | - Cesare Barbieri
- University of Padova, Department of Physics and Astronomy, Vicolo dell'Osservatorio 3, 35122 Padova, Italy
| | - Philippe Lamy
- Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille), UMR 7326, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France
| | - Rafael Rodrigo
- Centro de Astrobiologia, CSIC-INTA, 28850 Torrejon de Ardoz, Madrid, Spain.,International Space Science Institute, Hallerstraße 6, 3012 Bern, Switzerland
| | - Detlef Koschny
- Scientific Support Office, European Space Research and Technology Centre/ESA, Keplerlaan 1, Postbus 299, 2201 AZ Noordwijk ZH, The Netherlands
| | - Hans Rickman
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden.,PAS Space Research Center, Bartycka 18A, 00716 Warszawa, Poland
| | - Horst Uwe Keller
- Institut für Geophysik und extraterrestrische Physik (IGEP), Technische Universität Braunschweig, Mendelssohnstraße 3, 38106 Braunschweig, Germany
| | - Michael F A'Hearn
- University of Maryland, Department of Astronomy, College Park, Maryland 20742-2421, USA.,Akademie der Wissenschaften zu Göttingen and Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, 37077 Göttingen, Germany
| | - Jessica Agarwal
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, 37077 Göttingen, Germany
| | - Anne-Thérèse Auger
- Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille), UMR 7326, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France
| | - M Antonella Barucci
- LESIA-Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Universite Paris Diderot, 5 place J. Janssen, 92195 Meudon, France
| | - Jean-Loup Bertaux
- LATMOS, CNRS/UVSQ/IPSL, 11 boulevard d'Alembert, 78280 Guyancourt, France
| | - Ivano Bertini
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy
| | - Sebastien Besse
- Scientific Support Office, European Space Research and Technology Centre/ESA, Keplerlaan 1, Postbus 299, 2201 AZ Noordwijk ZH, The Netherlands
| | - Dennis Bodewits
- University of Maryland, Department of Astronomy, College Park, Maryland 20742-2421, USA
| | - Claire Capanna
- Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille), UMR 7326, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France
| | - Vania Da Deppo
- CNR-IFN UOS Padova LUXOR, via Trasea 7, 35131 Padova, Italy
| | - Björn Davidsson
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Stefano Debei
- Department of Industrial Engineering, University of Padova, via Venezia 1, 35131 Padova, Italy
| | | | - Francesca Ferri
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy
| | - Sonia Fornasier
- LESIA-Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Universite Paris Diderot, 5 place J. Janssen, 92195 Meudon, France
| | - Marco Fulle
- INAF-Osservatorio Astronomico, Via Tiepolo 11, 34014 Trieste, Italy
| | | | - Olivier Groussin
- Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille), UMR 7326, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France
| | - Pedro J Gutiérrez
- Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomìa s/n, 18008 Granada, Spain
| | - Carsten Güttler
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, 37077 Göttingen, Germany
| | - Stubbe F Hviid
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany.,Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, 37077 Göttingen, Germany
| | - Wing-Huen Ip
- National Central University, Graduate Institute of Astronomy, 300 Chung-Da Road, Chung-Li 32054 Taiwan
| | - Jörg Knollenberg
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany
| | - Gabor Kovacs
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, 37077 Göttingen, Germany
| | - Rainer Kramm
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, 37077 Göttingen, Germany
| | - Ekkehard Kührt
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany
| | - Michael Küppers
- Operations Department, European Space Astronomy Centre/ESA, PO Box 78, 28691 Villanueva de la Canada, Madrid, Spain
| | - Fiorangela La Forgia
- University of Padova, Department of Physics and Astronomy, Vicolo dell'Osservatorio 3, 35122 Padova, Italy
| | - Luisa M Lara
- Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomìa s/n, 18008 Granada, Spain
| | - Monica Lazzarin
- University of Padova, Department of Physics and Astronomy, Vicolo dell'Osservatorio 3, 35122 Padova, Italy
| | - Zhong-Yi Lin
- National Central University, Graduate Institute of Astronomy, 300 Chung-Da Road, Chung-Li 32054 Taiwan
| | - Josè J Lopez Moreno
- Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomìa s/n, 18008 Granada, Spain
| | - Sara Magrin
- University of Padova, Department of Physics and Astronomy, Vicolo dell'Osservatorio 3, 35122 Padova, Italy
| | - Harald Michalik
- Institut für Datentechnik und Kommunikationsnetze der TU Braunschweig, Hans-Sommer Straße 66, 38106 Braunschweig, Germany
| | - Stefano Mottola
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany
| | - Nilda Oklay
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, 37077 Göttingen, Germany
| | - Antoine Pommerol
- Physikalisches Institut der Universität Bern, Sidlerstraße 5, 3012 Bern, Switzerland
| | - Nicolas Thomas
- Physikalisches Institut der Universität Bern, Sidlerstraße 5, 3012 Bern, Switzerland
| | - Cecilia Tubiana
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, 37077 Göttingen, Germany
| | - Jean-Baptiste Vincent
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, 37077 Göttingen, Germany
| |
Collapse
|
23
|
Alí-Lagoa V, Delbo’ M, Libourel G. RAPID TEMPERATURE CHANGES AND THE EARLY ACTIVITY ON COMET 67P/CHURYUMOV–GERASIMENKO. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/2041-8205/810/2/l22] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
24
|
Spohn T, Knollenberg J, Ball AJ, Banaszkiewicz M, Benkhoff J, Grott M, Grygorczuk J, Hüttig C, Hagermann A, Kargl G, Kaufmann E, Kömle N, Kührt E, Kossacki KJ, Marczewski W, Pelivan I, Schrödter R, Seiferlin K. COMETARY SCIENCE. Thermal and mechanical properties of the near-surface layers of comet 67P/Churyumov-Gerasimenko. Science 2015; 349:aab0464. [PMID: 26228152 DOI: 10.1126/science.aab0464] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Thermal and mechanical material properties determine comet evolution and even solar system formation because comets are considered remnant volatile-rich planetesimals. Using data from the Multipurpose Sensors for Surface and Sub-Surface Science (MUPUS) instrument package gathered at the Philae landing site Abydos on comet 67P/Churyumov-Gerasimenko, we found the diurnal temperature to vary between 90 and 130 K. The surface emissivity was 0.97, and the local thermal inertia was 85 ± 35 J m(-2) K(-1)s(-1/2). The MUPUS thermal probe did not fully penetrate the near-surface layers, suggesting a local resistance of the ground to penetration of >4 megapascals, equivalent to >2 megapascal uniaxial compressive strength. A sintered near-surface microporous dust-ice layer with a porosity of 30 to 65% is consistent with the data.
Collapse
Affiliation(s)
- T Spohn
- Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany.
| | - J Knollenberg
- Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany
| | - A J Ball
- European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Noordwijk, Netherlands
| | | | - J Benkhoff
- European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Noordwijk, Netherlands
| | - M Grott
- Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany
| | | | - C Hüttig
- Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany
| | - A Hagermann
- Department of Physical Sciences, The Open University, Milton Keynes, UK
| | - G Kargl
- Space Research Institute, Austrian Academy of Sciences Graz, Austria
| | - E Kaufmann
- Department of Physical Sciences, The Open University, Milton Keynes, UK
| | - N Kömle
- Space Research Institute, Austrian Academy of Sciences Graz, Austria
| | - E Kührt
- Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany
| | - K J Kossacki
- Faculty of Physics, University of Warsaw, Warsaw, Poland
| | | | - I Pelivan
- Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany
| | - R Schrödter
- Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany
| | - K Seiferlin
- Physics Institute, University of Berne, Berne, Switzerland
| |
Collapse
|
25
|
Bibring JP, Langevin Y, Carter J, Eng P, Gondet B, Jorda L, Le Mouélic S, Mottola S, Pilorget C, Poulet F, Vincendon M. COMETARY SCIENCE. 67P/Churyumov-Gerasimenko surface properties as derived from CIVA panoramic images. Science 2015; 349:aab0671. [PMID: 26228154 DOI: 10.1126/science.aab0671] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The structure and composition of cometary constituents, down to their microscopic scale, are critical witnesses of the processes and ingredients that drove the formation and evolution of planetary bodies toward their present diversity. On board Rosetta's lander Philae, the Comet Infrared and Visible Analyser (CIVA) experiment took a series of images to characterize the surface materials surrounding the lander on comet 67P/Churyumov-Gerasimenko. Images were collected twice: just after touchdown, and after Philae finally came to rest, where it acquired a full panorama. These images reveal a fractured surface with complex structure and a variety of grain scales and albedos, possibly constituting pristine cometary material.
Collapse
Affiliation(s)
- J-P Bibring
- Institut d'Astrophysique Spatiale (IAS), CNRS/Université Paris Sud, Orsay, France.
| | - Y Langevin
- Institut d'Astrophysique Spatiale (IAS), CNRS/Université Paris Sud, Orsay, France
| | - J Carter
- Institut d'Astrophysique Spatiale (IAS), CNRS/Université Paris Sud, Orsay, France
| | - P Eng
- Institut d'Astrophysique Spatiale (IAS), CNRS/Université Paris Sud, Orsay, France
| | - B Gondet
- Institut d'Astrophysique Spatiale (IAS), CNRS/Université Paris Sud, Orsay, France
| | - L Jorda
- Laboratoire d'Astrophysique de Marseille (LAM), UMR7326,CNRS/INSU/Université Aix-Marseille, France
| | - S Le Mouélic
- Laboratoire Planétologie et Géodynamique, CNRS UMR6112 and Université de Nantes, Nantes, France
| | - S Mottola
- Deutschen Zentrum für Luft und Raumfahrt (DLR), Institute of Planetary Research, Berlin, Germany
| | - C Pilorget
- Institut d'Astrophysique Spatiale (IAS), CNRS/Université Paris Sud, Orsay, France
| | - F Poulet
- Institut d'Astrophysique Spatiale (IAS), CNRS/Université Paris Sud, Orsay, France
| | - M Vincendon
- Institut d'Astrophysique Spatiale (IAS), CNRS/Université Paris Sud, Orsay, France
| |
Collapse
|
26
|
Mottola S, Arnold G, Grothues HG, Jaumann R, Michaelis H, Neukum G, Bibring JP, Schröder SE, Hamm M, Otto KA, Pelivan I, Proffe G, Scholten F, Tirsch D, Kreslavsky M, Remetean E, Souvannavong F, Dolives B. COMETARY SCIENCE. The structure of the regolith on 67P/Churyumov-Gerasimenko from ROLIS descent imaging. Science 2015; 349:aab0232. [PMID: 26228151 DOI: 10.1126/science.aab0232] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The structure of the upper layer of a comet is a product of its surface activity. The Rosetta Lander Imaging System (ROLIS) on board Philae acquired close-range images of the Agilkia site during its descent onto comet 67P/Churyumov-Gerasimenko. These images reveal a photometrically uniform surface covered by regolith composed of debris and blocks ranging in size from centimeters to 5 meters. At the highest resolution of 1 centimeter per pixel, the surface appears granular, with no apparent deposits of unresolved sand-sized particles. The thickness of the regolith varies across the imaged field from 0 to 1 to 2 meters. The presence of aeolian-like features resembling wind tails hints at regolith mobilization and erosion processes. Modeling suggests that abrasion driven by airfall-induced particle "splashing" is responsible for the observed formations.
Collapse
Affiliation(s)
- S Mottola
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany.
| | - G Arnold
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - H-G Grothues
- DLR, Space Management, Space Science. Bonn, Germany
| | - R Jaumann
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany. Freie Universität Berlin, Institute of Geological Sciences, Berlin, Germany
| | - H Michaelis
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - G Neukum
- Freie Universität Berlin, Institute of Geological Sciences, Berlin, Germany
| | - J-P Bibring
- Institute of Space Astrophysics, Orsay, France
| | - S E Schröder
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - M Hamm
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany. Humboldt University Berlin, Germany
| | - K A Otto
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - I Pelivan
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - G Proffe
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - F Scholten
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - D Tirsch
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - M Kreslavsky
- Earth and Planetary Sciences, University of California, Santa Cruz, CA, USA
| | - E Remetean
- Centre National d'Études Spatiales, Toulouse, France
| | | | - B Dolives
- Magellium, Ramonville Saint-Agne, France
| |
Collapse
|
27
|
Biele J, Ulamec S, Maibaum M, Roll R, Witte L, Jurado E, Muñoz P, Arnold W, Auster HU, Casas C, Faber C, Fantinati C, Finke F, Fischer HH, Geurts K, Güttler C, Heinisch P, Herique A, Hviid S, Kargl G, Knapmeyer M, Knollenberg J, Kofman W, Kömle N, Kührt E, Lommatsch V, Mottola S, Pardo de Santayana R, Remetean E, Scholten F, Seidensticker KJ, Sierks H, Spohn T. COMETARY SCIENCE. The landing(s) of Philae and inferences about comet surface mechanical properties. Science 2015; 349:aaa9816. [PMID: 26228158 DOI: 10.1126/science.aaa9816] [Citation(s) in RCA: 190] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Philae lander, part of the Rosetta mission to investigate comet 67P/Churyumov-Gerasimenko, was delivered to the cometary surface in November 2014. Here we report the precise circumstances of the multiple landings of Philae, including the bouncing trajectory and rebound parameters, based on engineering data in conjunction with operational instrument data. These data also provide information on the mechanical properties (strength and layering) of the comet surface. The first touchdown site, Agilkia, appears to have a granular soft surface (with a compressive strength of 1 kilopascal) at least ~20 cm thick, possibly on top of a more rigid layer. The final landing site, Abydos, has a hard surface.
Collapse
Affiliation(s)
- Jens Biele
- Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany
| | - Stephan Ulamec
- Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany
| | - Michael Maibaum
- Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany
| | - Reinhard Roll
- Max-Planck-Institut für Sonnensystemforschung (MPS), Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Lars Witte
- DLR/Institut für Raumfahrtsysteme, Robert Hooke-Straße 7, 28359 Bremen, Germany
| | - Eric Jurado
- Centre National d'Études Spatiales, 18 Avenue Édouard Belin, 31400 Toulouse, France
| | - Pablo Muñoz
- European Space Agency/European Space Operations Centre (ESA/ESOC), Robert-Bosch-Straße 5, 64293 Darmstadt, Germany. Grupo Mecánica de Vuelo at ESA/ESOC - GMV Robert-Bosch-Straße 5, 64293 Darmstadt, Germany
| | - Walter Arnold
- 1. Physikalisches Institut, Georg August Universität, 37077 Göttingen, Germany; permanent address: Department of Materials Science, Saarland University, 66123 Saarbrücken, Germany
| | - Hans-Ulrich Auster
- Institut für Geophysik und Extraterrestrische Physik, Technische Universität Braunschweig Mendelssohnstrasse 3, 38106 Braunschweig, Germany
| | - Carlos Casas
- European Space Agency/European Space Operations Centre (ESA/ESOC), Robert-Bosch-Straße 5, 64293 Darmstadt, Germany. Grupo Mecánica de Vuelo at ESA/ESOC - GMV Robert-Bosch-Straße 5, 64293 Darmstadt, Germany
| | - Claudia Faber
- DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany
| | - Cinzia Fantinati
- Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany
| | - Felix Finke
- Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany
| | - Hans-Herbert Fischer
- Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany
| | - Koen Geurts
- Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany
| | - Carsten Güttler
- Max-Planck-Institut für Sonnensystemforschung (MPS), Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Philip Heinisch
- Institut für Geophysik und Extraterrestrische Physik, Technische Universität Braunschweig Mendelssohnstrasse 3, 38106 Braunschweig, Germany
| | - Alain Herique
- Université Grenoble Alpes and CNRS, Institut de Planétologie et d'Astrophysique de Grenoble, F-38000 Grenoble, France
| | - Stubbe Hviid
- DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany
| | - Günter Kargl
- Institut für Weltraumforschung (IWF) Graz, Austria Austrian Academy of Sciences, Space Research Institute, Schmiedlstraße 6, 8042 Graz, Austria
| | - Martin Knapmeyer
- DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany
| | - Jörg Knollenberg
- DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany
| | - Wlodek Kofman
- Université Grenoble Alpes and CNRS, Institut de Planétologie et d'Astrophysique de Grenoble, F-38000 Grenoble, France
| | - Norbert Kömle
- Institut für Weltraumforschung (IWF) Graz, Austria Austrian Academy of Sciences, Space Research Institute, Schmiedlstraße 6, 8042 Graz, Austria
| | - Ekkehard Kührt
- DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany
| | - Valentina Lommatsch
- Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany
| | - Stefano Mottola
- DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany
| | - Ramon Pardo de Santayana
- European Space Agency/European Space Operations Centre (ESA/ESOC), Robert-Bosch-Straße 5, 64293 Darmstadt, Germany. Grupo Mecánica de Vuelo at ESA/ESOC - GMV Robert-Bosch-Straße 5, 64293 Darmstadt, Germany
| | - Emile Remetean
- Centre National d'Études Spatiales, 18 Avenue Édouard Belin, 31400 Toulouse, France
| | - Frank Scholten
- DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany
| | | | - Holger Sierks
- Max-Planck-Institut für Sonnensystemforschung (MPS), Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Tilman Spohn
- DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany
| |
Collapse
|
28
|
Vincent JB, Bodewits D, Besse S, Sierks H, Barbieri C, Lamy P, Rodrigo R, Koschny D, Rickman H, Keller HU, Agarwal J, A'Hearn MF, Auger AT, Barucci MA, Bertaux JL, Bertini I, Capanna C, Cremonese G, Da Deppo V, Davidsson B, Debei S, De Cecco M, El-Maarry MR, Ferri F, Fornasier S, Fulle M, Gaskell R, Giacomini L, Groussin O, Guilbert-Lepoutre A, Gutierrez-Marques P, Gutiérrez PJ, Güttler C, Hoekzema N, Höfner S, Hviid SF, Ip WH, Jorda L, Knollenberg J, Kovacs G, Kramm R, Kührt E, Küppers M, La Forgia F, Lara LM, Lazzarin M, Lee V, Leyrat C, Lin ZY, Lopez Moreno JJ, Lowry S, Magrin S, Maquet L, Marchi S, Marzari F, Massironi M, Michalik H, Moissl R, Mottola S, Naletto G, Oklay N, Pajola M, Preusker F, Scholten F, Thomas N, Toth I, Tubiana C. Large heterogeneities in comet 67P as revealed by active pits from sinkhole collapse. Nature 2015; 523:63-6. [PMID: 26135448 DOI: 10.1038/nature14564] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 05/06/2015] [Indexed: 11/09/2022]
Abstract
Pits have been observed on many cometary nuclei mapped by spacecraft. It has been argued that cometary pits are a signature of endogenic activity, rather than impact craters such as those on planetary and asteroid surfaces. Impact experiments and models cannot reproduce the shapes of most of the observed cometary pits, and the predicted collision rates imply that few of the pits are related to impacts. Alternative mechanisms like explosive activity have been suggested, but the driving process remains unknown. Here we report that pits on comet 67P/Churyumov-Gerasimenko are active, and probably created by a sinkhole process, possibly accompanied by outbursts. We argue that after formation, pits expand slowly in diameter, owing to sublimation-driven retreat of the walls. Therefore, pits characterize how eroded the surface is: a fresh cometary surface will have a ragged structure with many pits, while an evolved surface will look smoother. The size and spatial distribution of pits imply that large heterogeneities exist in the physical, structural or compositional properties of the first few hundred metres below the current nucleus surface.
Collapse
Affiliation(s)
- Jean-Baptiste Vincent
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Dennis Bodewits
- University of Maryland, Department of Astronomy, College Park, Maryland 20742-2421, USA
| | - Sébastien Besse
- Scientific Support Office, European Space Research and Technology Centre/ESA, Keplerlaan 1, Postbus 299, 2201 AZ Noordwijk ZH, The Netherlands
| | - Holger Sierks
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Cesare Barbieri
- University of Padova, Department of Physics and Astronomy, Vicolo dell'Osservatorio 3, 35122 Padova, Italy
| | - Philippe Lamy
- Laboratoire d'Astrophysique de Marseille, UMR 7326, CNRS and Aix Marseille Université, 13388 Marseille Cedex 13, France
| | - Rafael Rodrigo
- 1] Centro de Astrobiologia, CSIC-INTA, 28850 Torrejon de Ardoz, Madrid, Spain [2] International Space Science Institute, Hallerstraße 6, 3012 Bern, Switzerland
| | - Detlef Koschny
- Scientific Support Office, European Space Research and Technology Centre/ESA, Keplerlaan 1, Postbus 299, 2201 AZ Noordwijk ZH, The Netherlands
| | - Hans Rickman
- 1] Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden [2] PAS Space Research Center, Bartycka 18A, 00716 Warszawa, Poland
| | - Horst Uwe Keller
- Institut für Geophysik und extraterrestrische Physik (IGEP), Technische Universität Braunschweig, Mendelssohnstraße 3, 38106 Braunschweig, Germany
| | - Jessica Agarwal
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Michael F A'Hearn
- 1] University of Maryland, Department of Astronomy, College Park, Maryland 20742-2421, USA [2] Akademie der Wissenschaften zu Göttingen and Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Anne-Thérèse Auger
- Laboratoire d'Astrophysique de Marseille, UMR 7326, CNRS and Aix Marseille Université, 13388 Marseille Cedex 13, France
| | - M Antonella Barucci
- LESIA-Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Universite Paris Diderot, 5 place Jules Janssen, 92195 Meudon, France
| | - Jean-Loup Bertaux
- LATMOS, CNRS/UVSQ/IPSL, 11 boulevard d'Alembert, 78280 Guyancourt, France
| | - Ivano Bertini
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy
| | - Claire Capanna
- Laboratoire d'Astrophysique de Marseille, UMR 7326, CNRS and Aix Marseille Université, 13388 Marseille Cedex 13, France
| | - Gabriele Cremonese
- INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
| | - Vania Da Deppo
- CNR-IFN UOS Padova LUXOR, via Trasea 7, 35131 Padova, Italy
| | - Björn Davidsson
- Centro de Astrobiologia, CSIC-INTA, 28850 Torrejon de Ardoz, Madrid, Spain
| | - Stefano Debei
- Department of Industrial Engineering, University of Padova, via Venezia 1, 35131 Padova, Italy
| | | | | | - Francesca Ferri
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy
| | - Sonia Fornasier
- LESIA-Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Universite Paris Diderot, 5 place Jules Janssen, 92195 Meudon, France
| | - Marco Fulle
- INAF Osservatorio Astronomico, via Tiepolo 11, 34014 Trieste, Italy
| | | | - Lorenza Giacomini
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy
| | - Olivier Groussin
- Laboratoire d'Astrophysique de Marseille, UMR 7326, CNRS and Aix Marseille Université, 13388 Marseille Cedex 13, France
| | | | - P Gutierrez-Marques
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Pedro J Gutiérrez
- Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomìa s/n, 18008 Granada, Spain
| | - Carsten Güttler
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Nick Hoekzema
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Sebastian Höfner
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Stubbe F Hviid
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany
| | - Wing-Huen Ip
- National Central University, Graduate Institute of Astronomy, 300 Chung-Da Rd, Chung-Li 32054, Taiwan
| | - Laurent Jorda
- Laboratoire d'Astrophysique de Marseille, UMR 7326, CNRS and Aix Marseille Université, 13388 Marseille Cedex 13, France
| | - Jörg Knollenberg
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany
| | - Gabor Kovacs
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Rainer Kramm
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Ekkehard Kührt
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany
| | - Michael Küppers
- Operations Department, European Space Astronomy Centre/ESA, PO Box 78, 28691 Villanueva de la Canada, Madrid, Spain
| | - Fiorangela La Forgia
- University of Padova, Department of Physics and Astronomy, Vicolo dell'Osservatorio 3, 35122 Padova, Italy
| | - Luisa M Lara
- Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomìa s/n, 18008 Granada, Spain
| | - Monica Lazzarin
- University of Padova, Department of Physics and Astronomy, Vicolo dell'Osservatorio 3, 35122 Padova, Italy
| | - Vicky Lee
- National Central University, Graduate Institute of Astronomy, 300 Chung-Da Rd, Chung-Li 32054, Taiwan
| | - Cédric Leyrat
- LESIA-Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Universite Paris Diderot, 5 place Jules Janssen, 92195 Meudon, France
| | - Zhong-Yi Lin
- National Central University, Graduate Institute of Astronomy, 300 Chung-Da Rd, Chung-Li 32054, Taiwan
| | - Josè J Lopez Moreno
- Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomìa s/n, 18008 Granada, Spain
| | - Stephen Lowry
- The University of Kent, School of Physical Sciences, Canterbury, Kent CT2 7NZ, UK
| | - Sara Magrin
- University of Padova, Deptartment of Physics and Astronomy, via Marzolo 8, 35131 Padova, Italy
| | - Lucie Maquet
- Operations Department, European Space Astronomy Centre/ESA, PO Box 78, 28691 Villanueva de la Canada, Madrid, Spain
| | - Simone Marchi
- Solar System Exploration Research Virtual Institute, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, Colorado 80302, USA
| | - Francesco Marzari
- University of Padova, Deptartment of Physics and Astronomy, via Marzolo 8, 35131 Padova, Italy
| | - Matteo Massironi
- Dipartimento di Geoscienze, University of Padova, via Giovanni Gradenigo 6, 35131 Padova, Italy
| | - Harald Michalik
- Institut für Datentechnik und Kommunikationsnetze der Technische Universität Braunschweig, Hans-Sommer-Straße 66, 38106 Braunschweig, Germany
| | - Richard Moissl
- Operations Department, European Space Astronomy Centre/ESA, PO Box 78, 28691 Villanueva de la Canada, Madrid, Spain
| | - Stefano Mottola
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany
| | - Giampiero Naletto
- 1] Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy [2] CNR-IFN UOS Padova LUXOR, via Trasea 7, 35131 Padova, Italy [3] University of Padova, Department of Information Engineering, via Gradenigo 6/B, 35131 Padova, Italy
| | - Nilda Oklay
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Maurizio Pajola
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy
| | - Frank Preusker
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany
| | - Frank Scholten
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany
| | - Nicolas Thomas
- Physikalisches Institut der Universität Bern, Sidlerstraße 5, 3012 Bern, Switzerland
| | - Imre Toth
- Konkoly Observatory of the Hungarian Academy of Sciences, PO Box 67, 1525 Budapest, Hungary
| | - Cecilia Tubiana
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| |
Collapse
|
29
|
Jutzi M, Asphaug E. COMETARY NUCLEI. The shape and structure of cometary nuclei as a result of low-velocity accretion. Science 2015; 348:1355-8. [PMID: 26022415 DOI: 10.1126/science.aaa4747] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 05/13/2015] [Indexed: 11/02/2022]
Abstract
Cometary nuclei imaged from flyby and rendezvous spacecraft show common evidence of layered structures and bilobed shapes. But how and when these features formed is much debated, with distinct implications for solar system formation, dynamics, and geology. We show that these features could be a direct result of accretionary collisions, based on three-dimensional impact simulations using realistic constitutive properties. We identify two regimes of interest: layer-forming splats and mergers resulting in bilobed shapes. For bodies with low tensile strength, our results can explain key morphologies of cometary nuclei, as well as their low bulk densities. This advances the hypothesis that nuclei formed by collisional coagulation-either out of cometesimals accreting in the early solar system or, alternatively, out of comparable-sized debris clumps paired in the aftermath of major collisions.
Collapse
Affiliation(s)
- M Jutzi
- Physics Institute, Space Research and Planetary Sciences, Center for Space and Habitability, University of Bern, Sidlerstrassse 5, 3012 Bern, Switzerland.
| | - E Asphaug
- School of Earth and Space Exploration, Arizona State University, PO Box 876004, Tempe, AZ 85287, USA
| |
Collapse
|
30
|
Sierks H, Barbieri C, Lamy PL, Rodrigo R, Koschny D, Rickman H, Keller HU, Agarwal J, A'Hearn MF, Angrilli F, Auger AT, Barucci MA, Bertaux JL, Bertini I, Besse S, Bodewits D, Capanna C, Cremonese G, Da Deppo V, Davidsson B, Debei S, De Cecco M, Ferri F, Fornasier S, Fulle M, Gaskell R, Giacomini L, Groussin O, Gutierrez-Marques P, Gutiérrez PJ, Güttler C, Hoekzema N, Hviid SF, Ip WH, Jorda L, Knollenberg J, Kovacs G, Kramm JR, Kührt E, Küppers M, La Forgia F, Lara LM, Lazzarin M, Leyrat C, Lopez Moreno JJ, Magrin S, Marchi S, Marzari F, Massironi M, Michalik H, Moissl R, Mottola S, Naletto G, Oklay N, Pajola M, Pertile M, Preusker F, Sabau L, Scholten F, Snodgrass C, Thomas N, Tubiana C, Vincent JB, Wenzel KP, Zaccariotto M, Pätzold M. Cometary science. On the nucleus structure and activity of comet 67P/Churyumov-Gerasimenko. Science 2015; 347:aaa1044. [PMID: 25613897 DOI: 10.1126/science.aaa1044] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Images from the OSIRIS scientific imaging system onboard Rosetta show that the nucleus of 67P/Churyumov-Gerasimenko consists of two lobes connected by a short neck. The nucleus has a bulk density less than half that of water. Activity at a distance from the Sun of >3 astronomical units is predominantly from the neck, where jets have been seen consistently. The nucleus rotates about the principal axis of momentum. The surface morphology suggests that the removal of larger volumes of material, possibly via explosive release of subsurface pressure or via creation of overhangs by sublimation, may be a major mass loss process. The shape raises the question of whether the two lobes represent a contact binary formed 4.5 billion years ago, or a single body where a gap has evolved via mass loss.
Collapse
Affiliation(s)
- Holger Sierks
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany.
| | - Cesare Barbieri
- Department of Physics and Astronomy, University of Padova, 35122 Padova, Italy
| | - Philippe L Lamy
- Laboratoire d'Astrophysique de Marseille, UMR 7326, CNRS & Aix Marseille Université, 13388 Marseille Cedex 13, France
| | - Rafael Rodrigo
- Centro de Astrobiologia, CSIC-INTA,28850 Madrid, Spain. International Space Science Institute, 3012 Bern, Switzerland
| | - Detlef Koschny
- Scientific Support Office, European Space Research and Technology Centre/ESA, 2201 AZ Noordwijk ZH, Netherlands
| | - Hans Rickman
- Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden. PAS Space Research Center, 00716 Warszawa, Poland
| | - Horst Uwe Keller
- Institut für Geophysik und extraterrestrische Physik, Technische Universität Braunschweig, 38106 Braunschweig, Germany. Deutsches Zentrum für Luft- und Raumfahrt, Institut für Planetenforschung, 12489 Berlin, Germany
| | - Jessica Agarwal
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - Michael F A'Hearn
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany. Department of Astronomy, University of Maryland, College Park, MD 20742, USA. Akademie der Wissenschaften zu Göttingen, 37077 Göttingen, Germany
| | - Francesco Angrilli
- Department of Industrial Engineering, University of Padova, 35131 Padova, Italy
| | - Anne-Therese Auger
- Aix Marseille Université, CNRS, Laboratoire d'Astrophysique de Marseille, UMR 7326, 13388 Marseille, France
| | - M Antonella Barucci
- LESIA-Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Université Paris Diderot, 92195 Meudon, France
| | | | - Ivano Bertini
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, 35131 Padova, Italy
| | - Sebastien Besse
- Scientific Support Office, European Space Research and Technology Centre/ESA, 2201 AZ Noordwijk ZH, Netherlands
| | - Dennis Bodewits
- Department of Astronomy, University of Maryland, College Park, MD 20742, USA
| | - Claire Capanna
- Aix Marseille Université, CNRS, Laboratoire d'Astrophysique de Marseille, UMR 7326, 13388 Marseille, France
| | | | | | - Björn Davidsson
- Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden
| | - Stefano Debei
- Department of Industrial Engineering, University of Padova, 35131 Padova, Italy
| | | | - Francesca Ferri
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, 35131 Padova, Italy
| | - Sonia Fornasier
- LESIA-Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Université Paris Diderot, 92195 Meudon, France
| | - Marco Fulle
- INAF - Osservatorio Astronomico di Trieste, 34014 Trieste, Italy
| | | | - Lorenza Giacomini
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, 35131 Padova, Italy
| | - Olivier Groussin
- Aix Marseille Université, CNRS, Laboratoire d'Astrophysique de Marseille, UMR 7326, 13388 Marseille, France
| | | | - Pedro J Gutiérrez
- Instituto de Astrofisica de Andalucia (CSIC), c/ Glorieta de la AstronomÌa s/n, 18008 Granada, Spain
| | - Carsten Güttler
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - Nick Hoekzema
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - Stubbe F Hviid
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany. Deutsches Zentrum für Luft- und Raumfahrt, Institut für Planetenforschung, 12489 Berlin, Germany
| | - Wing-Huen Ip
- Graduate Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan. Space Science Institute, Macau University of Science and Technology, Macao, China
| | - Laurent Jorda
- Aix Marseille Université, CNRS, Laboratoire d'Astrophysique de Marseille, UMR 7326, 13388 Marseille, France
| | - Jörg Knollenberg
- Deutsches Zentrum für Luft- und Raumfahrt, Institut für Planetenforschung, 12489 Berlin, Germany
| | - Gabor Kovacs
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - J Rainer Kramm
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - Ekkehard Kührt
- Deutsches Zentrum für Luft- und Raumfahrt, Institut für Planetenforschung, 12489 Berlin, Germany
| | - Michael Küppers
- Operations Department, European Space Astronomy Centre/ESA, 28691 Villanueva de la Canada, Madrid, Spain
| | | | - Luisa M Lara
- Instituto de Astrofisica de Andalucia (CSIC), c/ Glorieta de la AstronomÌa s/n, 18008 Granada, Spain
| | - Monica Lazzarin
- Department of Physics and Astronomy, University of Padova, 35122 Padova, Italy
| | - Cédric Leyrat
- LESIA-Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Université Paris Diderot, 92195 Meudon, France
| | - Josè J Lopez Moreno
- Instituto de Astrofisica de Andalucia (CSIC), c/ Glorieta de la AstronomÌa s/n, 18008 Granada, Spain
| | - Sara Magrin
- Department of Physics and Astronomy, University of Padova, 35122 Padova, Italy
| | - Simone Marchi
- Solar System Exploration Research, Virtual Institute, Southwest Research Institute, Boulder, CO 80302, USA
| | - Francesco Marzari
- Department of Physics and Astronomy, University of Padova, 35122 Padova, Italy
| | - Matteo Massironi
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, 35131 Padova, Italy. Dipartimento di Geoscienze, University of Padova, 35131 Padova, Italy
| | - Harald Michalik
- Institut für Datentechnik und Kommunikationsnetze der TU Braunschweig, 38106 Braunschweig, Germany
| | - Richard Moissl
- Operations Department, European Space Astronomy Centre/ESA, 28691 Villanueva de la Canada, Madrid, Spain
| | - Stefano Mottola
- Deutsches Zentrum für Luft- und Raumfahrt, Institut für Planetenforschung, 12489 Berlin, Germany
| | - Giampiero Naletto
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, 35131 Padova, Italy. CNR-IFN UOS Padova LUXOR, 35131 Padova, Italy. Department of Information Engineering, University of Padova, 35131 Padova, Italy
| | - Nilda Oklay
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - Maurizio Pajola
- Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, 35131 Padova, Italy
| | - Marco Pertile
- Department of Industrial Engineering, University of Padova, 35131 Padova, Italy. Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, 35131 Padova, Italy
| | - Frank Preusker
- Deutsches Zentrum für Luft- und Raumfahrt, Institut für Planetenforschung, 12489 Berlin, Germany
| | - Lola Sabau
- Instituto Nacional de Tecnica Aeroespacial, 28850 Torrejon de Ardoz, Madrid, Spain
| | - Frank Scholten
- Deutsches Zentrum für Luft- und Raumfahrt, Institut für Planetenforschung, 12489 Berlin, Germany
| | - Colin Snodgrass
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - Nicolas Thomas
- Physikalisches Institut, University of Bern, 3012 Bern, Switzerland. Center for Space and Habitability, University of Bern, 3012 Bern, Switzerland
| | - Cecilia Tubiana
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | | | - Klaus-Peter Wenzel
- Scientific Support Office, European Space Research and Technology Centre/ESA, 2201 AZ Noordwijk ZH, Netherlands
| | - Mirco Zaccariotto
- Department of Industrial Engineering, University of Padova, 35131 Padova, Italy. Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, 35131 Padova, Italy
| | - Martin Pätzold
- Rheinisches Institut für Umweltforschung, Abteilung Planetenforschung, Universität zu Köln, 50931 Köln, Germany
| |
Collapse
|
31
|
Gibney E. Science pours in from Rosetta comet mission. Nature 2015. [DOI: 10.1038/nature.2015.16777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
32
|
Hässig M, Altwegg K, Balsiger H, Bar-Nun A, Berthelier JJ, Bieler A, Bochsler P, Briois C, Calmonte U, Combi M, De Keyser J, Eberhardt P, Fiethe B, Fuselier SA, Galand M, Gasc S, Gombosi TI, Hansen KC, Jäckel A, Keller HU, Kopp E, Korth A, Kührt E, Le Roy L, Mall U, Marty B, Mousis O, Neefs E, Owen T, Rème H, Rubin M, Sémon T, Tornow C, Tzou CY, Waite JH, Wurz P. Cometary science. Time variability and heterogeneity in the coma of 67P/Churyumov-Gerasimenko. Science 2015; 347:aaa0276. [PMID: 25613892 DOI: 10.1126/science.aaa0276] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Comets contain the best-preserved material from the beginning of our planetary system. Their nuclei and comae composition reveal clues about physical and chemical conditions during the early solar system when comets formed. ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) onboard the Rosetta spacecraft has measured the coma composition of comet 67P/Churyumov-Gerasimenko with well-sampled time resolution per rotation. Measurements were made over many comet rotation periods and a wide range of latitudes. These measurements show large fluctuations in composition in a heterogeneous coma that has diurnal and possibly seasonal variations in the major outgassing species: water, carbon monoxide, and carbon dioxide. These results indicate a complex coma-nucleus relationship where seasonal variations may be driven by temperature differences just below the comet surface.
Collapse
Affiliation(s)
- M Hässig
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238, USA.
| | - K Altwegg
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Center for Space and Habitability (CSH), University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - H Balsiger
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - A Bar-Nun
- Department of Geosciences, Tel-Aviv University, Ramat-Aviv, Tel-Aviv, Israel
| | - J J Berthelier
- Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Institute Pierre Simon Laplace (IPSL), Centre national de recherche scientifique (CNRS), Université Pierre et Marie Curie (UPMC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), BP 102, UPMC, 4 Place Jussieu, F-75252 Paris Cedex 05, France
| | - A Bieler
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109, USA
| | - P Bochsler
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - C Briois
- Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), UMR 7328 CNRS - Université d'Orléans, France
| | - U Calmonte
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - M Combi
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109, USA
| | - J De Keyser
- Belgian Institute for Space Aeronomy (BIRA-IASB), Ringlaan 3, B-1180 Brussels, Belgium. Center for Plasma Astrophysics, KULeuven, Celestijnenlaan 200D, 3001 Heverlee, Belgium
| | - P Eberhardt
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - B Fiethe
- Institute of Computer and Network Engineering (IDA), TU Braunschweig, Hans-Sommer-Straße 66, D-38106 Braunschweig, Germany
| | - S A Fuselier
- Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238, USA
| | - M Galand
- Department of Physics, Imperial College London, Prince Consort Road, London SW7 2AZ, UK
| | - S Gasc
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - T I Gombosi
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109, USA
| | - K C Hansen
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109, USA
| | - A Jäckel
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - H U Keller
- Institute for Geophysics and Extraterrestrial Physics, Technische Universität (TU) Braunschweig, 38106 Braunschweig, Germany. German Aerospace Center, Institute of Planetary Research, Asteroids and Comets, Rutherfordstraße 2, 12489 Berlin, Germany
| | - E Kopp
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - A Korth
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - E Kührt
- German Aerospace Center, Institute of Planetary Research, Asteroids and Comets, Rutherfordstraße 2, 12489 Berlin, Germany
| | - L Le Roy
- Center for Space and Habitability (CSH), University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - U Mall
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - B Marty
- Centre de Recherches Pétrographiques et Géochimiques (CRPG), 15 Rue Notre Dame des Pauvres, BP 20, 54501 Vandoeuvre lès Nancy, France
| | - O Mousis
- Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille), UMR 7326, 13388, Marseille, France
| | - E Neefs
- Engineering Division, BIRA-IASB, Ringlaan 3, B-1180 Brussels, Belgium
| | - T Owen
- Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, USA
| | - H Rème
- Université de Toulouse, Université Paul Sabathier (UPS), Observatoire de Midi-Pyrénées (OMP), Institut de Recherche en Astrophysique et Planétologie (IRAP), Toulouse, France. CNRS, IRAP, 9 Avenue du Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4, France
| | - M Rubin
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - T Sémon
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - C Tornow
- German Aerospace Center, Institute of Planetary Research, Asteroids and Comets, Rutherfordstraße 2, 12489 Berlin, Germany
| | - C-Y Tzou
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - J H Waite
- Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238, USA
| | - P Wurz
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| |
Collapse
|